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The Analysis of Cane for Commercial Purposes in Queensland
Fifth Recension September 1, 1988
Gardens Point A22311079B The ana1ysls of for commercial puposes in Queensland.
Contents
Clossary Summary The Analysis of Cane for Commercial Purposes,in Queensland
1.0 Introduction 1 1.1 Background Information 1 1.2 Objective of Report 3 1.3 Authorisation 3 1.4 Sources of Information 3 1.5 Scope of Report 3
2.0 Sampling Cane for Analysis 4 2.1 Weighing and Sampling 5 2.2 Sample Tracking 7 2.3 Sampling for Extraneous Matter 8 2.4 Other Methods Investigated 9 2.4.1 Juice Scales 9 2.4.2 The Bundle Sampling System 1964-70 10 2.4.3 Automatic Cane Sampling and Direct Analysis
of Cane 1969-74 12 2.4.4 Core Sampler/Hydraulic Press Evaluation
System 1974- 13
3.0 Analysis of Cane and Its Products 16 3.1 Brix 17 3.2 Pol 18 3.3 Fibre 20 3.4 Net Titre 24 3.4.1 Pol in Raw Sugar 25 3.4.2 Ash in Raw Sugar 25 3.4.3 Reducing Sugars 25 3.4.4 Other Methods of Analysis 26
4.0 Organisation of Sugar Industry in Queensland 26 4.1 The Central Sugar Cane Prices Board 27 4.2 Local Sugar Cane Prices Boards 28 4.3 The Sugar Board 29
5.0 Development of Cane Payment Formula 29 5.1 The Existing Cane Payment Formula 30 5.2 Relative Cane Payment 31 5.3 Progressive Seasonal Payments 34 5.4 Allowable Deductions from Cane Price 34
6.0 Cane Recovery Formulae and Payment Systems 35 6.1 Recovery Formulae 35 6.1.1 The CCS Formula 35 6.1.2 The CCS Calculation 37
i i
6.2 Alternative Recovery Formulae 38 6.2.1 Alternative Recovery Formula A 38 6.2.2 Alternative Recovery Formula B
(Reduced Extraction and Winter-Carp) 41 6.2.3 Coring Methods 43 6.2.4 Recoverable Commercial Sugar 43 6.2.5 The Java Ratio 45 6.2.6 The Winter-Carp and SJM Formulae 46 6.2.7 Arceneaux's Universal Equation 46 6.3 Cane Payment Systems (Payment for Quality) 46 6.4 Cane Payment Formulae Used in Other Countries 48 6.4.1 Standard Cane with Premiums and Penalties 49 6.4.2 Sucrose in Cane - Direct Analysis of Cane 50
7.0 Determination of Mill Performance 50 7.1 The Coefficient of Work 50 7.2 Chemical Control 51
Glossary
ash:
ASIRF:
ASSCT:
bagasse:
Brix:
BSES:
CCS:
COW:
DAC:
EM:
first expressed juice:
the apparent inorganic material in raw sugar
Australian Sugar Industry Research Fund
Australian Society of Sugar Cane Technologists
the residue of cane after juice is extracted
the concentration (in g solute per 100 g solution) of a solution of pure sucrose in water, having the same density as the solution at the same temperature. If refractive index is adopted as an alternative basis of comparison, the value derived should be termed Refractometer Brix.
For solutions of pure sucrose in water, Brix is equal to the dry substance; but in the presence of soluble impurities this may not be, and usually is not, the case. Although gases and insoluble solids in suspension may alter the density of a solution, the term Brix refers exclusively to soluble solids. *
Bureau of Sugar Experiment Stations
commercial cane sugar
coefficient of work
direct analysis of cane
extraneous matter - trash, tops, roots, dirt, etc.
the juice expressed by the first two rollers of a mill tandem *
glucose:
the dry, insoluble matter in the cane. For commercial purposes, a standard method of determination of fibre per cent cane is specified.*
a non-sucrose sug
impurities:
massecui te:
International Commission for Uniform Methods of Sugar Analysis
Brix minus pol
the mixture of sugar crystals and mother liquor discharged from a vacuum pan *
Analysis of Cane and Its Products
Various methods of analysing cane and its products have been
tried. Even modern technology cannot completely overcome problems
caused by impurities; but experimental work continues.
To determine Brix, the refractometer and drying methods are often
used in factory laboratories; but Brix by hydrometer is still the most
commonly accepted method.
Pol is determined in various ways. These methods include isotope
dilution, chromatography, and near-infrared spectroscopy. But the
saccharimeter is still the universally accepted method.
Investigation of the complex problem of fibre determination is
still continuing.
The Sugar Board pays the miller for the raw sugar he produces in
terms of 94 Net Titre sugar.
Correction factors, used in conjunction with net optical rotation,
produce results that measure sucrose quite accurately.
Ash, the residue after all the organic material has been burned
off, can be measured with only limited accuracy, as can the quantity of
reducing sugars.
New techniques of analysis and their reliability and cost-
effectiveness are continually being evaluated.
Organisation of Sugar Industry in Queensland
The Queensland sugar industry is soundly organised and is
rationally controlled by legislation. The Cane Prices Act was passed
in 1915 and has been only slightly modified since then.
The 1915 Act set up the Central Sugar Cane Prices Board. The
Board assumed that growers' assets were twice the value of millers'
assets and that growers' costs were twice as great as the millers'
vii
costs. Therefore it decided to divide revenue in the proportion of
2:1; and a CCS of 12 and a COW of 90 were adopted as standards.
Each year, Local Sugar Cane Prices boards draw up Awards for their
respective mill areas. The Awards are intended to protect both growers
and millers and to reward them equitably.
The Sugar Board, set up in 1923, acquires the Queensland and New
South Kales output, disposes of the sugar, and determines the price to
be paid to the mills.
Development of Cane Payment Formula
The cane payment formula encourages growers to improve CCS beyond
the standard figure of 12. The formula also rewards millers for
raising the COW above 90.
The present formula for the price of cane was developed when there
had to be a price for every CCS from less than 7 to more than 20.
Relative cane payment takes into account the individual grower's
cane quality compared to the average of the quality of the cane supply
in each week of the season. This technique encourages a constant
supply of cane during the crushing season and removes anomalies between
growers.
The Sugar Board borrows money to pay for deliveries of cane during
the crushing season. The money is released to growers during the
entire year.
Legislation permits millowners to deduct up to 60 cents per tonne
(or to refuse to accept cane) when consignments are demonstrably
substandard. Because Australian cane is usually of high quality, only
a very small percentage of the 25 million tonne crop is subject to
penalties or rejection.
viii
Cane Recovery Formulae and Payment Systems
The CCS formula is
CCS
where P = pol per cent first expressed juice,
B = Brix per cent first expressed juice, and
F = fibre per cent cane.
The value of the CCS formula has been questioned. It depends on
the accuracy of the measurement of the three variables; and the
validity of the 3 and 5 factors (which were established early this
century) has been questioned.
One alternative formula for recovery of actual raw sugar per cent
cane is
1.024 P - 0.42 x Im - 0.0033 FP
Where P = pol per cent cane,
Im = soluble impurities per cent cane, and
F = fibre per cent cane.
Another alternative formula for pol recovery per cent cane is
P (1 - 0.0032
where P = pol per cent cane,
F = fibre per cent cane, and
J = pol purity of filtered mixed juice.
Guadaloupe and Louisiana use coring methods, which give rise to
the formula
ix
Dr A. P. Saranin's formula for recoverable commercial sugar (RCS)
is
(1 - 1.4 F) (1.4 P - 0.4 B)
where F = fibre per unit of cane,
P = pol per cent of the press juice, and
B = Brix per cent of the press juice.
The Java Ratio is an arbitrary milling ratio. The formula is
sucrose (pol) per cent cane x 100
sucrose (pol) per cent first expressed juice
The Winter-Carp formula is based on sugar of 100 purity and a
theoretical molasses purity of 28.57.
The SJM formula is R = 100 S (J - M)
J (S - M)
where R = percentage of sucrose in the raw material
recovered in the main product,
S = purity of sugar,
J = purity of juice, and
M = purity of molasses.
According to Arceneaux, the indicated available sugar per cent
cane is
xS - yB
where S = pol
B = Brix of primary juice, and
x and y are factors.
In Queensland, the result of the CCS analysis is fed into the
existing formula for the price of cane. The result is
Pc = Ps x 0.009 (CCS - 4) + C
where Pc = price of cane in dollars per tonne,
Ps = price of sugar in dollars per tonne, and
C = $0.328.
x
Some countries pay simply for the weight of cane delivered; others
use formulae of varying complexity to take into account the various
components of the cane.
In Louisiana, the payment for cane depends on the pol of the
undiluted juice, which is calculated by factors from the factory
crusher juice or laboratory mill juice. This formula rewards growers
for providing cane with little trash and high-quality juice.
In South Africa, cane prices depend on the sucrose content of the
cane. So the value of 100 tons of cane = pol per cent cane x
industrial average overall
recovery for season (per
cent) x grower's share
(per cent) x sugar price.
Determination of Mill Performance
In Australia, the coefficient of work (COW) is the most important
figure used to evaluate factory performance.
COW = tonnes 94 NT sugar x 100 tonnes CCS in cane
The COW depends largely on the accuracy of the NT and CCS
measures.
The pol balance is a measure of mill performance, but a very
inferior one. A much better index of performance is provided by
Reduced Overall Recovery.
Conclusions
The need for adequate sampling is recognised in Queensland, where
refined methods ensure the validity of samples under present
conditions.
Sampling juice appears to be the most satisfactory method provided
that established procedures are carefully followed.
xi
Cane payment systems range from simple to complex. The growth of
the Australian industry over the last sixty years is evidence that the
CCS formula has worked successfully in the past. Its value under
present conditions is being questioned.
The Analysis of Cane for Commercial Purposes
1.0 INTRODUCTION
1.1 Background Information
The sugar mills receive money principally by selling their product
- raw sugar. They also receive some income from the sale of their
major by-product, molasses. A few mills obtain a small income by
selling filter mud; and, some sell small quantities of surplus bagasse
(cane fibre). The factories burn bagasse to generate steam, hence
saving nearly all their fuel costs.
Canegrowers obtain their income by selling sugarcane to the mills.
Their cane is evaluated in accordance with the CCS (Commercial Cane
Sugar) formula, which implies that cane consists of
(a) water,
(b) sucrose (cane sugar),
(c) fibre (insoluble in water), and
(d) soluble impurities.
The solid portion of the cane is called fibre; the liquid portion is
called juice. Juice consists of water, sugar, and soluble impurities.
Sugar crystals are manufactured from the juice by a process of
clarification and crystallisation. If there were no soluble
impurities, all the sugar content in the juice could be recovered as
crystals of sugar. Those impurities, unfortunately, lead to loss of
sugar during manufacture. For every kilogram of impurities brought
into the factory in the juice, the CCS formula postulates that half a
kilogram of sugar is fixed in solution and cannot be economically
recovered in the factory.
1
The Sugar Board buys the raw sugar on behalf of the Queensland
Government and pays for it in instalments as the raw sugar is sold.
About 20 per cent of the sugar goes to refineries within Australia; the
remainder is sold overseas. Because raw sugar can vary in quality, a
standard of 94 Net Titre (NT) is adopted; and all raw sugar tonnage is
expressed in terms of 94 NT. Because the factory receives its income
for raw sugar by instalments spread over a large part of the year,
farmers receive payments over a similar period.
Australian factories, unlike those in a number of other sugar-
producing countries, carefully analyse cane for payment purposes. In
certain countries, cane is paid for by weight only. In Queensland, the
millers pay most of the cost of analysing the cane. The results of
this analysis are introduced into the CCS formula, and the grower
receives his first instalment according to the CCS and the weight of
his cane.
So three factors are involved in cane payment in Queensland:
(a) the analysis of the cane,
(b) the CCS formula, which uses that analysis to derive a figure
representing commercial value, and
(c) the price formula, which puts a cash value on CCS.
When the Sugar Board pays the miller for the tonnes of 94 NT sugar
he produces, that calculation also involves two factors:
(a) the analysis of the sugar and
(b) the incorporation of that analysis into the NT formula.
Millers measure their efficiency in a number of ways, one of which
is the coefficient of work (COW). This method simply expresses, as a
percentage, the ratio of tonnes of 94 NT sugar produced to the tonnes
2
of CCS received. Both components of the ratio are derived from
formulae incorporating arbitrary standards. (See section 6.1.)
1.2 Objective of Report
The objective of this document is to review and summarise the
various methods of cane sampling and analysis, the formulae used and
proposed, the cane payment systems, and the methods of evaluating mill
performance.
1•3 Authorisation
The compilation of this document was commissioned by the
Queensland Cane Growers' Council in its letter of 5 May 1988.
1.4 Sources of Information
The Queensland Canegrowers' Association provided ready access to
its expert staff and advisers and to its library of information on the
sugar industry.
1•5 Scope of Report
Although cane sampling and cane analysis are largely
interdependent processes, an attempt has been made to separate them.
Section 2 therefore deals with weighing, tracking, and various methods
of sampling. Section 3 deals with the components (both wanted and
unwanted) of cane. Section 4 explains how the industry operates in
3
Queensland. Section 5 explains the formulae used in analysing cane.
Section 6 examines the cane payment systems used in Australia and in
other countries. Section 7 explains three methods of determining mill
performance. Conclusions follow.
2.0 SAMPLING CANE FOR ANALYSIS
Methods of analysing the cane for its commercial value sometimes
involve methods of sampling other than that commonly used (that is,
analysis of the first expressed juice). The Queensland industry has
studied some of these other methods in depth: the Juice Scales, the
Wet Disintegrator, Bundle Sampling, and Press methods (see section
2.4).
In 1968, Queensland Canegrowers moved to have Direct Analysis of
Cane (DAC) introduced with automated cane sampling as in South Africa.
Extensive research up to 1972 resulted in the development of a system
of sampling and analysing the prepared cane delivered to a mill. But
no committee of enquiry was ever established to study this method,
which seemed reliable.
In 1976 Mr A. P. Saranin (now Dr Saranin), Chemist Member of the
Central Sugar Cane Prices Board, proposed an investigation of the Press
Method for fibre determination, a method that the BSES investigated
(see section 2.4.4). He proposed a Recoverable Commercial Sugar (RCS)
formula based on these analytical results and the industry's current
milling efficiency (see section 6.3.5).
4
2.1 Weighing and Sampling
Weighing is an essential part of cane evaluation. Formerly, the
cane was weighed on arrival at the factory and stored in the mill yard.
Now, weighbridges are usually very close to the cane carrier or part of
the bin tippler, so that virtually no weighed cane is held in stock,
and the delay between weighing and crushing is a matter of minutes at
most.
The tramway system that most mills use allows all stocks of cane
to be kept in bins on rail and lends itself to this minimum-delay
system.
Sampling and analysis procedures are specified in Regulations 57-
63 of the Cane Prices Act. These regulations require all mills to
adopt standard methods of sampling and determining Brix, pol, and
fibre. In addition, apparatus and instruments must be of approved
types properly calibrated. Qualified cane testers are appointed to
ensure that, each mill complies with these regulations and to carry out
other duties specified by the Central Board.
Although fibre in cane may be, and in most areas is, determined
according to varietal class, the first expressed juice of every
consignment is sampled. First expressed juice is defined as the total
quantity of juice extracted at or before the feed opening of the first
mill. The juice is collected in a trough fitted under the feed roller.
Through a vent at the lowest point of the trough, the juice is
discharged over a conical screen on top of a vessel connected to a pump
that delivers the juice to a mechanical sampler. The samplers are
usually automatic types located in or near the laboratory (see Figure
1). In an emergency, the regulations permit manual sampling.
5
There are three approved methods of juice sampling: spot,
semicontinuous, and continuous.
Under the spot method, certain bins of cane (usually one out of
five to eight bins) are methodically selected from the grower's weekly
delivery. Those bins are declared to be representative of all the cane
supplied by the grower for that week. There must be at least one
sample bin for every 30 tonnes of cane. Cane from the sample bins is
tracked to the first mill, and the juice sample is collected while the
cane is being crushed.
Figure 1: Arrangement for Juice Collection and Pumping Source: R. Price, Cane Evaluation in Queensland - Past, Present, and
Future, p.12.
6
The semicontinuous method is an extension of the spot method in
that the sample bins are similarly selected, but rakes containing one
or more sample bins are sampled continuously. The juice sample is
analysed, and the resultant CCS figure is recorded against each sample
bin in the rake. Short rakes not containing a sample bin are not
sampled.
The continuous method is practised where all growers supply large
rakes of cane. Each rake is sampled continuously, and the resultant
CCS figure applies to the total weight of cahe in the rake. Where
continuous or semicontinuous sampling is practised, and where the cane
tester (in consultation with the mill chemist) considers the number of
trucks in the rake to be unduly large, the delivery may be divided into
two or more parts for sampling. Each part may constitute a separate
sample provided that a single juice sample is not accumulated over more:
than twenty minutes.
2.2 Sample Tracking
For each consignment of cane, sampling begins at the weighbridge,
where the grower, the variety of cane, and the beginning and end bins
of each rake are identified. The sample bin or bins within each rake
are also identified. Tracking devices provide either visual
indications or automatic starting and finishing of each juice and fibre
sampling operation. The tracking devices can be mechanical,
electronic, or computerised.
A stream of first expressed juice is pumped to the laboratory,
where a sample of not less than 1 litre is collected by a mechanical
7
sampler. The rate of juice flow into the sample can is controlled
either by a time-splitter or by a stream-splitter.
The time-splitting of the flow is achieved by means of a solenoid-
operated spout that oscillates across a weir at preset times. The
oscillations are varied according to the number of trucks in the
sampled rake.
The stream-splitting of the flow occurs at a V-shaped weir fitted
with a positioner that regulates the flow into the sample-receiving
vessel. The positioner is adjusted (either manually or automatically)
according to the number of trucks in a consignment.
In recent years there has been a trend towards a single-vessel
sampler. After the juice from a particular rake is collected, a
measured volume of the juice is discharged into a can moving on a
conveyor-.
The juice samples are analysed for pol (by Schmitz's method) and
Brix (by hydrometer). The usual precautions are taken: the temperature
is controlled; solids are allowed to settle; air bubbles are removed.
Both the sampling and the analytical operations are carried out by mill
chemists under the supervision of cane testers.
2• 3 Sampling for Extraneous Matter
In most mill areas, the Local Board Awards provide for visual
inspection or physical analysis (or both) of all the cane deliveries
for extraneous matter (EM). The visual inspection is usually carried
out at the carrier by a mill officer and a cane tester, and the cane is
evaluated by a system of points for tops, trash, and soil. For
physical analysis, the cane is sampled by sidetracking of a bin or part
8
several factories then were), the quantities of Brix and pol in the
cane were measurable and that CCS could be determined in accordance
with that part of the CCS formula that reads "CCS = pol per cent cane
minus half the soluble impurities per cent cane." This method of
determining CCS obviated the need for the empirical 3 and 5 factors in
the existing CCS formula.
1n the event, the Committee endorsed juice scales accompanied by
bagasse weighers as technically satisfactory for analysing cane for
Brix, pol, and insolubles provided that approved equipment was
installed and a suitably high level of operation and supervision
(superior to that generally adopted in sugar mills) was maintained.
The members said that the results thus attainable, although not
perfect, were in general technically superior to results obtained from
analysing first roller juice and using the 3 and 5 correction factors.
The Committee also endorsed the use of the wet disintegrator when
used strictly according to recommended procedures as a satisfactory
alternative to juice scales and bagasse weigher (or to juice scales
used alone) and ratified the use of either a hammer mill or a cutter
grinder for fibre determination. However, the Committee also said that
the use of new methods and recovery formulae (as set out in its report)
would have implications "extending outside the technical sphere."
These findings have never been implemented.
2.4.2 The Bundle Sampling System 1964-70
The high sugar prices of the early 1960s led to a great expansion
of the industry and a considerable increase in the crushing rates of
all mills. To achieve the desired crushing rate for the 1964 season,
Inkerman Mill found it necessary to feed the carrier simultaneously
10
from three points. During 1963, all interested parties extensively
investigated the problem of sampling cane under these conditions. The
results of this work provided the framework for the regulations made
under the Regulation of Sugar Cane Prices Act - regulations that
contained precautions necessary for the protection of both canegrowers
and millowner operating under the proposed new system of sampling.
Briefly, the Inkerman Mill system (Bundle Sampling) operated as
follows:
* Sample trucks were selected as in the conventional sampling
system.
* A modified Toft grab (operating on a monorail above the main
carrier, truck tips, and rake) randomly sampled not less than
100 lb of cane from the sample truck.
* The bundle sample was crushed in a small mill, the total
juice being thoroughly stirred before being subsampled.
* This sample was analysed for Brix and pol of the juice, which
with the fibre of the cane (determined for each variety or
group of varieties) was used to calculate the farmer's
interim CCS.
* The first expressed juice of the milling train was
continuously sampled and regularly analysed for Brix and pol,
and samples of the prepared cane fed to the first mill were
also regularly collected and analysed for fibre. These
analyses were used to calculate the master CCS - that is ,
the CCS on which the mill had to base the payment to growers.
* At the end of each week, the averages of both the interim CCS
and the master CCS were calculated. These averages were used
to calculate a factor.
11
* This factor was then applied to each grower's interim CCS to
determine the CCS of his cane - on which his payment was
based.
This system operated during 1964 and 1965 (the factor
approximating 0.95). However, growers' dissatisfaction with the
instability of this factor necessitated changes for 1966. So the
Regulations were amended to provide
* that the juice selected for sampling comprise all the juice
collected from the back roll of the small mill and
* that the cane crushed for this purpose be taken in bundles of
not less than 200 lb.
Although modified bundle sampling operated at Inkerman Mill for
the following" five years, the suppliers to that mill were never
satisfied that they were receiving correct payment and the system was
abandoned.
2.4.3 Automatic Cane Sampling and Direct Analysis of Cane 1969-74
In 1968, Queensland Canegrowers moved to have direct analysis of
cane (DAC) introduced into the industry in conjunction with automated
cane sampling like that which shortly before had been introduced in
South Africa. The Council recommended that its staff, in conjunction
with other branches of the industry, investigate the problems of the
CCS formula. Discussions began with the Mossman Mill management, who
had expressed interest in DAC and who were considering carrying out
some work on the system at Mossman Mill during the 1968 season.
Arrangements were made for a program of research at Mossman to compare
cane quality determined under the CCS formula with that arrived at by
DAC (that, is, by the wet disintegrator method).
12
The wet disintegrator method has replaced the old hot digestion
method. A Jeffco or ASPA wet disintegrator is used. The ratio (by-
weight) of water to fibre is important. Queensland mills use 3 parts
of water to 1 of cane (the water/fibre ratio being 20:1). South
African mills use 2 parts of water to 1 of cane (the water/fibre ratio
being 13:1). The sample is treated for 15 to 40 minutes to allow
adequate homogenising.
Late in 1968, the then Chemist member of the Central Sugar Cane
Prices Board, Mr J.L. Clayton, accompanied Mr R. Price (the
Canegrowers' Technical Officer) to South Africa to study the system of
automatic sampling and direct analysis of cane being developed there.
In that country, fibre is sampled across a full carrier width of cane
from the bottom of the elevator, just before it reaches the first mill.
This sample is used for cane payment purposes. As a result of this
visit, appropriate equipment was purchased and extensive research work
carried out at Mossman Mill until 1972.
A recommendation was made that a committee of enquiry be set up to
investigate this matter further. When the Minister referred that
suggestion to the canegrowers' organisation early in 1974, a decision
was made to shelve the whole question.
2.4.4 Core Sampler/Hydraulic Press Evaluation System 1974-
In May 1976, the Central Sugar Cane Prices Board referred to the
industry for comment a proposal by its Chemist Member (Mr A.P. Saranin)
on the feasibility of using a press method of fibre determination for
cane payment purposes. The main advantages claimed for the system are
that
* the method is simple, quick, and relatively inexpensive;
13
* it provides information both on the sugar content and on the
physical state of the cane; and
* it is capable of automation and thus can be relatively free
from human interference.
The Board commissioned the BSES to investigate this method.
The survey concluded that the system used gave reliable and
satisfactory samples of prepared cane but added that some systems would
need to be modified to cope with the more frequent sampling of cane
usually associated with the press method of fibre determination.
After three years of research, the BSES concluded that the press
used would produce satisfactory results, comparable to those obtained
by the bag and the SRI methods for determining fibre. The BSES noted,
however, that the press method was unsuitable for analysing cane that
had deteriorated significantly. It was also concluded that no single
equation could suit all varieties in all districts in all seasons.
Mr Saranin continued his investigations as part of his Ph.D.
thesis and presented his findings at the 1986 ASSCT conference. He
listed the advantages of the core-press system as follows:
* The juice expressed at the compression limit (although
affected by the fibre content of the cane) correlates highly
with absolute juice.
* The samples taken can be stored under suitable conditions for
some time before they are analysed.
* Direct sampling and analysis of cane delivered by individual
growers would be less expensive than the present practice.
* Press fibre reflects the physical condition of the cane
(freshness or staleness, maturity, and EM), so there is no
• need for physical analysis of cane.
14
* The receiving station need not be manned continuously.
* Cane can be stored in bulk in mill yards so that trucks can
be quickly returned to the point of harvest.
Because the cane for analysis is sampled at the receiving station,
the first expressed juice will not have to be analysed for payment
purposes. The cane can therefore be precleaned (wet or dry) and either
fed directly into a diffuser or treated conventionally.
The disadvantage of the system would be the high cost of
development and (if the concepts were accepted) the high cost to the
mills of re-equipping. The loss of soil or trash during sampling is
another possible disadvantage of core sampling. However, Meade-Chen
(1977, 633) claim that the subsequent pressing of the subsample in the
hydraulic press retains the soil in the plug, so that the soil becomes
part of the fibre.
According to Meade-Chen (1977), ''Core sampling is now the standard
method adopted in Hawaii. By using the coring technique, it is not
necessary to determine the trash content as was done in the grab-
sampling system. Since the core sample includes the trash (leaves and
dirt), the direct pol determined in the sample reflects directly the
pol in gross cane. Since the sampling is completely mechanized, the
personal bias has been eliminated and the manpower requirement
minimized.
"In Hawaii ... the frequency of sampling is generally based on the
square root of the number of loads from each field or grower's lot"
(631). Meade-Chen (1977, 631-33) go on to explain the processes of
subsampling and analysis adopted in Hawaii.
15
3.0 ANALYSIS OF CANE AND ITS PRODUCTS
The sucrose content of solutions containing only sucrose can be
measured with considerable accuracy and precision. This measurement
can be made in a number of ways ranging from the comparatively simple
specific gravity (Brix) of the solution and the optical rotation of the
solution (pol) to more modern instrumental techniques - for example,
High Pressure Liquid Chromatography (HPLC). Charles Ivin of the SRI
has published papers on this method.
The sugar industry, however, extracts a natural product (sugarcane
Juice) and produces an intentional product (raw sugar) as well as by
products (molasses, bagasse, filter mud, and so on). These products
contain varying amounts of non-sucrose components.
The cane plant takes up moisture and nutrients from the soil; the
chlorophyll in the plant uses sunlight to manufacture sucrose, which is
stored in the stalk. Therefore, a load of cane stalks transported to
the factory contains not only sucrose but also all the other materials
that make up this complex natural material.
Practically all natural products are impure, and analytical
methods have been developed to enable the chemist accurately to
determine the concentration of the various constituents. A number of
analytical procedures involve steps that either remove the desired
constituent from the impurities (or interfering substances) or do the
opposite. Modern instrumental techniques often identify and quantify
wanted elements or compounds by means of their atomic or molecular
structure. These techniques have led to considerable savings in time
and hence in the cost of the analysis. (Similar savings occur in the
16
copper mining industry: X-rays can be used to determine the quantity
of copper in a given sample of ore because elements emit characteristic
spectra.)
The sucrose molecule does not lend itself to this type of analysis
with our present techniques, but work continues to be done to improve
the method of analysis for sucrose in impure solutions.
3.1 Brix
The Brix of a solution of pure sucrose in water is the mass
percentage of sucrose in that solution; it is commonly measured with an
hydrometer calibrated in degrees Brix. However, cane juices contain
soluble impurities as well as suspended impurities; and these soluble
impurities cause errors to the extent that they generally do not behave
like sucrose, for which the Brix "spindle" has been calibrated.
Brix can also be determined by means of a refractometer. This
device (used in most advanced sugar industries) operates on the
principle that light is bent (refracted) from its original path as it
passes from a medium of one density to a medium of another density.
Automatic refractometers are available, and it may be possible to link
them with automatic saccharimeters.
The Brix of a juice determined by spindle may differ slightly from
the Brix determined by refractometer because of the different
principles involved (specific gravity and refractive index).
Experimentation in Queensland has confirmed that the difference exists.
The most recent development has been specific gravity
determination using the DMA-45 Paar Digital Density Meter. In 1983 and
1984, the BSES tested this meter in fourteen factories in widely
17
varying geographical locations. The meter gave good results when
calibrated and used correctly. One of the disadvantages of this
instrument, though, is that a micro-filtration system is required to
supply clear juice. Dirty juice may result in a difference between the
Brix measured by a Paar Density Meter and an hydrometer.
The Paar Density Meter method is still being investigated. Brix
can also be determined by Westphal balance, by pycnometer, or by
drying. In practical operating laboratories, the refractometer and
drying methods are often used.
The pol of a sugar solution is the measure of its optical
rotation. Sucrose is an optically active substance; its concentration
can be measured with a saccharimeter (or polariscope). Unfortunately,
the pol reading is influenced by optically active substances such as
other sugars - glucose (dextrose) and fructose (laevulose). Because
the disaccharide sucrose molecule comprises one glucose molecule joined
to one fructose molecule, these monosaccharides are usually present in
commercial solutions - especially following the breakdown of the
sucrose molecule under hot, acidic conditions. Each of these sugars
affects the optical rotation differently as indicated by the specific
rotation_ expressed on the bases 20 C and the Sodium D line. The values
of ^3^20 for some common sugars areD
sucrose + 66.54,
glucose + 52.5,
fructose - 92.5, and
invert - 20.0.
18
Thus, when a sugar solution containing a mixture of sugars is
polarised, the reading on the scale is the net result of the positive
and negative effects of the sugars present and may not accurately
reflect the content of sucrose.
The pol of a fresh juice sample is closer to per cent sucrose than
the pol of a molasses, which contains significant quantities of
reducing sugars. Schmitz's method of analysing juice is almost
universal - the juice being clarified with dry lead, filtered, and then
read in a saccharimeter. This method also preserves the juice.
Spencer found that juice correctly leaded would retain its correct
polarisation for several days (Meade-Chen, 1977). When the juice
sample has deteriorated, or when juice from stale cane is analysed,
Herles's methods involving lead nitrate are used.
Automatic saccharimeters to determine pol have been in use for
some time; and a method that does not require the sample to be leaded
(thus saving time and money) is being investigated in Queensland.
When the chemical control is based on sucrose instead of pol,
sucrose is determined by Clerget's method.
The ICUMSA has recommended the isotope dilution method for
measuring sucrose in press juice. Other methods used include
chromatography - gas, paper, thin layer, gas liquid (GLC) and high
performance liquid (HPLC) - and near-infrared spectroscopy (NIR).
Gas chromatography was introduced in the 1950s. It has been
widely and thoroughly investigated and has been found appropriate for
measuring organic non-sugars in sugar products. The trimethylsilyl
ether derivatives of carbohydrates can be used in GLC and can
accurately determine sucrose content. The technique is widely used,
but not in factory laboratories.
19
P.C. Ivin (1986) of the SRI has investigated high-performance
liquid chromatography. The corn industry in the USA now uses HPLC
extensively for process and product control. "Polysaccharide analysis
is still limited although it has proven an excellent technique for
analyses of oligosaccharides of up to about 12 units developed for the
corn industry .... Early workers tried to use HPLC as a replacement for
pol and were generally unsuccessful because HPLC should not, at this
time, be regarded as a replacement for polarisation .... HPLC analysis
for sugars is fast becoming the recognised system for process control
in distilleries" (Clarke, 1985). HPLC is used in some juice
laboratories. And although nuclear magnetic resonators (NMR) can
determine sucrose, the instruments are still in the experimental stage
for sucrose products.
Near Infrared Spectroscopy (NIR) has moved out into the commercial
world and has found wide application in agriculture. Research workers
have used it to determine sugars in tobacco (Smith and Starr, 1986).
Workers at the Louisiana State University (French et al., 1986) have
reported that, in trials with sugarcane, they have found a fairly high
correlation between results for sugar between NIR analyses and the
Press Method. Further investigation of this method is proceeding
slowly at QIT.
3.3 Fibre
Fibre is another component used in the CCS formula for cane
payments. Fibre is the remains of the plant delivered to the factory
after all the water-soluble material has been washed out and the
material has been dried. It is essential that the cane be shredded
20
finely enough to rupture the cells so that all the sugars and other
soluble material (such as inorganic salts) can be removed.
One direct method of determining the fibre content (commonly used
in Australia) is to place a known weight of comminuted cane inside a
calico bag. The bag and its contents are then washed several times in
hot and cold water; at intervals, the bag is manually squeezed. (Some
researchers claim that the hot washing lowers the fibre figure.) Not
only soluble materials but also fine insoluble materials are washed out
of the bag. Soil, therefore, though part of the fibre content by
definition, may not be fully accounted for in the result. The washed
residue is then dried in an oven and weighed.
Another method is disintegration. Dr Saranin (1986b) states:
"There are sound technical premises and considerable practical
advantages in adopting compressibility as the basis for fibre
determination, instead of ... insolubility." This method requires 1 kg
of cutter-ground sample to be pressed at 25 MPa for three minutes. The
fibre per cent cane is then expressed as 0.5 W where W = plug mass per
cent cane.
The fibre content of cane can also be assessed indirectly from
bagasse figures. NIR methods, too, show promise of rapid fibre
determination.
The SRI has developed an automated method (Loughran et al, 1988,
89-96). In 1979, the BSES released the results of three years'
research and stated, in part, that "Comparisons of the precision of the
bag, the press, and the SRI methods for fibre determination indicate
that they are all of the same order ... [but the] press method cannot
be used successfully to analyse cane which has undergone any
significant degree of deterioration."
21
The disadvantages of the present method of fibre determination are
that the figures are communal rather than individual and that, because
of the time involved in the analysis, the figure used in the
calculation of a grower's CCS is actually the average of cane supplied
at a much earlier date.
One of the advantages of the Press Method is that the grower can
be allotted a fibre figure that is truly his own.
The use of mechanical harvesters has increased the EM in cane
supplies. (EM, by arbitrary standards, is considered not to form part
of clean cane. It consists of tops, roots, trash, soil, etc.) In the
analysis of cane for CCS, EM forms part of the fibre. Provision exists
in most Local Awards for the miller to make a deduction for dirty cane
- that is, cane containing a significant proportion of EM. The penalty
clause is implemented with the agreement of the cane tester. For this
reason, a separate analysis is sometimes carried out for EM.
Brotherton (1980, 7) has shown that EM has a detrimental effect on
mill operation and also a depressant effect on CCS and hence on
farmers' incomes. He says that "The rate of reduction of CCS is shown
by theory and experiment to be units for each one per cent
of EM where CCS is that of clean cane." EM "has a greater effect on CCS
than other factors usually considered to have a bearing on CCS."
Price (1965, 91) showed that 1 per cent of EM, consisting mainly
of tops, will increase fibre by about 0.125 per cent. One unit of
fibre lowers CCS by 0.18 units, so that each 1 per cent increase in EM
should lower CCS by an average of 0.023 units owing to the increase in
fibre.
Clarke and Player (1988, 81) claim that EM in CSR mills now
averages 5 to 6 per cent. They also claim that dirt increasingly
22
constitutes part of the EM, especially in wet weather. Muller et al.
(1982, 1-29) reported dirt levels ranging from 0.8 to 1.7 per cent in
mills geographically representative of the state's canegrowing areas.
Incoming dirt of the order of 1.2 per cent results in an increase of
cane fibre of 1.0 to 1.1 per cent and a decrease in CCS of between 0.17
and 0.19 (Churchward and Poulsen, 1988, 1-6).
The increasing harvesting of green cane in Queensland (in 1987, 65
per cent of the Macknade crop was cut green) could have some effect on
EM. Stewart and McComeskie (1988, 27-31) found in their trials that
green cane harvesting produced similar yields and a product comparable
with burnt cane in terras of EM, even in lodged cane (although on
average the green cane had a higher level of EM).
It is widely reported that cutting green cane increases the CCS
content by 0.4 to 1.0 unit (Fuelling et al., 1978). The BSES Annual
Report, 1987, states that green cane averaged 0.4 unit of CCS above
burnt cane for the 1986 crop. Churchward and Poulsen (1988) report
that BSES harvesting research does not indicate any conclusive
difference between soil in green cane and soil in burnt cane. They
report that, in general, EM is often 2 to 4 per cent higher in green
cane than in burnt cane. The presence of suckers can increase EM to 11
per cent in green cane.
Ridge and Dick (1988, 19-25) report that, per tonne of cane, $0.62
to $0.95 in mill maintenance costs has been attributed to dirt - which
is also an important contributor to maintenance costs for harvesters.
These researchers found that loose dirt was rejected mainly in the
base-cutter/buttlifter region but that dirt attached to the stool was
not readily rejected, particularly in wet weather. Investigation of
this problem continues under an ASIRF grant.
23
3.4 Net Titre (NT)
The Sugar Board pays the miller for the raw sugar he produces in
terms of tonnes of 94 NT sugar. There is a close parallel between the
purchase of cane by a mill and the purchase of raw sugar by a refinery.
In neither case is all the sugar in the raw material recoverable; and
NT applies to raw sugar as CCS applies to cane. Because the original
Cane Prices Act included (for price-fixing purposes) "the selling price
of sugar, raw and refined", its method of analysis and calculation
influences the price the grower receives for his cane.
NT is the percentage (by weight) of the quantity of raw sugar that
would be recovered as refined sugar (pure sucrose) if the refining
operations were conducted at a prescribed standard of efficiency. The
prescribed standard of efficiency assumes that the loss of weight in
refining will be 5 kg for each 1 kg of ash in the raw sugar, and 1 kg
for each 1 kg of reducing sugars. (Ash is the total content of the
inorganic material in the raw sugar. Reducing sugars (RS) consist
mainly of glucose and fructose. See sections 3.4.2 and 3.4.3.) In
other words,
NT = pol - 5 x percentage of ash - percentage of RS
So certain arbitrary allowances are made in the calculation of NT
- allowances just like the 0.5 in the CCS formula (Pol - 0.5
impurities).
Sugars of various qualities (Net Titres) are reduced to the common
basis of 94 NT as follows:
Tonnes 94 NT Sugar = Tonnes of sugar x actual NT "94
24
The reason for adopting 94 NT as the standard is lost in history;
but probably, when it was accepted, the quality of raw sugar was about
94 NT. In those days, 12 CCS and a COW of 90 were about average.
3.4.1 Pol in Raw Sugar
Because raw sugar consists primarily of sucrose and is low in RS
(glucose and fructose), the net optical rotation of the raw sugar
solution comes close to that of sucrose. However, the amount of lead
used in clarifying the sugar can affect the rotation. As in the
analysis of all mill products, the pol reading of a sugar is affected
by temperature; but a correction can be applied to convert to the
reading at 20 degrees C (the standard temperature). The corrected
result will not be an exact measure of sucrose, but it will be very
close to the true figure.
3.4.2 Ash in Raw Sugar
Ash is the residue after all the organic material has been burned
off, using sulphuric acid, a platinum crucible, and a specified method.
This residue is assumed to be representative of the inorganic content
of the sugar. But ash is not an absolute quantity.
3.4.3 Reducing Sugars
Certain sugars (and other substances) have the property of
reducing (or changing) cupric oxide to cuprous oxide if Fehling's
solution is prepared and used under specified conditions. Glucose and
fructose have this property; sucrose does not. Therefore the
quantitative use of the reaction, following a prescribed method, will
enable the quantity of reducing sugars to be determined.
25
The RS content of a sugar-bearing product, however, is not an
absolute measure of glucose and fructose because other minor components
may have "reducing" properties.
3.4.4 Other Methods of Analysis
Although many methods are available for determining sucrose in
juice, most of them are apparently still restricted to large central or
research laboratories. In factory laboratories, traditional methods
remain most suitable for day-to-day use. But this situation could
change: new techniques and their reliability and cost-effectiveness are
continually being evaluated.
For example, NIR spectroscopy has been studied at Louisiana State
University (Sverzut et al., 1986); and some work is also being done at
Queensland Institute of Technology in Brisbane. The analysis is carried
out on shredded cane. The instrument can determine moisture, fibre,
sugar, and pol in about 5 minutes - a considerable time saving. The
method shows promise: researchers have indicated that the NIR method
closely agrees with the Press Method.
4.0 ORGANISATION OF SUGAR INDUSTRY IN QUEENSLAND
Of all the primary industries in Australia, the Queensland sugar
industry exemplifies the advantages to be gained from sound
organisation. The sugar industry has implemented a rational system of
control of production. The system begins with the acquisition of a
cane farm, goes on to determine where, how much, and what varieties of,
cane may be grown, and sets out conditions that canegrowers and mill-
26
owners must adhere to during the harvest. The price to be paid on
delivery of the cane is also specified.
A considerable amount of legislation affects the industry and
those engaged in it either directly or indirectly. The Cane Prices Act
of 1915 was relatively brief. Apart from setting up the Central and
Local Boards and defining the mill and lands regulated by each Local
Board, its main purpose was to establish "the matters for consideration
in fixing prices":
(a) the estimated quantity of sugarcane to be treated at the mill
concerned;
(b) the estimated commercial cane sugar content of the cane;
(c) the crushing capacity and efficiency of the mill;
(d) the labour conditions under which the cane is grown,
harvested, and delivered to the mill;
(e) the selling price of sugar (raw and refined);
(f) any other local conditions; and
(g) any prescribed matters.
(The only substantial addition to these matters in today's Act is "the
cost of production of sugarcane and the cost of manufacture of sugar".)
4.1 The Central Sugar Cane Prices Board
The Central Sugar Cane Prices Board set up by the Act of 1915
consisted of a chairman (usually a judge or an ex-judge of the Supreme
or District Court), a millers' elected representative, a growers'
elected representative, a qualified sugar chemist, and an experienced
accountant. The primary function of the Board was to regulate the
distribution of sugar returns between miller and grower; but the Board
27
had many other duties, such as the allocation and control of
assignments of land for canegrowing and the supervision of cane payment
systems in the factories. The Central Board was assisted by Local
Sugar Cane Prices Boards set up in all mill areas to deal with certain
of the Central Board's functions.
Initially, the Central Board adopted the standard CCS and COW of
the day. The average CCS from 1914 to 1917 was 12.25; the average COW
was 89.4. So a CCS of 12 and a COW of 90 were adopted as standards.
The Board encountered difficulty in establishing the value of
growers' assets, so it assumed that the value of growers' assets was
twice the value of millers' assets. The Board also assumed that the
cost of producing cane was twice the cost of milling cane. So the
decision was made to divide the revenue in the proportion of 2:1 at 12
CCS and 90 COW.
4•2 Local Sugar Cane Prices Boards
There is a Local Sugar Cane Prices Board for each mill area in the
state. A Local Board consists of a chairman and two or four others, of
whom half are elected by the growers and half selected by the
millowner. The chairman is appointed by the Governor-in-Council and is
generally a magistrate or a Clerk of the Court stationed in the
district.
The duty of a Local Board, in each year, is to draw up an Award
for the mill area. An Award is a document dealing with matters related
to the harvesting, transport, handling, and crushing of the cane, the
payment for the cane, and the settling of disputes.
28
4.3 The Sugar Board
When the Queensland Government assumed control of sugar purchases
in 1923, the Sugar Board was set up to represetft the government in
acquiring the Queensland output, in purchasing the New South Wales
production, and in disposing of all the sugar produced. The Board
consists of a chairman, a millers' representative, and a growers'
representative. Additionally, the Sugar Board determines the amount of
sugar it can accept for marketing. It also determines the price to be
paid to the mills for the raw sugar they produce.
In 1920, the Sugar Agreement between the Commonwealth and
Queensland stipulated that 57 per cent of the increase of £9/6/8 per
ton should go to the grower and 43 per cent to the miller - a departure
from the original concept. The Board accepted the 1920 Agreement, and
allocated the increase in the agreed proportions. One outcome of their
deliberations was that a state-wide price for cane was instituted for
the first time.
The year 1924 was of considerable importance in the history of
cane pricing. The Board decided to revert to the principles existing
before the Sugar Agreement of 1920.
5.0 DEVELOPMENT OF CANE PAYMENT FORMULA
Of the gross revenue derived from every tonne of sugar, the
grower's costs of production and the miller's costs of manufacture were
to be reimbursed. The surplus of revenue over costs was to be divided
between the parties. Growers were to receive the full value of extra
sugar recovered at 90 COW from CCS units above 12. (The minimum
29
acceptable CCS was 7.) The miller was to receive the full value of any
extra sugar made by raising the COW above 90, with a reduction for
operating at a COW below 90.
According to this formula, the miller retains the value of 4 units
of CCS. The grower receives the value of the remaining units of CCS
assuming the efficiency of the mill to be 90 COW. The miller retains
the value of all additional sugar produced in the mill if the COW is
over 90. The incentives built into the formula have encouraged growers
to improve CCS and millers to increase sugar recovery.
5.1 The Existing Cane Payment Formula
Currently, the division between millers and growers of income from
the sale of raw sugar is determined by the following formula, which is
contained in every Local Cane Prices Board Award:
V = 0.009 P (a - 4) + $0.328
where V = the price of cane per tonne,
P = the price received for raw sugar ($ per tonne
94 NT),
a = CCS of cane, and
0.328 is the current adjustment to the formula. It
is the accumulation of decisions on price made by
the Central Board but has not been greatly changed
since 1949.
Although (theoretically) every grower obtains the same price for
cane of the same quality, two aspects of the Australian payment system
deserve special mention. The first is the relative payment used in
30
Australian mills. The other is the system of seasonal advances - a
system that determines how canegrowers obtain progress payments for
their cane from the time of its delivery to the announcement of a
seasonal price for sugar (about six months after the end of crushing).
The present formula for the price of cane was developed when it
was necessary to provide for "payment on analysis" - that is, there had
to be a price for every CCS from less than 7 to more than 20.
Relative payment is now widely adopted. Under that system, the
interim value for average cane is subject to some simple figuring and
negotiating. Next comes the unit value. Under Scheme B, the unit
value is not determined: it happens. Under Scheme A, in all cases,
the unit value adopted is 0.009 P; but there is no apparent technical
or economic reason for choosing that figure. The total cane revenue
must be distributed among the suppliers, and this distribution involves
considerations different from those affecting the division of revenue
between millowners and canegrowers.
5.2 Relative Cane Payment
Although not unique to Australia, relative cane payment is an
important part of the system because most mill areas have a marked
seasonal pattern in cane quality. A typical seasonal CCS pattern for
cane supplied to an Australian mill is shown in Figure 2.
A grower may harvest six to eight times during a season,
delivering 500 to 1000 tonnes each time. So he may harvest, say, 20
per cent of his cane in the June-July period when cane quality is low,
40 per cent between August and October when cane quality is high, and
the remainder in the post-October period, when cane quality is falling.
31
Relative payment takes into account the individual grower's cane
quality compared to the average of the quality of the cane supply in
each week of the season and applies that relativity to the overall
season average. It is best explained by a simple example.
If a grower's cane quality early in the season is, say, one unit
(1 per cent) of CCS higher than average, under relative payment that
grower is paid more than the suppliers of average cane - and vice
versa. Cane of 9 CCS supplied when the mill average is 9 is worth just
as much as cane of 15 CCS supplied when the mill average is 15. Of
TYPICAL CCS PATTERN FOR QUEENSLAND MILL
Week Numbers June-December
Figure 2: Typical CCS Pattern for Queensland Mill Source: R. Price, Cane Evaluation in Queensland - Past, Present and
Future, p.7.
course, during the season, the final average CCS is unknown; so it is
necessary to assume a level to start with (usually the average of the
32
last five years) and to adjust the level progressively as the crushing
proceeds. Because cane is only partly paid for shortly after delivery,
and because final settlement is not made until after the end of the
season, the price the growers receive is ultimately based on the true
mill average CCS.
If values were absolutely related to quality, the natural reaction
of cane suppliers would be to withhold deliveries of cane at the times
of lower quality and supply as much as possible at the peak period.
If that were to happen, the mill would not receive a regular supply of
cane.
Relative payment assists not only in obtaining an even supply of
cane to the mill during the season but also in removing anomalies
between growers - anomalies resulting from harvest interruptions due to
wet weather and the like.
Mr J. Clayton claims that, under Relative Scheme A, there is no
technical or economic reason for the unit to be 0.009 P (see section
6.1.2). He states: "It is a question of arranging a distribution of
the total cane revenue among the suppliers, and this involves
considerations different from those which enter into the division of
revenue between the mill owner and the canegrowers as a body."
5.3 Progressive Seasonal Payments
The second aspect of payment relates to progress payments made
throughout the harvesting season. Australia harvests cane over six
months of the year but sells the sugar produced over twelve months. So
about half of the proceeds from sugar production is unavailable until
after the crushing is over.
33
Consequently, the Government's sugar purchasing authority - The
Sugar Board - needs to borrow funds to support the flow of proceeds to
the mills during the season. Only 50-60 per cent of the final proceeds
from sugar is made available initially, and this forms a basis for
the cane price at the beginning of the season. By the end of the
crushing season, a grower has normally received 70-75 per cent of the
final value of his number one pool cane as a delivery advance. The
remainder of his entitlement is paid progressively over the next six
months.
5.4 Allowable Deductions from Cane Trice
Legislation administered by the Central Sugar Cane Trices Board
provides for deductions to be made from the price of cane in certain
circumstances.
The millowner is allowed to deduct up to 60 cents per tonne if
cane is dirty, trashy, stale, or diseased. The legislation also allows
the millowner to refuse to accept cane when it contains less than 7
CCS, or when it is very dirty, stale, or demonstrably unfit for
manufacture into sugar of good quality.
The high quality of Australian cane is indicated by the fact that,
despite these somewhat arbitrary standards, millowners reject less than
0.1 per cent of the 25 million tonne crop. And only a relatively small
percentage is subject to maximum penalties for staleness or dirtiness.
Although a universal penalty of about 10 cents per tonne applies
to all cane burnt for harvesting, until recently it was uncommon for a
grower to deliver green cane. Now, though, improvements in cane
harvesting machinery are enabling Australian growers increasingly to
34
deliver unburnt cane. As a result, during wet weather, cane does not
have to be left standing - and deteriorating - in the field.
Cultivation machinery that will work successfully in trash-covered
fields is now being developed. The growth of such activity indicates
that many Australian farmers now consider that the savings outweigh the
higher cane losses and harvesting costs associated with green cane.
6.0 CANE RECOVERY FORMULAE AND PAYMENT SYSTEMS
6.1 Recovery Formulae
6.1.1 The CCS Formula
When the CCS formula was first devised, cane was not burnt before
harvesting; it was free of trash and dirt; it was generally fresh; and
most canes were of the "noble" variety, yielding very pure juices at
maturity, with few manufacturing problems. However, there have been
considerable changes to varieties, cultivation, and harvesting
practices - changes that could lead to errors either way in the
estimation of CCS because of
* abnormal ratios of pol to sucrose;
* mis-statements of fibre due to EM; and
* errors in the 3 and 5 factors in the formula.
Therefore, the CCS formula was initially more precise than it is now.
Within the Cane Prices legislation, cane may be paid for on any chosen
basis; but the industry has voluntarily adopted a system of payment
according to quality as determined by the CCS formula. Provision for
this system is made generally in the Regulation of Sugar Cane Prices .
35
Act and specifically in Regulations 57-63 aade under the Act, in which
the CCS formula is set down and the procedures to be adopted for
sampling and analysis are specified. The CCS formula is one way of
relating the value of the cane to the value of the products that can be
recovered from the cane, using current technology.
The CCS formula is commonly written as follows:
CCS = 3 P (1 - F + 5) - 1 B (1 - F + 3) 2 100 2 100
where P = pol per cent first expressed juice,
B = Brix per cent first expressed juice, and
F = fibre per cent cane.
The 5 factor (pol factor) means that the first expressed juice is
roughly 6 per cent richer in pol than the absolute juice. The absolute
juice is all the solids in solution together with all the water in the
cane. That is,
absolute juice = cane minus fibre.
The 3 factor (Brix factor) means that the first expressed juice is
roughly 3.5 per cent richer in Brix than the absolute juice. The
formula assumes the 3 and 5 factors to be constant for all cane types
and for all levels of preparation and extraction.
The recovery of sugar - the principal product of cane - is
affected by the amount of fibre, the type and quantity of soluble
impurities, and the amount of EM. Raw sugar is paid for according to
its NT, which takes into account both the reducing sugar and the ash
content of the sugar. The value of sugar is also affected by floc,
starch, and colour; but the NT formula does not take these other
factors into account.
36
6.1.2 The CCS Calculation
CCS is calculated on the measurement of Brix , pol, and fibre, and
the subsequent calculation of impurities (Brix minus pol) in cane.
The fibre is determined by washing and drying a known mass of
prepared cane. Sugar in juice is determined by an instrument called
the polarimeter or saccharimeter, the sugar thus determined being pol.
The total soluble solids in juice (sugar plus impurities) are measured
with the Brix hydrometer, the total solids content thus determined
being known as Brix. The impurities are considered to be the
difference between Brix and pol.
The Cane Analysis Committee investigated alternatives to the CCS
formula. Its investigations can be divided into two parts. One phase
of the work was to determine Brix and pol in cane by using juice
scales, mass balance methods, and direct analysis. This technique
eliminates juice analysis and the use of the 3 and 5 factors. Another
phase of the work was to suggest recovery formulae alternative to the
"pol minus half the impurities," which is inherent in the CCS formula.
Clarke and Player (1988, 81-87) reviewed the 3 and 5 factors,
using data on juice scales (1959-73 Victoria and Coondi) and DAC (1970-
71, Coondi). They believe that "the ... data show that over the range
of first mill extractions and pol in open cells experienced from 1959-
73, there was no effect on the composition of the first expressed juice
that would distort the analysis of pol in cane using the 3 and 5
formulae". They further stated: "It is therefore concluded that
changes in extraneous matter are properly reflected in the 3 and 5
analysis". They believe that, despite the installation of powerful
shredders and first mills, whatever imperfections in the 3 and 5
formulae existed in 1960 have not been perceptibly changed since.
37
In practice, the juice analysed for sugar and impurities is the
first expressed juice (including pressure feeder juice), so called
because of its extraction at the first mill (see figure 1). This
juice, because the cane is not uniform in composition from point to
point within the stalk, is richer in sugar content than the total
(absolute) juice in the cane. The Brix and pol figures must therefore
be adjusted by the 3 and 5 factors.
The existing CCS formula includes two essential elements. First,
there are the 3 and 5 factors, used for calculating Brix and pol in
cane from the analysis of first roller juice. The second and basic
element of the CCS formula makes it a recovery formula, used to
calculate recoverable sugar from the analysis of cane.
Some researchers have questioned the value of the CCS formula. In
fact, the analytical results used in the formula are not necessarily
exact. For example, only an average figure for fibre analysis is used.
In addition, the 3 and 5 factors were established early this century
and have remained unaltered; so naturally their validity with modern
technology has been questioned.
6.2 Alternative Recovery Formulae
The Committee of Enquiry of 1965 suggested a number of formulae
alternative to the pol - 0.5 impurities of the CCS formula.
6.2.1 Alternative Recovery Formula A
An alternative formula can be devised, using modern sugar
technology and calculating each of the various losses - in molasses, in
muds, and in bagasse. After the calculated losses are taken into
38
account, and after rounding off, the recovery of actual raw sugar per
cent cane is given by the formula
1.024 P - 0.42 x Im - 0.0033 FP
where P = pol per cent cane,
Im = soluble impurities per cent cane, and
F - fibre per cent cane.
This formula was derived in the following manner:
Loss in Molasses A study of impurities in 1960, 1961, and 1962 at
three juice scale mills shows that the amounts of impurities in
molasses represented 60 per cent of those in cane (based on filtered
gravity Brix and pol of cane, and sucrose and total dry substances in
molasses).
If we take 40 purity molasses as standard, the ratio of sucrose to
impurities in molasses is 40 - i.e., 2. Hence the sugar loss in 60 3
molasses is 2 x 60 x Impurities in cane - i.e., 0.4 Im. 3 100
This factor is similar to the 1 Im factor of the CCS formula and 2
may be substituted to give P - 0.4 Im where Im represents soluble
impurities per cent cane.
Losses in Muds, etc. The formula allows for standard molasses
loss; but some pol is also lost in muds, in waste waters, and in
undetermined ways. To allow for these, we deduct 2 per cent of the pol
in cane:
0.98 P - 0.4 Im
Loss in Bagasse The literature of sugar technology lists many
formulae in which the pol lost, as a percentage of the pol introduced,
is taken to be proportional to the fibre content of the cane (F%). If
39
a 4 per cent loss, with 12.5 per cent fibre in cane is taken as the
starting point, the "reduced" loss with fibre per cent F is
0.04 P x F i.e., 0.0032 FP 12.5
Overall Pol Recovery Formula When bagasse loss is incorporated,
the recoverable pol per cent cane is calculated as
0.98 P - 0.4 Im - 0.0032 FP
Adjustment of Pol Recovery to 94 Net Titre Sugar Pol recovery is
adjusted to 94 NT by applying the factor 1.045 to the whole formula.
Thus we have
1.0241 P - 0.418 Ira - 0.003344 FP
(The factor 1.045 has been chosen after studying the relationship
between pol and Brand I 94 NT sugar for the Queensland industry over a
twelve-year period.)
Rounding off gives recovery of 94 NT sugar per cent cane:
1.024 P - 0.42 Im - 0.0033 FP
Analytical Methods:
(i) Cane J.S. procedure, gravimetric Brix on filtered
M.J. and bagasse extract, and pol.
(ii) Raw Sugar Pol and moisture by drying.
(iii) Molasses Sucrose by double polarisation, solids by
drying.
(iv) Bagasse Gravity Brix and pol on filtered extract.
(v) Mud Pol; gravimetric Brix on filtered extract
prepared in wet disintegrator.
40
6.2.2 Alternative Recovery Formula B (Reduced Extraction and Winter-
Carp)
It is common to calculate a "reduced extraction" of pol from cane
based on a nominal fibre content of 12.5 per cent in cane and a pol
loss to bagasse equal to 4 per cent of the pol in cane. This
calculation assumes that the loss of pol in bagasse is proportional to
the fibre content of the cane.
Reduced Extraction: (1 - 0.0032 F)
where F = fibre per cent of cane.
The calculated pol extracted in a milling train can be converted
into pol passing into raw sugar by numerous formulae. One of the
simpler ones is that of Winter-Carp. This formula was originally
derived from a statement that for each part of soluble impurities in
mixed juice, 0.4 parts of pol appeared in the final molasses: the
remainder of the pol in mixed juice was presumed to appear as raw
sugar.
The fraction of mixed juice pol recovered as raw sugar (i.e.
Boiling House Recovery) is
where J is the purity of filtered mixed juice and
O.n is parts of pol held in molasses per part of
soluble impurities in mixed juice.
41
where J is the purity of filtered mixed juice.
The Winter-Carp formula could be expressed in general terms as
follows:
In applying this formula to Australian conditions, figures were
taken from all mills supplying data to the Committee in 1962. These
figures showed that it was reasonable to use the Winter-Carp formula
with n = 4, as in the original formula.
Combining the expression for extraction and for boiling house
recovery, we have the following expression for pol recovery per cent
P (1 - 0.0032 F)
where P = pol per cent cane,
F = fibre per cent cane, and
J = pol purity of filtered mixed juice.
The combined formula does not allow for miscellaneous losses such as
mud, waster waters, and so on. So a factor of 0.98 is applied to allow
for total miscellaneous loss of 2% of the pol recovery figure:
1.024 P(1 - 0.0032 F)
P = pol per cent cane,
F = fibre per cent cane,
J = pol purity of filtered mixed juice.
42
0.98 F (1 - 0.0032 F)
To convert the pol recovery into 94 NT sugar, a factor of 1.045
has been adopted as in alternative formula A.
1.045 x 0.98 P (1 - 0.0032 F)
6«2.3 Coring Methods
Guadeloupe and Louisiana use coring methods. According to Meade-
Chen (1977, 819-20), "the following formula ijrused:
CRS = corrected recoverable sugar
« TRS x F
"where TRS = theoretical recoverable sugar,
F = liquidation factor =
RS = recoverable sugar."
6.2.4 Recoverable Commercial Sugar
Dr A.T. Saranin devised a formula for Recoverable Commercial Sugar
(RCS) based on core sampling and the press method of analysis. (See
section 6.2.3.) Dr Saranin (1986b, 39-45) claims that the formula for
calculating RCS is
(1 - 1.4 F) (1.4 P - 0.4 B)
where F = fibre per unit of cane,
P = pol per cent of the press juice, and
B = Brix per cent of the press juice.
He claims that the advantages of this formula over CCS are as follows:
(i) Pol in cane can be determined with greater accuracy by using
the factor C, which correctly accounts for fibre variation and
losses in milling.
Factor C = 1.01 (±0.02) - 0.35 (±0.2) x F
where F = fibre per cent of cane,
(ii) Pol losses in boiling house operations take current
technological efficiency into account.
(iii) The sugar content of cane and the raw sugar produced are
both expressed in terms of 94 NT sugar.
43
Factor C and its companion factor C1 relate the composition of the
absolute juice (100 - F) and the press juice for pol and Brix
respectively. The formula for pol is
Pc = C (1 - F) Pj
where Pc = pol in cane
C = a factor
F = fibre
Pj = pol in juice
Saranin then simplified this to
Pc = P(1.00 - 1.24 F)
He claimed that this gave a more accurate determination of pol in cane,
at all levels of fibre, than the present CCS formula constant "5".
Similarly, his simplified formula for Brix was
Bc = B(1.05 - 1.68 F)
where Bc = Brix in cane,
B = Brix in juice, and
F = fibre.
He claimed that this formula more accurately determined Brix in cane at
all levels of fibre than the present CCS formula constant "3". Dr
Saranin's proposals attracted much comment and did appear to contain
some contradictions. For example, he reported that the C factor for
Brix was 1.06 - 0.80 F (Saranin, 1986a, p.43); but in the RCS formula
(Saranin, 1986a, p.45) he applied the pol factor (1.01 - 0.35 F) to
1.4 P - 0.4 B, thereby using the pol factor for both pol and Brix. He
was in effect assuming that the purity of the absolute juice was equal
to the purity of the press juice - an assumption that contradicts other
evidence that the purities differ.
44
In his paper, Dr Saranin further states that "comparisons of the
recoverable sugar predicted by the CCS and the RCS formulae and the
actual recoveries for the 1080-1984 seasons [show] that the CCS formula
underestimates the recoverable sugar for the state as a whole, and has
considerable regional variation ....
"On the other hand, the RCS formula predicts recoveries on
regional and state bases that statistically are not significantly
different from the actual recoveries, thus demonstrating greater
accuracy and regional consistency of the RCS values."
6.2.5 The Java Ratio
The Java ratio is an arbitrary milling ratio.
The Java ratio = sucrose (pol) per cent cane x 100 sucrose (pol) per cent first expressed juice
The most practical use of the Java ratio is to convert pol in
sample juice to pol in cane. Numerous attempts have been made to
derive a Java ratio from primary data. Our 100 - f - 5
100
is one of the many formulae used to serve as the source of a presumed
Java ratio.
There is an analogous ratio for Brix - it has no name, but it may
be called Java Ratio (Brix). We have used 100 - f - 3, but the only
100
reason for using a Brix ratio is to provide an alleged purity of
absolute juice. Other means could be used.
45
6.2.6 The Winter-Carp and SJM Formulae
The Winter-Carp and SJM formulae are the bases of several cane
payment systems. The Winter-Carp formula is based on sugar of 100
purity and a theoretical molasses purity (28.57).
The SJM formula deals with the situation in which a raw material
(typified by juice) is processed to yield a recovered product (typified
by sugar) and a residual or by-product (typified by molasses) - there
being no gain or loss of solids. The percentage, R, of sucrose in the
raw material recovered in the main product is represented by
R = 100 S (J - M) J (S - M)
where S = purity of sugar,
J = purity of juice, and
M = purity of molasses.
6.2.7 Arceneaux's Universal Equation
According to Arceneaux, the indicated available sugar per cent
cane is xS - yB
where S = pol
B = Brix of primary juice, and
x and y are factors.
Arceneaux claims that this formula correlates well with the CCS formula
and Hugot's formula (used in Reunion).
6.3 Cane Payment Systems (Payment for Quality)
Cane payment systems range from simple to complex. In Queensland,
the result of the CCS analysis is fed into the existing formula for the
price of cane.
46
Pc = Ps x 0.009 (CCS - 4) + C
where Pc = price of cane in dollars per tonne,
Ps = price of sugar in dollars per tonne, and
C = $0.328.
This formula incorporates one term proportional to the price of sugar
and another term independent of the price of sugar.
The conditions attached to the original determination of price can
be reduced to the following:
(1) the price of cane was to vary with CCS according to the sugar
made at 90 COW and
(2) the growers were to receive two-thirds of the gross revenue
at 12 CCS and 90 COW.
The sugar made per unit of CCS at 12 and 90 is expressed by 0.009 x 12.
The millowner is to receive one-third 0.009 x 4. In the general case
of CCS = a, the sugar made at 90 COW is 0.009 x a; and, if the
millowner receives 0.009 x 4, the grower must receive 0.009 (a-4). In
cash, if the price of sugar is P, the price of cane is 0.009 P (a-4).
Note that the 4 was not selected - it was derived. Actually the 4
reflects the fact that every tonne of cane (which has no value as cane)
has a liability for the cost of processing to sugar, which has value.
The implication is that cane of 4 CCS has only enough sugar to pay for
its own milling; its net value is zero. The weakness is that the cash
value of 4 CCS depends a little on COW and a great deal on P.
Mr J. Clayton contends that the present system isolates growers
from COW and millowners from CCS. He has suggested that cash
allowances be made to offset (at least partly) the growers' and
millers' costs - for example, from an allowance of $18.00 per tonne of
cane, $12.00 would be paid to the grower and $6.00 to the miller. But
47
the $18.00 would have to be converted to a sum per tonne of sugar. His
suggested trial formula is
v = 0.01 P - 18 x 10* (a-5) + 12 ac
where v = price of cane in dollars per tonne,
P = price of sugar in dollars per tonne,
P - 18 x 104 - sugar revenue left for distribution, ac
18 x 104 = sum reserved per tonne of sugar, ac
a - CCS, and
c = COW.
(The adjustments of the minimum CCS from 4 to 5 and of 0.009 to 0.01
are arbitrary and are intended to reflect the present distribution of
funds.)
6.4 Cane Payment Formulae Used in Other Countries
Some countries make no adjustment for the components of cane,
paying simply for the weight of cane delivered. Each tonne of cane in
a season, therefore, is worth exactly the same as any other tonne.
It is usual in these cases for the total sum paid for cane to be a
proportion of the sugar proceeds, so that the actual yield of sugar
from cane, obtained in the factory, affects the price of cane.
Some countries and mills adjust for fibre. Others adjust for
soluble impurities. Still others make no adjustments for soluble
impurities, paying on pol or sucrose; and, in some regions, payment
depends on juice scales. Whereas many countries adjust for soluble
impurities in the cane, it is the exception to adjust for fibre.
48
6.4.1 Standard Cane with Premiums and Penalties
According to Meade-Chen (1977, 817-18), "A method prescribed by
the Department of Agriculture for cane purchase in Louisiana under
government quota systems depends on the pol (invariably called
'sucrose' in government as well as local discussions) of the so-called
normal (undiluted) juice as calculated by factors from the factory
crusher juice or from laboratory mill juice.
"DCF (dilution compensation Factor) = Brix undiluted crusher juice Brix sample mill juice
"DMF (dry milling factor) = Brix normal juice Brix undiluted crusher juice
= 0.97 (or by actual test)
"Brix factory normal juice = DCF x DMF x Brix sample mill/juice
"pol factory normal juice = Brix factory normal juice x purity
factory mixed juice
"By establishing daily a Brix factor and a pol factor between each
grower's sample mill juice and factory normal juice, the individual
grower's daily sample juice can be converted into grower's normal juice
Brix, pol, and purity. Then individual 'sucrose factor' and 'purity
factor' values can be found in tables published by the United States
government.
"grower's standard ton = gross ton x (1 - %trash) x 'sucrose
factor' x 'purity factor'
= net tons x quality factors
"The formula therefore shows that a grower can have a better return by
providing cane with lower trash and higher juice quality."
49
6.4.2 Sucrose in Cane - Direct Analysis of Cane
In South Africa, cane prices depend on the sucrose content of the
cane. In 1072-73, the previous cane payment system (based on the Java
ratio) was replaced by the Direct Analysis of Cane (DAC) method.
Revenue was shared with a grower according to the formula
value of 100 tons of cane = pol per cent cane x industrial
average overall recovery for season
(per cent) x grower's share (per
cent) x sugar price.
This method has been investigated in Australia by a Committee of
Enquiry.
7.0 DETERMINATION OF MILL PERFORMANCE
7.1 The Coefficient of Work
None of the sugar analyses in chemical control is perfect; but the
results obtained are consistent. In Australia, the COW is the most
important figure in evaluating the performance of a factory.
COW = tonnes 94 NT sugar x 100 tonnes CCS in cane
That is, the COW is the tonnes of 94 NT sugar produced per 100 tonnes
of CCS introduced into the factory in the cane. Therefore the COW
depends largely on the accuracy of the NT and CCS measures.
It is quite possible and allowable for the COW to exceed 100. For
example, if a factory attained a standard of performance specified by
the CCS formula, 100 tonnes of CCS would produce 100 tonnes of pure
sugar - that is,
50
100 x 100 = 106.4 tonnes of 94 NT sugar 94
King (170) illustrated that the COW could theoretically reach about
113. He further stated that in practice such a high figure would be
unattainable, but that a COW of more than 100 would be quite
legitimate.
In practice, from season to season and from mill to mill, the COW
varies. Because of its dependence on the limitations of CCS and NT,
the COW reflects the efficiency of the mill, but with a regrettably
high tolerance.
The increase in the COW and the decrease in Undetermined Loss
could be said to show that the factories have increased their overall
recovery efficiency. This would be only partially true: if changed
conditions cause the measured value of pol in cane to decline relative
to the true value, the COW will rise and the Undetermined Loss will
fall, even changing to Undetermined Cain.
7.2 Chemical Control
The pol balance is a measure of mill performance, but a very
inferior one. The critical item is overall recovery; a much better
index of performance is provided by Reduced Overall Recovery, it is
all a matter of the difference between fact and assessment.
Pol extraction is a quantitative fact;
Reduced extraction is a criterion of performance;
Boiling House Recovery is a fact;
Reduced BHR is a criterion;
Overall Recovery is a fact; and
Reduced Overall Recovery is a criterion.
51
8.0 CONCLUSIONS
The sampling of cane is really very much complementary to the
analysis. No matter how good the method, how well-trained the analyst,
or how accurate and precise the results, the analysis will be incorrect
(perhaps even misleading) if the sample is not truly representative of
the cane from which it is taken. Fortunately, the need for adequate
sampling appears to be recognised in Queensland, where refined methods
ensure the validity of samples. The Cane Testing Service plays an
important role in guaranteeing the correctness of the sampling and
analysis of the cane received at the mill.
Although there are several methods of sampling and analysing cane,
and although some of these have been extensively tested under
Australian conditions, no single method can be clearly identified as
best in all mill areas; nor does any single method meet with industry-
wide acceptance.
Expansion in the industry and the resulting increase in crushing
rates have meant that, in some areas where growers provide relatively
small consignments of cane, it is becoming more difficult to separate
the samples to analyse the first expressed juice.
Sampling juice appears to be the most satisfactory method provided
that cane from different growers can be separated and the juice sampled
as the cane passes through the mill rollers. Associated with a
suitable tracking device, automatic or semi-automatic sampling systems
(with reasonable care) can deliver a sample that truly represents the
cane being processed. The Australian method of sampling fibre across a
full carrier width of cane from the bottom of the elevator, just before
it reaches the first mill, compares favourably with other methods.
52
If a grower's consignments contain a significant amount of cane
(significant, that is, in the mill's crush), and if all prescribed
procedures are adopted, the collection and analysis of the first
expressed juice will satisfactorily ensure that the sample represents
the whole of the consignment.
The disadvantage of the other methods is that only a portion of
the consigned cane is sampled and the juice is extracted from that
sample. However, if the sample is taken randomly and with sufficient
frequency, and if the quantity taken each time is adequate, the sample
will be valid. The sub-sampling and final extraction of the juice can
be carried out under controlled laboratory conditions. Under the
Bundle Sampling system at Inkerman, the original random sample was not
less than 100 lb (45 kg); but this amount was later increased to 200 lb
(90 kg).
The Australian industry extends over a longitudinal distance of
2100 km, and cane is grown mainly within 50 km of the coast. Often, in
Australia, many different varieties of cane are grown under differing
climatic conditions; consequently, the selection of a uniformly
superior method of sampling and analysis for all areas in all seasons
is problematic.
Cane payment systems range from simple to complex. Cane payment
based on the analysis of cane delivered is much fairer to all parties
than either a flat price based on money received for sugar sales or a
price based on an average yield. The higher the quality of cane
delivered to a mill, the greater the financial reward - not only to the
mill owner but also to the individual grower. To some degree, the
payment system depends on the method used for sampling and analysis.
Besides the CCS formula, RCS (Recoverable Commercial Sugar) and the
53
Committee of Inquiry formula have been suggested. All involve the use
of a factor. Some cane payment systems are based on a fixed ratio of
the division of returns from the sale of sugar. The Queensland system
is based on the principle that the returns to each party (miller and
growers) should be proportional to the costs of production and
manufacture. Both parties are provided with incentives to increase
their efficiency.
The common use of factors (3 and 5 in the CCS formula, 4 and 0.009
in the cane payment formula, and 5 and 1 in the Net Titre formula)
identifies weaknesses in the analytical methods and in the formulae
themselves. The use of juice scales and that part of the CCS formula
which reads "CCS = pol per cent cane minus half the soluble impurities
per cent cane" obviates the need for the empirical 3 and 5 factors.
Nevertheless, the growth of the Australian industry over the last
sixty years is evidence that the CCS formula has worked successfully.
It has provided an incentive for the grower to provide better quality
cane of higher sugar content and for the miller to pursue more
efficient process technology and to produce better quality sugar.
However, its current validity is being questioned.
But changing the CCS method of analysing cane delivered to the
factory will not increase the total tonnes of sucrose supplied. Such a
change would alter only the distribution of value between district and
district, between grower and grower, between miller and miller, and
between grower and miller. Sampling is really part of the analytical
system; so any improvement in the accuracy of analytical procedures
must be complemented by valid sampling techniques.
54
The Queensland industry may decide
(a) to persist with a state-wide analytical system or
(b) to choose a demonstrably superior analytical system for a
particular region or mill area.
The industry may also
(c) persist with a state-wide cane payment system or
(d) introduce a cane payment system for a particular region or
mill area. (The choice of the sampling and analytical method
may have a bearing on this decision.)
Because the money from the sale of sugar is divided between the millers
and growers and is paid for on the basis of Net Titre, both parties
should question the validity of the 5 and 1 factors used in that
calculation given existing technology.
Although no method is clearly superior to the others, the position
is by no means static: at any time, a commercially applicable method
of accurate, economical cane analysis could become available. A better
cane payment formula should return to the farmer the commercial value
of all material he supplies and allow the miller to recover factory
losses caused by material in, or attached to, the cane.
At present, any change to any system requires the approval of both
parties. Therefore any change to the existing system will require
indisputable evidence that the proposed system is fair to both parties
and more accurate.
One option would be to allow an independent body to decide on
methods of sampling, analysis, and payment - not necessarily on a
state-wide basis. Whatever the ultimate formula, it - like the CCS
formula - must offer financial rewards both to growers (for cane
quality) and to mill owners (for factory efficiency).
55
The existing cost of the analysis for cane payment has been
estimated at 0.6 per cent of the cost of producing raw sugar.
However, the benefits to grower and miller are difficult to estimate.
It is hardly valid to compare the cost of analysis in Australia, where
cane is supplied mainly by family units, to costs in other countries,
where cane is grown on plantations.
Costs could be reduced by having the analyses carried out by a
single body (as in South Africa). The progressive automation of cane
analysis should make possible this delegation of responsibility
(automation is well established, for example, in the beet sugar
industry). The Cane Testing Service could provide the base for this
single, independent cane analysis arrangement.
56
References
Brotherton (1980), "The Influence of Extraneous Matter on CCS," ASSCT
Proceedings.
Churchward and Poulsen (1988), "A Review of Harvesting Development,"
ASSCT Proceedings.
Clarke, M.A. "HPLC in the Sugar Industry", Sugar y Azucar August 1985,
pp. 21-25.
Clarke and Player (1988), "The Validity of the Three and Five Formula
for the Analysis of Cane in the 1980's", ASSCT Proceedings.
Clayton, J.L. (1986) "Cane Payment - A Suggestion" (unpublished
paper).
French A., Sverzut, C.B., Verma, L.R. & Martin, F.A. "Use of NIR
Spectroscopy for the Analyses of Sugar Cane Quality", Louisiana
State University Agricultural Centre, Baton Rouge, Sugar y Azucar
June 1986, p. 23,
Fuelling et al. (1978), "Sugarcane Harvester Performance," ASSCT
Proceedings, pp. 209-16.
Ivin, P.C. (1986), "Measurement of Saccharides and Ethanol in Stored
Cane Billets Utilising HPLC," ASSCT Proceedings.
King, N. J., Mungomery, R. W., and Hughes, C. G., Manual of
Canegrowing, rev. ed., Angus and Robertson, Sydney, 1965.
Loughran et al. (1988), "A New Method and Apparatus for Determination
of Fibre in Cane," ASSCT Proceedings.
Meade-Chen (1977), Cane Sugar Handbook: A Manual for Cane Sugar
Manufacturers and Their Chemists, 10th ed., Wiley, New York.
Muller et al. (1982), "An Examination of the Input, Disposition, and
Effect of Dirt on Queensland Sugar Mills", ASSCT Proceedings.
57
Price, R., "Cane Evaluation in Queensland - Past, Present, and Future"
Lecture presented to Latin American and Caribbean Symposium on
Sugarcane Payment Systems, Sao Paulo, Brazil, Spetember 1987.
Price, R., (1965), "Individual Fibre Systems for Cane Payment",
Australian Year Book.
Ridge and Dick (1988), "Current Research on Green Cane Harvesting and
Dirt Rejection by Harvesters," ASSCT Proceedings.
Saranin, A. P. (1986a), "The Core-Press System of Sugarcane Quality
Determination, ASSCT Proceedings.
Saranin, A. P. (1986b), "The Press Method of Sugar Cane Analysis,"
ASSCT Proceedings.
Smith, D.B. and Starr, C., "Near Infrared Reflectance Analysis in Plant
Breeding", Plant Breeding Institute, Trumptington, Cambridge,
Analytical Proceedings. Vol. 23, April 1986, pp. 125-26.
Stewart and McComeskie (1988), "A Comparison of Green and Burnt Cane
Harvesting in the Burdekin", ASSCT Proceedings.
Sverzut et al. (1986) - see French et al.