60337484 an introduction to pectin

7/28/2019 60337484 an Introduction to Pectin

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AN INTRODUCTION TO PECTIN

Pectin describes a family of polysaccharides, which give structure and strength to certaintissues in many land plants. In this form the pectins are often insoluble because of the highmolecular weight, and due to the interaction with cellulosic material in and between the cellwalls. It is only as the molecular weight decreases and the bonds break, - is seen by thetissue softening or fruit ripening-, that the pectin becomes soluble.

Like all natural materials, the individual molecules of pectin are not identical but are of similar composition. For convenience the following discussions take account of this by consideringthe overall or average characteristics of the pectin.

The major constituent of pectin is galacturonic acid, which is simply a sugar, galactose,which carries an acid group. Several hundred of these units are linked together to form along chain molecule of poly galacturonic acid. A proportion of these individual galacturonicacid units are methoxylated and although it is not necessary to understand the chemistry of this, it is essential to understand that the amount of the methoxyl groups present stronglyinfluences the performance of the pectin. This value is so important that it has been given adefinition “Degree of methoxylation” (DM) is defined as the average number of methoxylgroups per 100 acid units, i.e., a simple ratio of methoxylated units per 100 units. Anexample of a pectin of 70% DM is where 7 out of every 10 units carry methoxyl group.

By convention, pectins are split into two groups. If the DM is greater than 50%, the pectin isreferred to as a High Methoxyl Pectin or HM for short. Thus the previous example of 70%DM was an HM pectin. Pectins of less than 50% are called Low methoxyl Pectins or LMs.Thus a pectin of 40% DM would be a LM pectin. There are two forms in which LM pectinscan be made, the first is conventional LM and the second is amidated LM, the differencebeing the second contains amide groups as well as methoxyl and acid groups. The “Degreeof Amidation” or DA is also very important to the performance of a pectin and it has asimilar definition to DM. DA is the average number of amidated units per 100 units. Thus wecan define any pectin in terms of its percent DM for HM and convetional LMs, and percentDM and DA for amide LMs, and these values should help us identify the behaviour that wewould expect from the pectin.

Although the major unit of pectin is galacturonic acid, other sugars or groups may also bepresent depending on the source of the pectin. Neutral sugars, such as rhamnose,arabinose, galactose and xylose may occur as side chains or on the backbone of the pectin.They may be present at up to 25% in certain pectins, such as that extracted from apple,while citrus pectins normally contain only low levels of these. The presence of these sugarsmodify the behaviour and the performance of the pectin, as can be seen with comparison of



apple and citrus pectins of the same DM. Typically apple pectins result in a more pasty, lesssmoothly gelled product. Apple pectin may also be contaminated by the presence of starchwhich unless specifically removed will also modify its performance. Again, this tends tocause pastiness or graininess and disrupts the gel structure.

Other groups may also affect the properties of pectin. For example, the acetyl groupspresent in pectins from sugar beet or sunflower disrupt the formation of the gel and as aresult these pectins are not common and would not be suitable to replace citrus or applepectins for gelation (unless modified to remove these groups).

Therefore, the major commercial sources of pectin are citrus peel and apple pomace, whichare residues from the juice industry. The quantity and quality of the pectin in these rawmaterials depend on several factors. The type of fruit has a major influence on the finalpectin quality, for example lime peel usually contains the highest obtainable quality and at

the largest levels. This is followed by lemons, oranges, and other citrus fruits. Apple pomacecontains lower levels of pectins than citrus fruit and due to the natural sugars and starch hasslightly different properties.

Quality and quantity are also affected by any factor influencing the fruit or peel, such asgrowing conditions, stage of ripeness and picking, severity of peel drying etc. Unfortunatelythe fruit are chosen for juice production, which is close but not at the optimum for pectinproduction. The extraction procedures also affect the quality and quantity of pectin recoveredand commercial extraction is in fact a compromise between the total amount of extractedpectin and its quality.

When peel is received at the factory, samples are taken for analysis of the extractable pectin,and the conditions for extraction optimized. The peel is washed in water to removeextraneous matter before the pectin is extracted in hot acidic water. The extraction is carriedout by transporting the peel through a series of tanks, where the pH, temperature and timeare controlled as determined previously. The pectin solution is then recovered from the peelresidue by filtration, it is clarified and then concentrated. The liquid concentrate may then behydrolysed at this stage if required to produce pectins of different DMs and thus differentperformances. The pectin is recovered from solution by precipitation. The precipitate iscollected and washed in aqueous alcohol to remove impurities and then the pH is adjustedby the addition of sodium carbonate, to control the solution pH of the pectin. The washed

pectin precipitate is then again recovered prior to drying, grinding and testing. The powderedpectin of known DM and performance is then blended as required and re-tested to confirmbehaviour before dispatch to the customer.

Pectins are usually blended with sugars to a specified gel strength or gel grade. However,where required, other ingredients can also be included, or the pectin may be standardized by



some other parameter such as viscosity or protein powder. Amide pectins are prepared in adifferent way and are manufactured by the treatment of the recovered pectin in alcohol withaqueous ammonia. Once prepared the amide pectins are similarly dried, ground, tested,blended and then re-tested.

In principle, there are two types of pectin, HM and LM, which because of the different DMs(and DAs, where appropriate) have quite different properties.

HMs are pectins with DM greater than 50%, but in practice the DM varies from about 75 to55%. LM pectins have a DM of less than 50% and the actual values are in the order of 30 to50% for conventional LM and 20 to 40% for amidated pectins. However, it is important toremember that these values are averages and that a pectin of 50% DM may be made up of an equal mixture of two pectins having DMs of 25 and 75% respectively. As the DM is knownthe performance of the gel of this pectin “50% DM” may not perform exactly as expected!

Further to this, although the cut-off for HM and LM pectins is 50%, the change in behaviour isgradual as the DM changes, and the characteristics do not suddenly alter at 49.9% to an LMpectin performance. Thus a pectin of 50% DM will exhibit a certain behaviour which due tothat DM and will reflect some HM and some LM characteristics. When producing pectin, wedo not normally mix pectins over radically different DMs, although during our blendingoperation we do blend together pectins of similar, but not exactly identical DMs.

HIGH METHOXYL PECTINS

High methoxyl pectins are defined as having a DM of greater than 50% and the exact valueof the DM affects the performance of the pectin. HM pectins have several quite distinctfunctions in the food industry, the most important property being gelation. However, thesepectins have other advantageous properties such as physiological, viscous, stabilizing andprotein protecting properties.

Pectin is a water soluble fibre which may be used in food to provide viscosity in the stomachand deliberately slow down the absorption of nutrients. It is also used in wound and similar dressing to absorb weeping to keep the wound dry.

Due to the viscosity of HM pectins, they find use in ready-to-drink and dilutable beverages,providing mouth feel and body, especially in low juice and low calorie products.

In acid milk systems, HM pectins protect the product from loss of texture due to theacidification or heat treatment. In this application the pectin reacts with the sensitive proteinslimiting or preventing adverse reactions.



The most important property of HM pectin is gelation and these pectins gel when thecondition sufficiently reduce the water activity (normally by the addition of sugars) and whenthe pH is sufficiently acidic. Normally an HM pectin will gel when the soluble solid content isgreater than 55% and the pH is in the range of 2.0 to 3.8. Generally the higher DM of an HM

pectin, the easier the gel forms. This is seen in the difference in the rate of set of pectins of different DM and it leads to the nomenclature of HM pectins. A pectin of very high DM, for example 72%, exhibits gelation at a very high temperature and thus sets very quickly. For this reason it is known as rapid set pectin. On the other hand a pectin of lower DM, for example 60%, will gel at a lower temperature and take longer to set, and is therefore, knownas a slow set pectin. Pectin of intermediate DM will show intermediate properties and isknown as a medium rapid set. Although many factors in a recipe may also influence thefinal setting temperature of a product, it is important to define the setting characteristics of apectin under standard conditions to allow the correct use of a pectin in a recipe. For example, if whole fruit pieces are present in a jam, it will be necessary to use a rapid set sothat the gel will form before the fruit pieces float to the top. A slow set pectin will not gelsufficiently quickly to stop the fruit from floating.

Therefore, when using HM pectins for gelation there are two main parameters, which shouldbe defined:

1. Strength. The strength of HM pectins is usually standardized by the USA SAGgrade, which defines the power of that pectin to gel under very tightly controlledconditions of pH, soluble solids content etc. Normally, HM pectins are blended withsugar to result in a SAG grade of 150 ± 5. Thus our customers can rely on the qualityof the pectin and can develop a standard recipe with a set addition rate.

2. Setting rate. The time the gel takes to develop, or the temperature at which thegel starts are both measures of the rate of set. In some countries the settingtemperature is used to define the pectin under a standard laboratory test methodand is used to measure this to ensure the pectin is correctly quantified and thusdescribed. (note: the results by this test do not indicate the performance in product,but rather in test method). However, in other countries the setting time may be usedto indicate the behaviour of the pectin. (This technique is also a laboratory based testwhich gives comparative, not actual figures.)

Typical values of HM pectins are:-

Type of Pectin Setting Temperature Setting Time

Rapid Set 80-95ºC Less than 90 seconds

Medium Rapid Set 75-79ºC 110-135 Seconds



Slow Set Less than 60ºC Greater than MRS

Having now defined the gel strength and setting rate or behaviour, the HM pectin is ready for use in a specific application. For example, slow set pectin would be chosen when producing

a jelly where there is no fruit to suspend, and where the air bubbles should rise to thesurface before the gel sets, resulting in a clear bubble free jelly.

Although the choice of pectin will depend on the performance of that pectin in principle, it canbe modified by other ingredients present in the recipe, the most important of theseparameters are pH, soluble solid content, type of soluble solids and cooling rate, and theycan be used independently or together to manipulate the performance of the chosen pectin.For example, a slow set pectin can be made to set faster if the pH is reduced or the solublesolid content is raised. As a result of the influence of these parameters it is essential thatthese should be set and held within the specification during production. Thus although the

performance of a pectin can be defined in a controlled standard method, the behaviour inproduct will be modified by other factors. These will be dealt with in each application section.

LOW METHOXYL PECTINS

LM pectins, whether conventional or amide, gel or thicken by interactions with calcium over abroad range of soluble solids contents, (or greater than 5% to about 85%), and over a broadpH spectrum from 2.6 to about 7. As a result low methoxyl pectins can be used in a very

much wider range of foods so long as there is sufficient calcium for the required interaction.the calcium may be added specially but fruit and milk may have sufficient calcium naturallypresent to cause the interaction. As the DM of HM pectins affects the rate of set, the DM andDA of LM pectin also influence the setting characteristics. This is because of the effect of these on the calcium requirements for optimum performance.

For any LM pectin, the gel strength and setting rate will depend on the calcium level. Thereis an optimum value of calcium, at which the gel is clear, elastic, strong, free from syneresis.

At lower levels of calcium, i.e., if the calcium content is reduced or limited, the gel will not bestrong but it will remain clear and bright. At very low levels a gel may not form at all, but theremay be an increase in the viscosity observed. However, if too much calcium is present, for example from the fruit, or too much is added, the pectin calcium interactions becomeexcessive and the gel network becomes too tightly pulled together, and like squeezing asponge, the aqueous phase gets squeezed out as syneresis. In addition, the gel becomescloudy and brittle and may become very grainy or sandy. If excessively high levels of calciumare present a coherent gel may not occur at all but rather a soup of jelly lumps in a sloppyliquid is formed. The DM (and DA) influences the actual value of calcium at which optimumgelation occurs and a range of LM pectins are available to ensure that required behaviour can be achieved. Generally as the DM is increased, the amount of calcium necessary toachieve optimum gelation is also increased. Thus a pectin of 30% DM will require lesscalcium than a pectin of 45 DM, the pectin of 30 DM being more calcium sensitive.



There is no international standard test for the gel strength or setting performance of LMpectins because they depend so heavily on the calcium content. However, a standardtechnique is used by Citrico to ensure that each pectin is correctly assessed for reactivity.

LM pectins are therefore selected according to the required performance in product in thesame way as HM pectins are selected, the other ingredients and processing parameters in aproduct can influence the performance of that pectin. The most important of theseparameters are pH, soluble solid content, type of soluble solids, available calcium asdetermined by the total calcium and the calcium sequestering ability and the method of production. In addition to the influence of the ingredients the method of preparation of theproduct widens an already broad range of possible products. For example, the behaviour toheat can easily be modified to provide heat stable or reversible products. In addition, thetextures can also be altered by the method of production, forming anything from a gel or foam to a sheer thinning viscous product.

LMs are therefore very much more versatile than high methoxyl pectins and are showinglarge sales growth as even more uses become clear.

Jams and Preserves

Early civilisations have preserved their seasonal fruits by either boiling on their own or together with some form of sugar. This not only destroys the naturally occurring enzymes butalso the water activity will be reduced to prevent the growth of spoilage organisms such asyeasts and moulds.

A the same time as effecting preservation, the heating in a solution will serve to extract thepectin in the fruit and when this combines with the naturally occurring sugar the pectin willthicken or gel the fruit system.

Whilst this process form s the basis of all present day large scale jam production, technologyalso plays a considerable role. Not only are commercially produced pectins use tocompensate for any deficiency from the fruit, but specially prepared types (low methoxylpectins) are widely used to set systems where the sugar content is too low for normal pectinsto be effective.



To appreciate the role and application of pectins in such products, it is useful to understand afew terms which are used to describe and characterise them.

HIGH METHOXYL (HM) AND LOW METHOXYL (LM) PECTINS

Whilst HM pectins are capable of forming sugar gels only at a high soluble solids level(greater than about 55%), LM pectins can also form low solids gels. These require thepresence of a controlled level of certain di- or polyvalent cat-ions, of which calcium is theonly one used in the food industry. Naturally occurring pectins are almost always of the HMvariety, with LM pectins normally being made from these by treatment under acidicconditions.

AMIDATED PECTINS

These are produced by the controlled treatment of HM pectin and ammonia. In mostsituations they behave in a similar way to LM pectins, although they do show certaindifferences which sometimes make their application preferred.

GRADE

The grade of a pectin is a measure of the ability of that pectin to form a gel under standardlaboratory conditions. For HM pectins, the USA-SAG or IFT method is most frequently used,standardisation being achieved by dilution with sugar to 150 or 200 grade (150X SAG or 200X SAG).

LM pectins are used under a much wider range of conditions and so there is less uniformityin the methods of grading which are applied.

SETTING TEMPERATURE AND SETTING TIME

HM pectins can be classified either by setting temperature or by setting time. The first of these is defined as the temperature at which setting occurs and the second as the time



between the pouring of a hot jelly mix and the occurrence of setting. These are measuredunder precise laboratory conditions and must not be confused with production setting rates.Neither parameter is normally specified for any LM pectin.

RAPID SET AND SLOW SET PECTINS

These terms are only used to describe HM pectins. Those exhibiting the highest SettingTemperature (and shortest setting time) are known as Rapid Set, whilst on progressive acidtreatment of these, the Setting Temperature will drop and the Setting Time increase untilSlow Set is reached.

PRODUCTION METHODS

Most preserves can be made in either of two general types of equipment although there aremany variations which can be applied within each.

OPEN PAN (ATMOSPHERIC) BOILING

This is the traditional method of production where water is driven off by boiling ingredients ina heater pan. Heating is normally indirect by steam and the process is batch rather thancontinuous.

VACUUM BOILING

By processing ingredients under vacuum, a lower boiling temperature is achieved. Thisreduces degradation of the pectin (both added and naturally occurring from the fruit) andalso gives better retention of both colour and flavour of the fruit.

Indirect steam heating is most frequently used with the following systems being commonlyfound:

Pot or Kettle Batch



Plate Evaporator Continuous

Scarped Surface Evaporator Continuous

Of these, the continuous systems are restricted to processes where large fruit pieces areabsent.

PRODUCT TYPES

Although certain novel systems are difficult to classify, most products can be placed in one of four main groups:

Conventional/traditional

Bakery/industrial

Low/reduced sugar

No added sugar

Conventional/traditional

These are essentially self preserving products of greater than 55% refractometer solids(soluble solids – s/s). They have appreciable fruit content and are normally sold direct to thefinal consumer in containers up to about 500g (up to about 5kg for catering and food serviceuse).

Quantity of pectin

As the pectin added is only needed to supplement that from the fruit itself, the quantityrequired will largely depend upon the variety, amount and quality of the fruit used. On thebasis of experience the following table gives an indication of levels required for jam of 65-68% s/s using whole, sieved or pulped fruit (g 150X SAG pectin per 100kg of finishedproduct).



Cherry Apricot Apple

Peach Blackberry Damson

Pear Blackcurrant Gooseberry

Pineapple Loganberry Greengage

Raspberry Guava Strawberry

Plum Quince Redcurrant

Fruit

Content

%

Marmalade

30 360-450 270-330 180-240

40 260-330 190-250 100-170

50 180-230 120-170 60-110

60 110-160 70-110 30-70

Weight of finished preserve

For jellies made with fruit juice, addition rates 25-50% higher than the above will be neededfor fresh juice and even more for depectinised juice. Other factors affecting addition rateinclude: strength of set required, final soluble solids, pH, length of boil, size of containersbeing filled.

Type of pectin

Rapid or Medium Rapid Set pectins are normally used in conventional/traditional productsexcept when:

i) Filling large containers.

ii) Filling at lower than normal temperature.



iii) Making jelly rather than jam.

iv) The soluble solids content is greater than about 72%.

v) The natural fruit pectin is very fast setting.

vi) Sugars other than sucrose are used which may appreciably raise the setting

temperature.

In all these situations Slow Set pectin should normally be used for open pan boiling. For vacuum boiling systems the choice of pectin will also depend upon the actual productiontechnique used.

Citrico Pectins available for use in conventional/traditional preserves are as follows:

Rapid Set

Medium

Rapid Set Slow Set

Type 7010 Type 7020 Type 7030

Type 7016 Type 7046

Pectins should always be added to a preserve as a solution and not as a dry powder.Methods and techniques for preparing such solutions are given in the Citrico bulletin“Storage and Dissolving”.

Processing Conditions:

i) pH

Inadequate pH control results in more substandard preserves than does any other parameter. To achieve optimum performance and consistency the pH must be correct both inthe finished product and at all stages of production process. Whilst there are many signsindicating an incorrect pH the commonest are pregelation, syneresis and floating of fruit.With acid being normally added at or near the end of the boil, the optimum product pHrequired is a function of pectin type, soluble solids and of the precise sugars used. For a



product made solely with sucrose the following should give acceptable results (measured at20ºC on a 50% solution of the preserves):

S/S - % pH

75-85

72-75

3.2-3.5

3.1-3.4

} Slow Set

68-75

64-68

60-64

55-60

3.0-3.3

2.9-3.1

2.8-3.0

2.6-2.8

} Rapid, Medium Rapid or Slow Set

ii) Soluble Solids

Apart from possible legal and direct cost penalty implications, poor control of soluble solidscan result in inconsistent texture and strength of set. Whilst the soluble solids content of thepreserve during production can be measured either directly by refractometer, or directly fromits boiling point, the first of these is strongly to be preferred.

When operating at other than normal soluble solids content of 65-68%, the pectin additionrate will need to be adjusted thus:

S/S - % Change in pectin

addition

70 -5%

65-68 -

60 +10 to +15%

55 +25 to +40%

These figures should only be taken as approximate.



iii) Filling temperature

Control is essential over the temperature at which filling takes place. For containers of up toabout 1kg, 82-88ºC should be regarded as acceptable even for jellies, where setting may

occur until about 60ºC. Above this, whilst at lower temperatures there are increased risks of pregelation and microbiological spoilage.

Within the range for acceptable gelation, a lower pH will produce a higher settingtemperature, and a higher pH a lower setting temperature.

As the setting temperature of a high methoxyl pectin is dependent upon the rate of cooling,very rapid cooling may be used to allow a lower product filling temperature e.g., when filling

larger containers.

iv) Use of sugars other than sucrose

For reasons of cost and of product taste and texture, the partial or complete replacement of sucrose by other sugars is now widely established, the most commonly used being highfructose corn syrup (HFCS – containing about 45% fructose) and 42 and 63 DE glucose(corn) syrups. Whilst the general effect of glucose (corn) syrups is to (i) weaken the set, (ii)

raise the optimum pH for gelation (iii) increase the setting temperature, changes resultingfrom the use of these and of HFCS can be quite pronounced and no simple guidelines canbe defined. Further details relating to these and other sugars are available on request.

Note When high levels of glucose (corn) syrups and HFCS are included it is normal to use aSlow Set rather than a Rapid Set pectin.

TYPICAL RECIPE

Ingredients

Fruit 400g



A Sugar 300g

Water 60g

B Sugar 310g

C Pectin Type 105 or 601 4% w/w soln 60g

D Citric Acid H2O 50% w/v soln 6ml

Final Batch Weight 1kg

pH (50% solution) 3.0-3.2

Soluble Solids 65-66%

Method

Heat ingredients A and bring to boil. After 1-2 minutes add sugar B and return to boil. Boil for further 1-2 minutes and mix in pectin solution C. Stirring well, boil down to required solublesolids and remove from heat. Mix in acid solution D, cool to about 85ºC with stirring, fill into

jars and seal at once.

Notes

1. Alter level of pectin to achieve required set.

2. Alter acid addition to maintain final pH of 3.0-3.2.

3. Acid should always be added at the end of the boil.

BAKERY/INDUSTRIAL

There are four main types, all of which are normally filled into large containers. Note –certain specialised uses of LM pectin are not included here although details are available onrequest.



i) Product of 65-70% s/s for spreading or depositing onto pastry before bakingand which will withstand oven temperatures without excessive melting or boiling out.Type 115 Medium Rapid Set or Type 611 Bakery Pectin should be used in the sameway as for conventional preserves except that a higher pectin level (0.6-0.8%

depending on fruit or juice content) and a higher pH (3.2-3.3) are essential, combinedwith a lower filling temperature of about 70ºC. The use of glucose (corn) syrup willalso tend to improve the level of heat resistance.

ii) Product of 68-75% s/s for depositing onto pastry or cake after baking and willnot soak into the base. Slow Set pectin such as Type 121, 621 or 622 should beused together with a proportion of glucose (corn) syrup. Production conditions aresimilar to those described for conventional preserves in large containers.

iii) Product of 50-70% s/s to be deposited hot onto already baked base andwhich sets on cooling to give a gelled, cuttable jam or jelly. Such systems whichinclude bakery glazes, make use of the heat reversibility and dilutability of gels basedon buffered amidated LM pectins such at type 1300B. Whilst normally containing onlylow levels of fruit or juice, specific recommendations are available depending uponthe exact requirements of use.

iv) Very stiff jam or jelly of 75-85% s/s for use as a biscuit filling after baking.Slow Set pectin should be used together with an operating pH of 3.2-3.5. Due to highsolids level more glucose (corn) syrup is used than with other bakery jams or jellies,certain special syrups being used ot over 50% of the total sugars.

LOW/REDUCED SUGAR

For jams and jellies of less than about 55% s/s, it is essential to use an LM pectin since HMtypes will not operate in this range. Whilst national regulations for these products varyconsiderably there are certain basic principles which are common to all systems.

TYPE OF PECTIN

Due to their greater tolerance of variations in operating conditions, amidated LM pectins aregenerally preferred to conventional types. Within each group, more calcium reactive types



should be used (i) at the lower end of the soluble solids range, (ii) when higher pH values arespecified, (iii) when a higher setting temperature is required, (iv) at lower fruit content, (v)when levels of available calcium are low and no more can be added, (vi) when more brittleand less elastic set is required. Conversely, less reactive pectins should be used when theseconditions are reversed.

LM Pectin Types

More Reactive Less Amidated 900 1000 2000 30004000

Conventional 170 172 173 174

QUANTITY OF PECTIN

The natural pectin is present in the fruit is high methoxyl and will contribute little or nothing tothe set of a low/reduced sugar jam. As a result neither the variety nor the amount of fruitused will have much effect on the quantity of LM pectin needed. Although the exact amountwill depend upon the ingredients and on the nature of product required, an addition of 0.7-1.0% is normal for amidated pectins and slightly higher for conventional types. In allsituations the LM pectin is best added as a predissolved solution.

PROCESSING CONDITIONS:

i) Calcium

Whilst it is essential to operate with the correct ratio of pectin to calcium, it must be notedthat this is the available rather than the total calcium in the system. As this cannot bemeasured analytically, the carrying out of preliminary trials is essential. In some systems,particularly those with a high fruit content, there will be sufficient available calcium whilst inothers a separate addition will be needed. This is best carried out at high temperatures

during the boil using solutions of a soluble calcium salt, such as the lactate or chloride.

ii) pH



A wider pH range is possible than with HM based products although, away from the optimumrange, other parameters such as pectin and calcium addition rates will need more precisecontrol. Whilst most products are made within range 3.0-4.0, no overall recommendationscan be given. Specific details are available on request.

iii) Soluble solids

As with conventional preserves, control is important. Due to the lower sugar concentrations aboiling point technique cannot be applied and use of a refractometer is essential.

iv) Filling temperature

To prevent separation of the fruit, containers must be filled only just above the settingtemperature of the system. With all LM pectins the actual setting temperature is a function of the system in which it is used and not an absolute property of the pectin itself. Unlike that of an HM the setting temperature of an LM pectin based system is independent of the rate of cooling, i.e., it is only the temperature and not temperature/time dependent.

Note Systems based on amidated pectin can often melt and reset on repeated heating andcooling, without significant loss in strength. This property is often referred to as heat or

thermo-reversibility.

v) Use of preservative

Since this type of product is not inherently self preserving once the container has beenopened, addition of a suitable permitted preservative may be advisable.

TYPICAL RECIPE

Ingredients



Strawberries 450g

A Sugar 405g

Water 100ml

B Amidated pectin type 2000 7g

Water 200ml

C Calcium lactate 5H2O 3% w/v soln 0-10ml

D Citric acid H2O 50% w/v soln 7ml

Final batch weight 1kg

pH 3.1-3.3

Soluble solids 45%

METHOD

Heat ingredients A together until sugar has dissolved. Add amidated pectin B, previously

dissolved in water at 55-70ºC using a suitable high speed mixer, and heat to boiling. Add Cfollowed by D and reduce to required soluble solids. Cool with stirring to 80ºC, fill into jarsand seal at once.

Notes

1. Set can be varied between soft and firm by altering calcium lactate withinquoted range.

2. Alter acid addition to maintain final pH of 3.1-3.3.

3. Preservative, if used, should be added at the very end of the process.

NO ADDED SUGAR



Products are now made in which the sugar has been replaced by concentrated fruit juice(normally apple or grape). These are mostly of below 55% s/s and require an LM pectin toachieve sufficient set. Due to the high level of fruit acids present from the concentrate, muchof the natural calcium present will be sequestered and therefore not available for gelation. To

overcome this one you can either use a pectin which is more calcium reactive or includeextra calcium in the form of a soluble salt such as lactate or chloride. In all other respectsthese products are similar to low/reduced sugar jams and jellies.

TYPICAL RECIPE

Ingredients

A Concentrated Apple Juice (70% s/s) 570g

Strawberries 450g

B Amidated Pectin Types 2200 5.5g

Water 200ml

C Sodium Benzoate 20% w/v soln 2.5ml

Final Batch Weight 1kg

pH approx. 3.0

Soluble Sodium 45%

METHOD

Heat ingredients A and add amidated pectin B, previously dissolved in water using a suitablehigh speed mixer. Bring to boil and reduce to required Soluble Solids. Add sodium benzoateand cool to 65ºC. Fill into jars and seal at once.



Notes

1. As this is a “no added sugar” product, the amidated pectin is one in whichcontains no standardising sugar (Type 2200 is the unstandardised version of Type

2000).

2. If set is too weak, either use a more calcium sensitive amidated pectin (Type1200) or add a quantity of suitable calcium salt (lactate or chloride – as solution).

3. Preservative is necessary in recipe due to the low setting/filling temperatureof the system. Mixture of conventional and amidated LM pectins will have a higher setting temperature and reduce the need for added preservative.

4. The concentrated fruit juice used should be kept consistent on order tominimise changes in sequestering power which would otherwise make formulationchanges necessary.

TRADITIONAL JAMSFAULTS AND FAILURES

In order to maintain sufficiently high quality standards when producing traditional jams andpreserves, the possession and regular application of three particular measuring instrumentsis strongly recommended. These are:-

i) An accurate thermometer up to at least 120ºC (248ºF)

ii) A refractometer calibrated directly in percent sugar solids and covering at leastthe range 55-70%.

iii) A pH meter capable of being read to the nearest 0.1 pH unit or better. For thistype of product, values are normally measured on a 50% solution (by weight).



Various problems which can occur in the manufacture of jams and their remedies arediscussed below:-

Possible cause Analysis/comments

A WEAK OR SLACK SET

1. Use of pectin which has been Check stock rotation. Refer

stored too long to pectin manufacturer if in doubt

2. Use of pectin which has been Store cool or dry. Refer to

stored under bad conditions pectin manufacturer if in doubt

3. Powder pectin not fully Solution should be smooth

dissolved before usewith no grittiness. Difficult to detectvisually in the finished product unlesssevere. Unlikely to cause setting problemsunless very severe. Check operatingprocedures

4. Use of stale pectin solution Solution is best used on day of preparation. Pectin enzymes can act very quickly.

5. Thermal degradation of pectin If prepared hot, pectin solution should

solution either be used immediately, or cooled to40ºC or below as soon as possible.

6. Low soluble solids content.Check final product with

refractometer. Results from insufficientboiling (note: compositional and labellingregulations).

7. (Open Pan Boiling only) Check recipe formulation for the amountExcessive boiling time of water to be removed by boiling. May

leading to breakdown also result in excessive sugar



of pectin. inversion when a high proportion of sucrose is used.

8. Incorrect pH:

(a) During boil Too low pH can lead to increasedbreakdown of pectin and in extreme cases

to pregelation in the boil.

(b) In the finalproduct Within the pHrange of satisfactory gelation (which isdetermined both by pectin type used andcomposition of sugars present) a lowering of pH will produce a faster and slightly stronger set. Below this range pregelation (possibly

even in boil) and syneresis may occur, whilsteven slightly above it little or no set will beobtained. Optimum pH values for gelationare higher for fast setting pectins than for slow setting.

9. Filling at too low a temperaturePartial setting before or during filling,

may result in a lumpy, grainy or broken settogether with possible syneresis. Check byobservation whilst filling. A slower settingpectin may be required.

10. Movement of filled containers May result in a broken set and syneresis.

before setting is completed

11. Filling at too high a temperature. Slow cooling at centre of container can(large container only) lead to thermal

degradation of the pectin together with possible caramelisation andhigh levels of sugar inversion. Can also occur

if a number of smaller containers are packed together whilst still too hot(“stack burn”).

12. Insufficient pectin added Should be considered only when other

factors are checked. May be due to either adeficiency or the low grade of the naturalpectin extracted from the fruit duringcooking. Cannot be determined by directanalysis of the fruit itself. Actual pectin



requirements can best be determined bypreparation of trial production batch.

B TOO FIRM SET

1. Too much added pectinIn extreme cases may lead to prematuresetting. Correct addition cannot bedetermined by direct analysis of the fruititself. Preparation of trial batch isrecommended.

2. Too much natural fruit pectin.In systems containing high level of good

quality fruit, the fruit itself can provide toomuch pectin even without any being added.Should be detected in trial batch. Problem israre and the best remedy will depend uponexact circumstances.

3. High soluble solids content. Results from over boiling. Check finalproduct with refractometer.

4. Incorrect pH in final product.Within the pH range for gelation,

a raising of pH will result in a slower and

slightly weaker set.

C SYNERSIS

1. Use of pectin which has been Check store rotation. Refer to

stored for too long pectin manufacturer if in doubt.

2. Use of pectin which has been Store cool and dry. Refer to

stored under bad conditions. manufacturer if in doubt.

3. Powder pectin not fully Solution should be smooth, with no

dissolved before use. grittiness. Difficult to detect visuallyin finished product unless severe. Unlikely tocause syneresis unless very severe. Check operating procedures.



4. Use of stale pectin solution. Solution is best used on day of preparation. Pectin enzymes can act very quickly.

5. Thermal breakdown of If prepared hot, pectin solution should

pectin solution. be used immediately, or cooled to 40ºC or

below as soon as possible.

6. Insufficient added pectinWeak setting can be associated withsyneresis. Maybe due to either a deficiencyor the low grade of the natural pectinextracted from fruit during cooking. Shouldbe detected in trail batch.

7. Low soluble solids content. Check final product with refractometer.Results from insufficient boiling.

8. Excessive boiling time Check recipe formulation for the amount

leading to breakdown of of water to be removed by boiling.

pectin (Open Pan Boiling only)

9. Incorrect pH in final product

(a) too low If pH is below range satisfactory gelation,pregelation can result in syneresis even

without significant loss in strength of set.

(b) too high If pH is above range for satisfactorygelation, weak setting can be associatedwith syneresis.

10. Filling at too low atemperature Partial setting beforeor during filling can result in syneresistogether with lumpy grainy or broken set.Check by observation whilst filling. A slower setting pectin may be required.

11. Movement of filling containers May also result in broken set.

before setting is complete

12. Difference in solids content Fruit pieces having the lower solids

between fruit and the content will slowly exude moisture to try



surrounding geland reach equilibrium with the gel. Check,using refractometer, soluble solids content of fruit and surrounding gel. Normally will onlyresult from faulty technique, and should bedetected in a trial batch.

13. High calciumlevels Unlikely to occur except with poor quality fruit when using slowsetting pectin. Check hardness of water andcalcium content of ingredients.

D FRUIT SEPARATION (FLOATING OR SINKING)

1. Use of pectin which is too Should be detected in trial batch.

slow setting Considered use of faster setting pectin.

2. Weak set due to low Check possible causes of weak

a setting temperature set as per section A.

3. Filling at too high atemperature Check fillingconditions. Unless containers are heat

treated after filling and sealing, excessivelowering of filling temperatures can lead tomicrobiological problems.

4. Use of fruit with high content Unlikely to be found except with

of slow setting pectin poor quality fruit or sulphited fruit whichhas been stored for too long. Consider use of

faster setting pectin.

5. Incorrect pH Fruit pieces having lower solids contentmay tend to float. Normally will only result

from faulty technique in not allowing penetration sugar into the fruit.Unlikely to produce separation by itself but will magnifythe effect due to any of the other causes listed.

6. Differences in solids content Fruit pieces having the lower solids

between fruit and surrounding content may tend to float. Normally



gel. will only result from faulty technique in notallowing penetration of sugar into the

fruit. Unlikely to produce separation byitself but will magnify the effect due to

any of the other causes listed.

E INCLUSION OF FOAM AND/OR BUBBLES

1. Excessive rapid setting produced by:

(a) Use of too fast setting pectin. use a slow setting pectin.

(b) Use of too much pectin. Set will be too firm.

(c) Filling at too low a temperature Check by observation whilst filling.

leading to premature setting.

(d) Too low pH. Check pH

(e) High solids content due Check using refractometer.

to overboiling.

Any of the above may prevent the release of any air bubbles or foam trapped in the product.These are not the only possible causes as faulty technique, particularly during filling canoften be responsible.

F CRYSTALLISATION

1. Too much inversion resulting Check reduced sugar content. May

in the formation of dextrose take some time to be initiated but

crystals. is likely to become more pronounced withlength of storage. Possible causes are: (a) too

low pH, (b) excessive boiling time, (c) too long standing before filling andcooling, (d) too much invert sugar added, (e) (large

container only), filling at too high atemperature also produces a poor set and



darkening at centre of the container. Over inversion is also likely to produce a somewhat cooked or syrupy flavour.

2. Formation of dextrose crystals Check recipe formulation.

due to use of added dextrose

monohydrate

3. Too little inversion resulting Check reducing sugar content. Is

in the formation of sucroselikely to become more pronounced crystals.with length of storage. Due to (a) too highpH, (b) too short a boiling time, (c) addition of too little inverted sugar or glucose syrupnormally only found under vacuum boilingconditions, but may also occur with fruit of low acidity under fast boiling, open panconditions.

4. Grape jelly only Check recipe formulation.

Crystals of tartar (potassium

hydrogen tartrate).

G COLOUR DEFECTS

1. Excessive boiling time Check recipe formulation for the

leading to caramelisation amount of water to be removed by boiling.May also lead to pectin breakdown or the

formation of too much invert sugar.

2. (Large containers only) Check centre for high invert sugar

Incorrect filling technique content. The centre may also show



resulting in darkening at a weak set.

centre of container.

3. Poor quality fruit Check fruit pulp visually. Many types of fruit show browning when over-ripe or

bruised.

4. Discoloured pulp. May be masked by Sulphur dioxide. Truecolour is not apparent until the

preservative has been removed by boiling.Strawberries are very susceptible to this.

5. Metallic contamination of Chemical analysis necessary.

product either from the fruit Various metals including tin,

or from the processing equipment copper, zinc, if present in excessive

quantities, may cause considerable haze or discoloration.

6. Cloudiness due to phosphates, Chemical analysis necessary. Most

oxalates or other insoluble salts noticeable in jellies and jelly

of calcium or magnesium. marmalade. Hard water may be partly

responsible.

7. Excessive buffer salts (either Check ingredients and recipe. May

natural or added). also delay or prevent setting.

H TOUGH FRUIT

1. Cooking of certain fruits in Blackcurrants and the peel of all

syrup without pre-boiling. citrus fruits will not absorb sugar

unless pre-boiled in water without

sugar for 10-15 minutes.

2. Use of hard water for Hard water will toughen skins and

pre-boiling. peel rather than soften them.



I MICROBIOLOGICAL FAULTS

1. (Non-hermetically sealed containers Microbiological tests necessary, e.g.

only) Storage under conditions of staining, culturing, under the

too high relative humidity or microscopic examination, etc. In

temperature. general, non-hermetically sealedcontainers (ie, those with non-vacuum

closures and most of those made from

plastic) have a much shorter shelf life.

2. Low Solids Content due Check soluble solids content with

to insufficient boiling refractometer. Danger levelbelow 68% if not hermetically sealed.

For hermetically sealed containers

danger level below 65% soluble

solids particularly if contaminated

before or during sealing.

3. Contamination of container Microbiological test necessary.

or closure before or during (a) certain moulds can grow even

seal. though the solids content is greater

than 68%. (b) Any condensation under the closure locally lowers the solids

content and permits the growth of any

yeast or mould spores already present.(c) Too low a filling temperature may

allow contamination to occur.

4. (Hermetically sealed

containers only):

(a) absence of vacuum (a) faulty containers



under closure (b) faulty closure

(c) faulty techniques, e.g. quantity of preserves on lip of container.

5. (vacuum boiling only) Microbiological tests necessary.

Insufficient sterilisation. Check processing temperatures.

J OTHER FAULTS

1. Flavour loss on storage. Frequently experienced with plasticcontainers (polystyrene polypropylene, etc) due

to their porosity.

2. Off-flavours.

(a) Contamination before or during sealing

(b) (plastic containers only) pick up of chemicals in the preparation of theplastic-solvents, plasticisers, etc)

(c) Salty taste due to high concentration of buffer salts.

60337484 an introduction to pectin

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