optimization of cornstarch/xanthan gum content … of... · optimization of cornstarch/xanthan gum...

OPTIMIZATION OF CORNSTARCH/XANTHAN GUM CONTENTFOR THICKENING OF COCOA SYRUPS

MAREK SIKORA1,4, STANISŁAW KOWALSKI1, MAGDALENA KRYSTYJAN1,JAN KRAWONTKA2 and MAREK SADY3

1Department of Carbohydrate Technology

2Department of Mathematical Statistics

3Department of Animal Products TechnologyUniversity of Agriculture

30-149 Krakow, ul. Balicka 122, Krakow, Poland

ABSTRACT

Blended cornstarch–xanthan gum systems were optimized for thickeningof cocoa syrups. For this purpose the sensory (whole and partial), textural(force of penetration, adhesiveness and stringiness) and rheological proper-ties (flow curves as well as viscosity/time and viscosity/temperature relation-ships) of cocoa syrups were studied.

Flow curves were described by rheological model of Casson, whichaccounted syrups under study for non-Newtonian, pseudoplastic and thixotro-pic fluids. Also models of Weltman and Arrhenius were applied for comparisonof obtained data. The areas of thixotropy hysteresis loops were also calculated.

Obtained data (sensory, textural and rheological) were used as a basefor mathematical calculations. The results were presented in the tables toenable their easier understanding. As a result, optimization of thickeners wasachieved – the best ranges of cornstarch (0.45–0.49%) as well as xanthan gum(0.15–0.17%) concentrations in cocoa syrups were selected.

PRACTICAL APPLICATION

The result of this study could be used as a guide for thickening of cocoasyrups by the application of cornstarch–xanthan gum combination, chemicallynonmodified thickeners. Mathematical method tried in this study for

4 Corresponding author. TEL: +(48 12) 662-47-74; FAX: +(48 12) 662-47-47; EMAIL: [email protected]

Journal of Food Quality 30 (2007) 682–702. All Rights Reserved.© 2007, The Author(s)Journal compilation © 2007, Blackwell Publishing

682

optimization of thickeners addition could be useful for optimization of theother thickeners and additives employed for different sauces, syrups, dress-ings, ketchups, mayonnaises, etc.

INTRODUCTION

Cocoa syrups are used as additives and decoration of fruit salads, pan-cakes, ice creams, desserts and cooked rice, enhancing their taste and aestheticqualities. Different thickeners can be applied for granting the textural, sensoryand rheological properties of syrups. In the previous papers, the use of suchpolysaccharide hydrocolloids as agar, carrageenan, carboxymethyl celluloseand xanthan gum in diversified concentrations for thickening of cocoa syrupswas proposed (Sikora et al. 2003a). For stabilization, thickening and texture-providing modified starches, such as acetylated distarch adipate and oxidizedstarch were also tested (Sikora et al. 2004).

Several benefits in controlling texture and sensory properties of food-stuffs, rheology of aqueous solutions of hydrocolloids come frompolysaccharide–polysaccharide interactions in their blends. By the use ofblends of native starch and xanthan gum, it is possible to obtain food withappropriate features. This kind of blends is an alternative solution as opposedto more expensive and often criticized chemically modified starches (Kulickeet al. 1996).

According to Tolstoguzov (2003) thermodynamic compatibility betweenpolysaccharides governs their intermolecular interactions. For example, whenstarch is concerned, two amylose molecules in aqueous solution tend to formorganized structures, because of their good compatibility. As a result retro-gradation occurs (Fredriksson et al. 1998), which is not a very desirablephenomenon in food technology. On the other hand, because of imperfectthermodynamic compatibility, retrogradation of amylopectin slows down(Gudmunsson 1994). Amylose and amylopectin in aqueous phases separatebecause of lack of thermodynamic compatibility between both polysaccharideconstituents (Kalichevsky et al. 1986; Lii et al. 2002).

Numerous studies on the properties of polysaccharide combinations havebeen published, because the prediction of any results of polysaccharide blend-ing is difficult. The results of such studies of the polysaccharide blends withstarches being one of the component of the blend have been reviewed bySikora and Kowalski (2006). Authors of the same research group have pub-lished many papers on the application of thickening blends in different foodsystems, e.g., sweet and sour sauces (Sikora et al. 2003c,d; Gibinski et al.2006a), mayonnaises (Gibinski et al. 2006b) and dessert sauces (Sikora et al.2006).

683OPTIMIZED CORNSTARCH/XANTHAN GUM CONTENT IN COCOA SYRUPS

An influence of starch–xanthan gum thickening systems on sensory,textural and rheological properties of cocoa syrups was also studied by Sikoraet al. (2003b). In this work (Sikora et al. 2003b), potato, as well as corn-starches in combinations with xanthan gum, was tried as thickening systems.As a result it was concluded that combinations of cornstarch with xanthan gumwere more suitable for thickening of cocoa syrups than those of potato starchwith xanthan gum.

The aim of the present work was to find an optimized composition ofthickeners’ combination. This combination was selected on the basis of theprevious publications concerning cocoa syrups and thickening systems (Sikoraet al. 2003a,b, 2004). Although all thickening systems tried in the previouspapers were more or less applicable, the selection of the combinationcornstarch–xanthan gum allowed to achieve stability of the systems and toavoid the need of declaration of the additives of restricted application in finalproduct. Such kind of optimization could be also useful for people working inthe practice production.

MATERIALS AND METHODS

Materials

Low saccharified starch syrup (ZPZ Wronki Ltd., Wronki, Poland),sucrose (sugar factory Siennica Dolna, Siennica Dolna, Poland), cocoapowder, fat content 10–12 g/100 g (Maspex Wadowice Ltd., Wadowice,Poland), sunflower oil (ZPT Warszawa S.A., Warszawa, Poland), cornstarch,cat nr. 4126 (Sigma Co, St. Louis, MO), lecithin (E 322, Jungbunzlauer,Vienna, Austria), xanthan gum (E 415, Jungbunzlauer) and distilled waterwere used in the study.

Methods

Cocoa Syrup Recipe Draw Up. Xanthan gum was blended with sucroseand dissolved in 2/3 of total water quantity by intensive mixing (300 rpm) inlaboratory homogenizer (Janke & Kunkel, IKA Werke GmbH, Staufen,Germany) in order to avoid clumping. Starch suspended in the rest of waterwas blended with xanthan gum/sugar solution. The blend was heated in waterbath (60 min, 95C). Then, starch/xanthan gum gel was blended with cocoapowder and sunflower oil (200 rpm, 70C, 60 min; Janke & Kunkel, IKAWerkeGmbH). During blending 0.01 g/100 g emulsifier (lecithin) was added andintensive mixing followed (200 rpm, 20 min). Carefully blended syrup wascooled at room temperature with continuous mixing (200 rpm, 20C, 20 min).

684 M. SIKORA ET AL.

Distilled water was used during the preparation of all samples. For thickeningof syrups, experimentally, by the use of trial and error method, variablequantities of both xanthan gum and cornstarch were applied. Such procedurewas introduced in order to obtain the consistency that allowed pouring ofsyrups from the container and parallely not fully flowing down from theproduct. Thus, xanthan gum (0.05–0.3%) and cornstarch (0.3–0.5%) weretried in relatively wide ranges. In weight percentage term, the share of par-ticular ingredients of syrups was as follows: starch syrup 54.19–54.64%,sucrose 8%, cocoa powder 4%, sunflower oil 1%, lecithin 0.01%, cornstarch0.3–0.5%, xanthan gum 0.05–0.3% and water 32%.

Sensory Analyses. The panel of 10 preliminary tested and subsequentlytrained experts carried out sensory analyses (Polish Standard PN-ISO 1996,1998a,b). Sensory analyses were conducted in two tests – whole and partial. Inthe whole sensory analysis of cocoa syrups, a five-point method was applied(Barylko-Pikielna 1975). Quality factors such as color, gloss, consistency,aroma and flavor were estimated. In order to define the share of particularquality factors, weighting coefficients were arbitrarily fixed: color, 0.15; gloss,0.10; consistency, 0.30; aroma, 0.10; and taste, 0.35. Taste and consistencyobtained relatively higher weighting coefficients because the first one influ-ences decisively consumer preferences, and the other one influences texturaland rheological features of syrups under study.

Partial sensory analysis was introduced in order to underline the role oftexture and rheology in determination of cocoa syrup’s quality (Barylko-Pikielna 1975; Surmacka-Szczesniak 1995; Polish Standard PN-ISO 1999),and its connection with thickeners’ blends used. In this test, five arbitrarilychosen parameters (viscosity, stringiness, sandiness, adhesiveness and mouth-feel) were defined and analyzed by five-point method. All the parameters hadequal weighting coefficients (Sikora et al. 2003a,b).

Both whole and partial sensory analyses were conducted by comparison ofthe quality features of the analyzed samples to those defined in previouslyprepared standard cards (calibration cards no. 1 and no. 2, seeAppendices 1 and2). The tasters were asked to compare the features of syrups with the sensoryattributes defined in the standard cards. Every attribute in the card was carefullydetermined and characterized by five descriptors. The task of the panelist was toevaluate each feature of the syrup, and to connect it with appropriate descriptor.Every descriptor had suitable quantity of points in the 5-point scale – from 1(bad quality) to 5 (excellent quality) (Barylko-Pikielna 1975).

Penetration Test. Penetration test was conducted by the use of textureanalyzer, equipped with ball probe P/1S, diameter 25.4 mm, speed 1 mm/s,temperature 20C (TA-X 2, Stable Micro Systems, Haslemere, U.K.). From


multiple parameters obtained during measurement, only three of them – forceof penetration, adhesiveness and stringiness – were chosen and used for theoptimization of cocoa syrups’ thickeners. The test was repeated several times(five to seven) and obtained data were averaged (Bourne 2002).

Rheological Study. Rheological measurements were conducted by theuse of Searle type rheometer RheoStress RS 1 (Gebrueder Haake GmbH,Karlsruhe, Germany), controlled by the program RheoWhin, v.2.7, measuringsystem – Z 41/ Z 43. In the study, four tests were applied.

Flow Curve Determination CR (Controlled Rate of Shear). Measure-ments were conducted at 25C. The rate of shear was changed from 0 to 300/s,during 600 s, followed by the constant rate of shear 300/s for 60 s, andsubsequent decrease of shear rate from 300 to 0/s, during 600 s. From CR testthe areas of thixotropy hysteresis loops were calculated.

Flow Curve Determination CS (Controlled Shear Stress). Measurementswere conducted at 25C by changing shear stress from 0 to 600 Pa, during600 s. Flow curves obtained from the tests were described by the Cassonmodel (Steffe 1996; Schramm 1998).

Viscosity Changes during Shearing. By the use of this test, the apparentviscosity changes during 3,600 s of shearing, at the constant shear of 100/swere determined. Measurements were conducted at 25C. Obtained data weredescribed with the model of Weltman (Rao 1999).

Viscosity versus Temperature Changes. The changes of apparent viscos-ity versus temperature were determined. The measurement was conducted inthe temperature range from 8 to 30C, during 3,600 s. Experimental data weredescribed by the Arrhenius equation (Rao 1999). All the rheological measure-ments were conducted at least in duplicates.

Statistical Analyses. Firstly, simple relations between sensory, textural,rheological features and cornstarch as well as xanthan gum content wereestimated. For this reason simple correlation coefficients between aforemen-tioned features (sensory, textural and rheological) and thickeners (cornstarch,xanthan gum) content were calculated. This allowed in the next step an optimalstarch and xanthan gum content to be indicated.

The start point in the search of optimum was the description and evalu-ation of analyzed relations with the help of multidimensional functionz = f(x,y), where z is the analyzed feature, x the cornstarch content and y thexanthan gum content.


An excellent and helpful tool was polynomial of second grade, with thegeneral equation:

z x y x xy y= + + + + +a a a a a a0 1 2 32

4 52

For this kind of equation, multiple correlation coefficients were calculated, andthe results were examined with the test of Fischer, at significance level,P = 0.05. An introduction of such tool was justified by simple use for practiceand interpretation possibilities. Another advantage of polynomial of secondgrade was the fact that the function of this type is continuous, differentiable,and in this way fulfils the condition necessary and sufficient for existence of anextreme. The spot of an extreme was possible by equilibration of partialderivatives of this function to zero. In sensory assessment, the pursuit toachieve maximum score of every quality factor analyzed was the main goal.In this situation, it was enough to solve the system of equations of partialderivatives:

∂∂

=∂∂

=z

x

z

y

0 0, ,and

for fixed function:

z x y x xy y= + + + + +a a a a a a0 1 2 32

4 52,

which after transformation has the form:

a a a

a a a3 4

3 4

1

2

2 0

2 0

+ + =+ + =

⎧⎨⎩

x y

x y .

From this it follows that the optimum could be achieved if:

x

y

=− +

−

=−

−

⎧

⎨⎪⎪

⎩⎪⎪

2

4

2

4

1 5 2 4

3 5

1 4 2 3

3 5

a a a a

a a a

a a a a

a a a

42

42 .

For these functions the extreme points and optimum ranges were calcu-lated. Computer programs such as Microsoft Excel and Statistica (Stat SoftInc., Tulsa, OK) were employed for statistical analyses. In case certain features


of the function fitted did not achieve extreme values, in the frames of experi-mental data, extreme values were searched at an additional assumption, thatcornstarch, as well as xanthan gum levels, was in the range foreseen in theexperiment. An efficacious and sufficient tool for that was an appendix Solverfrom the program Microsoft Excel.

RESULTS

Sensory Results

The results of whole sensory analyses are presented in Table 1 and thoseof partial sensory analyses, in Table 2.

Total scores of whole sensory analyses oscillated in the range 3.5–4.4,while an addition of 0.3% cornstarch lowered this range to 3.5–3.94, and anaddition of 0.4 and 0.5% cornstarch raised these ranges to 3.94–4.4, and4.14–4.35, respectively.

TABLE 1.RESULTS OF WHOLE SENSORY ANALYSES OF COCOA SYRUPS

Syrup thickened by Quality factor Totalscore

Consistency(0.30)*

Color(0.15)*

Gloss(0.10)*

Aroma(0.10)*

Taste(0.35)*

0.3% CS 0.05% XG 3.0 4.0 3.7 3.7 3.6 3.500.3% CS 0.10% XG 3.0 4.0 4.3 4.1 3.5 3.690.3% CS 0.15% XG 3.9 4.4 4.3 3.5 3.7 3.910.3% CS 0.20% XG 3.7 4.4 3.8 3.7 3.7 3.820.3% CS 0.25% XG 3.8 3.9 4.0 3.9 3.9 3.890.3% CS 0.30% XG 3.8 4.0 4.2 4.1 3.9 3.940.4% CS 0.05% XG 3.8 4.1 4.0 3.8 4.0 3.940.4% CS 0.10% XG 4.3 4.2 4.2 3.9 4.3 4.240.4% CS 0.15% XG 4.0 4.4 4.3 4.0 4.3 4.200.4% CS 0.20% XG 3.9 4.6 4.6 4.0 4.1 4.160.4% CS 0.25% XG 4.5 4.5 4.6 4.0 4.3 4.400.4% CS 0.30% XG 4.2 4.9 4.5 4.3 4.2 4.350.5% CS 0.05% XG 4.2 4.0 4.4 3.9 4.3 4.200.5% CS 0.10% XG 4.1 4.2 4.4 4.0 4.4 4.240.5% CS 0.15% XG 4.1 4.5 4.7 4.1 4.0 4.190.5% CS 0.20% XG 3.9 4.7 4.7 3.9 4.0 4.140.5% CS 0.25% XG 4.2 4.8 4.5 3.8 4.0 4.210.5% CS 0.30% XG 3.8 4.4 4.4 4.0 4.3 4.16

* Weighting coefficient.CS, cornstarch; XG, xanthan gum.


Simple correlations of sensory features with starch as well as xanthan gumcontent are shown in Table 3, whereas parameters of second-grade polynomialand optimal values of starch and xanthan gum content are shown in Table 4.

Statistical analyses resulted in the conclusion that simple correlations ofsensory features with starch as well as xanthan gum content were small, andstatistically significant relations concerned not all features. Similar resultswere presented in our previous paper (Sikora et al. 2003b). From Table 3 onecan conclude that aroma, viscosity and sandiness were not related to neitherstarch nor xanthan gum content.

The aim of the subsequent statistical analysis was an evaluation of cur-vilinear interrelations between analyzed sensory features and starch as well asxanthan gum content, and indication of the optimal content of thickeners. Asan example of such analyses for the feature “consistency,” the followingequation was obtained:

z x y x xy y= + − − −29.033 12.536 29.167 19.714 10.238 22

For this equation, the coefficient of multiple correlation (R = 0.314) andcalculated test of Fischer (F = 3.815) showed statistically significant relations.

TABLE 2.RESULTS OF PARTIAL SENSORY ANALYSES OF COCOA SYRUPS

Syrup thickened by Quality factor Totalscore

Viscosity Stringiness Sandiness Adhesiveness Mouthfeel


CS, cornstarch; XG, xanthan gum.


It is worth to add, that between the sensory features only “aroma” did not showstatistically significant relations at such function-type description. In theaforementioned function, the extreme value of consistency (4.24 points) wasachieved at 0.43% cornstarch, and 0.20% xanthan gum.

The other parameters obtained in both sensory analyses (whole andpartial) were treated in the same way. Parameters of experimental equations ofthe second-grade polynomial, concerning sensory features and optimal solu-tions of these equations (optimal values of cornstarch and xanthan gumcontent) are presented in Table 4.

Penetration Test

The results of penetration experiments are shown in Table 5. Force ofpenetration of the syrups under study varied with cornstarch concentration,

TABLE 3.COEFFICIENTS OF SIMPLE CORRELATION OF SENSORY,

TEXTURAL AND RHEOLOGICAL FEATURES –PARAMETERS WITH CORNSTARCH AND XANTHAN

GUM CONTENT

Sensory features Cornstarch Xanthan gum

Consistency 0.20 –Color 0.17 0.18Gloss 0.29 –Aroma – –Taste 0.24 –Viscosity – –Stringiness – 0.16Sandiness – –Adhesiveness – 0.43Mouthfeel – -0.21

Textural parametersForce of penetration – 0.93Adhesiveness – 0.75Stringiness -0.35 0.43

Rheological parameters*Area of thixotropy 0.35 0.48

A (Weltman’s parameter) 0.46 0.71B (Weltman’s parameter) 0.37 0.62Frequency factor 0.50 0.64Energy of activation · 105 – -0.55Yield stress – 0.88Viscosity of Casson 0.62 –

* Rheological parameters are described in the text.“–” denotes no correlation.


TAB

LE

4.PA

RA

ME

TE

RS

OF

SEC

ON

D-G

RA

DE

POLY

NO

MIA

LA

ND

OPT

IMA

LV

AL

UE

SO

FC

OR

NST

AR

CH

AN

DX

AN

TH

AN

GU

MC

ON

TE

NT

Feat

ure

Poly

nom

ial

equa

tion

para

met

ers

Opt

imum

valu

es

a 0a 1

a 2a 3

a 4a 5

Star

chX

anth

angu

mO

ptim

umsc

ore/

resu

lt

Sens

ory

feat

ures

Con

sist

ency

-3.2

629

.03

12.5

4-2

9.17

-19.

71-1

0.24

0.43

0.20

4.24

Col

or1.

2213

.43

2.26

-17.

5012

.29

-15.

710.

470.

264.

69G

loss

1.45

9.40

6.61

-8.3

3-2

.29

-13.

330.

500.

204.

64A

rom

a1.

6610

.20

0.87

-10.

83-5

.43

5.95

0.40

0.30

4.15

Tast

e-1

.60

23.5

74.

03-2

3.33

-13.

717.

380.

420.

204.

32V

isco

sity

5.40

-16.

3321

.85

23.3

3-1

7.14

-40.

240.

300.

214.

32St

ring

ines

s9.

18-3

8.93

27.5

050

.83

-12.

29-5

8.81

0.30

0.20

4.47

Sand

ines

s-0

.04

18.0

76.

65-1

8.33

-22.

298.

100.

320.

304.

45A

dhes

iven

ess

4.72

-12.

7717

.98

16.6

7-5

.14

-31.

190.

300.

264.

62M

outh

feel

3.12

4.73

1.82

-4.1

7-9

.43

-0.2

40.

500.

054.

31

Rhe

olog

ical

para

met

ers

Are

aof

thix

otro

py6,

721

-37,

271

17,1

7554

,795

-20,

627

-14,

398

0.40

0.30

1,96

1A

(Wel

tman

’spa

ram

eter

)11

5.6

-601

.035

1.4

958.

1-1

09.6

-263

.00.

330.

2278

.8B

(Wel

tman

’spa

ram

eter

)5.

13-3

5.56

30.2

057

.74

-33.

87-2

6.29

0.38

0.21

2.44

Freq

uenc

yfa

ctor

0.15

5-0

.072

1.86

62.

076

0.38

80.

084

0.50

0.09

0.83

Ene

rgy

ofac

tivat

ion

·105

3.13

8-7

.466

-1.6

269.

313

3.93

3-3

.257

0.38

0.13

1.57

1Y

ield

stre

ss11

.43

-31.

3319

0.60

54.2

1-1

50.2

4-2

16.3

10.

500.

1722

.6V

isco

sity

ofC

asso

n0.

314

-1.2

80-0

.329

2.07

51.

161

0.38

30.

470.

050.

19

Pene

trat

ion

test

Forc

eof

pene

trat

ion

0.12

8-0

.059

0.03

40.

120

-0.0

280.

375

0.43

0.19

0.14

3A

dhes

iven

ess

0.11

4-0

.346

0.82

80.

321

-0.2

64-0

.591

0.50

0.19

0.13

3St

ring

ines

s20

.84

-44.

5738

.84

42.1

75.

09-8

2.90

0.50

0.30

14.0


e.g., for 0.30% cornstarch – in the range 0.125–0.157 N, and for 0.40 and0.50% cornstarch – in the ranges 0.125–0.170 N and 0.128–0.166 N, respec-tively, and increased, however irregularly, with an increase of xanthan gumcontent in the blends.

Adhesiveness of syrups varied from 0.028 to 0.242 N · s, while highervalues were achieved at higher levels of xanthan gum, irrespectively to starchcontent. Stringiness also changed irregularly in the range 9.3–17.2 s, whilelower values of this parameter were achieved at rather lower xanthan gumcontent (Table 5). Similar irregularity of stringiness was observed by Sikoraet al. (2003b).

Simple correlations of penetration parameters with cornstarch andxanthan gum content were, as a rule, more powerful than those of sensoryfeatures. Simple correlation coefficients of penetration parameters with corn-starch and xanthan gum content are presented in Table 3.

The consecutive analysis was done in order to evaluate the curvilinearcorrelations between textural parameters searched (force of penetration, adhe-siveness and stringiness), and cornstarch as well as xanthan gum content, anddetermination of the optimum combination of thickeners. By the optimizationof penetration parameters, the attempts were made to find such cornstarch and

TABLE 5.RESULTS OF PENETRATION TEST OF COCOA SYRUP

Force of penetration [N] Adhesiveness [N · s] Stringiness [s]

Average SD Average SD Average SD


CS, cornstarch; XG, xanthan gum.


xanthan gum combination, which would enable to achieve the medium results.These medium results should characterize the best syrup textural parameters.At the evaluation of feature force of penetration, the following equation wasfound:

z x y x xy y= − + + − +0.128 0.059 0.034 0.12 0.028 0.375 ,2 2

for which coefficient of multiple correlation (R = 0.960) and calculated test ofFischer (F = 70.99) showed statistically strong, significant dependence. Anoptimum point for this function was found at 0.43% cornstarch and 0.19%xanthan gum. Near-optimal results included layer close to 0.20% xanthan gum,in whole range of cornstarch content. In Table 4, the parameters of experimentalequations of second-grade polynomial, concerning penetration results, as wellas optimal solutions of these equations are shown. Sudhakar et al. (1995)presented and described the effect of decrease of rheological and texturalparameters in the presence of high levels of sugars in the system. This level wasequally high in our experiment; however, in this case the total concentration ofcornstarch and xanthan gum was higher. This means that thickeners played amore important role in the systems and observed increase of texture profileanalyses parameters with the level of thickeners could be justified.

Rheological Results

The results of rheological measurements are presented in Table 6. Allsyrups showed non-Newtonian, pseudoplastic properties and thixotropy hys-teresis loops. The biggest area determined by the thixotropy hysteresis loop(3,817 W/m3) exhibited syrup thickened by 0.5% cornstarch and 0.10%xanthan gum, and the smallest (918 W/m3) thickened by 0.4% cornstarch and0.05% xanthan gum.

Among cocoa syrups the lowest value of parameter A of Weltman’sequation, reflecting shear stress in the first second of the test (Steffe 1996), hadsyrup thickened by 0.4% cornstarch and 0.05% xanthan gum (37.5 Pa), whichwas confirmed by its smallest yield stress (14 Pa) calculated from the model ofCasson. This syrup had also the lowest value of Weltman’s parameter B, whichreflects the stability in time, and the thixotropic behavior of the sample.Indeed, this value was confirmed by the smallest thixotropy area. The highestvalues of Weltman’s parameters A and B had syrups containing 0.5% corn-starch and 0.10, 0.25 and 0.30% xanthan gum, as well as 0.4% cornstarch and0.30% xanthan gum. However, these results were not confirmed by extremelyhigh values of yield stresses calculated from the model of Casson (Table 6).Changes of apparent viscosity described by the parameters of Arrhenius equa-tion (Steffe 1996), connected to changes of temperature are presented in


Table 6. The highest value of activation energy of flow (E) and one of thehighest frequency factors (h•) had syrup thickened by 0.5% cornstarch and0.10% xanthan gum. The interdependencies of rheological parameters oncornstarch/xanthan gum content are stronger than those of sensory features,which is clearly shown with the help of simple correlation coefficients, pre-sented in Table 3. Summarizing evaluation at this step, one can admit that inspite of bigger repeatability of data, sensory results did not give such confi-dence like rheological and textural ones.

The aim of the subsequent analysis was an evaluation of curvilinearcorrelations between rheological parameters searched (area of thixotropy hys-teresis loop, yield stress, Weltman’s parameters A and B, energy of activation,etc.; Steffe 1996) and cornstarch, as well as xanthan gum content, and deter-mination of the optimum content of thickeners combination. By the optimi-zation of rheological parameters (similarly to textural ones), the attempts weremade to find such cornstarch and xanthan gum content, which would enable toachieve the medium results. At the evaluation of an area of thixotropy hyster-esis loop, the following equation was found:

TABLE 6.RESULTS OF RHEOLOGICAL MEASUREMENTS OF COCOA SYRUPS

Area ofthixotropy

Model of Weltman Model of Arrhenius Model of Casson

A B h8 E ¥ 10-3 to hC

0.3% CS 0.05% XG 1,160 40.0 1.02 0.453 173.7 14.7 0.1050.3% CS 0.10% XG 1,458 49.2 1.29 0.507 154.5 20.0 0.1320.3% CS 0.15% XG 1,464 67.1 1.32 0.767 163.6 20.6 0.1760.3% CS 0.20% XG 2,056 75.9 2.86 0.682 149.8 26.7 0.1330.3% CS 0.25% XG 2,521 86.9 3.61 0.772 142.9 31.4 0.1310.3% CS 0.30% XG 2,430 85.1 2.90 0.844 136.1 31.7 0.1310.4% CS 0.05% XG 918 37.5 0.91 0.439 175.1 14.0 0.1140.4% CS 0.10% XG 1,542 60.4 1.72 0.683 162.2 18.4 0.1720.4% CS 0.15% XG 1,296 60.7 1.39 0.741 136.9 20.8 0.1560.4% CS 0.20% XG 1,742 75.1 2.38 0.748 175.5 27.0 0.1310.4% CS 0.25% XG 2,130 87.1 2.95 0.940 122.3 28.1 0.1740.4% CS 0.30% XG 1,947 113.6 3.01 1.344 133.1 24.9 0.2870.5% CS 0.05% XG 1,195 50.1 1.52 0.551 157.3 13.8 0.1360.5% CS 0.10% XG 3,817 124.9 4.18 1.327 187.4 18.9 0.3950.5% CS 0.15% XG 2,512 82.5 3.19 0.889 174.7 21.5 0.2020.5% CS 0.20% XG 2,013 94.0 3.30 0.871 167.8 25.3 0.1960.5% CS 0.25% XG 2,333 108.9 3.11 1.162 156.9 24.1 0.2690.5% CS 0.30% XG 2,767 119.2 3.35 1.213 157.2 24.4 0.310

Area of thixotropy hysteresis loop [W/m3]: A, parameter of Weltman’s equation [Pa]; B, parameter ofWeltman’s equation [–]; h•, frequency factor [Pa · s]; E, energy of activation [kJ/mol]; to, yield stress[Pa]; hC, viscosity of Casson [Pa · s].


z x y x xy y= − + − −6,721 37,271 17,175 0,627 14,398 ,2 22

for which the coefficient of multiple correlation (R = 0.739) and calculated testof Fischer (F = 7.236) showed statistically significant dependence. This func-tion in the range of cornstarch/xanthan gum content used in the experiment hadno extreme point. An optimal point, corresponding to the medium level ofthixotropy area for this function, was found at 0.40% cornstarch and 0.30%xanthan gum.

In Table 4, the parameters of experimental equations of second-gradepolynomial, concerning rheological parameters, as well as optimal solutions ofthese equations are presented. Wang et al. (2001) studied the interactions ofwaxy cornstarch and xanthan gum by viscometry and found that xanthan gumwas a better thickener than waxy cornstarch. They stated also that waxycornstarch and xanthan gum attracted each other, but did not show synergisticinteractions. Intermolecular interactions of polysaccharides depend on ther-modynamic compatibility/incompatibility between them (Tolstoguzov 2003).The effect of thickening of the studied systems could be explained in terms ofpolymers incompatibility.

Rheological and textural properties play an important role in the percep-tion of product’s quality by the consumer. Such multiparametric attributes liketexture and consistency can often decide of the choice and acceptability of theproduct. Apart from that, rheological and textural properties influence to a bigextent the taste perception. Understanding of interrelations between structureof products and their sensory properties is necessary in order to meet the needsof consumer (Wilkinson et al. 2000).

Apparently homogenous fluid substances, in reality contain differentsolid particles which can have highly differentiated, irregular shapes. On theother hand, soluble long-chain polymers exist in aqueous solutions, in whichthe chains interact mutually in various ways. The majority of practicallyexisting food systems consist not only of starch, other hydrocolloid and water.Usually they coexist with the other components, such as low-molecular sugars,alcohols, salts, proteins, fats or oils, and acids, which interact with hydrocol-loids. Thus, it is very likely that the nature of starch–hydrocolloid interactionscomprises several mechanisms, and their influences interlace mutually. Inter-pretation of results obtained in model systems is much easier than in the caseof market products, in which interactions between constituents, usually indifferent physical state, are multiparametric and multidirectional.

Final Statistical Results – Optimization of Obtained Results

Table 4 presents summary of sensory, textural and rheological tests, withoptimum scores concerning all features and parameters studied as well as


related concentrations of cornstarch and xanthan gum. As can be seen fromTable 4, optimal scores for sensory evaluation exceed 4.1 points, and formultitude of features in this test oscillates even on higher level (4.5 points).These best scores were achieved at the use of 0.2–0.3% xanthan gum (Table 4).The only exclusion was the feature “mouthfeel,” for which the best score wasachieved at the lowest level of xanthan gum – 0.05%. Concerning the corn-starch concentration, the best results could be achieved at whole range of itsconcentration used in the experiment.

In the case of both rheological and textural experiments – for the mostadvantageous the medium results were considered. The analysis of the bestresults of rheological measurements indicated that they could be more fre-quently achieved at medium level of cornstarch, and whole range of xanthangum used in the experiment. Analysis of textural test results brings about theconclusion that higher levels of both xanthan gum and cornstarch generateoptimal values (Table 4).

In Table 7, maximal ranges of cornstarch and xanthan gum levels areshown, in which ranges of optimal values are demonstrated. Presentation ofthese ranges enabled common range to be established. This range was only apartial solution (concerning sensory analyses) of the problem placed in thiswork. Its realization was possible after superposition of ranges with optimalsolutions for both kinds of sensory analyses (whole and partial). At theassumption that a good score is equal to 4.0 points, the optimal, commonsolution for all (partial) sensory parameters would exist in the range 0.45–0.50% for cornstarch and 0.12–0.17% for xanthan gum. Similarly, thecommon solution in whole sensory analysis would be in the range 0.33–0.50%for cornstarch and 0.22–0.30% for xanthan gum.

Such way of reasoning permitted to establish an optimal rheologicalassessment on the level 0.36–0.49% of cornstarch and 0.13–0.21% of xanthangum. Moving similarly the optimal textural test judgment could be achieved at0.30–0.50% cornstarch and 0.15–0.21% xanthan gum. Finally, one can sum-marize that the most frequent and common ranges generating optimal solu-tions are 0.45–0.49% cornstarch and 0.15–0.17% xanthan gum.

CONCLUSION

Studying carefully calibration cards nos. 1 and 2, one can conclude that4 points is considered a good score. At the assumption that scores 4 points andmore (good and excellent quality), are acknowledged as optimal in sensoryanalyses, and that medium values of textural and rheological parameters areconsidered optimal, it is possible to find optimal ranges of both cornstarch and


xanthan gum levels, used in blends for thickening of cocoa syrups. Theseranges could be established on the level 0.45–0.49% for cornstarch and 0.15–0.17% for xanthan gum.

ACKNOWLEDGMENT

The project was supported by the Polish Ministry of Science and Infor-matization, grant 2 P06T 079 26.

TABLE 7.RANGES OF OPTIMAL STARCH AND XANTHAN GUM CONTENT IN COCOA SYRUPS

Feature Ranges of optimal values for

Starch Xanthan gum

Whole sensory featuresConsistency 0.33–0.50 0.05–0.30Color 0.30–0.50 0.05–0.30Gloss 0.30–0.50 0.05–0.30Aroma 0.30–0.50 0.22–0.30Taste 0.30–0.50 0.05–0.30

Common part 0.33–0.50 0.22–0.30Partial sensory features

Viscosity 0.30–0.39 or 0.44–0.50 0.11–0.30 or 0.10–0.23Stringiness 0.30–0.36 or 0.45–0.50 0.11–0.30 or 0.11–0.26Sandiness 0.30–0.50 0.05–0.30Adhesiveness 0.30–0.50 0.13–0.30Mouthfeel 0.30–0.50 0.05–0.17

Common part 0.45–0.50 0.12–0.17Rheological parameters

Area of thixotropy 0.30–0.49 0.05–0.30A (Weltman’s parameter) 0.30–0.50 0.07–0.23B (Weltman’s parameter) 0.30–0.50 0.05–0.24h8 frequency factor 0.30–0.50 0.08–0.28Energy of activation · 105 0.30–0.50 0.12–0.29Yield stress 0.30–0.50 0.13–0.21Viscosity of Casson 0.36–0.49 0.05–0.30

Common part 0.36–0.49 0.13–0.21

Penetration parametersForce of penetration 0.30–0.50 0.15–0.22Adhesiveness 0.30–0.50 0.14–0.21Stringiness 0.30–0.50 0.07–0.30

Common part 0.30–0.50 0.15–0.21

Summarized common part 0.45–0.49 0.15–0.17


AP

PE

ND

IX1:

CA

LIB

RA

TIO

NC

AR

DN

O.1

.DE

FIN

ITIO

NS

AN

DW

EIG

HT

ING

CO

EF

FIC

IEN

TS

OF

WH

OL

ESE

NSO

RY

AN

ALY

SIS

OF

CO

CO

ASY

RU

PS

Qua

lity

feat

ure

Wei

ghtin

gco

effic

ient

Eva

luat

ion

scal

e–

desc

ript

ors

54

32

1

Con

sist

ency

0.3

Eas

ilysp

read

ing

over

the

surf

ace

ofa

prod

uct,

thic

k,co

hesi

ve,n

otve

rydu

ctile

and

stic

ky

Spre

adin

gov

erth

esu

rfac

eof

apr

oduc

t,th

ick,

cohe

sive

,sl

ight

lydu

ctile

,not

very

stic

ky

Spre

adin

gov

erth

esu

rfac

eof

apr

oduc

t,ac

cept

ably

thic

k,an

ddu

ctile

,or

less

thic

kan

dno

tve

ryco

hesi

ve

Too

thin

,lea

ving

too

thin

laye

rov

erth

esu

rfac

eof

apr

oduc

t,or

too

thic

k,gu

mm

yw

ithcl

umps

Thi

n,w

ater

y,or

very

thic

k,un

desi

rabl

e

Col

or0.

15V

ery

inte

nsiv

e,da

rkbr

own,

desi

rabl

e,ve

ryun

ifor

m

Inte

nsiv

e,da

rkbr

own,

desi

rabl

ean

dun

ifor

m

Dar

kbr

own,

less

inte

nsiv

ean

dun

ifor

m,h

owev

erty

pica

l

Bro

wn,

dist

inct

lych

ange

d,no

nuni

form

Not

typi

cal,

nonu

nifo

rm

Glo

ss0.

1V

ery

deep

and

inte

nsiv

e,re

flect

ing

light

,ver

yde

sira

ble

Refl

ectin

glig

ht,

brill

iant

,dee

pN

otve

ryde

ep,

slig

htly

brill

iant

Slig

htly

mat

t,no

tbr

illia

ntM

att,

unde

sira

ble

Aro

ma

0.1

Ver

yin

tens

ive

and

plea

sant

,dis

tinct

lype

rcep

tible

,typ

ical

for

coco

apr

oduc

ts

Plea

sant

,dis

tinct

lype

rcep

tible

,typ

ical

for

coco

apr

oduc

ts,

with

out

stra

nge

arom

a(s)

Not

very

perc

eptib

le,

typi

cal

for

coco

apr

oduc

ts,w

ithou

tst

rang

ear

oma(

s)

Not

very

typi

cal

for

coco

apr

oduc

ts,

slig

htly

perc

eptib

lest

rang

ear

oma(

s)

Unt

ypic

alfo

rco

coa

prod

ucts

,with

stro

ngly

perc

eptib

lest

rang

ear

oma(

s),

unde

sira

ble

Tast

e0.

35C

lear

lysw

eet,

typi

cal

for

coco

apr

oduc

ts,

very

tast

yan

dde

sira

ble

Swee

t,ty

pica

lfo

rco

coa

prod

ucts

,tas

tySw

eet,

typi

cal

for

coco

apr

oduc

ts,t

asty

,w

ithsm

all

stra

nge

tast

e(s)

Not

very

swee

tor

too

swee

t,w

ithsm

all

stra

nge

tast

e(s)

Not

tast

y,w

ithdi

stin

ctiv

ely

stra

nge

tast

e(s)


AP

PE

ND

IX2:

CA

LIB

RA

TIO

NC

AR

DN

O.2

.DE

FIN

ITIO

NS

OF

PAR

TIA

LSE

NSO

RY

AN

ALY

SIS

OF

CO

CO

ASY

RU

PS

Qua

lity

feat

ure

Eva

luat

ion

scal

e–

desc

ript

ors

54

32

1

Vis

cosi

tySp

read

ing

over

the

surf

ace

ofa

prod

uct,

slow

lyflo

win

gof

ffr

omth

esu

rfac

e

Spre

adin

gov

erth

esu

rfac

eof

apr

oduc

t,flo

win

gof

ffr

omth

esu

rfac

eto

osl

owor

too

fast

Spre

adin

gfa

stor

slow

over

the

surf

ace

ofa

prod

uct,

flow

ing

off

from

the

surf

ace

too

slow

orto

ofa

st

Rap

idly

spre

adin

gov

erth

esu

rfac

eof

apr

oduc

tor

spre

adin

gve

rysl

ow

Ver

yra

pidl

ysp

read

ing

over

the

surf

ace

ofa

prod

uct

orno

tsp

read

ing

atal

l

Stri

ngin

ess

Thi

cksy

rup,

brea

king

afte

rpo

urin

gou

tT

hick

syru

p,br

eaki

ngw

ithsl

ight

dela

yaf

ter

pour

ing

out

Thi

cksy

rup,

slig

htly

duct

ileaf

ter

pour

ing

out

Thi

cksy

rup,

sign

ifica

ntly

duct

ileaf

ter

pour

ing

out

Thi

cksy

rup,

very

duct

ileaf

ter

pour

ing

out,

stri

ngve

rydi

fficu

ltto

brea

k

Adh

esiv

enes

sPe

rfec

tlyad

hesi

ve,

leav

ing

onth

esu

rfac

eof

aco

ated

prod

uct

Adh

esiv

een

ough

,lea

ving

onth

esu

rfac

eof

aco

ated

prod

uct

inth

inla

yer

Slig

htly

adhe

sive

,lea

ving

onth

eal

mos

tw

hole

surf

ace

ofa

coat

edpr

oduc

t

Not

enou

ghad

hesi

ve,

leav

ing

onat

leas

t50

%of

the

surf

ace

ofa

coat

edpr

oduc

t

Not

enou

ghad

hesi

ve,

rapi

dly

pour

ing

off

from

the

surf

ace

ofa

coat

edpr

oduc

tor

leav

ing

onit

inir

regu

lar

form

Mou

thfe

elIm

med

iate

rele

ase

ofin

gred

ient

sin

mou

th,

very

good

deliq

uesc

ence

Goo

dre

leas

eof

ingr

edie

nts

inm

outh

,go

odde

lique

scen

ce

Med

ium

rele

ase

ofin

gred

ient

sin

mou

th,

deliq

uesc

ence

dela

yed

Del

ayed

rele

ase

ofin

gred

ient

sin

mou

th,

deliq

uesc

ence

very

dela

yed

Ver

yde

laye

dre

leas

eof

ingr

edie

nts

inm

outh

,de

lique

scen

cein

suffi

cien

t

Sand

ines

sU

nifo

rm,s

moo

thsu

bsta

nce,

all

part

icle

sdi

ssol

ved

Smoo

thsu

bsta

nce,

with

seve

ral

slig

htly

perc

eptib

leso

lidpa

rtic

les

Subs

tanc

ew

ithm

inor

solid

part

icle

sSu

bsta

nce

with

perc

eptib

leso

lidpa

rtic

les

Perc

eptib

lyan

dvi

sual

lysa

ndy

subs

tanc

e


REFERENCES

BARYLKO-PIKIELNA, N. 1975. Zarys analizy sensorycznej, pp. 307–321,Wydawnictwo Naukowo-Techniczne, Warszawa, Poland. (inPolish)

BOURNE, M. 2002. Food Texture and Viscosity. Food Science and Tech-nology International Series, 2nd Ed. (S.L. Taylor, ed.) pp. 362–367,Academic Press, Elsevier Science Imprint, London, UK.

FREDRIKSSON, H., SILVERIO, J., ANDERSSON, R., ELIASSON, A.-C.and AMAN, P. 1998. The influence of amylose and amylopectin charac-teristics on gelatinization and retrogradation properties of differentstarches. Carbohydr. Polym. 35, 119–134.

GIBINSKI, M., KOWALSKI, S., SADY, M., KRAWONTKA, J., TOMASIK,P. and SIKORA, M. 2006a. Thickening of sweet and sour sauces withvarious polysaccharide combinations. J. Food Eng. 75(3), 407–414.

GIBINSKI M., KOWALSKI S., SADY M. and SIKORA M., 2006b. Chapter16. Application of hydrocolloids and oat hydrolysate in mayonnaiseproduction. In Starch: Recent Achievements in Understanding of Struc-ture and Functionality (V.P. Yuryev, P. Tomasik and E. Bertoft, eds.)Nova Science Publishers, Inc., New York, NY.

GUDMUNSSON, M. 1994. Retrogradation of starch and role of its compo-nents. Thermochim. Acta 246, 329–341.

KALICHEVSKY, M.T., OXFORD, P.D. and RING, S.G. 1986. Incompatibil-ity of concentrated aqueous solutions of dextran and amylose and itseffects on amylose gelation. Carbohydr. Polym. 6, 75–84.

KULICKE, W., EIDAM, D., KATH, F., KIX, M. and KULL, A. 1996. Hydro-colloids and rheology: regulation of visco-elastic characteristics ofwaxy rice starch in mixtures with galactomannans. Starch/Staerke 48,105–114.

LII, C.Y., TOMASIK, P., HUNG, W.L. and LAI, V.M.F. 2002. Polysaccharide– polysaccharide interactions in pastes. Pol. J. Food Nutr. Sci. 11(4),29–33.

POLISH STANDARD PN-ISO 1996. 8586-1. Analiza sensoryczna. Ogólnewytyczne wyboru, szkolenia i monitorowania oceniajacych. Wybranioceniajacy. Sensory analysis. General guidance for selection, training andmonitoring of assessors. Part 1. Selected assessors (in Polish).

POLISH STANDARD PN-ISO 1998a. 3972. Analiza sensoryczna. Metodo-logia. Metoda sprawdzania wrazliwosci smakowej. Sensory analysis.Methodology. Method of investigating sensitivity of taste (in Polish).

POLISH STANDARD PN-ISO 1998b. 6658. Analiza sensoryczna. Meto-dologia. Wytyczne ogólne. Sensory analysis. Methodology. Generalguidance (in Polish).


POLISH STANDARD PN-ISO 1999. 11036. Analiza sensoryczna. Meto-dologia. Profilowanie tekstury. Sensory analysis. Methodology. Textureprofiling (in Polish).

RAO, M. 1999. Rheology of Fluid and Semisolid Foods. Principles andApplications, pp. 380–382, Aspen Publishers, Inc., Gaithersburg,MD.

SCHRAMM, G. 1998. Reologia. Podstawy i zastosowania, pp. 34–194,Osrodek Wydawnictw Naukowych, Poznan, Poland (in Polish).

SIKORA, M. and KOWALSKI, S. 2006. Chapter 5. Polysaccharide –polysaccharide hydrocolloids interactions. In Starch: Recent Achieve-ments in Understanding of Structure and Functionality (V.P. Yuryev, P.Tomasik and E. Bertoft, eds.) Nova Science Publishers, Inc., New York,NY.

SIKORA, M., JUSZCZAK, L. and SADY, M. 2003a. Hydrocolloids informing properties of cocoa syrups. Int. J. Food Properties 6, 1–14.

SIKORA, M., JUSZCZAK, L., SADY, M. and KRAWONTKA, J., 2003b.Use of starch/xanthan gum combinations as thickeners of cocoa syrups.Nahrung/Food 47(2), 106–113.

SIKORA, M., SADY, M., KRAWONTKA, J., PTASZEK, P. and KOWAL-SKI, S. 2003c. Chapter 13. Combinations potato starch – xanthan gumand modified starches – xanthan gum as thickeners of sweet and soursauces. Thickening and stabilizing of sauces with vegetables. In Starch:From Starch Containing Sources to Isolation of Starches and Their Appli-cations (V.P. Yuryev, A. Cesaro and W.J. Bergthaler, eds.) Nova SciencePublishers, Inc., New York, NY.

SIKORA, M., SADY, M., KRAWONTKA, J., PTASZEK, P. and KOWAL-SKI, S. 2003d. Chapter 12. Combinations potato starch – xanthan gumand modified starches – xanthan gum as thickeners of sweet and soursauces. Thickening of sauces without additives. In Starch: From StarchContaining Sources to Isolation of Starches and Their Applications (V.P.Yuryev, A. Cesaro and W.J. Bergthaler, eds.) Nova Science Publishers,Inc., New York, NY.

SIKORA, M., JUSZCZAK, L., SADY, M. and KRAWONTKA, J. 2004. Useof modified starches as thickeners of cocoa syrups. Food Sci. Technol.Int. 10(5), 347–354.

SIKORA, M., KOWALSKI, S., TOMASIK, P. and SADY, M. 2006. Rheo-logical and sensory properties of dessert sauces thickened by starch –xanthan gum combinations. J. Food Eng. 79(4), 1144–1151.

STEFFE, J.M. 1996. Rheological Methods in Food Process Engineering, pp.13–20, Freeman Press, East Lansing, MI.

SUDHAKAR, V., SINGHAL, R. and KULKARNI, P. 1995. Effect of sucroseon starch – hydrocolloid interactions. Food Chem. 52, 281–284.


SURMACKA-SZCZESNIAK, A. 1995. Opracowanie nowych produktówzywnosciowych. Food Product Development (J. Czapski, ed.) pp. 195–206, Wydawnictwo AR, Poznan, Poland (in Polish).

TOLSTOGUZOV, V.I. 2003. Thermodynamic considerations of starch func-tionality in foods. Carbohydr. Polym. 51, 99–111.

WANG, F., SUN, Z. and Wang, Y.-J. 2001. Study on xanthan gum/waxy cornstarch interaction in solution by viscometry. Food Hydrocolloids 15,575–581.

WILKINSON, C., DIJKSTERHUIS, G.B. and MINEKUS, M. 2000. Fromfood structure to texture. Trends Food Sci. Technol. 11, 442–450.


optimization of cornstarch/xanthan gum content … of... · optimization of cornstarch/xanthan gum...

Documents