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Vol. 30, 2012, No. 5: 442445 Czech J. Food Sci.

Effect of Thickening Agents on Perceived Viscosity

and Acidity of Model Beverages

Z PANOVSK, A VCHOV and J POKORN

Department of Food Analysis and Nutrition, Faculty of Food and Biochemical Technology,

Institute of Chemical Technolog y Prague, Prague, Czech Republic

Abstract

P Z., V A., P J. (2012): Effect of thickening agents on perceived viscosity andacidity of model beverages. Czech J. Food Sci., 30: 442445.

he effect of thickening agents methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, and xan-

than gum solutions on the sensory viscosity was investigated in the concentration range of 00.8%. he perceived

viscosity was proport ional to the logarithm of kinematic viscosity in the presence of cit ric and malic acids. he vis -

cosity was inversely proportional to the acidity at the viscosity levels higher than 10 mm 2/s. A liquid of high viscosity

thus possess lower acidity than aqueous or low-viscosity solutions. No significant differences were found between the

effects of different thickening agents.

Keywords: sensory evaluation; acid taste; cellulose derivatives; model samples; viscosimeter

he consumption of packed non-alcoholic bever-ages has increased in all countries in recent years,including the consumption of sweetened beverages.Sugar is often replaced with synthetic sweeteners inlight beverages , which can result in lower viscosityof the product. Substitution of intense sweetenersfor sugar is not satisfactory when only sweetnessmatching is considered, other functional proper-ties of sucrose must also be taken into account.

he presence of sucrose in the aqueous phase ofliquid food systems containing hydrocolloids canchange their flow behaviour: the effect can be eitheran increase or a decrease in the viscosity of thesystem due to increasing viscosity of the aqueousphase or reduction in the hydration of hydrocolloidmolecules, respectively (Y et al.2002).

he viscosity of food products cannot be pre-dicted theoretically, due to complicated physicaland chemical structure (G et al.2011).he role of thickening agents in beverages can

be different. Sometimes consumers prefer higherviscosity corresponding to beverages containingsucrose. herefore, thickening agents are usu-ally added in order to increase the viscosity andreplace the effect associated with sucrose. Higher

viscosity is perceived in some cases as a positivefactor, and can improve the flavour acceptabilitybecause it is encoded in primates as a marker ofthe higher energy content of food (G 1986,

1993). he viscosity of beverages through theaddition of thickening agents generally increasessatiety ratings but this is often associated with areduction of palatability (M et al.2001).

A similar attitude of consumers was observednot only in beverages, but also in fat emulsions,e.g. in mayonnaise ( et al.2001).

he majority previous works that studied howviscosity affects perceived taste intensities attrib-uted the decreased perceived intensities of differenttastes to reduced availabilities of the tastants to

Supported by the Ministry of Education, Youth and Sports of the Czech Republic, Project No. MSM 6046137305.


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Czech J. Food Sci. Vol. 30, 2012, No. 5: 442445

the oral receptors. hese works were done usuallyon salty and sweet tasting model products andfewer works were aimed at sour taste.

he acceptability of drinks is critically dependenton the acidity at which they are normally consumedand the so called Brix-acid ratio is an importantcontrol parameter in the citrus industry. MBand F (1990) demonstrated that the psycho-physically dominant characteristic in sugar-citricacid model systems is the acidity, which makes thegreatest contribution to the overall taste intensity.

In addition to sugar, organic acids, such as citric,tartaric or malic acid, are mainly added to softbeverages to increase the sour taste and also theperception of freshness, common in fruit beverages.he presence of acids decreases the sweetness of

sucrose. he interaction of tastes is influenced,however, by changes of viscosity. Increasing vis-cosity of the sample increased the stimulus andrecognition thresholds of basic test substances,including citric acid (P et al.1980). Similarlylike in the case of sweetness-acidity interactions,higher concentrations of citric acid reduced theperceived viscosity of the solution (C1980). It is probable that very viscous liquids inhibitthe access of hydrogen ions to taste receptors , thusdecreasing the perceived acidity.

he effect of methyl cellulose on the sensory ratingof acidity in model samples was described (et al.2004). In this paper we studied the effect ofhigh concentrations of common thickening agentson the perceived intensities of viscosity and acidity.

MATERIAL AND METHODS

Panellist s.Sensory assessors were selected,trained and monitored according to the respec-tive standard ISO 8586-1:993. An assessor panel

composed of 11 highly trained panellists (aged2060, seven women, four men) from the Sensorylaboratory IC participated in this study. Eachpanellist had experience of two years at least inthe sensory analysis, particularly with the sensoryprofiling and undergoes periodic revalidation andretraining.

Samples.Malic acid, p.a. (Sigma-Aldrich Chemie,Steinheim, Germany) and citric acid, p.a. (Penta,Prague, Czech Republic) were used.

Both acids 0.5% citric acid (pH 3.77) or 0.5%

malic acid (pH 3.71) were dissolved in deionisedwater as a solvent.

Four commercial thickening agents i.e. methylcellulose (Benecel 143-HR), hydroxyethyl cellulose(Natrosol) and sodium carboxymethyl cellulose(Blanose) were obtained from Herkules CZ (Prague,Czech Republic), and xanthan gum was a productof Sigma-Aldrich Chemie (Steinheim, Germany).hickening agents were dissolved in an aqueoussolution of citric and malic acids. Solutions con-tained 0.10, 0.20, 0.50, and 0.80% of the agent.

Methods . he preparation and serving of thesamples were described in et al.(2004). Un-structured graphical scales, constructed accordingto the standard ISO 4121:1985, were representedby straight lines 100 mm long. hey were orientedby descriptions at the two ends of the line (viscos-ity: 0 = very thin, 100 = very thick; acidity: 0 =

imperceptible, 100 = strongly acidic). he resultswere expressed in percent of the graphical scale.

Acidities of citric acid and malic acid solutionswere compared by the paired comparison test(20 pairs).

Viscosity measurements. An Ubbelohde S 1823viscometer (echnosklo, Drkov, Czech Republic)was used for the measurements. he capillarydiameters were 0.64 mm for samples containing0.10% of thickening agents and 1.13 mm for theother tested concentrations. he temperature was

25C. wo determinations were carried out at thesame time. he kinematic viscosity of the samplewas expressed in mm2/s.

Statistical analysis. Te MS Statistica 3 software(StatSoft CZ, Prague, Czech Republic) was used, theprobability level wasP = 0.05, unless otherwise stated.

RESULTS AND DISCUSSION

est samples containing either 0.5% citric acidor 0.5% malic acid were used. hickening agents

were dissolved in an aqueous solution of citricand malic acids. Four levels of each of the fourthickening agents were tested (0.10, 0.20, 0.50,and 0.80%). Kinematic viscosities of solutionsare shown in able 1. Linear regressions weretested and the respective correlation coefficientswere calculated. he logarithm of sample viscositywas a linear function of the concentration in thecase of methyl cellulose. In the other thickeningagents the logarithm of sample viscosity was alinear function of the concentration only up to

the concentration of 10 mm2

/s or slightly more.However, moderate deviations were observed at


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Vol. 30, 2012, No. 5: 442445 Czech J. Food Sci.

higher concentrations, espe cially at viscositieshigher than 100 mm2/s. Nevertheless, a linearexpression between the logarithm of kinematic

viscosity (K) and the concentration (Cin %) wasstill in significant agreement with experimentaldata in the set of all 40 samples (log K= 0.216 +2.90 C;N= 40, P= 0.95; r= 0.91).

he sensory analyses were based on 1342 de-terminations, carried out by 11 trained and ex-perienced assessors; some assessors participatedseveral times. Sensory viscosities varied in theinterval of 2592% of the graphical scale. Resultsobtained in the case of citric acid solutions werenot statistically different from those obtained withmalic acid solutions, therefore, they are treatedas a single set. he dependence between the loga-rithm of kinematic viscosity (K) and the perceivedsensory viscosity (V) was essentially of a sigmoidcharacter, but very close to linearity (Figure 1)

so that it could be considered as linear (log K=0.036 V 0.84; N= 40; P= 0.95; r= 0.94). Stillsome difference could be found as the increase ofperceived viscosity (V) was slightly higher in therange between 1 and 10 mm2/s, but slightly lowerat higher kinematic viscosities. he multiple lin-ear regression between the sensory viscosity (V)and the combination of kinematic viscosity (K)and the concentration of the thickening agent (C)

expressed still better the course obtained in theexperiments:

V= f(log K, C): R2= 0.899; N= 40; probabilitylevel of significance:P< 0.0000

C= f(log K, V); R2= 0.829; N= 40; probabilitylevel of significance:P< 0.00000

he relationship between the sensory viscosityand the acidity was nearly linear (r= 0.83), butin more detail, it consisted of two stages. At the

viscosit ies between 1 and 10 mm 2/s (correspond-ing to the range of sensory perceived viscositiesbetween 25% and 50% of the scale), the increase of

viscosity had only a small effect on the acidity. Athigher viscosities, however, the acidity decreasedproportionally to the increasing kinematic viscos-ity (Figure 2). A similar relationship was obtainedbetween the sensory viscosity and the acidity. Acidi-ties of citric acid solutions were signif icantly lowerthan acidities of malic acid solutions (determinedby the sign test, 20 pairs, 16 positive and 4 nega-tive;P= 0.95). hese differences were, however,only moderate, and not statistically significant forthe evaluation of viscosity/acidity interactions. Nosignificant differences were observed among thesolutions of different thickening agents (determinedby rank test, P= 0.95, 8 sets of cases, evaluatedaccording to Kramer; sums of rankings 1624).

able 1. Kinematic viscosities of test solutions (mm2/s)

Concentration of thickening agent (%) Benecel Natrosol Blanose Xanthan gum

0.10 1.98 2.80 5.70 4.20

0.20 3.10 9.00 22.80 11.50

0.40 9.76 9.76 209.00 149.00

0.80 50.00 50.00 699.00 721.00

0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

Log K

10

20

30

40

50

60

70

80

90

100

V

(%)

Figure 1. Relation between the kinematic viscosity K(mm2/s) and the sensory perceived viscosity V(%) Figure 2.Relation between the sensory acidityA(%) andthe kinematic viscosityK(mm2/s)

0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

Log K

10

20

30

40

50

60

70

A(

%)


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CONCLUSIONS

he effect of thickening agents on the perceivedintensity of acid taste was small but at higher concen-trations the ef fect was statistically significant. he

viscosity was inversely proportional to the acidity atthe viscosity levels higher than 10 mm2/s. A liquidof high viscosity thus possess lower acidity thanaqueous or low-viscosity solutions. No significantdifferences were found between the effects of dif-ferent thickening agents. Suppression of the aciditywould thus occur at higher viscosities only, but notin the viscosity range common in soft beverages.

R e f e r e n c e s

G M.V., B R., S V., Z M.C.,

C J. (2011): Comparison of the viscosity of treha-

lose and sucrose solutions at various temperatures: Effect

of guar gum addition. Food Science and echnology, 44:

186190.

G D. (1986): Geschmacksforschung bei Primate.

Vierteljahrsschrift der Naturforschenden Gesselschaft

in Zrich, 131: 92110.

Corresponding author:

Doc. Dr. Ing. Z P, Vysok kola chemicko-technologick v Praze, Fakulta potravinsk a biochemick

technologie, stav analzy potravin a vivy, echnick 5, 166 28 Praha 6, esk republika

tel. + 420 220 443 263, e-mail: [email protected]

G D. (1993): he effects of sweeteners in primates.

In: M M., K J.A., B G.G. (eds):

Sweet-aste Chemoreception. Elsevier, London: 353363.

C C.M. (1980): Effects of taste quality and in-

tensity on oral perceptionof viscosity. Perception & Psy-

chophysics, 28: 315320.

M R.D., R D. (2001): Beverage viscosity

is inversely related to postprandial hunger in humans.

Physiology & Behavior, 74: 551557.

M B L.L., F D.C. (1990). Perceptual integration

of tertiary taste mixture. Perception and Psychophysic

48: 326330

P K., H E.M. (1980): Te influence of solvent vis-

cosity on the threshold values of primary tastes. Chemical

Senses, 5: 2332.

A., P Z., P J. (2004): Effect of

viscosity on the perceived intensity of acid taste. CzechJournal of Food Sciences, 22: 143150.

P., V H., P J. (2001) : Rheological

properties and sensory texture of mayonnaise. European

Journal of Lipid Science and echnology, 103: 2328.

Y M., D L., C E. (2002): Effect of hydro-

colloid type and concentration on flow behaviour and

sensory properties of milk beverages model systems.

Food Hydrocolloids, 16: 605611.

Received for publication July 14, 2011

Accepted after corrections December 15, 2011

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