Vliv přídavku karagenanů na viskoelastické vlastnosti modelových tavených sýrů

ACTA UNIVERSITATIS AGRICULTURAE ET SILVICULTURAE MENDELIANAE BRUNENSIS SBORNiK MENDELOVY ZEMEDELSKE A LESNICKE UNIVERZITY V BRNE RocnikLV 7 Cislo 5, 2007 THE EFFECT OF ADDITION OF SELECTED CARRAGEENANS ON VISCOELASTIC PROPERTIES OF MODEL PROCESSED CHEESE SPREADS M. Cemikova, F. Buiika, V. Pavlinek, P. Brezina, J. Hrabe, S. Kracmar Received: May 20,2007 Abstract CERNIKOV A, M., BuNKA, F., PAVLlNEK, v., BREZINA, P., HRABE, J., KRACMAR, S.: The ef fect of addition of selected carrageenans on viscoelastic properties of model processed cheese spreads. Acta univ. agric. et silvic. Mendel. Brun., 2007, LV, No.5, pp. 51-58 The effect of 0.25% w/w K-carrageenan and t-carrageenan on viscoelastic properties of processed cheese were studied using model samples containing 40% w/w dry matter and 45 and 50% w/w fat in dry matter. Experimental samples of processed cheese were evaluated after 14 days of storage at the temperature of 6 ± 2°C. Basic parameters of processed cheese samples under study (i.e. their dry matter content and pH) were not different (P ;::: 0.05). There were no statistically significant differences in values of storage modulus G' [Pal, loss modulus G" [Pal and tangent of phase shift angle tan () [-] for the reference frequency of 1 Hz between processed cheese with K-carrageenan applied in the form of powder and in the form of aqueous dispersion (P;::: 0.05). The addition of 0.25% w/w K-carrageenan and t-carrageenan (in the powder form) resulted in an increase in storage (G') and loss (G") moduli and a decrease in values of tan () (P < 0.05). As compared with control (i.e. without added carrageenans), samples of processed cheese became firmer. Iota-carrageenan added in the powder form in concentration of 0.25% w/w showed a more intensive effect on the increase in firmness of processed cheese under study than K-carrageenan (P < 0.05). processed cheese, fat in dry matter, kappa-carrageenan, iota-carrageenan, rheology Hydrocolloids (carrageenan, pectin, modified starch, gums, etc.) are used as stabilizing and thickening agents in the processed cheese production. Processed cheese is cheese-base food produced by comminuting, melting and emulsifying into a smooth homogeneous molten blend, one or more natural cheeses and optional ingredients using heat, mechanical shear and emulsifying salts (Guinee et al., 2004). Carrageenans are anionic linear polysaccharides extracted from red seaweed (Rhodophyceae), consisting of alternating a-1,4 and ~-1,3 linked anhydrogalactose residues. There are three major fractions (Kkappa, t-iota and A-lambda) with varying number and position of sulphate groups. Kappa-carrageenan and t-carrageenan undergo a temperature-dependent coil 51 (disordered state) to helix (ordered state) transition (in aqueous solution). Kappa-carrageenan usually forms firm, brittle gels and t-carrageenan usually generates soft elastic gels. Gel strength of both polysaccharides strongly depends on cations present -K-carrageenan is especially sensitive to potassium and t-carrageenan to calcium. Lambda-carrageenan is not able to build up stable gels (Syrbe et aI., 1998; Tziboula and Horne, 1999; Imeson, 2000; Singh et aI., 2003; Ribeiro et al., 2004; Spagnuolo et al., 2005). Casein micelles are complex of individual casein fractions: as!' aS2' ~ and K-casein. Kappa-casein is located on the periphery of micelle, providing an electrostatic stabilising outer layer (Bourriot et aI., 1999; de Kruif and Tuinier, 2001). Interactions ----------- 52 M Cernfkowi, F Buiika, V. Pavlfnek, P. Brezina, J. Hrabe, S. Kracmar K-carrageenan and t-carrageenan with milk proteins, especially with casein micelles, have been widely studied (Thaiudom and Goff, 2003). "Milk reactivity" of K-carrageenan and t-carrageenan is mostly attributed to interactions between the negative sulphated groups of the carrageenans and a positively charged region situated between residues 97 and 112 of K-casein at the surface of the casein micelle (Gamier et al., 2003; Vega et al., 2005). Behaviour of milk protein-carrageenan systems depends on a many parameters, such as hydrocolloid, protein and dispersed particle concentration, pH, ionic environment (e.g. potassium and calcium concentration), sugar content, temperature, molecular weight, milk protein processing, thermal history (Syrbe et al., 1998). In nature cheese (raw material for processed cheese production) there is neither casein in micellar form nor K-casein ("natural" with full 169 residues). In the processed cheese there is no significant amount of micellar casein (excluding of situation when skim milk powder or other materials containing casein micelles are added). Only a few studies have dealt with interactions of K-carrageenan and t-carrageenan with non-micellar casein systems or individual casein fractions except K-casein (e.g. as and P). Lynch and Mulvihill (1996) proposed that ability of as and Pcaseins to interact with carrageenans requires the presence of calcium ions and ester-bound phosphorus on seryl residues of casein fractions. The object of this paper was to use K-carrageenan and t-carrageenan in processed cheese production (products with 45% w/w and 50% w/w fat in dry matter) and find out differences in viscoelastic properties of both of applied carrageenans in model concentration. MATERIAL AND METHODS Model samples of processed cheese spreads containing 40% w/w dry matter (DM) and 45% w/w or 50% w/w fat in dry matter (FDM) were manufactured from a mixture of natural cheese (Edam block cheese with 30% w/w FDM and Edam block cheese with 45% w/ w FDM), butter, deionized water (to assure a constant concentration of ions) and commercially supplied emulsifying salts. In the first part of this experiment (Group I), the effect of the form of added K-carrageenan on viscoelastic properties of model processed cheeses containing 45% w/w and 50% w/w FDM was studied. Kappacarrageenan was applied into both types of cheese (i.e. with 45% w/w and 50% w/w FDM) in concentration of 0.25% w/w, partly in the form of powder and partly in the form of aqueous dispersion (in deionized water, which was used in such amount that did not influenced the DM content in the final products). Two control samples (for both FDM contents under study) were prepared as well. In the second part ofthis experiment, four groups of model processed cheese samples were used (i = II, III, IV, V). All of them were manufactured using the same technology (see below), and carrageenans in powder form were applied to each of them. In particular, each of these four groups consisted of six types of samples (batches): (1) product with 0.25% w/w ofK-carrageenan (Ke) and with 45% w/w FDM; (2) product with 0.25% w/w of t-carrageenan (IC) and with 45% w/w FDM; (3) product with 0.25% w/w KC and 50% w/w FDM; (4) product with 0.25% w/w IC and 50% w/w FDM; (5) control sample without carrageenan and with 45% w/w FDM; (6) control sample without carrageenan and with 50% w/w FDM. In the second part of this experiment, samples of natural cheese with a different degree of maturity were used (Group II - 6 weeks; Group III - 8 weeks; Group IV - 10 weeks and Group V - 16 weeks). In individual test groups, the initial firmness of control samples was different (see values of storage (GO) and loss (G") moduli in Tabs II and III). For that reason the conclusions concerning effects ofKC and IC addition were related to the control sample of each group. This experimental layout was used to reach a higher information capability and representativeness of results for industrial practice where it is sometimes difficult to assure a constant degree of maturity of the basic raw material (i.e. natural cheese). Processed cheese spreads were manufactured using the equipment Vorwerk Thermomix TM 21 blender cooker (Vorwerk & Co. Thermomix; GmbH, Wuppertal, Germany); the melting temperature was 92 °C (the time interval necessary to reach the melting temperature was 9-10 min. and the melting temperature was maintained for 1 min.). Thereafter the processed cheese was cooled down to 6 ± 2 °C and stored for 14 days at the same temperature. Carrageenans (KC and IC) used in this experiment were supplied by the company Sigma Aldrich, Inc., St. Louis, USA. The content of DM was determined at the temperature of 102 ± 1 DC, which was maintained till the loss of weight remained to be constant (Berger et al., 2002). Values of pH were measured with the pHmeter Gryf 209 S with a combined glass electrode at 22 ± 1 DC. Viscoelastic properties of processed cheese samples were measured by Bohlin Gemini (Malvern Instruments, UK) rheometer with parallel plate geometry (diameter of 40 mm, gap 1 mm) at the temperature of 20 DC. All the experiments were performed in the control shear stress mode at frequency ranging from 0.1 to 50 Hz. The amplitude of shear stress 50 Pa was chosen in the region of linear viscoelasticity. The exposed edge of parallel plates geometry was covered with a thin layer of silicone oil to prevent the samples ~ - ----------------~,------- The effect of addition of selected carrageenans on viscoelastic properties of model S3 from dehydration. Values of storage modulus G', loss modulus G" and tangents of phase shift angle (tan 0 = G" /G') were chosen for comparison of cheese properties. Treatments were statistically evaluated by Wilcoxon test for comparison of mean values. Non-parametrical procedures were chosen due to a low amount of available data (Agresti, 1984). To show the significance, differences among comparisons had to achieve P < O.OS. RESULTS AND DISCUSSION At first, the rheological analysis of model processed cheese from Group I containing 40% w/w DM and 4S% w/w or SO% w/w FDM was performed with the aim to evaluate the effect of a dosing procedure of 0.2S% w/w KC (in the form of powder and aqueous suspension) on viscoelastic properties of the final 10' .. e:. .. = -g ~ 10' b l:! " ...l "C = " C 10' :. .. .. .9 '" 10' 0.1 .. e:. :; "C ~ 10' b ~ ...l "C = " b 10' :. E ;l 10' 0.1 product. The basic analysis revealed that all samples had practically the same content of DM (i.e. ranging from 40.62 to 41.1S% w/w; P:::: O.OS) and that also their pH was very similar (i.e. ranging from S.86 to S.92; P:::: O.OS). These similar characteristics enabled to compare the effect of KC application because both showed a high effect on the consistency of processed cheese (Marchesseau et at., 1997; Lee et at., 2004). As shown in Tab. I and Fig. 1 the form, in which the K-carrageenan is applied (i.e. either as a powder or as dispersed in water prior to the application into the raw material), did not show any significant effect on storage (G') and loss (G") moduli (P:::: O.OS). The efficiency ofKC applied in concentration ofO.2S% w/w was not dependent on its physical form and for that reason it was decided to use it as a powder. From the economic point of view this method of application is easier and thus also cheaper. A 10 B 10 Frequency f [Hz) 1: Dependence of storage G' (full symbols) a loss G" (open symbols) moduli onfrequencyffor control sample (110), KC in powder form (4D 0) a KC in aqueous dispersion ( .... .6.) in group I of processed cheeses with 45% w/w (A) and 50% w/w (B) FDM 54 M Cernikowi, F. Buiika, V. Pavlfnek, P. Brezina, J. Hrabe, S. Kracmar I: Values of storage (G') and loss (G '') moduli and tan 8 for reference frequency 1 Hz in processed cheese group I with addition of 0.25% w/w K-carrageenan applied in powder form and dispersed in water * The fat in dry matter Form of applied G' G" tan 8 content of processed cheeses (% w/w) K -carrageenan [Pal [Pal [- ] none 596 ± 89.2 a 760 ± 54.6' 1.275 45 powder form 1682 ± 167.7b 1397 ± 132.7b 0.831 dispersed in water 1525 ± 159.1 b 1296 ± 116.3 b 0.850 none 145 ± 21.6' 284 ± 19.1 a 1.959 50 powder form 612 ± 66.3 b 653 ± 53.5 b 1.067 dispersed in water 522 ± 58.2b 590 ± 37.4 b 1.130 * Storage G' and loss G" moduli are presented by mean ± S.D.; tan 8 = G" /G'. Means (n = 4) within a column followed by no common superscript letter differ (P < 0.05); samples with 45% w/w and 50% w/w FDM were evaluated separately. Thereafter, the rheological analysis of model processed cheese samples from Groups II to V with 40% w/w DM and 45% w/w or 50% w/w FDM was performed. Both KC and IC were applied in the target concentration of 0.25% w/w in the final product. The results of a basic analysis indicated that samples from all four groups under study showed a practically identical content of DM (ranging from 40.20-41.13% w/ w; P ~ 0.05) and also pH values (ranging from 5.855.93; P ~ 0.05). As shown in Tabs II and III and Figs 2 and 3, in which results of a dynamic oscillation rheometry of Groups II-V with the contents of 45% w/w and 50% w/w FDM are presented, the applied concentration of carrageenans (0.25% w/w) increased significantly the values of both storage (G') and loss (G") moduli (P < 0.05) within the whole range of tested frequencies (0.1-50Hz) as compared with corresponding controls. This effect was observed in all tested Groups (11V) irrespective of degree of maturity. These changes indicate that the presence of 0.25% w/w of both KC and IC in processed cheese can change the character of its gel: as compared with control, the firmness of test samples was higher. This can be explained by the fact that interactions of both KC and IC chains contribute to the formation of a more complex matrix in samples of processed cheese (Langendorff et a!., 1999; Langendorff et a!., 2000). II: Values of storage (G') and loss (G '') moduli and tan 8 for reference frequency 1 Hz in processed cheese groups II and III with addition of 0.25% w/w K-carrageenan (KC) and t-carrageenan (IC) applied in powder form * The fat in dry Type of Group of processed cheese matter content of added II III processed cheeses carrageenan G' G" tan 8 G' G" tan 8 (%w/w) [Pal [Pal [- ] [Pal [Pal [- ] none 2952 ± 153.5' 2267 ± 82.3' 0.767 1627 ± 76.6' 1436 ± 57.3' 0.882 45 KC 5835 ± 121.9b 3270 ± 127.1 b 0.561 3826 ± 112.9 b 2424 ± 287.4 b 0.635 IC 8714 ± 404.8 c 4445 ± 295.7c 0.510 3197 ± 156.2 c 2107 ± 268.5 b 0.659 none 1275 ± 102.2' 1329 ± 97.5 a 1.043 352 ± 32.3' 563 ± 62.4' 1.600 50 KC 4098 ± 99.7 b 2719 ± 132.0 b 0.664 641 ± 45.2b 721 ± 104.1 b 1.126 IC 5288 ± 275.3 c 2969 ± 186.4c 0.561 2750 ± 154.6c 1722 ± 243.4 c 0.627 * Storage G' and loss G" moduli are presented by mean ± S.D.; tan 8 = G"/G'. Means (n = 4) within a column followed by no common superscript letter differ (P < 0.05); samples with 45% w/w and 50% w/w FDM were evaluated separately. The effect of addition of selected carrageenans on viscoelastic properties of model 55 III: Values of storage (G') and loss (G '') moduli and tan 8 for reference frequency 1 Hz in processed cheese groups IV and Vwith addition of 0.25% w/w K-carrageenan (KC) andt-carrageenan (IC) applied in powder form * The fat in dry Type of Group of processed cheese matter content of added IV V processed cheeses carrageenan G' G" tan 8 G' G" tan 8 (%w/w) [Pal [pa] [- ] [pa] [Pal [- ] none 1509± 87.4' 1483 ± 91.8' 0.983 352 ± 10.1" 525 ± 16.8' 1.488 45 KC 2616 ± 48.6b 1958 ± 142.7b 0.748 1179 ± 132.4 b 1155 ± 23.5 b 0.979 IC 3450 ± 122.9 c 2387 ± 159.0c 0.692 1452 ± 60.0 c 1143 ± 16.1 b 0.787 none 178 ± 28.9' 337 ± 26.6' 1.889 46 ± 3.6' 128 ± 11.2' 2.762 50 KC 322 ± 76.0b 500 ± 37.1 b 1.552 597 ± 14.3 b 552 ± 18.7b 0.926 IC 1335 ± 129.5 c 1133 ± 82.8c 0.848 924 ± 69.2c 796 ± 25.6 c 0.863 * Storage G' and loss G" moduli are presented by mean ± S.D.; tan 8 = G" /G'. Means (n = 4) within a column followed by no common superscript letter differ (P < 0.05); samples with 45% w/w and 50% w/w FDM were evaluated separately. 'i" e:. 10' 10' :; ~ b ~ 10' 10' 1 ~ , I! ~ A B 10' 10' 0.\ 10 0.1 10 ~ 10' 10' iI ~ ~ ! 1 10' 10' .. ~ k c 10' 10' 0.1 10 0.1 10 Frequency f [Hz) Frequency f [Hz) 2: Dependence of storage G' (full symbols) a loss G" (open symbols) moduli onfrequency ffor control sample (110), KC in powder form (eo) a lC in powder form (A..L:,) for processed cheeses with 45% w/w FDM (A -group 11, B -group Ill, C - group IV and D -group V). 56 M Cernikova, F. Buiika, V Pavlinek, P. Brezina, J. Hrabe, S. Kracmar 'ii' 10' 10' E!!. := .. ~ 6 10' 10' :a oS "0 Ii b 10' 10' ~ !! ~ A B 10' o· 10' 0.1 10 0.1 10 ~ 10' 'i ~ b 10' 10' ~ ...:I '8 II b 10' 10' i c 10' o· 0.1 10 0.1 10 Frequency f [Hz) Frequency f [Hz) 3: Dependence of storage G' (full symbols) a loss G" (open symbols) moduli onfrequencyffor control sample (II 0), KC in powder form (CD 0) a IC in powder form (A. 1:::,.) for processed cheeses with 50% w/w FDM (A -group IL B -group IlL C - group IV and D -group V). Tabs II and III and Figs 2 and 3 also indicate that application of IC in concentration of 0.25 % w/w resulted in the formation of a firmer gel than that ofKC (P < 0.05). An explanation of a better efficiency ofIC is not simple, especially with regard to the findings published by !meson (2000) that KC formed firm gels and IC soft elastic gels. The answer can be looked for e.g. in the ionic environment (especially in the presence of ions), which shows a significant effect on the strength of carrageenan network (Nickerson et al., 2004). In natural cheese, which is the basic raw material for production of processed cheese, the content of calcium ions is approximately ten-times higher than that of potassium ions (Fox et aI., 2000). It is known that IC is more sensitive to potassium while KC is more susceptible to calcium ions (!meson, 2000). As mentioned by Spagnuolo et al. (2005) not only absolute amounts of calcium and potassium ions but also the ratio between these ions may be important. Hence, dominance in concentration of Ca++ ions over K+ ions may play a key role in the firmness ofKC and IC gels, respectively. In this context it is also appropriate to take into account results published by MacArtain et al. (2003) who mention that in case ofKC there is an optimal concentration of calcium ions in the medium and that within the range of suboptimal concentrations their increasing content results in a higher firmness ofKC gel. However, if the concentration of calcium ions surpassed its optimum within a given system, any further increase resulted in a decrease in values of storage (G') modulus (i.e. in the firmness) of the produced gel. CONCLUSION In this paper the effect of addition of 0.25% w/w of K-carrageenan and t-carrageenan on viscoelastic properties of model samples of processed cheese containing 45% w/w and 50% w/w fat in dry matter was evaluated. It was found out that at a target concentration of 0.25% w/w of carrageenans their effect on the consistency of processed cheese was not dependent on the form of applied additive (tested were its powder form and its aqueous dispersion). The addition of 0.25% w/w of both carrageenan under study resulted in the formation of firmer and less spreadable products in compare to control samples without carrageenan addition. The effect oft-carrageenan was higher than that of K-carrageenan. The effect of addition of selected carrageenans on viscoelastic properties of model 57 SOUHRN Vliv pfidavku vybranych karagenanu na viskoelasticke vlastnosti modelorych tavenych syru Vliv pi'idavku 0,25 % w/w K-karagenanu a t-karagenanu na viskoelasticke vlastnosti taveny~~ ~yru byl sledovan u modelovy-ch vzorkU s 40 % w/w susiny a 45 % w/w, resp. 50 % w/w tuku v susme. Tavene syry byly hodnoceny po 14 dnech skladovani pi'i teplote 6 ± 2°C. Sledovane tavene syry se nelisily v zakladnich parametrech -susine a pH (P 2': 0,05). Nebyly zjisteny statisticky vy-znamne rozdily hodnot elastickeho modulu pruZilosti G' [Pal, ztratoveho modulu pruZilosti G" [Pal a tangentu Uhlu fazoveho posunu tan 8 [-] pro referencni frekvenci 1 Hz mezi tavenymi syry s aplikaci K-karagenanu v praskove forme a ve forme disperze ve vode (P 2': 0,05). V dusledku pi'idavku 0,25 % w/w K-karagenanu i t-karagenanu (v praskove forme) byl zaznamenan narust elastickeho G' a ztratoveho G" mod~lu pruznosti a pokles hodnot tan 8 (P < 0,05). Tavene syry se staly tuzsimi ve srovnani s kontrolniml vzorky bez pi'idavku karagenanu. Iota-karagenan pi'idany v praskove forme byl pro koncentraci 0,25 % w/w pi'i zvysovclni tuhosti sledovanych tavenych syru liCinnejsi nez K-karagenan (P < 0,05). taveny sy-r, tuk v susine, kappa-karagenan, iota-karagenan, reologie This work was kindly supported by a project of Czech Ministry of Education, Youth and Sports (Grant No. MSM 7088352101). REFERENCES AGRESTI, A.: Analysis of ordinal categorical data. John Wiley & Sons, Inc., 1984,287 p. AUGUSTIN, M. A., PUVANENTHIRAN, A. and MCKINNON, 1. R.: The effect of K-carrageenan conformation on its interaction with casein micelles. Int. Dairy J., 1999,9: 413--414. ISSN 0958-6946. BERGER, w., KLOSTERMEYER, H., MERKENlCH, K. and UHLMANN, G.: Processed Cheese Manufacture. A JORA Guide. BK Giulini Chemie GmbH & Co. OHG Ladenburg, 2002, 238 p. BOURRlOT, S., GARNIER, C. and DOUBLIER, J. L.: Micellar-casein-K-carrageenan mixtures. 1. Phase separation and ultrastructure. Carbohyd. Polym., 1999,40: 145-157. ISSN 0144-8617. DE KRUIF, C. G. and TUINIER, R.: Polysaccharide protein interactions. Food Hydrocolloids, 2001, 15: 555-563. ISSN 0268-005X. FOX, P. F., GUINEE, T. P., COGAN, T. M. and MCSWEENEY, P. L. H.: Fundamentals of Cheese Science. Aspen Publication, 2000, 559 p. ISBN 0-8342-1260-9. GARNIER, C., MICHON, C., DURAND, S., CUVELIER, G., DOUBLIER, J. L. and LAUNAY, B.: Iota-carrageenan/casein micelles interactions: evidence at different scales. Colloid Surface B., 2003, 31: 177-184. ISSN 0927-7765. GUINEE, T. P., CARIC\ M. and KALAB, M.: Pasteurized Processed Cheese and Substitute/Imitation Cheese Products. In. Cheese: Chemistry, Physics and Microbiology. Volume 2: Major Cheese Groups. Eds. Fox, P.F., Elsevier Applied Science London and New York, 2004,349-394. ISBN 0-1226-3651-8. IMESON, A. P.: Carrageenan. In Handbook of hydrocolloids. Eds. Phillips, G.O. and Williams, P.A. Woodhead Publishing Limited and CRC Press: Boca Raton, 2000,87-102. ISBN 0-8493-0850-X. LANGENDORFF, v., CUVELIER, G., MICHON, C., LAUNAY, B., PARKER, A. and DE KRUIF, C. G.: Effects of carrageenan type on the behaviour of carrageenan/milk mixtures. Food Hydrocolloids, 2000, 14: 273-280. ISSN 0268-005X. LANGENDORFF, v., CUVELIER, G., LAUNAY, B., MICHON, c., PARKER, A. and DE KRUIF, C. G.: Casein micelle/iota-carrageenan interactions in milk: influence of temperature. Food Hydrocolloids, 1999, 13: 211-218. ISSN 0268-005X. LEE, S. K., ANEMA, S. and KLOSTERMEYER, H.: The influence of moisture content on the rheological properties of processed cheese spreads. Int. J. Food Sci. Tech., 2004,39: 763-771. ISSN 0950-5423. LYNCH, M. G. and MULVIHILL, D. M.: Rheology of t-carrageenan gels containing caseins. Food Hydrocolloids, 1996, 10: 151-157. ISSN 0268-005X. MACARTAIN, P., JACQUIER, J. C. and DAWSON, K.A.: Physical characteristics of calcium induced K-carrageenan networks. Carbohyd. Polym., 2003, 53: 395--400. ISSN 0144-8617. MARCHESSEAU, S., GASTALDI, E., LAGAUDE, A. and CUQ, J. L.: Influence of pH on Protein Interactions and Microstructure of Process Cheese. J. Dairy Sci., 1997,80: 1483-1489. ISSN 0022-0302. NICKERSON, M. T., PAULSON, A. T. and HALLETT, F. R.: Dilute solution properties of K-carrageenan polysaccharides: effet of potassium and calcium ions on chain conformation. Carbohyd. Polym., 2004, 58: 25-33. ISSN 0144-8617. 58 M Cernikowi, F. Bufzka, V Pavlinek, P. Brezina, J Hrabe, S. Kracmar RIBEIRO, K. 0., RODRIGUES, M. I., SABADINI, E. and CUNHA, R. L.: Mechanical properties of acid sodium caseinate-K-carrageenan gels: effect of co-solute addition. Food Hydrocolloids, 2004, 18: 71-79. ISSN 0268-005X. SINGH, H., TAMEHANA, M., HEMAR, Y and MUNRO, P. A.: Interfacial compositions, microstructures and properties of iol-in-water emulsions formed with mixtures of milk proteins and K-carrageenan: 1. Sodium caseinate. Food Hydrocolloids, 2003, 17: 539-548. ISSN 0268-005X. SPAGNUOLO, P. A., DALGLEISH, D. G., GOFF, H. D. and MORRIS, E. R.: Kappa-carrageenan interactions in systems containing casein micelles and polysaccharide stabilizers. Food Hydrocolloids, 2005, 19: 371-377. ISSN 0268-005X. SYRBE, A., BAUER, W. J. and KLOSTERMEYER, H.: Polymer Science Concepts in Dairy Systems - An Overview of Milk Protein and Food Hydrocolloid Interaction. Int. DairyJ, 1998,8: 179-193. ISSN 0958-6946. THAIUDOM, S. and GOFF, H. D.: Effect of K-carrageenan on milk protein polysaccharide mixtures. Int. DairyJ, 2003,13: 763-771. ISSN 0958-6946. TZIBOULA,A. and HORNE, D.S.: Influence of milk proteins on K-carrageenan gelation. Int. Dairy J, 1999,9: 359-364. ISSN 0958-6946. VEGA, C., DALGLEISH, D. G. and GOFF, H. D.: Effect of K-carrageenan addition to dairy emulsions containing sodium caseinate and locust bean gum. Food Hydrocolloids, 2005, 19: 187-195. ISSN 0268-005X. Address MVDr. Michaela Cemikova, Ing. Frantisek Builka, Ph.D., prof. Ing. Pavel Brezina, CSc., doc. Ing. Jan Hrabe, Ph.D., prof. lng. Stanislav Kracmar, DrSc., Ustav potravinai'skeho inzen,Yrstvi, doc. Dr. Ing. Vladimir Pavlinek, Centrum polymemich materialu, Univerzita Tomase Bati ve Zline, nam. T. G. Masaryka 275, 762 72 Zlin, Ceska republika, e-mail: [email protected].