engleski

Rheological properties of carboxymethylcellulose and whey model solutions before and after freezing

Hydrocolloids, macromolecular carbohydrates are added to many foodstuffs with the aim to achieve the appropriate rhoelogical properties, to prevent syneresis or to increase the viscosity and stability of foodstuffs. In this work, the influence of the type and concentration of commercial hydrocolloids (carboxymethylcelluloses) on the rheological properties of model solutions of whey, whey proteins, sucrose, sorbitol and lactose was examined. The influence of freezing on rheological properties of model solutions was also checked. Measurements were done using a Brook-field DV-III rotational viscometer at temperature of 20 oC. The results have shown that all examined systems are non-Newtonian. Depending on the chemical composition and on the mass fraction of hydrocolloids, they exhibited pseudoplastic or dilatant properties. All CMC effected a significant increase of the model solutions viscosity. The freezing process had no significant effect on the viscosity of the model solution prepared with water. However, whey based solutions had a greater viscosity after freezing. The results of variance analysis showed that all examined sources of variation (composition of model solution, type of CMC and freezing process) had a significant influence on the rheological parameters.

rheological properties; carboxymethilcelluloses; whey proteins; freezing

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