Changes on the physicochemical properties of caprine whey protein concentrates

PUPPO M.; AYUNTA C.; ITURRIAGA L.

Cordoba

Congreso; VI Congreso Internacional de Ciencia y Tecnología de los Alimentos; 2016

Ministerio de Ciencia y Tecnología de Cordoba

Whey proteins are used as food ingredients because of their high nutritional value and interesting physicochemical properties. Functionality of ingredients is important in the preparation, processing, storage, quality, and sensory attributes of foods. The physicochemical and functional properties of proteins are affected by environmental factors such as temperature, pH, and ionic strength and processing effects (heating, freezing, drying, among others). Commercial whey proteins concentrate (WPC) and isolate (WPI) derived mainly from bovine whey. Caprine milk products are suitable as potential substitutes of bovine milk in children´s diets, particularly for those with cow milk allergies (Pandya y Ghodke, 2007), since preliminary studies in mice indicated that goat milk was less allergenic than cow´s milk (Lara-Villoslada y col, 2004). The objective of this study was to follow the changes induced by thermal treatment (90ºC 30 minutes) and the effect of pH (2, 4, 5, 7, and 10) in solubility, zeta potential, surface hydrophobicity, and thiol availability of caprine whey protein concentrates (WPCc) obtained by an ultrafiltration process (UF) and diafiltration (DF). The results indicated that the solubility was high for systems without heat treatment and it was enhanced in the presence of NaCl. The solubility was strongly affected by the heat treatment. Zeta potential measurements showed that, the ionic strength (NaCl) modifying the isoelectric point. By SDS-PAGE electrophoresis changes are observed in protein fractions, mainly at pHs 2 and 10. The results of solubility, zeta potential and SDS-PAGE, were consistent among them. In samples without thermal treatment, free sulfhydryl groups were independent of pH, however at pH 7 and 8, the samples subjected to heat treatment showed higher content of free sulfhydryl groups. The surface hydrophobicity was high at acid pH and showed an increase with heat treatment. The samples of WPCc exhibited good solubility that is the most important property and an excellent index for their functionality. Also WPCc presented high surface hydrophobicity and reactivity of free thiol group, especially with the application of heat treatment. These results indicate that the WPCc obtained by UF and DF present good properties to be used in food formulations.