CHANGES ON THE PHYSICOCHEMICAL PROPERTIES OF CAPRINE WHEY PROTEIN CONCENTRATES

AYUNTA CAROLINA ANABEL; MONTENEGRO MIGUEL; PUPPO MARÍA CECILIA; ITURRIAGA LAURA BEATRIZ

Córdoba

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

Ministro de Ciencia y Tecnología Gobierno de Córdoba

Whey proteins are used as food ingredientsbecause of their high nutritional value and interesting physicochemicalproperties. Functionality of ingredients is important in the preparation,processing, storage, quality, and sensory attributes of foods. Thephysicochemical and functional properties of proteins are affected byenvironmental factors such as temperature, pH, and ionic strength andprocessing effects (heating, freezing, drying, among others). Commercial wheyproteins concentrate (WPC) and isolate (WPI) derived mainly from bovinewhey.  Caprine milk products are suitableas potential substitutes of bovine milk in children´s diets, particularly forthose with cow milk allergies (Pandya y Ghodke, 2007), since preliminarystudies in mice indicated that goat milk was less allergenic than cow's milk (Lara-Villosladay col, 2004). The objective of this study was to follow the changes induced bythermal treatment (90ºC 30 minutes) and the effect of pH (2, 4, 5, 7, and 10)in solubility, zeta potential, surface hydrophobicity, and thiol availabilityof caprine whey protein concentrates (WPCc) obtained by an ultrafiltration process(UF) and diafiltration(DF). The results indicated that the solubility was high for systemswithout heat treatment and it was enhanced in the presence of NaCl. Thesolubility was strongly affected by the heat treatment. Zeta potentialmeasurements showed that, the ionicstrength (NaCl) modifying the isoelectric point. By SDS-PAGE electrophoresischanges are observed in protein fractions, mainly at pHs 2 and 10. Theresults of solubility, zeta potential and SDS-PAGE, were consistent among them. In samples without thermal treatment, freesulfhydryl groups were independent of pH, however at pH 7 and 8, the samplessubjected to heat treatment showed higher content of free sulfhydryl groups. Thesurface hydrophobicity was high at acid pH and showed an increase with heattreatment. The samplesof WPCc exhibited good solubility that is the most important property and an excellentindex for their functionality. Also WPCc presented high surface hydrophobicity and reactivity of freethiol group, especially with the application of heat treatment. These resultsindicate that the WPCc obtained by UF and DF present good properties to be usedin food formulations.