Physicochemical properties of caprine and commercial bovine whey protein concentrate

Whey protein from caprine milk, a by-product of cheese manufacturing, was recovered by ultrafiltration technology and dried by lyophilization. A caprine whey protein concentrate (WPCc) with 64.60% of protein content was prepared. The physicochemical properties of WPCc samples under different solutions (water or 0.1 M NaCl aqueous solution) and thermal conditions (25 degrees C and treatment at 90 degrees C for 30 min) were evaluated and compared with commercial bovine whey protein concentrate (WPCb). The chemical composition and the amino acid profiles were also determined. Both WPCc and WPCb showed high solubility in 0.1 M NaCl (almost 100%) and low solubility (38%) under heat treatment and at pH 5 (close to the isoelectric point). WPCc had a greater content of free sulfhydryl groups and higher positive and negative zeta potentials at extreme pH values than WPCb; however, the surface hydrophobicity of WPCc was lower. With respect to bovine whey protein concentrate, the caprine whey proteins presented higher amounts of basic amino acid and also of isoleucine, methionine, glycine and histidine. Results obtained in this work indicated that the caprine whey protein concentrate presents good and similar physicochemical properties to those observed for bovine whey protein concentrate and that it could be used for the same food applications.