Physico-chemical properties of acid whey protein concentrates prepared from buffalo milk by various methods I. Composition and physico-chemical changes in proteins.

摘要

Buffalo milk whey protein concentrates (WPC) were isolated by 4 methods using precipitation with 0.07 M sodium hexametaphosphate (SHMP), precipitation with acidulated water at pH 3.2 containing 0.352% carboxymethylcellulose (CMC), gel filtration (GF) on Sephadex G-25 and ion-exchange chromatography (IE) on CM Sephadex C-50. GF- and IE-WPC had a high protein content and a low carbohydrate content compared with the other WPC. GF on Sephadex G-100 resolved acid whey into 4 fractions, while WPC prepared using SHMP, CMC and GF on Sephadex G-25 were resolved into 2 or 3 components. With IE, all the whey proteins were eluted in a single fraction which corresponded to the void volume. Vertical gel electrophoresis showed that SHMP- and GF-WPC had the samepattern as that of their original whey, while CMC-WPC showed incomplete resolution. The IE-WPC did not resolve into any component but showed streaking. SDS-electrophoresis showed that acid whey gave 4 bands corresponding to bovine serum albumin (BSA), adimer of beta-lactoglobulin, a monomer of beta-lactoglobulin and alpha-lactalbumin. SHMP- and CMC-WPC from acid whey showed only 2 bands which corresponded to a monomer of beta-lactoglobulin and alpha-lactalbumin, while GF-WPC showed a similar pattern tothat of the original whey. IE-WPC showed 2 additional bands with molecular weights of 30 550 and 22 390 Da.