羊乳蛋白质组成及消化特性

应用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和体外模拟消化研究羊乳蛋白质组成和消化特性。结果表明：羊乳蛋白质主要由酪蛋白和乳清蛋白组成，酪蛋白主要由αs1-酪蛋白、αs2-酪蛋白、β-酪蛋白和κ-酪蛋白组成，在酪蛋白中的相对含量分别为23.10%、30.39%、38.09%和8.42%；乳清蛋白主要由α-乳白蛋白、β-乳球蛋白、乳铁蛋白、血清白蛋白和免疫球蛋白组成，在乳清蛋白中的相对含量分别为24.59%、57.50%、4.35%、8.69%和4.88%；羊乳酪蛋白主要在肠液中消化，在胃液中消化120 min时

Protein Composition and Digestion Characteristics of Goats' Milk

The protein composition and digestion characteristics of goats’ milk were studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and in vitro simulated digestion. The results showed that goats’ milk proteins mainly included casein (αS1-casein, αS2-casein, β-casein and κ-casein, accounting for 23.10%, 30.39%, 38.09% and 8.42% of the total casein, respectively) and whey protein (α-lactalbumin, β-lactoglobulin, lactoferrin, serum albumin and immunoglobulin, accounting for 24.59%, 57.50%, 4.35%, 8.69% and 4.88% of the total whey protein, respectively). Casein was mainly digested in the intestinal juice, and the digestibility reached more than 99.00% after 120 min in the gastric juice, while it only took 2 min to reach more than 99.00% digestibility in the intestinal juice. The digestibility of lactoferrin, serum albumin and immunoglobulin in the gastric juice and intestinal juice was significantly higher than that of α-lactalbumin and β-lactoglobulin (P < 0.05), and α-lactalbumin and β-lactoglobulin were not easy to digest in the gastric and intestinal juice. The digestibility of α-lactalbumin and β-lactoglobulin was 67.53% and 50.82% in the gastric juice at 120 min, and 58.16% and 64.04% in the intestinal juice at 30 min, respectively. Gastrointestinal juice digestion also showed that casein in goats’ milk was more digestible than whey protein in goats’ milk.