Riddet Institute, Massey University, Palmerston North 4442, New Zealand; Institute of Food, Nutrition and Human Health, Massey University, Auckland, New Zealand.
Riddet Institute, Massey University, Palmerston North 4442, New Zealand.
Colloids Surf B Biointerfaces. 2013 Nov 1;111:80-7. doi: 10.1016/j.colsurfb.2013.05.034. Epub 2013 May 29.
Most studies on the in vitro lipid digestion of protein-stabilized emulsions have been carried out under simulated gastric and intestinal conditions. In this study, the digestion behaviour of whey protein isolate (WPI)-stabilized emulsions was examined under simulated intestinal fluid (SIF) conditions (pH 7.5, 2.5mg bile salts/mL and 0.8 mg pancreatin/mL) after the emulsions had been digested in a model simulated gastric fluid (SGF) containing pepsin (pH 1.6 and 3.2mg pepsin/mL) for different times. The droplet size, ζ-potential, microstructure, surface protein and amount of free fatty acids released were examined. The results indicated that WPI emulsions did not undergo pronounced changes in droplet size and microstructure during SGF digestion followed by coalescence during the subsequent SIF digestion. When WPI emulsions were treated with SGF, α-lactalbumin and a portion of β-lactoglobulin proteins adsorbed at the interface were hydrolysed by pepsin, resulting in small peptides being produced as characterized by sodium dodecyl sulphate polyacrylamide gel electrophoresis. In general, digestion in SGF containing pepsin accelerated coalescence of the emulsion droplets during subsequent digestion in SIF containing pancreatic lipase. However, the changes in the size, the microstructure and the proteolysis of the interfacial proteins of the emulsions under gastric conditions did not influence the rate and the extent of lipid digestion in the subsequent intestinal environment.
大多数关于蛋白质稳定乳液的体外脂质消化的研究都是在模拟胃和肠道条件下进行的。在这项研究中，在含有胃蛋白酶（pH 1.6 和 3.2mg 胃蛋白酶/mL）的模拟胃液（SGF）中消化一段时间后，研究了乳清蛋白分离物（WPI）稳定乳液在模拟肠液（SIF）条件（pH 7.5、2.5mg 胆汁盐/mL 和 0.8mg 胰酶/mL）下的消化行为。研究了乳液的粒径、ζ-电位、微观结构、表面蛋白质和释放的游离脂肪酸的量。结果表明，WPI 乳液在 SGF 消化过程中粒径和微观结构没有明显变化，随后在随后的 SIF 消化过程中发生聚结。当 WPI 乳液用 SGF 处理时，α-乳白蛋白和一部分β-乳球蛋白蛋白质在界面被胃蛋白酶水解，导致产生小肽，如十二烷基硫酸钠聚丙烯酰胺凝胶电泳所示。一般来说，在含有胃蛋白酶的 SGF 中消化加速了后续在含有胰脂肪酶的 SIF 中的乳液液滴的聚结。然而，在胃条件下乳液的界面蛋白质的大小、微观结构和蛋白水解的变化并没有影响随后在肠道环境中的脂质消化的速率和程度。
