Partial replacement of animal protein sources with plant proteins is highly relevant for the food industry, but potential effects on protein digestibility need to be established. In this study, the in vitro protein digestibility (IVPD) of four protein sources and their mixtures (50:50 w/w ratio) was investigated using a transient pepsin hydrolysis (1 h) followed by pancreatin (1 h). The protein sources consisted of napin-rich rapeseed (Brassica napus L.) protein concentrates (RPCs; RP1, RP2) prepared in pilot scale and major bovine whey proteins (WPs; α-LA, alpha-lactalbumin; β-LG, beta-lactoglobulin). IVPD of individual protein sources was higher for WPs compared to RPCs. The RP2/β-LG mixture resulted in an unexpected high IVPD equivalent to β-LG protein alone. Protein mixtures containing RP1 showed a new IVPD response type due to the negative influence of a high trypsin inhibitor activity (TIA) level. Improved IVPD of RP1 alone and in protein mixtures was obtained by lowering the TIA level using dithiothreitol (DTT). These results showed that napin-rich protein products prepared by appropriate processing can be combined with specific WPs in mixtures to improve the IVPD.

中文翻译：

---

油菜籽和牛乳清蛋白混合物的体外消化率

用植物蛋白部分替代动物蛋白源与食品工业高度相关，但需要确定其对蛋白消化率的潜在影响。在这项研究中，使用短暂的胃蛋白酶水解（1小时），然后是胰酶（1小时），研究了四种蛋白质来源及其混合物（50:50 w / w的比例）的体外蛋白质消化率（IVPD）。蛋白质来源由富含napin的油菜籽（甘蓝型油菜）组成L.）浓缩蛋白（RPCs; RP1，RP2）以中试规模制备，以及主要的牛乳清蛋白（WPs;α-LA，α-乳白蛋白;β-LG，β-乳球蛋白）。与RPC相比，WP的单个蛋白质来源的IVPD更高。RP2 /β-LG混合物产生了意想不到的高IVPD，相当于单独的β-LG蛋白。由于高胰蛋白酶抑制剂活性（TIA）水平的负面影响，含有RP1的蛋白混合物显示出新的IVPD反应类型。通过使用二硫苏糖醇（DTT）降低TIA含量，可以提高RP1单独和蛋白质混合物中的IVPD。这些结果表明，通过适当加工制备的富含Napin的蛋白质产品可以与特定的WP混合使用，以改善IVPD。