Effect of Acid Whey Protein Concentrate on the Rheological Properties, Antioxidant Capacities, and Biological Activities of Bioaccessible Fractions in Fermented Camel Milk

The production of set-type camel milk yogurt is challenging due to its unique physicochemical properties, which differ from those of other milk species. The present study aimed to evaluate the effects of camel milk supplementation with different levels (0, 3, and 6%) of whey protein concentrate (WPC) on the texture, rheological properties, antioxidant capacity, and biological activity of camel milk yogurt compared to bovine milk (BM) yogurt. These characteristics were evaluated before and after in vitro digestion of yogurt samples after 1 and 15 days of storage at 4°C. The results show that using WPC, particularly at 6% (WPCA6), significantly affected the characteristics of yogurt. The water-holding capacity increased by increasing the level of WPC and showed higher values than BM yogurt. Furthermore, the adhesiveness in yogurt samples containing 6% of WPC was significantly higher than other treatments, representing 6.3 and 6.1 mJ after 1 and 15 days, respectively. The apparent viscosity of WPCA6 was also higher than other yogurt treatments at different shear rates throughout storage, indicating a thicker and more viscous yogurt. Camel milk yogurt showed higher DPPH values, representing 74.1, 71.6, and 78.1% for WPCA0, WPCA3, and WPCA6, respectively, compared to BM yogurt (22.9%). The biological activities, including α-amylase, α-glucosidase, and angiotensin-converting enzyme inhibitions, increased after in vitro digestion of yogurt samples. Principal component analysis underscored the distinct bioactive profile of WPCA6, distinguishing it from other yogurt treatments and highlighting its superior properties.由于驼奶与其他乳类具有独特的理化特性，凝固型驼奶酸奶的生产颇具挑战。本研究旨在评估添加不同浓度（0%、3%、6%）乳清蛋白浓缩物（whey protein concentrate, WPC）的驼奶酸奶，相较于牛乳（bovine milk, BM）酸奶，其质地、流变学特性、抗氧化能力及生物活性的变化。本研究在4℃条件下储存1天和15天后，分别对酸奶样品进行体外消化前后的上述特性检测。结果表明，添加乳清蛋白浓缩物，尤其是6%浓度组（WPCA6），可显著改善酸奶的各项特性。随着乳清蛋白浓缩物添加浓度提升，酸奶的持水性逐渐升高，且均高于牛乳酸奶。此外，添加6%乳清蛋白浓缩物的酸奶样品的黏附性显著高于其他处理组，在储存1天和15天后分别为6.3 mJ和6.1 mJ。在整个储存周期内，不同剪切速率下WPCA6组的表观黏度均高于其他酸奶处理组，说明其质地更为浓稠、黏度更高。驼奶酸奶的DPPH自由基清除率更高：WPCA0、WPCA3、WPCA6组分别为74.1%、71.6%、78.1%，而牛乳酸奶仅为22.9%。经体外消化后，酸奶样品的α-淀粉酶抑制活性、α-葡萄糖苷酶抑制活性及血管紧张素转换酶抑制活性等生物活性均有所提升。主成分分析结果显示，WPCA6组具有独特的生物活性特征，与其他酸奶处理组区分明显，凸显出其优异的产品性能。