Valuation, Security and Food Analysis Laboratory, National Engineering School of Sfax, Sfax University, Tunisia; UMR-STLO: Science and Technology of Milk and Egg, INRA, Agrocampus Rennes, France.
UMR-STLO: Science and Technology of Milk and Egg, INRA, Agrocampus Rennes, France.
Food Chem. 2020 Dec 15;333:127514. doi: 10.1016/j.foodchem.2020.127514. Epub 2020 Jul 10.
This study investigated the effect of pH on the denaturation extent, the surface chemical composition, the water sorption isotherm and the glass transition temperature of camel and bovine whey protein's powders. The LC-MS analysis indicated that the β-Lactoglobulin was the most denatured protein in bovine whey powders regardless the pH value, while this protein was totally absent in camel whey. The α-Lactalbumin was relatively heat stable after drying and predominated the powder surface (X-ray photoelectron spectroscopy results) in both camel and bovine whey powders regardless the pH (neutral (6.7) or acidic (4.3 and 4.6)). Analysis of the water sorption isotherms indicated that decreasing the pH induced the increase of the water activity of lactose crystallization for camel and bovine whey powders. Finally, decreasing the pH led to the decrease of the glass transition temperature of camel and bovine whey powder (at 0.13, 0.23, and 0.33 of water activity).
本研究考察了 pH 值对骆驼和牛乳清蛋白粉末变性程度、表面化学成分、水分吸附等温线和玻璃化转变温度的影响。LC-MS 分析表明，β-乳球蛋白是牛乳清粉末中变性程度最高的蛋白质，而在驼乳清中则完全不存在。α-乳白蛋白在干燥后相对热稳定，并且无论 pH 值如何（中性（6.7）或酸性（4.3 和 4.6）），都在驼乳和牛乳清粉末的表面占主导地位（X 射线光电子能谱结果）。水分吸附等温线分析表明，降低 pH 值会导致骆驼和牛乳清粉末中乳糖结晶的水活度增加。最后，降低 pH 值会导致骆驼和牛乳清粉末的玻璃化转变温度降低（在 0.13、0.23 和 0.33 的水活度下）。
