Dileep Kavya, Meletharayil Hari, Amamcharla Jayendra K
Department of Animal Sciences and Industry, Food Science Institute, Kansas State University, Manhattan, KS 66506, USA.
Dairy Management Inc., Rosemont, IL 60018, USA.
Foods. 2024 Nov 28;13(23):3832. doi: 10.3390/foods13233832.
The influence of heating as a pretreatment on the structural and functional attributes of milk protein concentrate (MPC) powders derived from ultrafiltered/diafiltered (UF/DF) skim milk is under-reported. This research delves into the impact of pH and heat treatment on skim milk's properties before UF/DF and how these changes affect the resulting MPC powders. By adjusting the pH of skim milk to 6.5, 6.8, or 7.1 and applying thermal treatment at 90 °C for 15 min to one of two divided lots (with the other serving as a control), we studied the protein interactions in MPC. Post-heat treatment, the skim milk's pH was adjusted back to 6.8, followed by ultrafiltration and spray drying to produce MPC powders with protein content of 82.38 ± 2.72% on a dry matter basis. MPC dispersions from these powders at 5% protein (/) were also evaluated for particle size, viscosity, and heat coagulation time (HCT) to further understand how the protein interactions in skim milk influence the properties of MPC dispersions. Capillary electrophoresis was used to assess the casein and whey protein distribution in both the soluble and colloidal phases. Findings revealed that preheating skim milk at pH 7.1 increased serum phase interactions, while heating skim milk preadjusted to a pH of 6.5 promoted whey protein-casein interactions at the micellar interface. Notably, the D (4,3) of casein micelles was larger for dispersions from milk with a preheated pH of 6.5 compared to other pH levels, correlating positively with enhanced dispersion viscosity due to increased volume fraction. These results support the potential for tailoring MPC powder functionality in various food applications through the precise control of the milk's pre-treatment conditions.
作为预处理的加热对源自超滤/渗滤（UF/DF）脱脂乳的乳蛋白浓缩物（MPC）粉末的结构和功能属性的影响鲜有报道。本研究深入探讨了pH值和热处理对脱脂乳在UF/DF之前的特性的影响，以及这些变化如何影响最终的MPC粉末。通过将脱脂乳的pH值调节至6.5、6.8或7.1，并对两份分开的样品之一在90°C下进行15分钟的热处理（另一份作为对照），我们研究了MPC中的蛋白质相互作用。热处理后，将脱脂乳的pH值调回6.8，然后进行超滤和喷雾干燥，以生产干物质基础上蛋白质含量为82.38±2.72%的MPC粉末。还对这些粉末在5%蛋白质（/）浓度下的MPC分散体的粒度、粘度和热凝固时间（HCT）进行了评估，以进一步了解脱脂乳中的蛋白质相互作用如何影响MPC分散体的特性。采用毛细管电泳评估酪蛋白和乳清蛋白在可溶性和胶体相中的分布。研究结果表明，在pH 7.1下预热脱脂乳会增加血清相相互作用，而预热至pH 6.5的脱脂乳加热会促进乳清蛋白与酪蛋白在胶粒界面的相互作用。值得注意的是，与其他pH水平相比，预热pH为6.5的牛奶分散体中酪蛋白胶粒的D（4,3）更大，这与由于体积分数增加而导致的分散体粘度增强呈正相关。这些结果支持了通过精确控制牛奶的预处理条件来定制MPC粉末在各种食品应用中的功能的潜力。
