浓缩乳蛋白（MPC）通常是具有功能和营养特性的干燥高蛋白粉，可以通过修改加工条件（包括温度，pH，过滤和干燥）来定制它们。然而，具体地，研究了加工条件对液体MPC（流体超滤牛奶）的结构功能特性的影响。在此报告中，将液态MPC的pH [13％蛋白质（以70％蛋白质DM为基准，pH 6.7）调整为6.5或6.9，并对pH 6.5、6.7和6.9的样品进行了85°热处理。 C持续5分钟或125°C持续15 s。十二烷基硫酸钠PAGE用于确定酪蛋白和变性乳清蛋白在可溶性和胶束相中的分布，HPLC用于定量天然乳清蛋白的变性，根据加工条件。两种热处理在每个pH值下均导致乳清蛋白大量变性，其中β-乳球蛋白的变性程度比α-乳白蛋白的变性程度大。在4°C储存期间，在d 1、5和8监测液体MPC的理化性质变化。无论pH值和加热条件如何，热处理后以及随着时间的推移粘度都会增加，这表明乳清蛋白变性和聚集的作用以及它们与酪蛋白胶束的相互作用。在温度和时间条件下，在pH 6.9下处理的MPC样品的粘度均明显高于在pH 6.5或6.7下加热的MPC样品。在85℃下处理5分钟的样品的粘度高于在125℃下加热15 s的样品的粘度。粒度分析表明，在pH 6.9加热后，MPC储存5天和8天后，存在较大的颗粒。与125°C处理15 s相比，在85°C处理5分钟后，液体MPC的酸诱导凝胶化导致明显更高的凝胶硬度。同样，由MPC调节至pH 6.5制成的凝胶具有更高的储能模量，具有时间和温度组合，证明了变性乳清蛋白与酪蛋白胶束的pH依赖性缔合在凝胶网络形成中的作用。这些发现使人们能够更好地了解有助于液体MPC的结构和功能特性的加工因素，并且有助于为各种食品定制乳蛋白成分的功能。与125°C处理15 s相比，在85°C处理5分钟后，液体MPC的酸诱导凝胶化导致明显更高的凝胶硬度。同样，由MPC调节至pH 6.5制成的凝胶具有更高的储能模量，具有时间和温度组合，证明了变性乳清蛋白与酪蛋白胶束的pH依赖性缔合在凝胶网络形成中的作用。这些发现使人们能够更好地了解有助于液体MPC的结构和功能特性的加工因素，并且有助于为各种食品定制乳蛋白成分的功能。与125°C处理15 s相比，在85°C处理5分钟后，液体MPC的酸诱导凝胶化导致明显更高的凝胶硬度。同样，由MPC调节至pH 6.5制成的凝胶具有更高的储能模量，具有时间和温度组合，证明了变性乳清蛋白与酪蛋白胶束的pH依赖性缔合在凝胶网络形成中的作用。这些发现使人们能够更好地了解有助于液体MPC的结构和功能特性的加工因素，并且有助于为各种食品定制乳蛋白成分的功能。证明了变性乳清蛋白与酪蛋白胶束的pH依赖性缔合在凝胶网络形成中的作用。这些发现使人们能够更好地了解有助于液体MPC的结构和功能特性的加工因素，并且有助于为各种食品定制乳蛋白成分的功能。证明了变性乳清蛋白与酪蛋白胶束的pH依赖性缔合在凝胶网络形成中的作用。这些发现使人们能够更好地了解有助于液体MPC的结构和功能特性的加工因素，并且有助于为各种食品定制乳蛋白成分的功能。

"点击查看英文标题和摘要"

Milk protein concentrates (MPC) are typically dried high-protein powders with functional and nutritional properties that can be tailored through modification of processing conditions, including temperature, pH, filtration, and drying. However, the effects of processing conditions on the structure-function properties of liquid MPC (fluid ultrafiltered milk), specifically, are understudied. In this report, the pH of liquid MPC [13% protein (70% protein DM basis), pH 6.7] was adjusted to 6.5 or 6.9, and samples at pH 6.5, 6.7, and 6.9 were subjected to heat treatment at either 85°C for 5 min or 125°C for 15 s. Sodium dodecyl sulfate PAGE was used to determine the distribution of caseins and denatured whey proteins in the soluble and micellar phases, and HPLC was used to quantify native whey proteins as a measure of denaturation, based on the processing conditions. Both heat treatments resulted in substantial whey protein denaturation at each pH, with β-lactoglobulin denatured more extensively than α-lactalbumin. Changes in liquid MPC physicochemical properties were monitored at d 1, 5, and 8 during storage at 4°C. Viscosity increased after heat treatment and also over time, regardless of pH and heating conditions, suggesting the role of whey protein denaturation and aggregation, and their interactions with casein micelles. The MPC samples processed at pH 6.9 had a significantly higher viscosity than those heated at pH 6.5 or 6.7, for both temperature and time conditions; and samples processed at 85°C for 5 min had higher viscosity than those heated at 125°C for 15 s. Particle size analysis indicated the presence of larger particles after 5 and 8 d of MPC storage after heating at pH 6.9. Acid-induced gelation of the liquid MPC led to significantly higher gel firmness after processing at 85°C for 5 min, compared with 125°C for 15 s. Also, gels made from MPC adjusted to pH 6.5 had higher storage moduli, with both time and temperature combinations, demonstrating the role of pH-dependent association of denatured whey proteins with casein micelles in gel network formation. These findings enable a better understanding of the processing factors contributing to structural and functional properties of liquid MPC and can be helpful in tailoring milk protein ingredient functionality for a variety of food products.