Midwest Dairy Foods Research Center, Dairy and Food Science Department, South Dakota State University, Brookings 57007; Idaho Milk Products, Jerome, ID 83338.
Midwest Dairy Foods Research Center, Dairy and Food Science Department, South Dakota State University, Brookings 57007.
J Dairy Sci. 2021 Jan;104(1):134-137. doi: 10.3168/jds.2020-18937. Epub 2020 Nov 12.
This study aimed to investigate the heat stability of dispersions from reconstituted reduced-calcium milk protein concentrate (RCMPC) with 80% protein or more. The tested RCMPC powders were produced from skim milk subjected to CO treatment before and during the process of ultrafiltration. The CO injection was controlled to obtain 0 (control, no CO injection), 20, 30, and 40% reduction in calcium levels in the RCMPC powders. The RCMPC powders were reconstituted to 10% (wt/wt) protein in deionized water. These dispersions were tested for heat stability in a rocking oil bath at 140°C at unadjusted, 6.5, 6.7, 6.9, and 7.1 pH. Calcium ion activity (CIA) and ionic strength measurements were carried out using a Ca ion-selective electrode and conductivity meter. Unadjusted pH of the dispersions varied from 6.8 in control to 5.96 in 40% RCMPC dispersions. The CIA of unadjusted dispersions ranged from 1.31 mM in control to 2.83 mM in 40% RCMPC. Heat stability, expressed as heat coagulation time (HCT) of unadjusted dispersions decreased as the level of Ca removal in powders increased (from 13.81 min in control to 0.46 min in 40% RCMPC) and was negatively correlated with the CIA of the dispersions. For control RCMPC dispersions, the minimum and maximum heat stability were observed at dispersion pH of 6.5 and 6.9, respectively, followed by a decrease at pH 7.1 (CIA was the lowest). Dispersions from 40% RCMPC and pH 7.1 had the maximum HCT of 30.94 min among all RCMPC dispersions at all pH values. From this study, it can be concluded that improved heat stability in high protein formulation beverages subjected to UHT processing could be achieved through calcium reduction in milk protein concentrates using CO injection.
本研究旨在探究再构成的低钙乳浓缩蛋白（RCMPC）分散体的热稳定性，其蛋白含量在 80%以上。测试的 RCMPC 粉末由经过 CO 处理的脱脂乳制成，CO 处理在超滤过程中进行。通过控制 CO 的注入量，使 RCMPC 粉末中的钙含量降低 0（对照，无 CO 注入）、20%、30%和 40%。将 RCMPC 粉末在去离子水中再构成 10%（wt/wt）的蛋白质。将这些分散体在未调节的、6.5、6.7、6.9 和 7.1pH 值的油浴摇床中于 140°C 下测试热稳定性。使用钙离子选择性电极和电导率仪进行钙离子活度（CIA）和离子强度测量。未调节的分散体的 pH 值从对照的 6.8 变化到 40%RCMPC 分散体的 5.96。未调节的分散体的 CIA 范围从对照的 1.31mM 变化到 40%RCMPC 的 2.83mM。热稳定性，以未调节的分散体的热凝固时间（HCT）表示，随着粉末中钙去除水平的增加而降低（从对照的 13.81 分钟降低到 40%RCMPC 的 0.46 分钟），并且与分散体的 CIA 呈负相关。对于对照的 RCMPC 分散体，在分散体 pH 值为 6.5 和 6.9 时观察到最小和最大的热稳定性，然后在 pH 值为 7.1 时降低（CIA 最低）。在所有 pH 值下，所有 RCMPC 分散体中，40%RCMPC 和 pH 值 7.1 的分散体的最大 HCT 为 30.94 分钟。从这项研究可以得出结论，通过在乳浓缩蛋白中使用 CO 注入来降低钙，可以在 UHT 加工的高蛋白配方饮料中实现改善的热稳定性。
