Abstract

Physicochemical characteristics of whey protein concentrate (WPC35, 35% protein), whey protein isolate, sodium, and calcium caseinate powders were studied by storing them at 25, 35, and 45 °C and 11, 44, and 85% relative humidity (RH) for 21 days. Monolayer moisture content (M_o) in these powders increased with increasing protein content. The glass transition temperature (T_g) of all of these powders decreased with increasing RH at all storage temperatures. Lactose crystallization occurred in WPC35 at 85% RH at all temperatures and 44% RH and 45 °C, and this caused caking. Caking was also observed in whey protein concentrate and isolate, and sodium and calcium caseinate powders at 85% RH and 45 °C, despite having low (0.2–1.5%, w/w) lactose content. Surface fat content was higher in powders stored at higher temperatures and RH. All powders developed browning, which was especially pronounced at 85% RH. These findings help better understand the temperature and humidity dependent behavior of whey protein and casein powders during storage.

摘要

通过将乳清蛋白浓缩物（WPC35，35％的蛋白），乳清蛋白分离物，钠和酪蛋白酸钙粉的理化特性研究，将其分别储存在25、35和45°C和11、44和85％相对湿度（RH）下），持续21天。这些粉末中的单层水分含量（M _o）随着蛋白质含量的增加而增加。玻璃化温度（T _g在所有储存温度下，所有这些粉末的d）随RH的增加而降低。在所有温度以及44％RH和45°C的相对湿度下，WPC35中的乳糖结晶均在WPC35中发生，这导致结块。尽管乳糖含量低（0.2-1.5％，w / w），但在乳清蛋白浓缩物和分离物中以及酪蛋白酸钠和酪蛋白酸钠粉末在85％RH和45°C时也观察到结块。在较高温度和相对湿度下储存的粉末中，表面脂肪含量较高。所有粉末均出现褐变，在相对湿度85％时尤为明显。这些发现有助于更好地了解乳清蛋白和酪蛋白粉在存储过程中与温度和湿度有关的行为。