原料乳离心除菌对UHT乳品质的改善作用

Improvement of UHT Milk Quality by Bactofugation of Raw Milk

离心除菌可以改善原料乳的质量,本文研究了常规UHT(N-UHT)乳和离心除菌UHT乳(C-UHT)在贮藏过程中理化性质、蛋白分布变化。结果表明:UHT乳贮藏期颜色变深、粒度增加、Zeta电位绝对值降低、黏度增加、酸度增加和纤溶蛋白酶活性增加,乳胶体稳定性降低;离心除菌UHT乳(C-UHT)的物理化学稳定性优于普通UHT乳(N-UHT)。贮藏过程中酪蛋白(CN)含量变化不显著,乳清蛋白含量(WN)逐渐降低,非蛋白氮(NPN)含量逐渐增加;贮藏6个月后,N-UHT和C-UHT的NPN分别从4.2%增加到8.7%和7.9%;C-UHT的蛋白降解程度低于N-UHT。

Bactofugation can significantly improve the quality of raw milk.The paper focuses on the changes of physical and chemical properties and protein distribution for normal UHT(N-UHT)milk and bactofugation UHT milk(C-UHT)during storage.During the storage of UHT milk,the color became darker,the particle size increased,the absolute value of zeta potential decreased,the viscosity increased,the acidity increased,the fibrinolytic activity increased,and the emulsion stability decreased.The physical and chemical stability of bactofugation UHT milk(C-UHT)was better than that of normal UHT milk(N-UHT).During storage,the content of casein(CN)did not change significantly,the content of whey protein(WN)decreased gradually,and the content of non protein nitrogen(NPN)increased gradually.After 6 months of storage,the NPN of N-UHT and C-UHT increased from 4.2%to 8.7%and 7.9%,respectively.The protein degradation of C-UHT was lower than that of N-UHT.