热处理对牛乳理化特性的影响

Effect of heat treatment on physical and chemical properties of milk

热加工是杀灭牛乳中致病微生物的有效途径,但对牛乳的成分和性质也会产生影响。以F1和F2两个工厂的巴氏乳和超高温瞬时杀菌乳(UHT)为研究对象,原料乳作为对照,研究了热处理之后牛乳理化性质的变化。结果表明巴氏乳和UHT乳中脂肪、蛋白质、乳糖以及固形物的总量与原料乳中的基本一致,但巴氏和UHT热处理造成了乳中维生素C的损失以及泛酸含量的升高。游离氨基酸总量在F1和F2之间差异显著(P<0.05),但是它受热处理方式的影响不显著。巴氏杀菌和UHT热处理对于乳粒径的影响不显著。牛乳的黏度和感官特性受巴氏和UHT热处理的影响显著,两个工厂UHT乳的黏度均较大。F1工厂UHT乳的风味得分较高,而F2工厂的巴氏乳风味得分更高。

Thermal processing is an effective way to kill pathogenic microorganisms in milk, but it also affects the composition and properties of milk. Pasteurized milk, and ultra-high temperature instantaneous sterilized milk(UHT milk) from two factories(F1 and F2) were used as research objects, and the changes in physical and chemical properties of milk after heat treatment were analyzed with raw milk as control. The results showed that the total amount of fat, protein, lactose, and solids in pasteurized milk and UHT milk was basically the same as that in raw milk, but the heat treatment of pasteurization and UHT caused the loss of vitamin C and the increase of pantothenic acid in milk. The total amount of free amino acids differed significantly between F1 and F2, but it was not significantly affected by the heat treatment. The effect of pasteurization and UHT treatment on the particle size of the milk was not significant. The viscosity and sensory properties of milk were significantly affected by the heat treatment of pasteurization and UHT, and the viscosity of UHT milk in both factories was relatively large. The UHT milk from F1 had higher flavor scores, while pasteurized milk from F2 scored higher.