贮存温度对巴氏杀菌乳中游离氨基酸组成及品质的影响

Effects of Storage Temperature on the Composition and Flavor of Free Amino Acids in Pasteurized Milk

在巴氏杀菌乳的贮存过程中,由于其中微生物、酶和各种生化反应的参与,其游离氨基酸含量会不断变化,进而也影响着乳的营养品质和滋味。结合酸度以及滋味的变化,采用反向高效液相色谱法对不同贮存条件下巴氏杀菌乳游离氨基酸的含量进行测定与分析。结果表明,0℃9 d内贮存的巴氏杀菌乳中游离氨基酸含量相对稳定,其游离氨基酸组成也不变。4℃条件贮存的巴氏杀菌乳中,Met、Cys的含量在12 d内保持稳定;Asp、Glu、Tyr、Arg和Ala含量均在4℃贮存3 d后急剧下降,此时巴氏杀菌乳的营养品质大大降低,不能保证人体对氨基酸的摄取。在10℃、15℃、25℃贮存条件下,贮存3 d后,巴氏杀菌乳的游离氨基酸组成由16种氨基酸变为5种,均未检出必需氨基酸Leu、Ile、Val、His。推荐巴氏杀菌乳贮存条件为0℃9 d内、4℃3 d内,不建议10℃、15℃、25℃下贮存。此外,Lys与五种味感均呈现显著相关性,表明Lys是影响巴氏杀菌乳滋味的特征氨基酸。

In the storage process of pasteurized milk, due to the participation of microorganisms, enzymes and various biochemical reactions,the free amino acid content will constantly change, which in turn affects the nutritional quality and taste of the milk. Combined with acidity and taste changes, The content of free amino acids in pasteurized milk under different storage conditions was determined and analyzed by reversed-phase high performance liquid chromatography(HPLC). The results showed that the content of free amino acids in pasteurized milk stored in 0 ℃ for 9 days was relatively stable, and the free amino acid composition remained unchanged. The content of Met and Cys remained stable in the pasteurized milk stored at 4 ℃ for 12 days;the contents of Asp, Glu, Tyr, Arg and Ala decreased sharply after storage for3 days at 4 ℃, At this time, the nutritional quality of pasteurized milk is greatly reduced.and the body’s intake of amino acids cannot be guaranteed. At 10 ° C, 15 ° C, 25 ° C storage conditions, after storage for 3 days, the free amino acid composition of pasteurized milk changed from 16 amino acids to 5, and the essential amino acids Leu, Ile, Val, His were not detected. It is recommended that the storage conditions of pasteurized milk be within 0 ℃ for 9 days and within 4 ℃ for 3 days. It is not recommended to store at 10 ℃, 15 ℃, and 25 ℃. In addition, Lys showed a significant correlation with the five taste sensations, indicating that Lys is a characteristic amino acid that affects the taste of pasteurized milk.