UHT灭菌乳在不同保藏条件下品质的变化

Quality Changes of UHT Sterilized Milk under Different Storage Conditions

以市售利乐枕装UHT灭菌乳为研究对象,考察不同保藏条件下UHT灭菌乳品质的变化。结果表明,除4℃冷藏的UHT灭菌乳风味物质散发效果不好外,感官品质的总体变化趋势是保藏时间越长、温度越高,感官品质下降越明显。保藏期间,乳中蛋白质含量、乳糖含量及乳脂肪含量随保藏时间的延长呈下降趋势,而滴定酸度呈上升趋势;保藏温度越高,以上变化越明显。在整个试验保藏期(32 d)内,不同保藏条件下,原液、10-1、10-2 3个浓度的UHT乳样液中大肠菌群的最大可能数(MPN)均未检出。

The Tetra-pillow-pack UHT sterilized milk was used as the research object in order to examine the quality changes under different storage conditions. Results showed that the distribution of flavor substances of the UHT sterilized milk under 4℃ was not good; the sensory quality of the trend was the more long time and more high temperature, the more obvious drops of sensory evaluation index. The prolonged storage time resulted in a reduction of protein, lipid, lactose and an increase of titration acidity. These changes also could be accelerated due to higher temperature during storage. Throughout the storage period of 32 d the maximum possible number （MPN） of fecal coliform of UHT milk samples was not detected.