| Summary: | 碩士 === 東海大學 === 畜產與生物科技學系 === 105 === High-temperature short-time (HTST) thermal pasteurization has been effectively used for decades as a method to extend the shelf life of fluid milk. The purpose of this study is to test the HTST full cream milk quality, xanthine oxidase activity, shelf life and nutritional content after microfiltration treatment (MF). After separating the cream, microfiltration is using 1.5μm filter paper to filtrated the skim milk and support by pump. Separated cream will heat through 121℃, 15min, and followed by standardization, homogenization and pasteurized by HTST treatment. The results showed microfiltration treatment can effectively reduce the number of the somatic cells, the total number of bacteria and the content of protein and non-fat solids (SNF) are no significant difference. The shelf life of the MF-HTST full cream fresh milk refrigerated at 4℃ can be extended to 21 days. After cream heat treatment (121℃, 15min), xanthine oxidase activity becomes significantly lower then un-heated treatment. In conclusion, the best way to decrease xanthine oxidase activity and extend the shelf life of HTST milk will to sterilize 20% fat content cream before standardizing the MF skim milk and through HTST processing. This study may provide a suitable method to produce the lower xanthine oxidase activity of long shelf life HTST fresh milk.
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