在牛乳品質方面，經過脫脂以及1.5?m濾膜微過濾後，體細胞(somatic cell)方面由生乳的48.121萬/mL過濾後下降到0.743萬/mL，有效提高了牛乳品質。營養成分方面使用微過濾處理後之脫脂生乳其總蛋白質含量雖略有下降 (0.02-0.04％)，但蛋白質成分和比例則不變；乳糖及無脂固形物則與過濾前之差異不顯著。在貯存期方面為經熱處理乳油再標準化之HTST處理之鮮乳於4℃下可延長貯存期至14天。20%含脂率之乳油經均質及121℃, 15min熱處理後，再回填至脫脂生乳經標準化為3%微過濾HTST鮮乳(3%MF-HTST)之結果顯示，黃嘌呤氧化?活性皆顯著低於乳油無熱處理組 (P<0.05)，且可將貯存期延長至21天。綜上所述，欲降低乳中黃嘌呤氧化?活性及延長HTST鮮乳之保存期，宜將分離之乳油以商業滅菌處理再回填至經微過濾脫脂生乳中，續以HTST處理可將黃嘌呤氧化活性降至最低，並宜作為改善現行牛乳加工程序以製造低活性黃嘌呤氧化?及延長貯存期之HTST鮮乳之參考。 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.
