SDS-凝膠電泳檢測羊乳中摻雜牛乳之研究

Detection of Cow Milk in Goat Milk by SDS-Polyacrylamide Gel Electrophoresis

曹博宏(Po-Hung Tsao) ； 林世斌(Shih-Bin Lin) ； 吳輔祐(Fu-Yu Wu)

《宜蘭技術學報》 9期生物資源專輯 (2002/12) Pp. 33-39

https://doi.org/10.6179/nit.job.2002.09.14

摘要

本實驗探討用SDS-凝膠電泳（SDS-PAGE）檢測羊乳中摻雜牛乳之簡易方法。生羊乳與牛乳經離心脫脂，調酸沉澱分離酪蛋白及乳清，使用15%迷你凝膠電泳，凝膠以coomassie brilliant blue染色。結果羊乳有一最深色之band位於31 kDa，其上另有一band位於36.5 kDa。牛乳則為兩條相等深色之30與35 kDa band。直接以脫脂生乳未經分離酪蛋白電泳，即可看出差別。以銀染色凝膠則羊乳36.5 kDa和牛乳35 kDa之band較不易呈色。電泳時樣品染液bromophenol blue跑出凝膠後，繼續以20 mA電泳2hr，可增加各band之分離效果。脫脂羊乳添加0.5、1、2、5、10、20%脫脂牛乳，依上法電泳，以coomassie brilliant blue染色，純羊乳在31和36.5 kDa之間只有兩條band，如果添加牛乳則有3條band，亦即多出牛乳之35 kDa，可檢出5%牛乳。以銀染色法則緊臨於羊乳31 kDa的主要band下面多出牛乳的30 kDa band，靈敏度可達2%。牛乳特有之30與35 kDa band不受添加來源為生乳或還原乳的影響。台灣常見五種山羊品種所產之羊乳，亦不見此牛乳特有之band。本法簡易，設備普遍，有實際應用的價值。

關鍵字

羊乳 ； 牛乳 ； 凝膠電泳

並列摘要

This study was to establish a simple method for detection of cow milk adulterated in goat milk. Goat and cow milks were defatted by centrifugation, acid precipitated to separate casein and whey proteins, electrophorized with 15% mini SDSPAGE, and stained with coomassie brilliant blue. Goat milk contained a major dark band at location near 31 kDa and a clear light band at 36.5 kDa. However, cow milk contained two evenly dark bands at 30 and 35 kDa. These differences could be clearly distinguished both on the gel of samples with or without milk protein separation. With silver staining, the 36.5 kDa band of goat milk and 35 kDa of cow milk were not stained as dark in proportion as other bands. The banding separation could be enhanced with two more hours of electrophoresis after the dye front eluted from the gel. Defatted goat milk added with 0.5, 1, 2, 5, 10, 20% of cow milk were electrophoresized and stained as above. Gel of goat milk showed only 2 bands between 31 kDa and 36.5 kDa, whereas goat milk added with cow milk showed 3 bands with extra band of 35 kDa from cow milk. The difference could be distinguished do to 5% cow milk adulteration. With silver staining, the cow milk's 30 kDa band appeared closely next to goat milk's 31 kDa, and 2% adulteration could be distinguished. The difference was not affected by the source of cow milk either from w milk or reconstituted milk. All five breeds of dairy goat commonly raised in Taiwan did not have cow milk's 30 and 35 kDa bands. This method is ease and the equipment is commonly available, thus is practical.

並列關鍵字

Goat Milk ； Cow Milk ； SDS-PAGE