|a英文題名:Immunoassays for Studying the Effects of Heating Conditions on the Characteristics of Milk Proteins
|a供飲用的牛乳需經過加熱殺菌或滅菌。本研究在模式系統下觀察牛乳蛋白質與乳糖混合溶液經不同加熱處理，對其結構、免疫反應性及抗氧化性的影響；並探討加熱處理之生乳及市售乳品其蛋白質組成與免疫反應性的變化。利用pH 4.6沉澱、Native-PAGE、還原性與非還原性SDS-PAGE、免疫轉漬法、酵素連結免疫吸附法分析牛乳蛋白質之變化與相互作用之情形。並在模式系統下以ABTS清除自由基的能力、螯合亞鐵離子能力及還原力測其抗氧化性。模式系統的電泳與免疫轉漬法結果顯示，隨著溫度上升會增加β-Lg、α-La、酪蛋白間的交互作用與聚合反應的程度。酵素連結免疫吸附法以β-Lg和α-La抗體偵測的結果，免疫反應性隨溫度上升而增加，這代表結構的舒展與暴露出更多的抗原決定區。加熱至80 ℃以上時，抗氧化性質有顯著增加，但含酪蛋白的模式系統中，僅還原力結果顯示如此。生乳的結果與模式系統相似；市售乳在電泳與免疫檢測法相互搭配下，可分辨出不同加熱程度的牛乳。|uMilk products have to be pasteurized or sterilized. In this study, milk proteins-lactose model systems were used to investigate the effects of heat treatments on the structure, immunoreactivity, and antioxidant capicity of proteins. The changes of protein composition and immunoreactivity on heated raw milk and commercial milk products were also investigated. Precipitation at pH 4.6, Native-PAGE, reducing and non-reducing SDS-PAGE, Western blot analysis, and ELISA were used to elucidate the changes and the interactions among milk proteins. In model systems, the antioxidant capacity was analyzed by ABTS radical scavenging ability, ferrous ion chelating ability and reducing power methods. The results of electrophoresis and Western blot showed that the interactions and degree of polymerization increased among β-Lg, α-La and casein as the heating temperature increased. The immunoreactivity of β-Lg and α-La increased, measured with ELISA using β-Lg and α-La antibodies, as the temperature increased, indicating the protein unfolding and exposure of more epitopes. At temperatures above 80 ℃, the antioxidant properties increased significantly. However, only reducing power followed the above trend for model systems containing casein. The changes of protein composition and immunoreactivity for heated raw milk were similar to those in model systems. Combining electrophoresis and immunoassay could differentiate different heat-treated commercial milk products.
|aImmunoassays for Studying the Effects of Heating Conditions on the Characteristics of Milk Proteins