摘要
乳品加工和储藏过程中乳蛋白和乳糖美拉德反应的发生是一个很受关注的问题,采用乳制品中主要含有的酪蛋白、β-酪蛋白和乳清蛋白,分别在干法条件下(温度60℃,相对湿度79%)和湿法条件下(温度65℃,2.5%蛋白溶液)观察和分析发生美拉德反应发生的程度与进程。结果表明,在干法和湿法条件下加热,随着加热时间的延长,3种乳蛋白和乳糖体系的吸光值均逐渐增高;乳清分离蛋白分别在加热4h(干法)和1d(湿法)时吸光值显著性增高(p<0.05),而酪蛋白和β-酪蛋白分别在加热8h(干法)和2d(湿法)时吸光值出现显著性增高(p<0.05);同时,L值均逐渐减小,而a值和b值均逐渐增大,在加热4h(干法)和1d(湿法)时,3种色差值都出现显著性变化(p<0.05);蛋白和糖的含量均逐渐降低,在加热8h(干法)和2d(湿法)时蛋白和糖含量均有显著性降低(p<0.05);由SDS-PAGE可知,加热之后各体系均出现高分子蛋白条带。在干法条件下,乳清分离蛋白加热4h后蛋白条带开始上移,并在高分子区域出现条带,而酪蛋白和β-酪蛋白在加热16h后在高分子区域产生了新的条带;在湿法条件下,3种乳蛋白在加热2d后在高分子区域出现新的条带,并且随着加热时间的延长,高分子条带密度越来越大。综上所述,3种乳蛋白与乳糖体系的美拉德反应发生的时间在干法条件下比湿法条件下出现更早。在相同条件下,乳清分离蛋白的美拉德反应性要比酪蛋白和β-酪蛋白强,而酪蛋白与β-酪蛋白的美拉德反应性则无明显差别。
The Maillard reaction between milk protein and lactose is a concern during processing and storage of dairy products. Investigated development of Maillard reaction in three milk protein and lactose systems of casein, β-casein and whey protein isolate in both dry condition （60 %, protein powder at relative humidity 79%） and wet condition （65 ℃, protein solution of 2.5%）. The results showed that the absorption values in all three milk protein and lactose systems were gradually increased as heating time increasing in both dry and wet conditions. Furthermore, absorption values of whey protein isolate-lactose system were significantly increased （p〈0.05） after heating for 4 hours under dry condition and 1 day under wet condition, while absorption values of casein and β-casein-lactose systems were significantly increased （p〈0.05） after heating for 8 hours under dry condition and 2 days under wet condition. At the same time, L values of three protein and lactose systems were decreased, while a and b values were gradually increased; L, a, b values were significant changed （p〈0.05） after heating for 4 hours under dry condition and 1 day under wet condition. Protein and sugar contents were decreased significantly （p〈0.05） after heating for 8 hours under dry condition and 2 days under wet condition. High molecular protein bands appeared on SDS-PAGE of three milk protein and lactose systems. Under dry heating condition, the bands of whey protein isolate started to move upward after heating for 4 hours and new bands appeared in high molecular region, while casein and [8-casein have new bands in high molecular region after heating for 16 hours. When three milk protein and lactose systems were heated under wet condition, the new protein bands appeared in high molecular region after heating for 2 days, and density of the high molecular protein bands was increased with the prolongation of heating time. In conclusion, Maillard reaction occurred much earlier in dry condition than in wet condition in three milk protein and lactose systems. Under the same conditions, Maillard reaction reactivity of whey protein isolate is higher than that of casein and β-casein, while no significant difference observed between casein and β-casein.
出处
《食品科技》
CAS
北大核心
2013年第6期58-66,共9页
Food Science and Technology
基金
"十二五"农村领域国家科技计划项目(2011BAD09B0302)
关键词
酪蛋白
Β-酪蛋白
乳清分离蛋白
乳糖
美拉德反应
干法
湿法
casein
β-casein
whey protein isolate
lactose
Maillard reaction
dry condition
wet condition
