奶粉加速破坏性实验中质量参数的确定

Determination of milk powder quality change during accelerated shelf life test

在35℃和45℃的恒湿贮存条件下,考察了全脂和脱脂奶粉的脂肪氧化以及参与美拉德反应的蛋白质变性情况。全脂奶粉由于脂肪含量高,45℃下的硫代巴比妥酸反应物(TBARS)在10d以后便开始递增,明显早于30d才变化的反映美拉德反应的荧光强度,说明首先导致全脂奶粉品质变化的原因是脂肪氧化。在35℃和45℃下,脱脂奶粉荧光强度的增加都先于全脂奶粉,并且增加的幅度都很大,通过运用SDS-PAGE对蛋白质结构进行分析对照,荧光强度可以实时反映蛋白质的变性程度。

The lipid oxidation and protein denaturation involved with Maillard reaction of whole milk powder and skimmed milk powder were investigated at 35℃and 45℃storage temperature. Thiobarbituric acid reactive substances(TBARS) of whole milk powder began to increase slowly after 10 days storage at 45℃due to its high fat content while the measurement of fluorescent intensity resulted from Maillard reaction increased after 30 days storage. The fluorescent intensity e of skimmed milk powder increased obviously prior to the whole milk powder at both 35℃and 45℃. The protein analysis with SDS-PAGE showed that the measurement of fluorescent intensity was in agreement with the whey protein denaturation.