牛初乳IGF-I在常用乳品加工条件下的稳定性研究

Study on stability of bovine colostrums insulin-like growth factor-I under normal dairy processing conditions

目的:探讨常用乳品加工条件对牛初乳IGF-I的稳定性影响。方法:采用加热、调整pH、均质以及乳酸菌发酵等常用的乳品生产加工单元操作处理牛初乳IGF-I,并检测处理前后IGF-I的含量变化。结果:常用的LTLT(65℃30min或72℃20s)或HTST(80℃15s)等巴氏杀菌条件对bc-IGF-I的含量影响不大,但随着温度的升高和时间的延长,IGF-I含量逐渐降低;37℃、30min条件下,pH在2～7的范围内时,IGF-I的保留率较高;当pH在8～12的范围内时,保留率明显下降;55℃、10～20MPa的均质条件对牛初乳IGF-I的含量几乎无影响;酸乳发酵和储存过程对牛初乳IGF-I的含量有一定影响,6h发酵结束时保留率平均为70.61%,4℃储存20d后保留率平均为45.99%。结论:常用的LTLT或HTST巴氏杀菌、均质、调酸对牛初乳IGF-I的含量影响不大,但乳酸菌发酵造成含量明显损失。

Objective ：to study the effect of normal dairy processing conditions on the stability of bovine insulin-like growth factor-I. Methods： using the unit process of heating, adjusting pH, homogenizing and fermenting to treat insulin-like growth factor-I and detecting the activity variance.Result：thermal stability of bc-IGF-I in ultra high temperature（UHT） milk showed that normal LTLT（65℃ 30min or 72℃ 20s）and HTST（80℃ 15s）pasteurizations had little effect on stability of IGF-I in milk, but the thermal stability of bc-IGF-I gradually decreased with the prolonged time and increased temperature.The activity rate of bc-IGF-I were relatively higher at pH 2-7 than at pH 8-12.The homogenization process had no significant effect on stability of IGF-I at 55℃,10-20MPa. Yogurt fermentation and storage impacted the stability of IGF-I ,the activity rate of bc-IGF-I was 70.61% at the end of fermentation at 6h and 45.99% during storage at 4℃ for 20d. Conclusion： normal LTLT or HTST pasteurization, adjusting acid, and homogenization had little effect on the activity of IGF-I,but fermentation caused obvious loss.