Kang S H, Kim J U, Imm J Y, Oh S, Kim S H
Institute of Dairy Food Research, Seoul Dairy Cooperative, Ansan 425-838, Korea.
J Dairy Sci. 2006 Feb;89(2):402-9. doi: 10.3168/jds.S0022-0302(06)72104-X.
The effects of several dairy processes on insulin-like growth factor-I (IGF-I) concentrations in milk and the storage stability of IGF-I-fortified dairy products were examined. The IGF-I content in raw milk determined by radioimmunoassay was significantly changed by the strength of heat treatments. In commercial manufacture of whole milk dry powder, IGF-I concentration was not significantly changed. A significant reduction in IGF-I content was found as the result of fermentation with a commercial starter culture. The IGF-I content in fortified milk and dried milk powder exhibited no significant changes over the tested storage periods (12 d for milk, 4 wk for dried milk powder), but the IGF-I content in the yogurt decreased significantly during storage. The use of IGF-I was varied by lactic strains and was apparent in the viable cells. When IGF-I was encapsulated using the surface-reforming process, the remaining IGF-I content after fermentation was significantly higher compared with that of the untreated control. Therefore, enteric coating of IGF-I before fermentation might be an effective method for the prevention of IGF-I degradation during fermentation.
研究了几种乳制品加工过程对牛奶中胰岛素样生长因子-I（IGF-I）浓度以及IGF-I强化乳制品储存稳定性的影响。通过放射免疫分析法测定，生牛奶中的IGF-I含量会因热处理强度而发生显著变化。在全脂奶粉的商业生产中，IGF-I浓度没有显著变化。使用商业发酵剂进行发酵会导致IGF-I含量显著降低。在测试的储存期内（牛奶为12天，奶粉为4周），强化牛奶和奶粉中的IGF-I含量没有显著变化，但酸奶中的IGF-I含量在储存期间显著下降。IGF-I的利用因乳酸菌菌株而异，并且在活细胞中很明显。当使用表面改性工艺对IGF-I进行包封时，发酵后剩余的IGF-I含量与未处理的对照相比显著更高。因此，在发酵前对IGF-I进行肠溶包衣可能是防止发酵过程中IGF-I降解的有效方法。
