基于静动高压联合处理法的驴乳加工工艺优化及贮藏期内品质变化

Static-dynamic High Pressure-based Processing Optimization and Storage-induced Quality Changes of Donkey Milk

该研究以鲜驴乳为原料,采用静态超高压(High-Pressure Processing,HPP)联合动态超高压(Ultra-High Pressure Homogenization,UHPH)技术对鲜驴乳进行处理,以杀菌效果及酸度、pH值等指标为考察因素,利用单因素试验及正交实验优化驴乳加工工艺,并对其贮藏期内品质变化进行观察。结果表明,采用静动高压联合处理(High-Pressure Processing+,HPP+)驴乳,最佳工艺为HPP最佳处理压力为550 MPa,HPP处理最佳保压时间为12 min,UHPH最佳处理压力为150 MPa,通过该工艺加工驴乳酸度为2.67°T,pH值为7.10,菌落总数为8 CFU/mL。在4℃冷藏条件下,以巴氏灭菌(Pasteurization Treatment,PAST)(72℃,15 s)驴乳为对照,对HPP+驴乳进行贮藏期品质变化研究发现,PAST驴乳贮藏时间到达14 d时已不适合饮用与销售,HPP+驴乳贮藏时间到达21 d时出现酸败气味,并于28 d出现分层现象,建议PAST驴乳最佳饮用时间为7 d内,HPP+驴乳最佳饮用时间为14 d内。综上所述,驴乳经HPP+技术处理后可有效杀灭其中所含微生物并有效延长驴乳的货架期。该研究可为HPP+技术在乳品加工行业提供一定的理论基础。

In this study,fresh donkey milk was used as the raw material,and static ultra-high pressure processing(HPP)combined with dynamic ultra-high pressure homogenization(UHPH)technology was used to treat the fresh donkey milk.Taking indices such as the sterilization effect,acidity,and pH value as the test factors,donkey milk processing was optimized by both the single factor and orthogonal experiments,and the quality changes of the treated milk were examined over storage.The results showed that the optimal conditions for processing donkey milk by Static-dynamic High Pressure-based Processing(HPP+)were pressure of 550 MPa and holding time of 12 min for HPP,and 150 MPa for UHPH.Under such optimal processing conditions,the lactic acid level of the donkey milk was 2.67°T,with its pH value being 7.10 and total number of colonies being 8 CFU/mL.,The quality changes of the donkey milk treated by HPP+were studied over refrigerated storage at 4℃with the donkey milk subjected to the pasteurization treatment(PAST;72℃,15 s)as the control.It was found that the PAST donkey milk was not suitable for drinking and sales after 14 d of storage,whilst rancid odor and stratification were found in the HPP+donkey milk stored after 21 d and 28 d,respectively.Thus,it is suggested that the best drinking time is within 7 d for the PAST donkey milk and within 14 d for the HPP+donkey life.This study could provide a theoretical basis for the application of HPP+technology in dairy processing industry.