充氮包装对乳粉贮存过程中水分、水分活度及益生菌活菌数变化的影响

将充氮及普通包装形式的益生菌乳粉贮存于37℃及45℃加速条件下,测定乳粉贮存过程中的水分、水分活度(aw)和双歧杆菌活菌数,以分析充氮包装对乳粉贮存过程中各指标的影响。结果:充氮包装不影响乳粉贮存过程中的水分,且同一时间点两种包装形式乳粉的水分不存在显著差异(p>0.05)。在加速条件下,37℃贮存,充氮包装乳粉和普通包装乳粉的aw变化趋势一致,且相同时间点其值无显著差异;45℃贮存,充氮包装乳粉的aw波动略低于普通包装乳粉(从贮存的第6周起,同一时间点充氮包装乳粉的aw都低于普通包装)。在相同加速条件下,充氮包装乳粉的双歧杆菌活菌数比普通包装乳粉双歧杆菌活菌数高。因此充氮包装可以降低乳粉贮存过程中aw的波动,提高双歧杆菌在乳粉中的稳定性。

Effect of Nitrogen-filled packaging on the moisture content,water activity and viable count of probiotic milk powder during storage

Changes of moisture content,water activity(aw)and viable count of Bifidobacterium were detected under the 37℃and 45℃during the storage of milk powder with or without nitrogen-filled packaging.Results:the moisture content of the milk powder was not affected by the nitrogen-filled packaging,and there were no significant difference(p >0.05)between milk powder with or without nitrogen-filled packaging at the same storage time.At 37℃,the aw change trend of milk powder with or without nitrogen-filled packaging was consistent,and there were no significant differences at the same time point.While at 45℃,aw volatility of nitrogen filling packing powder is slightly lower than ordinary packing powder which is without nitrogen filling.From the sixth week of storage,the aw of the nitrogen-packed milk powder was lower than the ordinary packaging at the same time point.Under the same acceleration condition,the viable count of Bifidobacterium in the nitrogen-filled packaging milk powder was higher than that in the ordinary packaging.Conclusion:nitrogen-filled packaging could reduce the fluctuation of aw during milk powder storage and improve the stability of Bifidobacterium in milk powder.