目的 生鲜乳的冷却是牛奶安全生产的重要环节,比较不同制冷模式对生鲜乳品质的影响非常重要。方法 本项目对比了速冷和直冷两种生鲜乳制冷模式对生鲜乳冷却时间、温度、酸度、菌落总数的影响,以期为更好地利用和推广生鲜乳速冷技术提供参考。结果 速冷模式可以在1~3 min内将生鲜乳温度冷却至4 ℃,效率远高于常规直冷模式,综合经济效益显著;在奶罐温度保持上,在4 h内速冷模式下,生鲜乳温度（5.12 ℃）、酸度（13.47 ^OT）、菌落总数（1.58 CFU/mL）极显著优于直冷模式的温度（5.55 ℃）、酸度（12.92 ^OT）、菌落总数（4.06 CFU/mL）;对温度、酸度、菌落总数双变量相关分析结果表明,在直冷模式下,温度与酸度、菌落总数相关性不显著;在速冷模式下,温度与酸度呈显著的负相关性,与菌落总数无显著相关性。结论 采用速冷模式可有效降低菌落总数,减少微生物繁殖,保障生鲜乳的质量,综合效益显著,为传统牧场奶厅改造,保障优质乳生产提供了可行性方案。

[Objective] The cooling of fresh milk is an important link in the safe production of milk. It is very important to compare the effects of different cooling modes and rates on the quality of fresh milk. [Method] In this study,the effects of quick cooling and direct cooling on the cooling time,temperature,acidity and total number of colonies of fresh milk were compared. [Result] The quick cooling mode can cool the temperature of fresh milk to 4 ℃ within 1 ~ 3 min,and the efficiency is much higher than that of the conventional direct cooling mode,and the comprehensive economic benefit is significant; In terms of temperature maintenance of milk tank,the temperature （5.12 ℃）, acidity （13.47 °T） and total number of colonies （1.58 CFU/mL） of fresh milk were significantly lower than the temperature （5.55 ℃）, acidity （12.92 °T） and total number of colonies （4.06 CFU/mL） of direct cooling mode under the 4 hour rapid cooling mode.The results of bivariate correlation analysis of temperature,acidity and total number of colonies showed that under direct cooling mode,the correlation between temperature,acidity and total number of colonies was not significant; In the rapid cooling mode,the temperature had a significant negative correlation with the acidity,but no significant correlation with the total number of colonies. [Conclusion] The rapid cooling mode can effectively reduce the total number of colonies,reduce microbial reproduction and ensure the quality of fresh milk. The comprehensive benefits are significant. It provides a feasible scheme for the transformation of traditional dairy farm and the production of high-quality milk.