牛乳比热与贮藏温度和时间关系的实验研究  

Experimental Study on Milk Specific Heat in Different Storage Conditions

作　　者：谷雪莲[1] 华泽钊[1] 

机构地区：[1]上海理工大学医疗器械与食品学院,上海200093

出　　处：《制冷学报》2007年第4期50-53,共4页Journal of Refrigeration

基　　金：国家自然科学基金资助项目(50376040);上海市科委重大项目(OSD219102);上海市高校选拔优秀青年教师专项基金(358535)资助

摘　　要：利用差示扫描量热仪(Differential Scanning Calorimeter,DSC)测量了牛乳分别在277.15K、283.15K、288.15K、298.15K存放1~5天后的比热变化。研究结果表明,与新鲜牛乳的比热(326.15K^338.15 K)相比,在277.15K、283.15K存放2天内,牛乳的比热没有显著的变化,而在288.15K、298.15K存放1天后,牛乳的比热有显著的变化。新鲜牛乳在277.15K、283.15K、288.15K、298.15K存放5天后,其比热(约329.15K)由3.870×10-3J/(kg.K)增加至3.939×10-3J/(kg.K),3.945×10-3J/(kg.K),3.961×10-3J/(kg.K),3.962×10-3J/(kg.K)。以牛乳存放277.15K下1~5天后,各营养成分随存放时间的变化为例,对牛乳的比热进行了估算。牛乳比热的估算结果小于比热实测值。存放不同时间的牛乳比热实测值变化量与估算值的变化量之间的偏差小于0.008×10-3J/(kg.K)。Specific heat of cup-packaged milk was measured when the milk was stored at 277. 15K,283.15K,288.15K, and 298.15K for one to five days with Differential Scanning Calorimeter （DSC）, respectively. The results show that the change of milk specific heat was not obvious for the storage in the first two days at 277.15K and 253.15K, while it was obvious for one day storage at 288.15K and 298.15K compared with the fresh milk at 326.15K 338.15K. When the milk was stored in experimental temperatures for five days, the milk specific heat （at 329. 15K） increased from 3,870×10^-3J/（kg·K）to 3.939 × 10^-3J/（kg·K）, 3.945 × 10^-3J/（kg·K）, 3.961 × 10^-3J/（kg·K）, 3.962× 10^-3J/（kg·K）, respectively. The specific heat was estimated by taking example for cup-packaged milk stored at 277.15K for one day to five days. The difference of the variation in specific heat between measurement and value estimated is less than 0.008 × 10^-3J/（kg·K）.

关 键 词：食品包装与储藏 差示扫描量热法 比热 牛乳 冷藏链 

分 类 号：TS205[轻工技术与工程—食品科学] TB66[轻工技术与工程—食品科学与工程]