冻干物料内部孔隙率影响因素的实验研究  

作　　者：肖鑫[1] 陶乐仁[1] 陈隽[1] 

机构地区：[1]上海理工大学低温与食品冷冻研究所,上海200093

出　　处：《食品工业科技》2007年第3期78-81,共4页Science and Technology of Food Industry

基　　金：上海市教育基金会曙光计划(2003);上海市重点学科项目(T0503)

摘　　要：以草莓为研究对象,针对不同的物料形状、不同的干燥温度,分别进行了冻干实验。采用微CT扫描成像、图像重构及软件分析计算,得到了各种情况下冻干物料的孔隙率值。同时测量了冻干过程失水率、冻干后复水比,用二甲苯-二氯靛酚比色法测定了冻干前后抗坏血酸的值。结果表明,圆形物料的孔隙率相对最大,外表面积最大的正三角形物料的孔隙率最小。干燥温度越高,冻干之后孔隙率越大,其复水比也越大。在同样干燥条件下,8mm切片抗坏血酸保持得最好;在同样厚度下,一次干燥-10℃,二次干燥20℃,抗坏血酸保持得最好。In this study, strawberry slices with different shapes and thicknesses were freeze-dried at different drying temperatures. The dried strawberries were scanned with micro-CT scanner. By calucation of the reconstructed cross-sections with software, the porosity in all kinds of situations was obtained. Simultaneously the dehydration ratio during freezedrying and rehydration ratio after freeze-drying were measured. The content of ascorbic acid （AA） was determined before and after freeze-drying using dimthylbenzene-two, six-dichlor indophenol＇s, It is concluded that the porosity of circular sample is maximum, and the porosity of triangular sample with the maximum surface area is minimum. The higher the drying temperature, the higher porosity after freeze-drying, and the higher rehydration ratio. Under the same drying condition, 8mm slice could get the best AA keeping. Under the same thickness, when the first drying temperature was -10℃, the second drying temperature was 20℃, AA could be kept best.

关 键 词：冷冻干燥 草莓 形状 干燥温度 孔隙率 

分 类 号：TS205.7[轻工技术与工程—食品科学]