柠檬片的低温冻结与真空冷冻干燥工艺研究

Research on the Processing Technology of Freezing and Vacuum Drying of Lemon Slices

考察预处理方式、冻结温度(-40、-60、-100℃和液氮滴淋)等因素对柠檬片真空冷冻干燥的影响,并以产品复水率、色差L值、菌落总数、大肠菌群数为指标,探讨冻结方式对柠檬片贮藏过程中的品质变化影响。试验结果表明,柠檬的共晶点在-23℃^-25℃范围内,共熔点在-20℃^-22℃范围内;实验条件下的最佳冻结温度为-100℃,此时的真空干燥时间为11.2 h,贮藏3个月后的色差L值为78.65,且菌落总数低于180 cfu/g,大肠菌群低于3 MPN/g,均达到有关标准要求。

Influence of pretreatment method, freezing temperature(-40,-60,-100 ℃ and liquid nitrogen dripping)on the vacuum freeze drying of lemon slices, as well as taking complex water rate, color difference L value, total number of bacteria colonies and Escherichia coli group as index, effects of freezing method on the quality of lemon slices during storage were explored in this paper. Results showed that co-melting point and eutectic point of lemon were-23 ℃--25 ℃,-20 ℃--22 ℃ respectively. The optimal freezing temperature was-100 ℃ under experimental conditions, and vacuum drying time 11.2 h, color difference L value 78.65, as well as total number bacteria colonies and Escherichia coli group of product was lower than 180 cfu/g and 3 MPN/g respectively after 3 months storage time, which reached relevant standards.