篌竹笋真空冷冻干燥工艺研究

STUDIES ON THE VACUUM FREEZE-DRYING TECHNOLOGY OF PHYCLASTACHYS NIDULARIA BAMBOO SHOOT

采用正交试验、均匀设计试验和对比试验,对篌竹笋护色、预处理、真空冷冻干燥条件和不同干燥方法的干燥效果等进行探讨。采用0.2%抗坏血酸、0.1%柠檬酸和0.5%氯化钠溶液烫漂篌竹笋4min,进行护色处理,然后在43℃、2%蔗糖和8%麦芽糊精混合溶液中浸泡26min,进行预处理,可以明显提高篌竹笋冻干产品的复水比和感官品质。预处理篌竹笋的共晶点为-25℃,真空冷冻干燥条件为:物料预冻温度-35℃,预冻时间3h￣4h,冷阱温度-55℃左右,干燥室真空度7Pa￣9Pa,解吸阶段搁板加热温度40℃,物料冻干所需时间12h。真空冷冻干燥所得产品的质量明显优于热风干燥和真空干燥。

The purpose of this study is to optimize the conditions for prevention of discoloration, pre-processing, and vacuum freeze-drying of Phyclastachys nidularia bamboo shoot, by using orthogonal experiment and uniform design experiment, The optimum conditions for prevention of discoloration is ascorbic acid 0.2 %, citric acid 0.1% ,sodium chloride 0.5 % and blanching time 4 min, then soaking 26 min at 43 ℃, sucrose 2 %, maltodextrin 8 %, the optimum effect of pre-processing can be obtained. The co-crystal temperature of material pretreated is -25℃. Meanwhile, the vacuum freeze-drying conditions were determined as follows： the pre-freezing temperature -35 ℃, the pre-freezing time 3 h-4 h, the cold trap temperature about -55 ℃, the vacuum 7 Pa-9 Pa, the material shelf temperature in analytic drying phase 40 ℃, and the vacuum freeze-drying time 12 h. Results show that the quality of the products with vacuum freeze-drying is evidently better than vacuum drying or hot-air drying.