高活性益生菌发酵枸杞粉的真空冷冻干燥工艺优化

Optimization of Vacuum Freeze Drying for Preparation of Fermented Goji Berry(Lycium barbarum L.) Powder with Probiotics

以植物乳杆菌发酵枸杞浆为研究对象,通过差示扫描量热仪和冻干显微镜分析益生菌发酵枸杞浆的物性参数,采用正交试验对保护剂进行选择和优化,并绘制冻干曲线,旨在开发出一套制备富含活性益生菌的发酵枸杞粉的工艺方法.结果表明:运用差示扫描量热仪,采用经过退火处理的连续扫描法,在退火温度-5℃、升温速率5℃/min条件下,测得的益生菌发酵枸杞浆物料的物性参数为:共融点-5.28℃,结晶点-19.59℃,玻璃态转化温度-31.82℃,崩解温度约-36℃.根据已确立的参数确定发酵枸杞浆的预冻温度为-40℃,预冻时间为4 h,升华干燥阶段的温度为-45℃.最佳复配保护剂组合为:20%麦芽糊精、14%乳糖、6%海藻糖.复配后样品的升华干燥温度为-30℃,分别绘制真空冷冻干燥过程中的冻干曲线.益生菌发酵枸杞冻干粉后活菌数达9.6(lg(CFU/g)),含水量低于3%,色泽完好,复水性强,产品质量佳.

This study aimed to develop a vacuum freeze drying method for preparing fermented goji berry powder with active Lactobacillus plantarum. Differential scanning calorimetry (DSC) and freeze drying microscopy were used to analyze the physical properties of fermented goji berry pulp. The type and concentration of lyoprotectant were optimized by orthogonal array design, meanwhile, and freeze-drying curves were obtained. By using DSC with continuous scanning after annealing at .5 ℃ with a heating rate of 5 ℃/min, the physical parameters of the fermented goji berry pulp were determined as follows: co-melting point .5.28 ℃, eutectic point .19.59 ℃, glass transition temperature .31.82 ℃, and disintegration temperature .36 ℃. On this basis, the pre-freezing temperature was .40 ℃, pre-freezing time 4 h, and sublimation drying temperature .45 ℃. The optimal lyoprotectant combination was 20% maltodextrin, 14% lactose and 6% trehalose, and the resulting sublimation drying temperature was .30 ℃. The viable cell count of the fermented goji berry powder, with good color and rehydration characteristics, was 9.6 (lg (CFU/g)), and the water content was lower than 3%, indicating high quality of the product.