正交实验优化铁皮石斛冷冻干燥工艺研究

Optimization of freeze-drying process of Dendrobium officinale by orthogonal test

目的:以铁皮石斛为研究对象、石斛多糖和甘露糖含量为实验指标,研究切片厚度、真空度、升华干燥温度和升华干燥时间对铁皮石斛品质的影响,建立正交实验,得到优化的冷冻干燥工艺参数,为铁皮石斛冷冻干燥加工提供理论依据。方法:本实验采用正交实验考察不同真空冷冻干燥工艺对铁皮石斛有效成分含量的影响,与烘干铁皮石斛进行对比。铁皮石斛多糖含量主要采用苯酚硫酸显色法和紫外分光光度法检测,甘露糖含量采用PMP(即1-苯基-3-甲基-5-吡唑啉酮)衍生化法和HPLC测定。结果:真空冷冻干燥后的铁皮石斛多糖、甘露糖含量高于烘干铁皮石斛。在-30℃下预冻1 h,-40℃后预冻1 h,40℃下解析干燥6 h的条件下,最佳的冷冻干燥工艺是:切片厚度为3 mm,升华干燥温度为-19℃,升华干燥时间为15 h,真空度为70 Pa。结论:该真空冷冻干燥工艺对铁皮石斛的外观及多糖和甘露糖含量影响较小,能够保证铁皮石斛质量,可作为铁皮石斛真空冷冻干燥加工的参考依据。

Objective: Taking Dendrobium officinale as the research object and the contents of polysaccharide and mannose as the experimental indexes, the effects of slice thickness, vacuum degree, sublimation drying temperature and sublimation drying time on the quality of Dendrobium officinale were studied and the orthogonal experiment was established to obtain the optimized freeze-drying process parameters, in order to provide theoretical basis for the freeze-drying process of Dendrobium officinale.Methods: Orthogonal test was used to investigate the effect of different vacuum freeze-drying process on the content of active components in Dendrobium officinale, and the method was compared with drying process. The content of polysaccharides in Dendrobium officinale was determined by phenol sulfuric acid coloration and UV spectrophotometry, and the content of mannose was determined by PMP(1-phenyl-3-methyl-5-pyrazolone) derivatization and HPLC.Results: The contents of polysaccharides and mannose in vacuum freeze-dried Dendrobium officinale were higher than those in dried D. officinale. Under the conditions of prefreezing for 1 h at-30 ℃, prefreezing for 1 h at-40 ℃ and analytic drying for 6 h at 40 ℃, the best freeze-drying process was as follows: slice thickness was 3 mm, sublimation drying temperature was-19 ℃, sublimation drying time was 15 h and vacuum degree was 70 Pa.Conclusion: The vacuum freeze-drying process has little effect on the contents of polysaccharide and mannose, ensuring the quality of Dendrobium officinale. The method can be used as the basis for the vacuum freeze-drying process of the drug.