谷朊粉与乙基纤维素对冻干苹果粉吸湿性的影响

Effects of Wheat Gluten and Ethyl Cellulose on Hygroscopicity of Freeze-Dried Apple Powder

为加强谷朊粉(wheat gluten,WG)对冻干苹果粉吸湿性的抑制作用,提高其贮藏品质,选用具有低吸湿性的乙基纤维素(ethyl cellulose,EC)按不同比例替代部分WG制备冻干苹果粉,研究WG与EC对冻干苹果粉吸湿行为、宏观形貌及水分迁移规律的影响。结果表明,在相对湿度75%环境下,EC添加量每增高10%,冻干苹果粉的平衡吸湿率约降低2.26%。Peleg模型对该类冻干苹果粉样品的吸湿等温线拟合效果最好,且这些样品的吸湿等温线均属于Ⅲ型。此外,冻干苹果粉的宏观照片和低场核磁共振分析结果表明,苹果浆、WG和EC的最优添加配比为7∶2∶1,不仅对冻干苹果粉吸湿性有一定抑制作用,还可避免EC添加量过高导致的高自由度水分增多,更有利于冻干苹果粉保持良好的粉末状态。

In order to enhance the inhibitory effect of wheat gluten(WG)on the hygroscopicity of freeze-dried apple powder and to improve its storage quality,ethyl cellulose(EC),with low hygroscopicity,was selected to substitute for WG in different proportions in the production of freeze-dried apple powder.The effects of WG and EC on the hygroscopic behavior,macromorphology and moisture migration of freeze-dried apple powder were studied.The results showed that at 75%relative humidity,the equilibrium moisture content of freeze-dried apple powder decreased by about 2.26%for every 10%increase in EC addition.The Peleg model had the best fitting effect on moisture adsorption isotherms of freeze-dried apple powder,which belonged to type III.In addition,macroscopical photographs and low field-nuclear magnetic resonance analysis of freeze-dried apple powder showed that the optimal ratio of apple pulp to WG to EC was 7:2:1.This ratio not only had a certain inhibitory effect on the hygroscopicity of freeze-dried apple powder,but also avoided an increase in the proportion of free water caused by excessive addition of EC,which was conducive to keeping freeze-dried apple powder in a good powder state.