香蕉皮果胶萃取及果胶保鲜膜制备的研究

采用4种不同的方法萃取果胶，分析果胶结构，研究成膜因素对制备膜性能影响，探索制备膜的最佳工艺。结果表明，各种方法萃取的产品都为果胶，酸解盐析法萃取果胶效果最好，萃取率达1.311%；果胶底物浓度和变性淀粉用量影响制备膜的抗拉强度和断裂伸长率；影响制备膜抗拉强度的因素主要顺序为成膜助剂用量 >果胶浓度> 变性淀粉用量，但果胶+助膜剂+交联淀粉制备的膜其结构、抗拉强度都为最好，最佳制备膜的工艺参数为果胶底物浓度2.4%、助膜剂用量0.5%、变性淀粉用量1.0%。

Study on Pectin Extraction from Banana Peel and Preparation of Pectin Fresh-keeping Film

Pectin was extracted from banana peel by four different methods, and their extraction efficiencies were compared. The pectin structure was analyzed with Fourier transform infrared spectrometer. Furthermore, the effects of pectin concentration and modified starch on the properties of edible pectin film were investigated, the preparation conditions of the edible pectin film were optimized through single-factor and orthogonal test, and scanning electronic microscope was used to observe the cross-section structure and analyze the tensile strength (TS) of the film. The results showed that all the products are pectin extracted from banana peel by four different methods. Under the same extraction temperature, time and substrate concentration, the extraction efficient of the hydrochloric acid hydrolysis and salting-out method is the highest with an extraction rate of 1.311%. In the extraction efficient of ethanol precipitation method, sulfurous acid is better than hydrochloric acid as extraction agent. When the pectin concentration is more than 1%, TS and elongation at break (EB) both raise with the increase of the pectin concentration. Also, TS and EB are improved following with the increase of thickness of films and the amount of modified starch. The main sequence of the factors affecting TS of pectin film is as follows: glycerol concentration > pectin concentration > crossed-starch concentration. Especially, the structure and TS of films prepared by pectin, glycerol and crossed-starch are the best, and the optimum concentrations of pectin, glycerol and crossed-starch are 2.4%, 0.5% and 1.0%, respectively.