Abstract:

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.

Key words: pectin from banana peel, extraction, preparation of fresh-keeping film