| Edible films have been used to extend shelf life and to improve the quality of fruits and vegetables during the past few years. Chitosan is a good material, but it can only be dissolved in soul solvent which may induce the bad mouth taste. Objective of this study was to investigate whether chitosan and N,O-carboxymethyl chitosan, which is water soluble,were able to apply on Huanghua pears, and compared the effect of these two films, thereout to solve the mouth taste problem.Pears were dipped into aqueous solution of 2% chitosan and 2% N,O-carboxymethyl chitosan coating for 15 seconds, then stored at 4℃and 95% RH for 60 days. Three parts of the change in Huanghua pears were evaluated every 15 days.1) The quality of postharvest Huanghua pears was studied. Changes in VC, total soluble solids (TSS), weight loss, relative electrical conductivity and respiration rate were evaluated and magnetic resonance imaging (MRI) was used to investigate the inside change of the pears. 2) The textural characteristics of each coating pears were studied. Through the investigation of pectin esterase, peroxidase activity and cell wall materials to analyze the change of Huanghua pear's texture. The textural characteristics were determined with a texture analyzer (TA-XT2i).3) The color of pear was monitored and studied during storage. Harvested pears are prone to browning. Therefore the color of the pear pericarp has become the most important index among postharvest qualities. This thesis used CIELAB system to quantify the color of pears and the different treatments were analyzed.Application of coatings maintenance the colour, firmness and nutrition well after 60 days'storage, at the same time, the control pears'quality had been changed. The results showed that application of chitosan and N,O-carboxymethyl chitosan coating could effectively maintained the quality attributes and extended shelf life of the Hunaghua pears in the low temperature environment, and N,O-carboxymethyl chitosan was more suitable.
|
PDF Full Text Request