Study On Bentonite/PVA Fresh-Keeping Film And Which Applied In The Preservation Of Mango

In order to reduce rot and extend shelf life of mango, this study is carried out to develop Ca-bentonite/PVA fresh-keeping film, and to investigate the effect of film on the physicochemical and physiological properties of mangos. Ethylene is caused by the maturity of mangos after postharvest and it further promotes ripening of the fruits that makes for speeding up rot and shortening shelf life in Guangxi Zhuang Autonomous Region in the harvest season of mangos with high temperature and high humidity. So the adsorption of bentonite and preservation materials of bentonite loaded chemical additives on ethylene was studied firstly. Then the polyvinyl alcohol (PVA) material was used as a substrate material and bentonite was filled as an inorganic filler for improving some properties of the film. Single factor analysis was applied to study the influence of the mass of glycerin, the concentration of PVA solution and the control mode of materials on the physical and mechanical properties of the film. Furture, the bentonite/PVA film was applied in the preservation of mangos, and the effect of bentonite/PVA film on the quality of mango during storage was studied by tracking the changes of a series of quality indexes. The main quality indexes include weight loss, respiration rate, decay index, titratable acidity content, soluble sugar content, soluble solid content, solid content, soluble pectin content, protopectin content, vitamin C content and so on. In addition, function of bentonite/PVA film to delay riping and reduce rot for mangos is explored. The results show:1. Bentonite and bentonite loaded chemical additives have adsorption to ethylene and the adsorption capacity of purified bentonite and bentonite loaded citric acid are better than others.2. The bentonite/PVA film demonstrates the best comprehensive property when the content of the concentration of PVA solution, with glycerin are8%and20%, respectively. And the method to make the suspension is to add PVA solid to suspension of bentonite in stirring and heating.3. Tensile strength and elongation at break of the PVA film modified by adding bentonite decline, but its water resistance is enhanced. The images of SEM show that bentonite is distributed uniformly in PVA and forms uniform membrane structure.4. Using the bentonite/PVA film to wrap mango for preservation can significantly reduce weight loss of mango, inhibit fruit rot, postpone respiration peak of mango, slow down ripening of mango, maintain higher nutritional value, as well as extend shelf life. And the mango wrapped by the film added10%bentonite obtains the best comprehensive effect of fresh-keeping.5. The bentonite/PVA fresh-keeping film makes an environment with lower O2and higher CO2, such environment can inhibit effectively respiratory action of mango, decrease water loss, prevent attack of outside bacteria and reduce the propagation of anthracnose and stem-end rot, retard the physiological metabolism of fruits. In addition, adsorption of bentonite on ethylene could postpone ripening of mango and enhance the preservation effect.