Study On Mechanism Of Fruit Deterioration And Preservation Technology Of Chinese Barberry

Chinese barberry(Myrica rubra(Lour) Zucc.) is a popular fruit with full of juicy. However, It was harvested at high temperature and humidity season, no skin protection and metabolic exuberant, which result in the short storage life. Therefore, it is crucial to elucidate the mechanism of deterioration and exploit the preservations for the barberry during storage. In this paper, we used Chinese barberry as experimental material, studied the mechanism of polysaccharides metabolism in cell wall during the process of fruit development; change of the microbial diversity in the barberry fruit development processes; and applied VC, VE and e-polylysine in postharvest barberry preservation; which aimed to extend the Chinese bayberry storage life. The main results were summarized as following:Experiments were conducted to investigate the modification of cell wall polysaccharide in Chinese Bayberry (Dongkui) during ripening. Cellular wall materials were isolated from Chinese Bayberry fruit at four ripening stages. Three pectin fractions and two hemicellulose fractions were obtained and their compositional changes were analyzed. As ripening progressed, fruit firmness decreased gradually, which was associated with the increase in the water soluble pectin (WSP) and1mol/L KOH-soluble hemicellulose (HC1) fractions and the decrease in Na2CO3-soluble pectin (SSP) and4mol/L KOH-soluble hemicellulose (HC2) fractions, suggesting the solubilization and conversion of cell wall components. However, the content of CDTA-soluble pectin (CSP) changed slightly. Furthermore, arabinose, as the major branch monosaccharide, decreased in three pectin fractions during the whole ripening period, whereas the relative content of rhamnose, the backbone monosaccaride, tended to decrease in CSP and SSP pectin fractions, but increased gradually in WSP pectin during ripening. In HCl, the breakdown of the branch chain of matrix xyloglucan, arabinoxylan and arabinogalactan are predominant while more backbones of xyloglucan, arabinoxylan and arabinogalactan were depolymerized in HC2. Moreover, it was found that the molecular weight of WSP decreased gradually throughout ripening while the depolymerization of ionically CSP and covalently SSP mainly occurred at late and early ripening stages, respectively. Loosely bound (HCl) and tightly bound (HC2) hemicellulose fractions exhibited distinct molecular mass downshift throughout ripening stages, especially at late ripening stage. Overall, fruit softening of Chinese bayberry during ripening involved in differential modification of pectin and hemicellulose.The degeneration gel electrophoresis (DGGE) technology was applied to separate and indentify microbial DNA in different development period of Chinese bayberry fruit. The results showed that in the early stages of Chinese barberry development, no cultivable bacteria infection was observed. The cultivable microbe emgerged in turn color period (stage B), and a total of18dominant microbe was detected during the whole fruit development process, which included6bacteria species and12fungi species. Among them, Pseudomonas fluorescens, Methylobacterium radiotolerans, Sporobolomyces, Aureobasidium pullulans and Aspergillus existenced ever since early (B) stage to mature period. Meanwhile, the results also showed the dominant bacteria resulted in barberry fruit rotting were Burkholderia, Weissella cibaria, Diaporthe and Aspergillus Niger, and their rapid propagations leaded to fruits decay.Finally, we explorated the flesh effects of VC, VE and ε-polylysine treatments on postharvest preservation in Chinese bayberry fruit. Overal, VC, VE and ε-polylysine treatments retarded the decreasing in hardness, sugar content and titratable acid content, slowed down the cellular metabolism and the hydrolysis of unsaturated fatty acids during the storage period. Meanwhile, VC, VE and ε-polylysine treatments also enhanced the antioxidant capacity and free radical scavenging rate, alleviated the accumulations of MDA and H2O2contents. The results showed that VC, VE and s-polylysine were promising flesh preservation agents in Chinese bayberry postharvest handling, and its application would accelerate the utilization of this fruit resources.