The Characteristics Of Texture Change And Cell Wall Polysaccharides Degradation In Yali And Jingbaili Pear(Pyrus Spp.) Fruits

In this paper,‘yali’pear and ‘jingbaili’ pear were systematically studied ontexture, cell wall degradation and relative enzymatic activity from development,maturation to softening and discussed the softening effect of pears being treated byethephon and1-MCP. The results showed that fruit texture development and softeningof pear was a complex physiological and biochemical process, regulated by a varietyof factors, and there were significant differences among pear cultivars. The mainresults obtained were shown as follows:(1) During pear fruit development and ripening process, water soluble pectin wasthe main content, then the covalent binding pectin, the ionic pectin content was thelowest, both water soluble pectin and ionic pectin content showed rising trend, whilethe covalent pectin dropped off. During the storage period, pectin molecular showeddepolymerization and1-MCP could restrain pectin depolymerization of ‘jingbaili’pear while the restrain action was unconspicuous for ‘yali’ pear.(2) During fruit storage time, the firmness of ‘yali’ pear decreased slowly, and itcould remained its original texture greatly and the influence was insignificant by1-MCP and ethephon; while firmness of ‘jingbaili’ pear decreased fast,1-MCP couldstrongly inhibited the firmness reduced rate of ‘jingbaili’ pear, delayed respiratoryclimacteric, ethylene peak and prolonged the storage period, ethephon could promotethe respiration rate and ethylene production a certain extent but could not promotefirmness declining rate.(3) The result showed that the changes of PG, PME, β-Gal and α-Af showedsignificant difference in different pears, four enzymes showed obvious change in‘jingbaili’ pear and they were the main enzymes for fruit softening, β-Gal and α-Afshowed more significant roles in ‘jingbaili’ pears than ‘yali’ pears.(4) During development, mature and ripening period, the fruit texture parametersshowed different features for different cultivars, Feature, Firmness and Chewiness of‘yali’ pear were the evaluation parameters and Feature, Firmness, Adhesiveness, Cohesiveness, Resiliance and Chewiness were the main evaluation parameters for‘jingbiali’ pear.In short, cell wall degradation was in the major position in fruit development andsoftening, there were significant difference among cell wall composition, cell walldegradability and hydrolytic enzyme activity change of different breeds.