Since the carbohydrate content affects pear flavor during the process of growth, it is necessary to determine the sugar components that accumulate in the fruit. We analyzed the fruit carbohydrate content, and the gene expression and activity ofacid invertase(AI), neutral invertase(NI), sucrose synthase(SS), and sucrose phosphate synthase(SPS) during the development of "Huangguan" and "Yali" pears. The results demonstrate that during development, the fruit sugar metabolism of the "Huangguan" pear follows a typical sorbitol–starch-soluble sugars middle model, whereas the "Yali" pear fruit follows a typical sorbitol–sucrose–starch-soluble sugars middle model. In the "Huangguan" pear, we found the AI and NI gene expressions, as well as AI( P < 0.05) and NI( P < 0.01) enzyme activities, to be positively correlated, whereas we found the NI gene expression and NI enzyme activity of "Yali" pear to be negatively correlated( P < 0.01). We observed the high levels oflate-stage AI and early-stage SS during development to roughly correspond with the gene expression found in the late and early stages, respectively, suggesting their potential regulatory roles in "Huangguan" pear fruit development. Our results indicate that the primary function of SPS during the early developmental stage is to accumulate sucrose, whereas the primary function of AI is to promote hexose accumulation during the late developmental stage ofmature "Yali" pear fruit.
The development of edible coatings has been lauded with respect to their safety and effectiveness.In this study,we researched the effects of edible coatings(2%CaCl_2,1%chitosan and 1%pullulan) on the nutrient content and antioxidant abilities of jujube(Zizyphus jujuba Miller cv.Dongzao).Using the new analysis technique for order of preference by similarity to ideal solution(TOPSIS),we evaluated the effects of these coatings.Compared with the control fruit group,test results showed that coating treatment significantly delayed fruit senescence.Specifically,CaCl_2 treatment not only maintained fruit storage quality and antioxidant activity but also restrained the production and accumulation of malondialdehyde in jujube.Chitosan treatment delayed decreases in secondary metabolites and superoxide dismutase and catalase activity.Pullulan coatings performed better in terms of proanthocyanidin and cyclic adenosine monophosphate(cAMP).We also used TOPSIS to evaluate the preservation effect of different film coatings and found 2%CaCl_2 to be the best treatment for jujube,followed by 1%chitosan and 1%pullulan.Based on the appropriate materials and concentration of the film coatings,edible coatings have the potential to retain the quality and antioxidant capacity of the Chinese jujube cv.Dongzao.
