Study On Fresh-keeping Technology And Change Of Postharvest Physiology Of MiZao

The experiment was focus on Mizao from Mianyang. After studying some quality indicators(such as soluble sugar、TSS、Vc、titratable acid、the rate of turn red and rot), physiological indicators (SOD、POD、PPO、CAT) and regularity for change of aroma components of Mizao under different storage conditions, and then screening out the optimal temperature and concentration of preservative and best conditions of controled atmosphere for the storage of Mizao, in order to provide some preservation technology of Mizao for the planting area.1. Studying on physiological characteristics of post-harvest Mizao. The research showed that, Mizao was a typical climacteric fruit, which had obvious respiratory peak during the storage. As the storage times went by, the hardness, soluble sugar content and Vc content turned out different respiratory peak, especially after the peak, the consumption level of nutrient substance increased and the harmful metabolites growing, so all kinds of resistant enzymes began to work, which played an important adjustment role in post-harvest Mizao.2. Screening out the optimum storage temperature conditions. After placing Mizao under O×1℃,4±1℃,8±1℃and the normal temperature for the storing for30d, the lowest weight loss rate was1.42%from the storage under O±1℃, which was followed by1.47%under4±1℃. The difference didn’t reach significant level. The weight loss rate under8±1℃and the normal temperature were1.85%and42%. Besides, the rates of fruit decay and turning red were26%and88.3%from the storage under4±1℃, which were both the lowest, and the differecns reached very significant level. Thus the optimum storage temperature was4±1℃, after the overall analysis of the data3. Screening out the optimum storage concentration of preservative and best conditions of controled atmosphere. Screening at the following different concentration of preservative:Combined antistaling agent among0.6%,0.8%and1.0%, chitosan among0.5%,1.0%and1.5%and1-MCP among0.6mg/L、0.9mg/L1.2mg/L. Screening the best gas composition from4%O2+1%CO2+95%N2、4%O2+2%CO2+94%N2and4%O2+5%CO2+91%N2. The result turned out that, a more satisfactory results of inhibition of light to red ratio, decay and weight loss rate, coming from the storage under the concentration at0.8%in antistaling agent,1.5%in chitosan and0.9mg/L in MCP and the gas composition of4%O2+1%CO2+95%N2.4. Screening out the optimum method for the storage. After treating Mizao with0.8%antistaling agent,1.5%chitosan and0.9mg/L MCP and the gas composition of4%O2+1%CO2+95%N2, placed the Mizao under4±1℃for storing. After30d, between the groups with antistaling agent and Controled Atmosphere, the hardness were13.54kg/cm2and13.4kg/cm2, the soluble sugar content were14.1%and15.1%, the Vc content were270mg/100g and250mg/100g; the rotting rate were16%and15%. Not only the result was much better than the other treaments, the nutritional value of Mizao remained well with very good taste. The result illustrated that the best storage method for Mizao were the gas composition of4%O2+1%CO2+95%N2, and antistaling agent at0.8%under4±1℃.5. Studying on aroma components of Mizao. After analysing, aroma components at different stages of storage and studying the influences on aroma components under different storage conditions. By using HS-SPME and GC/MS, studying the changes of flavour substances of Mizao which came from different treatments. The research indicated the changes were greatly during storing. The main aroma components were aldehydes, ketones, organic acid, alcohols and esters. The flavour substances changed obviously at the end of the storage, and the amount of aldehydes and ketones showed a decreasing trend while the amount of organic acid, alcohols and esters were gradual upward. The changes among different treatments were different under cold storage at4±1℃.