Analysis and Evaluation on the Differences of Indexes of Postharvest Quality in Four Litchi Cultivars during Low-temperature Storage

In order to investigate the effect of low temperature condition of(4±1) ℃ on the indexes of postharvest quality of four litchi cultivars including "Feizixiao","Guiwei","Nuomici" and "Huaizhi",the general quality indexesforcolor changes,browning index,good fruit rates,soluble solid contents,titratable acidity and respiration intensity were used to evaluated litchi. The regression equation of quality and evaluation model were constructed by principal component analysis(PCA)in order to evaluate the four cultivars comprehensively.The results showed that the color changes of four litchi cultivars were various with the extension of storage time,"Feizixiao" was the most stable. The browning indexes of four litchi cultivars all kept an increasing trend,which of "Nuomici" increased most obviously,it was 4.267 with the good fruit rates of zero.The degree of browning of "Feizixiao" and "Guiwei" were low,their browning indexes were 2.250 and 2.417,respectively,and the good fruit rates were still more than 60%.The contents of total soluble solids of "Guiwei" changed most significantly during storage,decreased by 7.19%.However,the soluble soilds of "Huaizhi" changed most minimally,its contents increased by 0.34%. The contents of titratable acids rose then dropped,titratable acids of "Nuomici" decreased by 32.14% during the first two weeks’ storage. But "Huaizhi" changed not obviously,and titratable acids of other two cultivars decreased significantly at 21th day,decreased by 38.78% and 35.37%,respectively. The respiration intensity of "Nuomici" was much higher than that of the other three cultivars at 14 to 28 days,which showed that its respiration was greatly vigorous. The comprehensive scores of PCA from high to low:"Feizixiao" > "Guiwei" > "Nuomici" > "Huaizhi".Therefore,in low-temperature condition,"Feizixiao" and "Guiwei" were more resistant to storage,and their quality indexes were better,"Nuomici" and "Huaizhi" could not stand storage,their quality indexes were worse.