四个荔枝品种采后低温贮藏品质指标差异分析及评价

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

为了探讨(4±1)℃低温条件下贮藏对"妃子笑"、"桂味"、"糯米糍"、"淮枝"四个荔枝品种品质指标的影响,以色差值、褐变指数、好果率、可溶性固形物、可滴定酸、呼吸强度为指标进行研究,并采用主成分分析建立线性回归方程和评价模型,对四个品种进行综合评价。结果表明:随着贮藏时间的延长,四个荔枝品种色差值变化不同,"妃子笑"最稳定。褐变指数均呈递增趋势,"糯米糍"增加最明显,贮藏7 d,其褐变指数为4.267,好果率为0,"妃子笑"和"桂味"褐变程度低,贮藏14 d时,褐变指数分别为2.250和2.417,好果率仍高于60%。整个贮藏期间,"桂味"的可溶性固形物含量变化最大,下降7.19%,"淮枝"变化最小,含量升高0.34%。可滴定酸含量先升后降,贮藏14 d,"糯米糍"下降幅度最大,达32.14%,"淮枝"变化不明显,另外两个品种在贮藏第21 d时才明显下降,分别下降38.78%和35.37%。在14~28 d内,"糯米糍"的果实呼吸强度明显高于其他三个品种,其呼吸作用旺盛。主成分分析综合得分不同,得分从大到小依次是"妃子笑">"桂味">"糯米糍">"淮枝"。因此,在低温下,"妃子笑"和"桂味"更耐贮藏,品质指标更好;"糯米糍"和"淮枝"不耐贮藏,品质指标更差。

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 21 th 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.