| Harvested apples undergo the increase of commercial value due to ripening and senescence. Apples of same variety from a same field would present different rate of quality decline when they are stored under different environment or with different methods, and would show different storage life. Therefore, an urgent need exists in apple industry to find out accurate forecasting methods for storage life of apples from specific condition. In this research, ’Gala’ and ’Fuji’ were used as materials, were investigated to forecast apple storage life. ’Gala’ fruits were stored at four temperatures(0, 5, 15, 25℃ C) and ’Fuji’ at three temperatures(0, 10, 20℃). During storage of sensory quality, respiration intensity, physical and chemical indices(weight loss rate, firmness, soluble solids content, titrable acid, ascorbic acid content, color L* a* b* value) were measured. By analysis of the line-correlation relationship between temperature and each indices, indices owning statistically significant correlation will be selected as key factors. Indices-storage time function in combining with the Arrhenius equation were all applied to establish the quality and storage life prediction model.The results are as following.Changes of respiration and physicochemical indicators in two varieties of apples were measured at different temperatures. In ’Gala’, changes of firmness, weight loss and sensory quality evaluation at four temperature with time linear relationship was extremely significant(P≤0.01), and good gradient relationships between drop rate and temperature were formatted. Titratable acid, ascorbic acid, soluble solids content in the regression equation is not significant under some temperatures. ’Gala’ had no significant changes in respiration rate with temperature. Similarly in ’Fuji’, changes of firmness, weight loss and sensory quality evaluation of linear relationship were extremely significant(P≤0.01), and responded good laws to temperature. Titratable acid, ascorbic acid, soluble solids content in no linear laws at all. The respiration rate of Postharvest ’Fuji’ obviously affected by temperature, low temperature could effectively delay the respiratory peak, and reduced respiratory strength. After comparison, between 0~25 ℃ with storage, the lower the temperature, the more effectively inhibition the decline of apple over the quality indexes.Changes of peel color indicators in the ’Gala’ and ’Fuji’ apples stored at different temperatures were measured, and the results showed that b*, C, ΔE value of ’Gala’ increased with significant regression correlation, and the variation with temperature was obvious under three temperatures. a* value of ’Gala’ had linear rules except 0℃, L* had no significant linear laws at each temperature. The results in ’Fuji’ showed, the color difference b*, C, ΔE also showed good linear laws, and there were gradient relationships response to the temperature. Trends a* value of ’Fuji’ and ’Gala’, had contrary trends, and significant correlation coefficient of the regression equation. The variation of L* value of ’Fuji’ was not obvious. Within a certain range, lower temperature had slower rate of change with apple peel color a*, b*, C and ΔE values.Key indicators which responded well to time and temperature(Firmness, weight loss, b *, C, ΔE, a*(only ’Fuji’))were received. With analysis, it showed that the zero order kinetics can describe the changes of firmness and color parameters during storage of apple at 0 to 25℃. On the basis of the Arrhenius kinetic equation, a shelf-life prediction model was established on basis of reaction activation energy(Ea),(55.2±3.9)k J/mol for ‘Gala’ apple and(49.03±1.154)k J/mol for ‘Fuji’ apple. Verification test showed that the prediction model established using b* reports more accurate results below 10℃ for ‘Gala’ which relative error kept less than 15%, and ‘Fuji’ model with b* and ?E can predict shelf-life at 0 and 10℃, which relative error kept 6.79% to 16.67%. |
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