Cumulative Respiration-Based Regression Analysis of the Physical Changes in Peach Fruits at Different Storage Temperatures

Abstract

　To develop a regression model for the prediction of the physical properties, applicable to peach fruits stored at different temperatures, the respiration rate (CO₂ output rate) and five physical parameters of peach fruits (cv. Kanoiwa-Hakutou) were investigated in the context of storage at 0, 5, 10, 15, 25, and 35℃. The firmness index of the peach fruits was measured using a hand-held firmness tester, whereas the maximum load, spring constant at small and large deformations, and flesh firmness were measured using a universal firmness tester. The changes in the five physical parameters over time showed similar tendencies, and the physical parameters correlated well with cumulative respiration. Consequently, we developed a mathematical model for the prediction of the physical parameters of individual samples based on their cumulative respiration, which followed a sigmoid-type function. The data obtained for these five physical parameters using the model showed a high correlation coefficient (R²＝0.819－0.921), and the spring constant at a small deformation showed the highest value among all parameters. These results indicate that developing a model using cumulative respiration as a variable is feasible and allows the prediction of changes in the firmness characteristics of peach fruits during the postharvest period.