Peach fruits are very susceptible to mechanical stress and are therefore typically harvested before they are ripe and softened. However, there is limited information available on the damage characteristics of fruits varying in firmness. In this study, we conducted a shock test (29.4－1,802.8 m・s－2) of peach fruit (cv. 'Kanoiwa-Hakutou') that varied in firmness across four ranges and identified the damage characteristics. The results showed that the effect of shock on damage to peach fruits can be reflected as S-N curves, in which the function of relationships between shock acceleration and the number of cycles to lose the commercial value. Based on these findings, we developed a regression models for the prediction of the S-N curve parameters (α, β) according to the fruit firmness (R2＝0.74 and 0.90, respectively). The determination of S-N curve parameters of fresh produce that change their damage characteristics at postharvest period could be used to select an appropriate cushioning material or transport destination, which can reduce loss induced by shock damage during the distribution phase.
