For peaches and nectarines, establishing fruit maturity at harvest is a crucial issue, since fruit shelf-life potential and quality are closely related to fruit maturity. A portable instrument that measures IAD (the index of absorbance difference between 670 and 720 nm) was used for monitoring the progression of ripening in two peach cultivars. IAD was measured at harvest in ‘Oded’ (an earlyseason, fast melting flesh peach) and ‘September Snow’ (a lateseason, slow melting flesh peach) fruit. After harvest the fruit were divided into comparable lots and held at 20 °C. The IAD and firmness were measured daily on a different lot. Firmness decay during shelf-life was analyzed by non-linear regression, using the IAD measured at harvest to determine the maturity of the fruit and to estimate the biological shift factor (BSF) which is related to the biological age of fruit. A logistic model developed for firmness decay with maturityassessment by time-resolved reflectance spectroscopy was used, where the time-resolved measurement was substituted by IAD. The R2 for ‘Oded’ softening was 0.86, while that of ‘September Snow’ was 0.66. IAD decay was analyzed by non linear mixed effects analysis, obtaining higher than 0.96 for both cultivars. IAD showed the same decay rate in the two cultivars, while softening rate was five times lower in the late ‘September Snow’ than in the early ‘Oded’ fruit. The measurement of IAD at harvest could be used to separate fruit into different groups according to their potential shelf-life.
- resolved reflectance spectroscopy
- biological shift factor