An innovative use of DA-meter for peach fruit postharvest management

The DA-meter is a hand-held instrument developed from vis/NIR spectroscopy that measures the index of absorbance difference (IAD) correlated with the flesh chlorophyll-α content of fruit. It was used to divide in two different ripening classes, class I (climacteric peak) and class II (onset of climacteric), harvested fruit belonging to three peach cultivars. At harvest and after 6 days of storage at 20 °C, quality parameters such as flesh firmness (FF), soluble solid contents (SSC), ethylene emission and brown rot incidence were evaluated. Data on ethylene production reported a different emission of phytormone at harvest relating to peach variety and among the two IAD classes. In addition, the IAD values showed a high correlation with FF, while SSC being ethylene-independent did not show marked differences between ripening stages. With respect to brown rot, after 3 days of shelf-life, data from artificial infections, revealed a lesion diameter significantly larger on fruits of class I (10 and 13 mm) than those on class II (8 and 9 mm) for 'Springbelle' and 'Redhaven', respectively. Similarly, in all trials, the incidence of Monilinia rots in fruit natural infected was significantly higher within class I compare to class II. The present work showed the possibility of sorting asymptomatic fruit, harvested at a commercial maturity, by DA-meter, into two IAD classes that will show different brown rot incidence during storage.