THE QUALITY AND STORABILITY OF APPLES CV. ´JONAGORED´ SELECTED AT-HARVEST BY TIME-RESOLVED REFLECTANCE SPECTROSCOPY

Abstract

Apple maturity at harvest is a critical factor which affects ripening and determines the post-harvest utilization of fruits. A new non-destructive technique, Time-Resolved Reflectance Spectroscopy (TRS), which measures separately the two optical properties of absorption and scattering at a deepness of 1-2 cm in the fruit flesh, has been successfully used for determining the maturity at harvest of nectarines in order to predict their softening rate and so to choose their marketing destinations. The aim of this work was to evaluate the usefulness of the absorption coefficient measured at 630 nm (μ a 630) by TRS to assess apple quality at harvest and after storage. 'Jonagored' apples were picked on 30 August and 13 September 2002. 150 fruits/pick were ranked by decreasing μ a 630 (from less to more mature) and divided into three maturity classes (less, medium and more mature). At-harvest, at the end of six months' storage at 1°C in normal or Controlled Atmosphere (1% O 2 , 2% CO 2 ) and after 7 days of shelf-life at 20°C, apples were analysed for fruit mass, skin colour, firmness, soluble solids (SS) and titratable acidity (TA). At the end of shelf-life, less and more mature fruits were assessed by sensory analyses and for juice content. The absorption coefficient μ a 630 was significantly higher in first harvest apples. Apples with higher μ a 630 had lower fruit mass, lower % blush both at harvest and after storage. Fruits classified as more mature by TRS had less TA at harvest and more SS after storage; at sensory analyses these fruits were significantly sweeter, more aromatic and pleasant. It can be concluded that TRS can be used to select apples according to maturity and so to separate fruits of different quality within the same batch.