CHANGES IN SUGAR AND ACID COMPOSITION OF ‘AMBRA ’ NECTARINES DURING SHELF LIFE BASED ON NON-DESTRUCTIVE ASSESSMENT OF MATURITY BY TIME-RESOLVED REFLECTANCE SPECTROSCOPY

One of the non-destructive techniques which have been developed to estimate fruit quality is time-resolved reflectance spectroscopy (TRS). TRS measures the absorption (μa) and scattering (μs’) of pulses of laser light passing through the fruit. The absorption coefficient at 670 nm coincides with the absorption peak of chlorophyll, and has been used to estimate maturity of nectarines at harvest and to predict their softening rate during shelf life. A relatively lowμa at 670 nm indicates that the fruit is more mature and that it will soften earlier, whereas a relatively highμa at 670 nm indicates that the fruit is less mature and that it will soften later. The aim of this research was to study the relationships between maturity of nectarines at harvest time as measured by TRS and its sugar and organic acid composition during shelf life. Nectarines of the cultivar ‘Ambra ’ were harvested on the second commercial picking date (July 5, 2004). The fruit were sorted by size and were measured for their absorption coefficient (μa) using TRS at 670 nm. Fruit of each maturity class were randomized among the different samplings, so that the fruit from whole range of µa was represented in each sample. Total soluble solids (TSS), titratable acidity (TA), sugars and organic acids were measured at harvest time and at various times during S. Jacob et al