Fruit canopy position effects on quality and storage response of 'Tarocco' oranges

Quality characteristics of mature 'Tarocco' oranges harvested from the northern, southern and interior part of tree canopy was investigated over 10 weeks of storage at 9 degrees C plus 1 week of simulated marketing period at 21 degrees C. No significant differences in fruit mass loss and decay percentage were observed after 5 or 10 weeks of cold storage. After simulated marketing period (SMP) mass loss was significantly higher in fruit from northern part of tree canopy. Differences in mass loss between fruit from interior and southern parts were insignificant. Decay percentage was significantly lower in "southern" fruit with minimal differences between "northern" and "interior" fruit, h* colour values were significantly higher in fruit from interior canopy. After SMP differences in h* colour were insignificant. Fruit canopy position did not affect endogenous ethylene concentration. Ar harvest and after 10 weeks of cold storage respiration rate was higher in "northern" fruit, lower in "southern" fruit and intermediate in fruit from the interior part of canopy. After SMP differences in respiration rates were not significant. Freshly harvested fruit from the external southern side of the tree had higher soluble solids concentration (SSC) and lower acid levels, resulting in higher SSC: acid ratio and improved taste in comparison to fruit from northern and interior parts of canopy. By the end of SMP these differences tended to level out. At harvest ethanol level in the juice was significantly higher in fruit from southern part of canopy. By the end of cold storage and after SMP a sharp increase in ethanol concentration was detected in all samples, with no significant differences in relation to canopy position. SMP resulted in off-flavour development, presumably due to the high levels of ethanol in the juice.