Comparison postharvest quality of conventionally and organically grown ‘Washington Navel’ oranges

Abstract

This study aimed to compare postharvest quality of conventionally and organically grown ‘Washington Navel’ oranges. Oranges from the conventional and certified organic citrus orchards were harvested at commercial maturity and kept at 4°C for 5 months. Changes in weight loss, juice percentage, titratable acidity (TA), total soluble solid (TSS), sugars (fructose, glucose and sucrose), organic acids (citric, malic and ascorbic acid) content and incidence of fungal decay and chilling injury were determined at a month interval during storage. Conventionally grown oranges had lower weight loss and higher juice percentage than organically grown oranges during storage. Rind color (L*, C*, hº), TSS, sugar (fructose, glucose and sucrose) and malic acid content were not affected by the production systems at harvest and during storage. In both conventionally and organically grown oranges, rind color become darker (lower L*), more intense (higher C*) and deeper orange color (lower hº) while malic acid content remained constant during 5 months of storage. As storage time extended, a significant increase in TSS and sugar content and a decrease TA and citric acid content occurred in fruits from both production system. Compared to conventionally grown oranges, organically grown oranges had lower TA and citric acid, but better taste scores since they attained higher TSS/TA ratio at harvest and during storage. The taste of conventionally and organically grown oranges was rated as an acceptable throughout the storage period. Although there was no significant difference in  ascorbic acid content of fruits between two production systems at harvest, lower ascorbic acid content was found in organically grown oranges, compared to conventionally grown oranges during storage. Incidence of fungal decay was low in conventionally and organically grown oranges after 5 months of storage and the production system did not affect the sensitivity to fungal decay. Chilling injury was not observed any of fruits from both production systems throughout storage period.