Effects of preharvest applications of natural antimicrobial products on tomato fruit decay and quality during long-term storage

The effects of preharvest sprays of Thyme essential oil, Propolis and Chitosan on postharvest quality and decay of a “long-storage” tomato, called “Vesuviano”, stored at room temperature for 120 days, were investigated. Postharvest fruit quality [number of swollen-healthy fruits (SF), withered-healthy fruits (WF) and rotten fruits (RF)], organoleptic-related indexes (dry matter, soluble sugars, organic acids, volatiles) and health-related compounds (total carotenoids and phenols) were investigated at 40, 80 and 120 days post-harvesting (T40, T80, T120). Propolis and Chitosan were able to reduce rotten fruits starting from T80, while the effect of Thyme was evident as early as T40. Furthermore Chitosan delayed fruit senescence (as expressed by SF/WF ratio) during the long-storage period. All treatments did not affect the overall postharvest quality, nevertheless some compounds (such as total soluble sugar for Chitosan and Thyme; total carotenoids and flavonols for Chitosan; total organic acids, 2-(E)-hexenal, 2-isobutylthiazole and terpenes for Propolis), were better retained than the control during postharvesting period. Among the three natural fungicides, Chitosan was most effective in reducing fruit senescence, maintaining a good quality of the fruits over a long-term.