Effect of methyl jasmonate treatments on the bioactive compounds and physicochemical quality of 'Fuji' apples
Recently, plant growth regulators have been used for various purposes in apples. Methyl jasmonate (MeJA) has significant effects on the physiology, postharvest biology, processing, and chemical composition of apples. In the present study, the effects of MeJAMeJa treatments on the physicochemical quality and bioactive compounds (total antioxidant activity, total phenolics, and total anthocyanins) of 'Fuji' apples were investigated. The following doses of MeJa were used: 0 (control); 1; 120; 2,240; and 4,480 mg L-1. The highest geometric mean diameter, fruit mass, flesh firmness and skin thickness were obtained from the 2,240 mg L-1 MeJA treatment. Fruits harvested from control trees exhibited the highest total soluble solids content (TSSC) and pH, whereas the lowest TSSC and pH values were obtained from the 4,480 mg L-1 MeJA treatment. The titratable acidity was lower in the control as compared to the other treatments. The total phenolics of the fruit flesh decreased with increasing MeJa doses. The highest total antioxidant activity for both the FRAP and TEAC of fruit flesh was obtained from the 1,120 mg L-1 MeJA dose. The total anthocyanin content was higher in the 4,480 mg L-1 MeJA treatment than in the other treatments. Hue angles for both the sun- and shade-exposed sides of the fruit skin and flesh were lower in the 4,480 mg L-1 MeJA treatment as compared to the other treatments. Apples without full color formation are sold at lower prices in markets, which results in significant economic losses for producers. MeJA may be used as an efficient treatment to promote color formation in apple species with weak coloring due to genetic and climate conditions.