Changes in phenolics and organic acid contents of postharvest eggplants in response to preharvest fertilizer applications and postharvest edible coatings

Pre- and postharvest techniques play a key role in improving the quality and shelf life of fresh horticultural products. The aim of this 2-year study was to evaluate the postharvest phenolic and organic acid content in eggplants under different fertilizers and postharvest treatments. Before planting, all plots were treated with 2000 cc da−1 of humic acid through a drip irrigation system. Plots treated only with humic acid were considered the control group. Fifteen days after planting, the other plots were treated with 2000 cc da−1 of liquid vermicompost fertilizer or 2000 cc da−1 of organomineral fertilizer via drip irrigation. Postharvest, 2% sodium alginate + 1% glycerin, 2% pectin + 1% glycerin, or 1% carboxymethyl cellulose (CMC) + 1% glycerin were applied to plants cultivated under different fertilizer regimes. The eggplants in the control group had higher organic acid and phenolic acid content compared to humic acid with liquid vermicompost and organomineral fertilizer applications. This can be attributed to humic acid alone leading to the synthesis of secondary metabolites. The organic and phenolic acid content in eggplant fruit was higher in samples treated with pectin and CMC than sodium alginate, regardless of preharvest fertilizer treatments. Similarly, respiration rate was generally lower in fruit treated with edible coating materials. Significant differences were observed not only among fertilizer treatments but also among coating treatments on all parameters studied.