Post-harvest quality management of 'Yaqouti' table grapes: Efficacy of chitosan and aloe vera gel in preserving quality and extending shelf life

Grapes ( Vitis vinifera L.) are highly perishable fruits that, despite being rich in bioactive compounds and having high nutritional value, require effective strategies to extend their post-harvest shelf life. This study aimed to investigate and optimize the effects of pre-harvest chitosan application (0-3% CS) and post-harvest aloe vera gel coating (0-50% AV) on enzymatic properties (total phenolics (TPC), total anthocyanin content (TAC), peroxidase activity (POD) and polyphenol oxidase (PPO)) of table Yaqouti grapes during 40 days of storage at 4°C using response surface methodology (RSM) and central composite design (CCD). The results indicated that CS concentration had the strongest effect on TPC, TAC, and PPO activity, due to enhanced protective effects, stronger defense responses, and inhibition of enzymes related to cell wall softening, while POD activity was mainly influenced by storage time. Under the optimal conditions (3% CS and 50% AV), the predicted values were 137.31 mg 100 g -1 (TPC), 60.01% (TAC), 50.08 U g -1 (POD), and 799.89 U g -1 (PPO), with a desirability coefficient of 0.98. These findings demonstrate that the combined application of CS and AV can effectively enhance enzymatic properties and prolong grape shelf life, thereby mitigating post-harvest quality deterioration and reducing commercial losses.