Physiological and biochemical responses of sapodilla to oleic acid-enriched xanthan and carboxymethyl cellulose coatings during cold storage.

Sapodilla (Manilkara zapota) is a tropical climacteric fruit with a notably short postharvest life due to rapid softening and water loss. This study investigated the efficacy of three edible coating formulations-Xanthan gum (Xan) 0.1 % + oleic acid (OA), carboxymethyl cellulose (CMC) 1 % + OA, and CMC 1 % + Xan 0.1 % + OA in preserving sapodilla fruits stored at 8 °C and 85-90 % relative humidity over 40 days. Results showed that all coated fruits significantly outperformed the control in terms of postharvest quality. The CMC 1 % + Xan 0.1 % + OA treatment recorded the lowest weight loss (10.8 %) and the highest firmness (78.32 N) by day 40. The lowest respiration rate (19 mg CO₂/kg.h) observed in fruit treated with Xan 0.1 % + OA, significantly lower than the control (62.3 mg CO₂/kg/h). Fruits coated with CMC 1 % + Xan 0.1 % + OA exhibited the lowest chilling injury (0.64), malondialdehyde (MDA) content (0.48 nmol g FW) and electrolyte leakage (78 %), indicating better membrane integrity. Additionally, this formulation maintained higher levels of ascorbic acid (106 mg/100 g FW), total phenolics (35.6 mg GAE/100 g FW), and flavonoids (6.84 mg QE/100 g FW). This treatment significantly elevated antioxidant enzyme activities, with catalase reaching 4.42 U/g FW, peroxidase 0.8 U/g FW, and superoxide dismutase 3.4 U/g FW, while notably reducing polyphenol oxidase (PPO) activity to 23.5 U/g FW. Principal component analysis (PCA) clearly differentiated the CMC 1 % + Xan 0.1 % + OA treatment from other treatments and the control, confirming its superior efficacy. In conclusion, the CMC 1 % + Xan 0.1 % + OA significantly extends the shelf life and preserves the physicochemical and nutritional quality of sapodilla, making it a promising and sustainable postharvest strategy.