Chitosan–carnauba wax composite edible coatings for shelf-life extension and quality preservation of Psidium guajava L. during cold storage

Guava is a nutrient-rich climacteric fruit that is very perishable during storage. This study aimed at determining the influence of edible coating of chitosan and carnauba wax, incorporating glycerol as a plasticizer and Tween 80 as an emulsifier, in preserving the postharvest quality of guava. The coated samples were analyzed for Physiological loss in weight, color, firmness, spoilage percentage, titratable acidity, total solids, ascorbic acid content, antioxidant, and total phenolic acid content at different storage intervals (0, 7, 14, & 21 days). The results revealed that fruits coated with 3% carnauba wax (T 3 ) showed significantly lower moisture loss (6.02±0.09) and decay (3.2%), higher firmness (18.02±0.36), and better retention of color lightness (L* = 59.5±0.8) after 21 days of storage compared to the uncoated control (13.89±0.15, 14.2%, 7.02±0.07, and L* = 50.1 ±0.9, respectively). The treatment (T 3 ) effectively retarded the decrease in titratable acidity (from 0.85 to 0.75%) and ascorbic acid (from 122.00 to 98.33 mg/100 g) over 21 days of storage at 6 °C. Moreover, T 3 showed the highest radical scavenging activity (50.3%) and minimal decline in total phenolic content (140.00 to 137.53 mg GAE/100 g). Sensory evaluation based on 9-point hedonic scale indicated that T 3 received the highest overall acceptability. These findings suggest that a composite edible coating containing 3% carnauba wax and 3% chitosan effectively maintains the physicochemical quality, antioxidant potential, and sensory attributes of cold-stored (6±1 °C) guavas, thereby extending their postharvest shelf life.