Enhancement of chitosan coating performance by hot water treatment: Effects on stability, nutritional quality, and antioxidant retention during storage in litchi cv. China3

Litchi (Litchi chinensis Sonn.) is a high-value tropical fruit, yet it suffers from rapid postharvest deterioration. This research appraised the combined effects of chitosan (CHT) coatings and hot water (HW) treatments on the shelf life, physicochemical quality, and antioxidant retention of litchi cv. China-3. Fruits were treated with 0.5% or 1% CHT, alone or following HW immersion (50°C for 5 minutes), and stored at ambient temperature. The combination of CHT with HW significantly reduced weight loss, decay, and browning index, while extending shelf life 35.71% longer than untreated fruits. This treatment preserved firmness, attenuated the decline in titratable acidity (TA), and minimized increases in total soluble solids (TSS). After 9 Days of Storage (DAS) at ambient temperature, fruits treated with 0.5% CHT + HW maintained higher levels of β-carotene (6.84 µg/100 g), total sugar (TS) (21.27%), ascorbic acid (46.99 mg/100 g), phenolics (12.60 mg/g), and flavonoids (3.13 mg/g) compared to untreated fruits, indicating a beneficial effect on the nutritional quality of the fruits. The antioxidant activity (DPPH* scavenging activity) was also significantly higher (45.04%) in treated fruits compared to the control (29.75%). Furthermore, compared to the control, the treatment delayed colour degradation, preserved lightness (L*=22.14), and achieved superior sensory ratings in flavour, sweetness, appearance, and overall acceptability. These findings suggest that combining 0.5% CHT with HW is an eco-friendly postharvest strategy to enhance storage stability, retain nutritional and sensory qualities in litchi.