The Effects of Coating Made from Chitosan, Nisin, and Tannin on Some Quality Indicators of Green-skin Pomelo (Citrus grandis) During Preservation

Background: Pomelos have high economic value; however if not properly preserved, their quality deteriorates rapidly. This study aimed to determine the effect of biofilms made from chitosan, nisin, and tannin at various concentrations by evaluating pomelo quality indicators during preservation. Methods: Each experimental batch was conducted on 20 ripe green-skin pomelos, collected from June to September 2024 in Mekong River Delta region, Vietnam. A mixture solution was prepared from chitosan, nisin, and tannin in a ratio of 8:1:1 at different concentrations (0.5, 1.0, 1.5, 2.0, and 2.5%) for coating. Pomelo quality indicators-including: spoilage rate, Total Soluble Solids, Total Acid (TA), and weight loss rate-were monitored at 15, 30, 45, 60, 75 and 90 days. Statistical analysis was performed using IBM SPSS Statistics 19 (IBM Corp., Armonk, NY, USA), based on the Tukey HSD. Results: After 90 days of preservation, the additive mixture at a concentration of 1.5% maintained the best quality indicators: the lowest spoilage rate of 22.20%; the highest TSS of 12.05 °Bx; TA remained stably low value at 0.68 g/100ml; and the lowest pomelo weight loss rate of 42.95%. Coating made from chitosan, tannin, and nisin (8:1:1) at a concentration of 0.15% was found to be the most suitable for maintaining pomelo quality. At this concentration, both the weight loss and spoilage rates reached the lowest value after 90 days of ambient storage; TSS increased steadily and stabilized; and TA gradually decreased during the presrevation period. Conclusion: The study findings provide valuable reference information for food manufacturers and traders in selecting appropriate storage conditions to ensure the optimal grapefruit quality.