Enhancing the Shelf-Life of Date Fruits by Application of Chitosan-Based Nanoemulsion Enriched with Grape Seed Oil

Background: This study evaluated the effectiveness of chitosan-based nanoemulsion coatings, enriched with 3.5% Grape Seed Oil, in extending the shelf-life and preserving the quality of date fruits over a 21-day storage period. Methods: Fresh date fruits (totalling 20 kg) harvested in August 2024 were coated with 0.5 and 1.0% high molecular weight chitosan. Quality parameters including moisture content, pH, acidity, Total Soluble Solids (°Brix), phenolic content, antioxidant activity (2,2-diphenyl-1-picrylhydrazyl inhibition), texture (hardness and elasticity), color, and microbial load (yeast and mold counts) were monitored during storage. Statistical analysis was performed using Excel 2016 and two-way ANOVA, with significance at p<0.05. Results: The 1.0% chitosan coating was particularly effective; maintaining moisture levels at 63% by day 21 versus51% in the control. The pH of coated samples increased more gradually, reaching 7.2 in the 1.0% chitosan group, while the control’s increased to 7.0. Acidity decreased more slowly in coated samples, with lower levels than controls. Phenolic content and antioxidant activity were also better preserved in the coated fruits, with the 1.0% chitosan treatment retaining 65% 2,2-diphenyl-1-picrylhydrazyl inhibition by day 21, compared to 1.4% in the control. Yeast and mold counts were drastically reduced in coated fruits, dropping from 1,100 Colony Forming Unit (CFU)/g to around 100 CFU/g by day seven and remaining low throughout the storage period. In terms of texture, the coated fruits exhibited better firmness and elasticity retention, with slower degradation of hardness compared to the uncoated control. The coatings also contributed to less discoloration, with the 1.0% chitosan treatment maintaining higher lightness (L value) and color stability (a and b values) throughout the storage period. Conclusions: These newly developed chitosan-based nanoemulsion coatings demonstrated significant potential in preserving the postharvest quality of date fruits, maintaining moisture, texture, color, and antioxidant activity during storage. DOI: 10.18502/jfqhc.12.2.18864