Postharvest Shelf-Life Assessment of Treated Fresh-Cut Onions Under Vacuum Packaging

This study evaluated the effectiveness of sodium benzoate and potassium metabisulfite in preserving fresh-peeled onions stored at 4°C for 21 days. Five treatments were applied: control (no preservative; T0), 0.05% sodium benzoate (T1), 0.1% sodium benzoate (T2), 0.01% potassium metabisulfite (T3), and 0.08% potassium metabisulfite (T4). Samples were vacuum-packed and assessed periodically for physicochemical properties (pH, weight loss, total soluble solids [TSS], texture, and firmness), microbial load (total plate count [TPC], E. coli, and lactic acid bacteria), and sensory attributes. Results showed that T1 (0.05% sodium benzoate) was most effective in maintaining quality, with higher firmness, TSS, and titratable acidity (TA), and the lowest weight loss. All treatments exhibited increasing TSS, TA, and weight loss, while pH and firmness declined over time. T1 also recorded the lowest TPC, and E. coli and lactic acid bacteria were absent in all samples. Sensory evaluation rated T1 highest in overall acceptability. These findings suggest that 0.05% sodium benzoate effectively preserves the quality and extends the shelf-life of vacuum-packed fresh-peeled onions for up to 21 days under refrigerated conditions.