Changes in qualities of minimally processed litchis: Effect of antibrowning agents, osmo-vacuum drying and moderate vacuum packaging

Abstract Litchi fruits (litchis) are highly susceptible to pericarp browning which lowers their commercial value even though the edible portion (aril) remains in excellent condition. Therefore, minimal processing of litchis was carried out. Litchis were peeled, destoned, and arils were treated with antibrowning agents (4.9 g/kg cysteine, 20 g/kg ascorbic acid and 0.134 g/kg 4-hexyl resorcinol) along with osmo-vacuum dehydration (OVD) (502 g/kg sucrose syrup for 10 min at 570 mmHg vacuum followed by a relaxation of 10 min at atmospheric pressure) and stored at 4±2 °C. The samples were analyzed for physicochemical, sensory and microbiological qualities during storage. Changes were found to become significant ( P ⩽0.05) after 4 days of storage. During storage for 24 days, a decrease in pH, TSS (°brix), sugars (g/kg), ascorbic acid (g/kg), total phenolics (g/kg), firmness (N), color ( L * value) and sensory characteristics was observed whereas an increase in microbial counts (log cfu/g), acidity (g/kg) and drip losses (ml/kg) was observed. The combined treatment of litchis with antibrowning agents and osmo-vacuum dehydration treatment were found to be most effective in preventing the changes and the samples were acceptable (sensory score >7.0) upto 24 days, whereas the samples given only OVD treatment lost acceptability due to poor color after 16 days as compared to 8 days for the control samples (dipped in water for 10 min) during refrigerated storage.