Hydrocooling delays pericarp browning, enzymatic activities and maintains quality of litchi fruits under cold chain conditions

The role of hydrocooling on storage life of litchi (Litchi chinensis Sonn.) cultivar ‘Dehradun’ was investigated. The bunches of litchi fruits cv. Dehradun were harvested at the physiological mature stage i.e. when fruit attained full rosy red colour. Thereafter, small bunches of about half kilogrammes fruits were prepared and subjected to hydrocooling treatments for 10, 20 and 30 min. The temperature of water was maintained at 4°C with auto-cut refrigeration system. The fruits without hydrocooling were kept as control treatment. The temperature of cooling media and fruit pulp was regularly monitored with digital thermometer. Immediately after giving hydrocooling treatments, fruits were air-dried to remove the surface moisture and thereafter packed in corrugated fibre board boxes and stored in walk-in-cold room maintained at temperature 2–3°C and 90–95% relative humidity. The stored samples were evaluated periodically at weekly interval till four weeks various physiological, biochemical parameters and enzymatic activity. The results of the study indicated that litchi fruits hydrocooled for 30 min. maintained lower physiological weight loss (3.88%), browning index 3 (¼ to ½ browning), retained higher organoleptic score (7.15 out of 9), TSS (19.14°B), acidity (0.32%), total anthocyanins (0.31 δA/g FW) and total phenols (246.33 mg/100 g) during storage. The fruits subjected to hydrocooling for 30 min. also maintained the lowest activity of PPO activity as compared to control and other treatments. The study demonstrates the effectiveness of hydrocooling treatment in prolonging the storage life of litchi fruits for 21 days as compared to 7 days in case of control fruits.