Browning control, shelf life extension and quality maintenance of frozen litchi fruit by hydrochloric acid Original Research Article

Litchi fruit can be stored at −18 °C without obvious adverse effects on the aril, but the pericarp darkens and browns when they are frozen or thawed. Experiments were conducted to test effects of hydrochloric acid on browning inhibition of litchi fruit pericarp for displacement of sulphur application. Litchi fruit were soaked in 0.5%, 1% and 2% HCl for 2–10 min. Fruit appearance and membrane leakage were assessed after 1 day of storage under ambient conditions of 25 °C and 80–90% relative humidity. In terms of browning control of and fruit pericarp damage, treatment with 1% HCl for 6 min gave the best red colour and minimal damage. 1% HCl treatment markedly inhibited polyphenol oxidase activity and maintained high anthocyanin content in litchi fruit pericarp tissue. Fruit treated with 1% HCl and stored at −18 °C for 12 months had a shelf life of 12 h at ambient temperature, with a uniform red colour and acceptable quality. Use of 1% HCl could be considered for commercial application in extending shelf life and maintaining quality of frozen litchi fruit following storage and during marketing.