Abstract: In order to optimize the current peeling techniques and develop a new one, the effects of different peeling methods, including manual peeling, hot water treatment, and alkali treatment and power ultrasound treatment alone and their combination on the peeling efficiency and quality parameters of tomatoes were compared. The peeling efficiency was evaluated based on the ease of peeling and weight loss, and the quality of peeled tomato based on texture, color, lycopene yield, pH, and titratable acid. Scanning electron microscopy (SEM) was used to compare the microstructure of tomato skins obtained by different peeling methods. Results showed that compared with hot water and alkali treatments, power ultrasound treatment achieved easier peeling of tomatoes with lower weight loss, higher lycopene yield and similar quality. Combined power ultrasound and alkali treatment reduced the difficulty of peeling but caused too high peeling loss than the other peeling methods. Power ultrasound caused more severe destruction to the cuticular structure of tomato skins than hot water and alkali as observed by SEM, likely because ultrasound cavitation allowed easier separation between the flesh and the skin to reduce peeling loss. Therefore, power ultrasound is potentially an environmental friendly way of peeling tomatoes.

Key words: tomato, peeling, peeling efficiency, quality