Conventional and novel peeling methods for fruits and vegetables: A review

This review explores the effects of various peeling technologies on the peeling performance of fruits and vegetables and peeled product quality. The peeling methods include conventional peeling approaches using hot-water, steam and lye and novel peeling techniques employing infrared radiation heating, ohmic heating and power ultrasound. The working principles, technology characteristics, the major factors affecting the processing efficacy, and limitations of conventional and novel peeling approaches are identified and discussed. Infrared radiation heating, ohmic heating and ultrasound-assist peeling methods have been successfully used to the peeling of tomatoes and other fruits and vegetables. The novel technologies can reduce the use of lye and can improve peeling performance and peeled product quality compared to conventional peeling. The process conditions and food properties are the major determinants affecting the processing efficacy. Future research needs are proposed to scaling-up the technology and exploring other technology used for peeling. Industrial relevance: As a key operation in the fruits and vegetables processing industry, peeling not only directly affects product quality, but also influences the processing cost and the management cost of waste generated by peeling. An unsuitable peeling process may result in low peeling efficiency and quality, high water and energy consumption, and high discharge of waste liquid, leading to the decline of economic benefits and environmental issues. The current work provides important information for selecting suitable peeling methods for high quality and safe products.