Advances in peeling techniques for fresh produce

摘要

Peeling is a significant stage of post-harvest processing of fruits or vegetables. The most adopted peeling methods are mechanical, steam, chemical, and manual peeling. Apart from these methods, some other methods such as enzymatic, infrared, and some methods like ohmic heating, ultrasound-assisted lye peeling, and pulse electric field-assisted steam peeling are also used. To concern the freshness of the product, manual peeling is the most ideal method but it consumes an inefficient amount of time and physical labor. Mechanical method consumes less time and under this process, the collected peel can be utilized in the by-product stream. Lye peeling is an efficient method but the disposal of lye after the process is an environmental concern. Adjusting this system to include ultrasound, ohmic heating and CO2 laser drilling coupled with moderate electric fields can be used to reduce the lye requirement. Enzymatic peeling produces good quality products with low waste but can only be applied to fruits whose distinct separation of peel from the flesh is needed. PEF-assisted steam peeling helps immensely in terms of cost-saving by reducing the high use of steam. Infrared dry-peeling only heats the superficial layer of fruits and possesses minimal effect in an edible inner portion of fruit. It uses less time with low peeling loss, high peelability, high peeling yields, thin skin is peeled-off, but needs more research to justify industry implementation. In conclusion, the novel method assisted peeling can be used to save the time, environment, and quality of the fruit or vegetables. Practical applications Peeling is the primary post-harvest process applies to the group of foods and it is crucial to have minimal damage to the products at this stage. For utilization of the peeling process in any processing, the knowledge of the all available and efficient peeling process for the individual fruit or vegetable is necessary. The main objective of the review is to outline the applicable current and novel peeling techniques for the commodities with their process conditions, mechanisms, advantages, and disadvantages.