Pear peeling using infrared radiation heating technology

Abstract

Infrared radiation (IR) heating could be a potential alternative peeling method to address the long-term water supply and wastewater disposal issues involved in the conventional lye peeling process of pears. The objective of this study was to investigate the feasibility of IR peeling technology as an environmentally friendly alternative practice to efficiently produce peeled pear products with superior quality and yield. A pilot IR Dry-Peeling System consisting of catalytic IR emitters, roller conveyor, and peeler remover was developed and used for this research. Effects of the pear firmness and heating time on the peeling performance and product quality were studied. Under the continuous loading condition, the most desirable peeling result was achieved for Bartlett pears in the initial firmness range of 22 to 31 N after 99 s of IR heating. The results of IR peeling indicated superior product quality with relative thin cooking ring (0.76 ± 0.20 mm), limited peeling loss (9.25 ± 1.25%), and fairly ease of peeling (5.33 ± 1.00). According to SEM photomicrographs of pericarp cross-section, IR heating caused loss of integrity and compartmentalization of cells of the hypodermal layer to only “ripe” pears (firmness of 26.5 ± 2.8 N). Thermal effect of IR heating dramatically disrupted the middle lamella of hypodermal cells and resulted in mechanical failure of those cells and subsequent layer loosening of “ripe” pears.