Pear peeling using infrared radiation heating technology

Authors: SHEN, YI - University Of California, Davis; KHIR, RAGAB - University Of California, Davis; Wood, Delilah - De; McHugh, Tara; PAN, ZHONGLI - University Of California, Davis

Submitted to: Innovative Food Science and Emerging Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2020
Publication Date: 7/31/2020
Citation: Shen, Y., Khir, R., Wood, D.F., McHugh, T.H., Pan, Z. 2020. Pear peeling using infrared radiation heating technology. Innovative Food Science and Emerging Technologies. 65. Article 102474. https://doi.org/10.1016/j.ifset.2020.102474.
DOI: https://doi.org/10.1016/j.ifset.2020.102474

Interpretive Summary: Bartlett pears are one of the major commodities in the fruit and vegetable processing industry and are generally peeled using lye. Lye processing involves the use of intensive energy and water consumption that also yields large quantities of wastewater that require neutralization prior to discharge. Neutralized lye water also has high salinity and organic contamination. Concerns about the long-term water supply and wastewater management of the lye peeling technology need to be addressed to achieve the sustainability of the pear processing industry. Development of a sustainable pear peeling technology that reduces water consumption and disposal is a critical issue. One such technology is infrared heating that may be controlled to heat fruit to a limited, specific depth. We found that infrared peeling has potential for commercialization as an alternative to conventional lye peeling as it reduces water consumption and disposal. Infrared peeling can also increase fruit yield by controlling the depth of peel such that less peel is removed compared to lye processing. Specific operation parameters and conditions at the commercial scale need to be developed. Relevant issues to be addressed in a commercial system include operation and maintenance, peel depth control, pre-sorting based on size and firmness, and limiting juice leakage.

Technical 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.