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United States Department of Agriculture

Agricultural Research Service

Research Project: New Sustainable Processing Technologies to Produce Healthy, Value-Added Foods from Specialty Crops and their Co-Products

Location: Healthy Processed Foods Research

Title: Peeling mechanism of tomato under infrared heating

Authors
item Li, Xuan -
item Pan, Zhongli
item Atungulu, Griffiths -
item Wood, Delilah
item McHugh, Tara

Submitted to: Journal of Food Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 22, 2013
Publication Date: December 28, 2013
Citation: Li, X., Pan, Z., Atungulu, G., Wood, D.F., McHugh, T.H. 2013. Peeling mechanism of tomato under infrared heating. Journal of Food Engineering. 128:79-87.

Interpretive Summary: Peeling is a particularly important unit operation in the production of canned fruits and vegetables. The analysis presented in this study provides a fundamental understanding of tomato peel loosening and cracking phenomena that occurred during IR heating. Mechanical stress analyses coupled with experimentally measured failure stress of tomato skin were integrated to interpret the occurrence of peel cracking resulted from infrared heating within a framework of elastic thin shell theory. With the use of light microscopy and scanning electron microscopy, it was observed that peel loosening from infrared heating appeared to result from reorganization of extracellular cuticles, thermal expansion of cell walls, and collapse of several cellular layers, differing from samples treated by hot lye and steam. Crack behaviors of tomato skin were attributed to the rapid rate of infrared surface heating which causes the pressure build-up under the surface and reduced skin puncture stress resulting in loosened skin. This research was the first time using the integrated approach to discover the peeling mechanism of IR

Technical Abstract: Critical behaviors of peeling tomatoes using infrared heat are thermally induced peel loosening and subsequent cracking. However, the mechanism of peel loosening and cracking due to infrared heating remains unclear. This study aimed at investigating the mechanism of peeling tomatoes under infrared heating for developing a sustainable infrared dry-peeling technology. Microstructural changes in tomato epidermal tissues due to infrared radiation heating were compared with those of fresh, lye and steam treated samples. Mechanical stress analyses coupled with experimentally measured failure stress of tomato skin were integrated to interpret the occurrence of peel cracking resulted from infrared heating within a framework of elastic thin shell theory. With the use of light microscopy and scanning electron microscopy, it was observed that peel loosening from infrared heating appeared to result from reorganization of extracellular cuticles, thermal expansion of cell walls, and collapse of several cellular layers, differing from samples treated by hot lye and steam. Crack behaviors of tomato skin were attributed to the rapid rate of infrared surface heating which causes the pressure build-up under the surface and reduced skin puncture stress resulting in loosened skin. In order to achieve a sufficient skin separation for effective peeling under infrared heating, promoting rapid and uniform heating on the tomato surface is essential. The findings gained from this study provide new information about the peeling mechanism of tomato under infrared heating.

Last Modified: 12/18/2014
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