Fourier transform infrared spectra of zucchini squash stored at chilling or non-chilling temperatures

Abstract

Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that might be suitable. Fourier transform infrared spectroscopy (FTIR) was used to investigate spectral changes in the epidermis of zucchini squash resulting from low temperature storage-chilling (5°C) or non-chilling (15°C). Increased levels of fluid (water) were found in the tissue after 2 days of 5°C storage. This increase was reversed to harvest levels when chilled squash were warmed to room temperature for 1 day. After 3 days at 5°C and 1 day at room temperature, a further increase in fluid levels was found in the epidermis. Squash chilled for 3 days were apparently beyond recovery as indicated by spectral changes, although visual symptoms of chilling injury were not apparent until another 3 days of exposure to 5°C. Spectra of epidermis tissues from squash stored at 15°C indicated a pattern of increased non-reversible fluid accumulation when storage was prolonged. These results suggest that FTIR spectroscopy may be a rapid way to detect changes in chilled tissues before the eventual appearance of visible symptoms.