ISHS Acta Horticulturae 555: II International Symposium on Edible Alliaceae
CHANGES IN S-ALK(EN)YL CYSTEINE SULFOXIDES AND PRECURSOR INTERMEDIATES DURING STORAGE AMONG SHORT- AND LONG-DAY ONION CULTIVARS |
| Authors: | D.E. Kopsell, W.M. Randle, M.A. Eiteman |
| Keywords: | Allium cepa, flavor, ACSO, HPLC |
| Abstract:
Flavor precursor and &gama;-glutamyl peptide intermediate changes during storage were evaluated for two short-day (SD) and one long-day (LD) onion (Allium cepa L.) cultivars. Onion cultivars were greenhouse-grown, harvested, and stored under similar conditions. Cultivars differed in flavor changes during storage. (+) S-methyl-L-cysteine sulfoxide (MCSO) levels decreased, (+)-S-(1-propenyl)-L-cysteine sulfoxide (PRENCSO) levels increased linearly, and (+) S-propyl-L-cysteine sulfoxide levels decreased during storage. Of the peptide intermediates measured, S-2-carboxypropyl glutathione changes were variable, and &gama;-L-glutamyl-S-(1-propenyl)-L-cysteine sulfoxide levels decreased linearly among the cultivars. Enzymatically formed pyruvic acid levels (EPY) increased for ‘Granex 33’, but decreased for ‘Dehydrator #3’ and ‘Pukekohe’ during storage. The change in total S-alk(en)yl cysteine sulfoxide (ACSO) levels for the cultivars followed the changes in MCSO and PRENCSO. However, the behavior of MCSO and PRENCSO did not explain EPY changes for the cultivars. Because the behavior of the ACSO compounds cannot fully explain EPY changes, a more detailed understanding of the enzymatic reaction may be needed. Understanding flavor changes over time could be used to meet the specific flavor demands industry places on onions coming out of storage. | |
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