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Roasting effects on fatty acid distributions of triacylglycerols and phospholipids in sesame (Sesamum indicum) seeds

Yoshida, H.; Abe, S.; Hirakawa, Y.; Takagi, S.

Journal of the Science of Food and Agriculture 81(7): 620-626

2001


ISSN/ISBN: 0022-5142
DOI: 10.1002/jsfa.857
Accession: 003551290

Sesame seeds were roasted at different temperatures (180-220 degrees C) using a domestic electric oven. The positional distribution of fatty acids in triacylglycerols (TAGS) and phosphatidylcholine (PC) isolated from total lipids in these seeds was investigated as well as the naturally occurring antioxidants that are present. Major lipid components were TAGS and phospholipids (PLs), while steryl esters (SEs), free fatty acids (FFAs) and sn-1,3- and sn-1,2-diacylglycerols (DAGs) were minor ones. Following roasting, a significant increase (P < 0.05) was observed in FFAs and in both forms of DAG (primarily sn-1,3-DAG). The greatest PL losses (P < 0.05) were observed in phosphatidylethanolamine (PE), followed by PC and phosphatidylinositol (PI). On the other hand, the amounts of upsilon-tocopherol and sesamin remained at over 80 and 90% respectively of the original levels after roasting at 220 degrees C. The principal characteristics of the positional distribution of fatty acids were still retained after 25 min of roasting: unsaturated fatty acids, especially linoleic and/or oleic, were predominantly concentrated in the sn-2-position, and saturated fatty acids, especially stearic and/or palmitic, primarily occupied the sn-1- or sn-3-position. The results suggest that unsaturated fatty acids located in the sn-2-position are significantly protected from oxidation during roasting at elevated temperatures.

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