Roasting influences on molecular species of triacylglycerols in sunflower seeds (Helianthus annuus L.)

Sunflower seeds (Helianthus annuus L.) were exposed to microwaves for 6, 12 , 20 or 30 min at a frequency of 2450 MHz. The nucleoluses were separated f rom the seeds roasted in a domestic microwave oven. Molecular species and f atty acid distributions of triacylglycerols (TAGs) isolated from the total lipids in the nucleoluses were analysed by a combination of argentation thi n-layer chromatography (TLC) and gas-liquid chromatography. A modified arge ntation TLC procedure, developed to optimise the separation of the complex mixture of total TAGs, provided 14 different groups of TAGs, based on both the degree of unsaturation and the total chain-length of fatty acid groups. Dilinoleolein (25-26.2%), trilinolein (14.4-17.7%), dilinoleostearin (15.1 -15.8%), dioleolinolein (12.2-12.4%) and triolein (10.5-11.3%) were the mai n components during microwave roasting. Roasting for 20 min caused a signif icant decrease (P <0.05) not only in molecular species containing more than four double bonds, but also in the amount of diene species present in TAGs . (C) 2001 Elsevier Science Ltd. All rights reserved.