Fat Utilization in Germinating Douglas Fir Seed

Abstract

Lipids from nongerminated and stratified Douglas fir seeds, and from germinated seedlings of 4 size groups were separated into fractions of free fatty acids, acetone-insoluble phospholipids, glycerides, and unsaponifiables. The fatty acids in phospholipids and glycerides were isolated, and the fatty acid mixtures were analyzed by gas-liquid chromatography using diethylene glycol succinate as liquid phase. Total fats decreased rapidly with germination from 36% to 12% of the dry weight, which also decreased from 1.31 mg to 21.1 mg/individual seed. Glycerides were utilized during germination and a diminution of 86% to 59% of the total fats was found. Acetone-insoluble phospholipids increased from 5% to 25% of total fats, of which fatty acids comprised approximately 30% at any stage of germination. A small reduction from 2.5% to 1.5% of total fats, then an increase of 5% was observed in the fraction of free fatty acids during germination. A small but consistent gain from 1% to 5% of unsaponifiable material was related to germination. A total of 22 fatty acids was found in these materials. In the free fatty acid fraction, 30% of the acids had carbon chain length less than 17 in non-germinated seed. The major components of free fatty acids were linoleic (27-41%), oleic (16-23%), palmitic (14-21%) and arachidic (6-11%) acids. The major components in phospholipids were linoleic (40-45%), oleic (13-26%), and palmitic (13-21%) acids. More long chain fatty acids were found in this fraction than in free form and in glycerides. Little change of percentage distribution of various fatty acids in glycerides was observed with germination. The major components in glycerides were linoleic (43-50%), oleic (19-23%), and arachidic (14-19%) acids. A preferential utilization of linoleic acid in glycerides and a preferential increase of linoleic and palmitic acids in phospholipids were clearly demonstrated.