Aspects of lipid metabolism in higher plants—II. The identification and quantitative analysis of lipids from the pulp of pre- and post-climacteric apples

Abstract

The identity, composition and concentration of each individual lipid in the pulp of apples has been determined for fruit in both the pre- and post-climacteric stages of ripening. The fatty acid composition of each acyl lipid is similar for apples at both stages of ripening. Although linoleic acid was the main fatty acid component of most of the major acyllipids, linolenic acid was the predominant acid in mono- and di-galactosyl diglycerides. Glucocerebrosides contained only hydroxylated fatty acids. The decrease in the level of linolenic acid in the total lipid at the post-climacteric stage was mainly due to a decreased concentration at this stage of galactosyl diglycerides. The concentration of phosphatidyl glycerol was also lower in the post-climacteric fruit. Most other lipids showed no marked differences in concentration between the two stages. The results, which suggests a selective degradation of plastid membranes during ripening, are discussed in relation to current theories of fruit ripening.