Steryl Lipid Content and Composition in Bell Pepper Fruit at Three Stages of Ripening

Abstract

Abstract The content and sterol composition of free sterols (FS), steryl esters (SE), acylated steryl glycosides (ASG), and steryl glycosides (SG) in pericarp tissue of bell pepper fruit from three cultivars (Capsicum annuum L. cv Gator Bell, Bell Tower, and Lady Bell) were determined at three stages of ripening (mature-green, turning, and red-ripe). In each cultivar, FS were predominant at all stages of ripening, with ≈5- to 20-fold lesser amounts of SE, ASG, and SG. The proportions of the sterol conjugates (SE, ASG, and SG) varied somewhat between cultivars, but there was a consistent increase in the ratio of SG to ASG with ripening. The sterol composition of steryl lipids was quite similar in the three cultivars, and only minor changes occurred with ripening. Sitosterol was always the major sterol, followed by campesterol. Sitosterol plus campesterol comprised 89% to 95% of the total sterols in FS, ASG, and SG, and 74% to 91% in SE. Cholesterol and stigmasterol were always present as minor (1% to 4%) constituents. In general, small increases in stigmasterol and several minor, unidentified sterols occurred with ripening, at the expense of sitosterol and campesterol. These changes were greatest in SE.