The non‐glyceride saponifiables of shea butter

Abstract

AbstractTriterpene alcohols and sterols were found to be present in a commercial sample of shea butter (the seed fat of Butyrospermum parkii, Sapotaceae) as esters of both cinnamic and fatty acids. These non‐glyceride saponifiables represented 6% by weight of the shea butter under study, whereas free triterpene alcohols and sterols accounted for only 1 % by weight. Cinnamic acid was found neither in the free form, nor esterified to glycerol. Saponification of the non‐glyceride saponifiables yielded the triterpene alcohols α‐amyrin, butyrospermol, lupeol, β‐amyrin and germanicol as major components. Other alcohols identified were parked, 24‐methylenelanost‐9(11)‐en‐3‐ol, dammaradienol, 24‐methylenedammarenol and the two sterols α‐spinasterol and Δ7‐stigmastenol. Esterified to these alcohols were cinnamic (trans and cis), palmitic, stearic, oleic, linoleic and arachidic acids. The fatty acid composition of the non‐glyceride saponifiables is different from that of the glycerides. No selectivity was observed in the esterification of these fatty acids by triterpene alcohols and sterols. Investigation of the products from acid catalysed transmethylation has led to two new experimental findings: (i) the difference in reaction rate of fatty acid and cinnamic acid esters and (ii) the formation of methoxylated artifacts from alcohols having unsaturation, in the C17 side chain, between C24 and C25 by the addition of methanol across the double bond. Analysis of the lipids extracted from shea kernels confirmed that the cinnamic acid esters were only present as non‐glyceride saponifiables.