Effect of Temperature on the Synthesis of Jojoba Wax

Abstract

Seed was collected from jojoba [Simmondsia chinensis (Link) Schneider] plants growing at three field sites in two years. The wax percentage was determined by nuclear magnetic resonance and the compositions of the wax and the ethanolysis products (one site only) were determined by gas chromatography.

The mean wax concentration varied from 49.2 to 55.1% over all sites and years. The percentage of long-chain wax esters (>C₄₀) decreased linearly with increase in mean maximum temperature during the period of linear seed growth (r² = 0.93). The decrease in long-chain esters was associated with a decrease in the C₂₂ and C₂₄ fatty acids and alcohols.

Data from controlled environment studies and from field studies were used to assess the effect of temperature on the percentage elongation, reduction and esterification of acyl-CoAs of carbon lengths 18-22. High temperature lowered the specificity for elongation of C₂₀-C₂₂ and of C₂₂-C,₂₄ and increased the specificity for reduction of the C₂₀ acid to its corresponding alcohol.

The amount of C₄₂ wax ester was greater than would be expected by random association of the alkoxy-acyl groups but this preference was not as great at high temperatures.