Differential scanning calorimetry index for estimating level of saturation in transesterified wax esters

Differential scanning calorimetry (DSC) thermograms of fatty esters can give valuable information on melting characteristics and heats-of-fusion enthalpy (ΔH). A series of jojoba liquid wax esters was constructed by transesterifying native jojoba oil with 5–50% completely hydrogenated jojoba wax esters. This series, when subjected to a standardized DSC tempering method with heating/cooling cycles, exhibited an excellent correlation for level of saturation based on area changes in endothermic ΔH. Endothermic events were recorded for native (ΔHA) and completely hydrogenated (ΔHC) jojoba wax esters. A third endotherm, ΔHB, was observed when they were transesterified. Based on a multiple regression program, the best fit (R2=0.98) using ΔH data was: % saturation=16.847–0.162 (ΔHA)+0.209 (ΔHB)+0.600 (ΔHC). Standard errors for predictions were approximately 1.045 at 0% saturation, 0.770 at 25% saturation, and 1.158 at 50% saturation. Endothermic events A, B, and C each represent the respective diunsaturated, mounounsaturated, and saturated contents of wax esters in the transesterified blends. This was verified by measuring the dropping points for both the native and completely hydrogenated wax esters. These findings provide an index which can predict the degree of saturation in transesterified wax ester blends and serves as a research tool in process and product developments.