Fatty Acids and Tocopherols Content in Fractionated Oils from Five Wild Oilseed Plants Native to Kahuzi-Biega National Park, Kivu-DR Congo

Abstract

Aims: Most natural oils only have limited application in their crude forms, but fractionation can provide a variety of food applications. The objective  was to fractionate crude oils from five selected plants growing wild in Kahuzi-Biega National Park (KBNP) in DR Congo, to analyze fatty acids and tocopherols contents in their respective resulting olein and stearin fractions, and to evaluate whether fractionation improves food quality.  Methods: Solvent fractionation of oil, Gas Chromatography (GC) for FAs analysis and High Performance Liquid Chromatography (HPLC) for Tocopherols analysis were used. Studied plants include Carapa grandiflora (Meliaceae), Cardiospermum halicacabum (Sapindaceae), Maesopsis eminii (Rhamnaceae), Millettia dura (Fabaceae) and Pentaclethra macrophylla (Fabaceae). Results: Fractionation gave the highest olein value yield (79.3%) from M. eminii oil and the highest stearin value yield (53.4%) from C. grandiflora oil. Eighteen FAs were detected, from plamitic acid (16:0) to very long chain FA cerotic acid (26:0). Differences were found between the profiles of fractions obtained and their corresponding crude oils. The profile of C. halicacabum olein is dominated by MUFAs (77%) and close to the known profile of olive oil (77%). In all olein and stearin fractions, unsaturated FAs dominated SFAs, contrary to the palm oil. M. dura and                P. macrophyla oils are richest in active vitamin E compounds (tocopherols, tocotrienol and plastochromanol) with the highest content 9.6 mg/100 g in M. dura stearin and olein fractions. Conclusions: The solvent fractionation used is relatively efficient to modify the proportions of SFA-MUFA-PUFA content in olein and stearin fractions. By its profile, C. halicacabum olein has similarities with olive oil, and would thus be used as a substitute for this expensive oil after some adaptations. Fractionation allows adding nutritional value to crude oils by increasing essential unsaturated fatty acids like nevronic acid while reducing the levels of unwanted fatty acids such as behemic acid. The high content of tocopherols in M. dura stearines also adds nutritional value to future derivate food products. It would be possible to adjust the final cooling temperature of the crude oils in order to modify processing yield and generate fractions of different qualities.