Raphia sese unconventional oil from the Congo Basin: Comparison between chemical and screw press extraction

Abstract

This study highlights the importance of adding value to Raphia sese (raffia) from the Congo Basin, by using a screw press to extract its pulp oil that can be used in agri-food industry. A 2^k factorial experiment was used to study the influence of the intrinsic parameters of the press (rotation speed and diameter of the output die) on the oil extraction efficiency. Screw press extraction efficiency yield was of 43.3 ± 1.7%, representing an extraction rate of 80.8 ± 6.2%. Mechanical extracted raffia oil was chemically characterized measuring acidity and peroxide values; fatty acid (FA), tocopherol, and sterol compositions, and carotenoids content. These results were compared to those obtained from the analysis of a solvent-extracted oil. The screw press extracted raffia oil exhibited good quality (richer in monounsaturated FA and total sterols; similar total contents in unsaturated FA, tocopherols, and carotenoids; lower acidity and peroxide values), surpassing the solvent-extracted one. Raffia oil's composition would offer a promising alternative to palm oil (obtained from the pulp of Elaeis guineensis fruit). Compared to palm oil, the press- and solvent-extracted raffia oils presented a similar content in saturated FA, ~3.3-fold less monosaturated FA, ~3.4-fold more polyunsaturated FA, 3.5-fold more linoleic acid, and between 2.4 and 2.8-fold more linolenic acid. Raffia oil's use in food products as a replacement for palm oil would thus allow to diversify edible oil sources, stimulate the local economy, and promote healthier and more sustainable diets.