Processamento de grãos de Moringa oleifera Lam. e seu efeito no rendimento e qualidade do óleo e da torta

Abstract

Moringa oleifera Lam. is a resistant plant that can survive in poor soils, yielding up to three harvests per year. This culture has wide employability in the cosmetics, medicinal, food industry and also as a potential for water purification, its grains have high lipid and protein contente. Despite its wide use there are few studies on its processing. Thus, the objectives of this work were to study the behavior during the drying process, at temperatures of 40°C, 55°C e 70°C, applying mathematical models to the experimental data, thus selecting the best model according to the drying kinetics curves, to evaluate. The effect of this phenomenon on the efficiency of mechanical extraction of moringa oil, and the physicochemical quality of oil and cake for the chemical and mechanical oil extraction methods. Pre dried Moringa oleífera Lam. grains from the city of Barreirinhas (MA) from the second semestre of 2018 were used. Artificial drying was performed until the constant weight of the grains, using a mechanical drying machine fixed-layer laboratory with forced convection at na air velocity of 0.33m.s-1 with controlled drying air temperatures of 40°C, 55°C and 70°C. Nonlinear regression analysis was performed by the Quase-Newton method to fit 11 mathematical models to the experimental data. The extraction of the oil was done by mechanical method, using expeller type press, and chemical with hexane organic solvente, with the soxhlet type equipment. The yield and efficiency of the press were calculated from the difference in lipid content obtained by the initial chemical extraction of the grain and iodine índices, as well as the chemical composition of the fatty acids by gas chromatography of the dried samples at the diferente drying air temperatures. The pies from mechanical extraction were evaluated for water contente, ether extract, crude protein, ashes and neutral detergente fibers. The two-term exponential equation best characterized all drying temperatures for the collected values. The increase in drying air temperature caused greater volume shrinkage of the moringa grains, which affected the oil extraction yield, resulting in lower mechanical press efficiency. Drying air temoeratures of 40°C, 55°C, 70°C significantly affected the physicochemical quality of the oil and moringa. Best results are samples from dried beans at 40°C. The composition of the main fatty acids was not altered according to the applied statistical method. Chemical extraction of oil, although more eficiente than mechanical, showed higher levels of acidity and peroxide. The oil and moringa pies, reached by mechanical pressing of the dried grains at the drying temperature of 40°C, had better quality.