Antioxidant capacity, total phenolic compounds and fatty acids composition in walnut oil and bagasse pellets produced at different parameters of the screw press

Abstract

Different rotational speeds and nozzle diameters of screw press were used to process walnut kernels. To evaluate the influence of pressing conditions on the quality of walnut oil and bagasse pellets the oil pressing temperature, yield of oil, total phenolic compounds, antioxidant capacity and fatty acid composition were measured. The results show that the pressing at different conditions affected the antioxidant capacity and TPC of either bagasse pellets and pressed oil. Higher values of antioxidant capacity and TPC were measured in bagasse pellets than in pressed oils. Higher amount of pressed oil was yielded by using lower nozzle diameter, however, by lowering the nozzle diameter the oil pressing temperature was rising, which affected the fatty acids. Positive correlations with oil pressing temperatures were calculated at saturated fatty acids, while the correlation coefficients of polyunsaturated fatty acids were positive, but not significant. Monounsaturated fatty acids were negatively affected by higher oil pressing temperatures showing, that monounsaturated fatty acids were more susceptible to higher temperatures than polyunasturated and saturated fatty acids.