Comprehensive Investigations into Oil Extraction Process of Yellowish and Blackish Sesame Varieties, Parameters Optimization and Absorbance Spectra Characteristics

The demand for sesame oil is increasing due to its nutritious qualities. The present study investigated heating conditions (heating temperature and time) on the oil extraction of yellowish and blackish sesame varieties under screw pressing operation. Using the factorial design, the three-level factors for heating temperatures were 40, 50, and 60 °C and the heating times were 15, 30, and 45 min. In total, twenty-six experimental runs were conducted for the sesame varieties. The moisture content of yellowish and blackish sesame samples was determined to be 3.49 ± 0.19 % w.b. and 6.69 ± 0.07 % w.b. In that order, the oil content of the samples was 38.73 ± 2.61 % and 45.31 ± 6.51 %. The overall optimal factor levels for explaining the dependent parameters (weight loss, seedcake, sediments in the oil, extraction loss, extracted crude oil, oil yield, and oil expression efficiency) were the heating temperature of 50 °C and time of 22.5 min for yellowish sesame, whereas those of blackish sesame were 60 °C and 15 min. The determined regression models with the significant terms predicted the crude oil, oil yield, and oil expression efficiency of yellowish sesame with the amounts of 25.496 g, 25.806 % and 66.631 % in comparison with blackish sesame with the amounts of 20.449 g, 22.215 % and 49.029 %. The absorbance-wavelength curves of yellowish and blackish sesame oils were not significantly affected by the heating conditions. It was found that yellowish sesame produced higher oil output than blackish sesame under the heating conditions.