Study On Aqueous Enzymatic Extraction Of Safflower Oil, Eyhyl Esterification And Purification

Safflower oil is a kind of high-grade edible oils with huge market potential, but many inadequacies still exist in its extraction and deep processing. This paper studied the ultrasonically accelerated aqueous enzymatic extraction of safflower oil and the oil was used as material to prepare fatty acid ethyl esters by transesterification reaction assisted with ultrasound. Finally, fatty acid ethyl esters would be purified by a molecular distillation equipment to get ethyl linoleate.Cellulase and trypsin were chosen as the enzymes for hydrolysisi and frozen demulsification was chosen to extract oil in the emulsion layer. Through the orthogonal experiment, the optimal conditions of stepwise enzymatic hydrolysis were gotten as follows: solid-liquid ratio 1:6, ultrasound power 120W, addition of cellulase 150U/g, enzymatic time of cellulase 5h, addition of trypsin 100U/g, enzymatic time of trypsin 3h. The extraction yield reached 86.74% in the conditions.The fatty acid composition of safflower oil was analyzed by GC-MS, and the results showed that safflower oil was composed of 6 kinds of fatty acids. The content of linoleate acid was the highest, reached 64.23%, and the content of oleic acid was 19.62%, followed by linoleate acid. The total content of unsaturated fatty acid was 84.64%.Fatty acid ethyl esters were prepared by transesterification reaction assisted with ultrasound. Through the orthogonal experiment, the optimal conditions were gotten as follows:ethanol-oil molar ratio 8:1, the amount of catalyst 0.9%, ultrasound power 280W, reaction time 25min. Under the conditions, the conversion was 94.82%.The reaction order of transesterification reaction assisted with ultrasound was 1.5, and the rate constant were 0.2581 (mol/L)·min-1 and 0.1932 (mol/L)·min-1 at 328K and 338K respectively. The activation energy was 27.76kJ·mol-·K-1, and frequency factor was 4.56×103 (mol/L)·min-1. The kinetic equation was gotten after the study above.The RSD% in precision test and stability test were 0.54% and 0.47%, and the result of recoveries test was 99.79%. The method was proved to be simple, accurate and reliable.Molecular distillation equipment was applied to purify ethyl linoleate. Through the analysis of response surface experiment, the optimal conditions were gotten as follows: distillation temperature 105℃, feed rate 1.6mL/min, scraping film speed 220r/min, pressure 0.34Pa. Under the conditions, the purity of linoleate ethyl was 79.68%.The effect of multi-stage distillation on the purification of linoleate ethyl was studied preliminary. The result showed that the purity of linoleate ethyl reached 87.21% after three-stage distillation compared with that of 79.68% before experiment, but the recoveries of the heavies decreased from 72.23% to 24.70%.