Study On The Extraction Of Kiwi Fruit Seed Oil By Supercritical Carbon Dioxide

The various factors that had effects on the extraction efficiency of the kiwi fruit seed oil, such as operative parameters and pie-treatment of raw material etc, were systematically studied with supercritical carbon dioxide fluid extraction(SCFE-CO2) technology. According as the results of single factor experiments, the operative parameters (extraction pressure, extraction temperature,CO2 flow rate) were optimized. The mechanism is analysed for processing kiwi fruit seed oil with SCFE-CO2 ,which is based on the principle of the fluid kinetics. The oil with SCFE-CO2 under optimal conditions was compared to crude oil extracted by petroleum ether. GC analysis showed that kiwi fruit seed oil contained plent of a-linolenic acid(a-LNA) which has a great potential as a functional oil source. The conditions that concentrating a-LNA from kiwi fruit seed oil by SC-CO2 extraction-fractionation technology was studied. It was available for further studying and exploiting.At the same granularity of raw material, the amount of influx had great effect on extraction efficiency. In the range of experiment, 300g was the optimal amount of influx. Granularity of raw material is also important to extraction, 40-60mu is of benefit to improving extraction efficiency.Extraction pressure and temperature were principal factors for SCFE-CO2. In a certain temperature, the density of SC-CO2 was increased with increasing extraction pressure, and the capability that SCF solved kiwi fruit seed oil was also enhanced, but it didn't show liner relationship. When exceeding 35Mpa,the increase of extraction efficiency was very low with the raise of extraction pressure. However, working with higher pressure is not practical (very high investing and operating costs), therefore extraction pressure had a optimal value. The influence of temperature was related to the extraction pressure. The transformation pressure of SCFE-CO2 of kiwi fruit seed oil was 27Mpa. Under this transformation pressure, the solubility of oil decreased with the raise of temperature. When the extraction pressure surpassed 27Mpa. The case is just opposite. The CO2 flow rate has two different effects on extraction efficiency, so it has also a optimal value. Taking the extraction pressure, extraction temperature and CO2 flow rate as the variables of Box-Behnken Design, the results of response surface analysis(RSA) showed that the effect sequence of the above three factors was extraction pressure, extraction temperature, CO2 flow rate. And these variables had evident crossing action. The optimum parameters ofSCFE-CO2 were extraction pressure 35Mpa, extraction temperature 45 , CO2 flow rate 27kg/hr.Within the operating conditions, the extraction time depended on the extraction pressure and CO2 flow rate. The kiwi fruit seed oil can be extracted fully for 120-150min.Based on the principle of fluid kinetics, the mechanism of SCFE-CO2 was discussed. Shrinking Core model can well describe the process of SCFE-CO2.Comparing to the effect of extraction with petroleum ether, SCFE-CO2 had several virtues. The technology is simpler, operating time is shorter, moreover, it gained better color and lower acid value and didn't need degumming. The a-LNA contents was more than 60% in the oil, so kiwi fruit seed oil has available value in exploitation and utilization. The oxidative stability of oil with SCFE-CO2 was not good, so we must do more research work in the future.Enrichment of a-LNA from kiwi fruit seed oil by SC-CO2 extraction-fractionation technology indicated that fractionation efficiency will be improved with the increase of temperature gradient of fraction column and stages of controlling temperature. The fractionation time will decreased with the increase of CO2 flow rate. When fraction column pressure was 13 Mpa,CO2 flow rate was 15kg/hr and temperature range was 40-55-70-85 , a-LNA contents reached 70%.