Abstract
The purpose of this paper is to explore the possibilities of subcritical dimethyl ether extraction (SDME) of oil from tuna liver with high-moisture content. The results showed that the oil and water were successfully co-extracted from the liver, and could be easily separated by centrifugation. In addition, the response surface method was employed to optimize the process parameters of SDME, including temperature/pressure, time and stirring speed. It was predicted that a temperature/pressure of 42/0.80 °C/MPa, time of 50 min and stirring speed of 925 rpm were the optimum within the experimental ranges, with an oil yield of 17.46 ± 0.23%. Furthermore, supercritical carbon dioxide extraction (SC-CO(2)) was studied comparatively. Only minor differences were observed between the oils extracted by SDME and SC-CO(2), which indicated the high-quality of the SDME-oil. With no freeze-drying procedure and the relatively low pressure used in SDME, SDME could be a promising technique for extraction of marine fish liver oil.