Supercritical Fluid Extraction of Oil from Brown Rice

摘要

Brown rice contains much useful nourishment, compared with white rice. However, brown rice is not good in taste and difficult to boil. The crucial reason is that oil exists mainly on the surface of the rice. This oil creates hydrophobic surface. Therefore, it disturbs water to permeate into oil layer. The objective of this study is to develop tech-brown rice, whose oil was removed on its surface without loss of any other element. Tech-Brown Rice was prepared by supercritical extraction using supercritical CO2. Since water can be also soluble in supercritical CO2, rice samples were dehydrated during extraction. Extraction rate of water diminished with decrease in CO2 flow. In contrast, there was no considerable change in the extraction rate of oil with increase or decrease in solvent flow rate. The reason was thought that oil content was too small to take an effect, considering its solubility. To inhibit dehydration, water was added into supercritical CO2 as a co-solvent. Water-saturated supercritical CO2 was thought to loose the solvating power to the water. Therefore, it is possible to extract only oil on the surface of sample. Many experiments were performed at various flow rates and the ratios between flow rates of supercritical CO2 and water.