Simple and Economical Downstream Process Development for Edible Oil Production from Oleaginous Yeast Lipomyces starkeyi

The production of palm oil, which is used in various foods, is associated with environmental destruction and climate change risks; therefore, there is an urgent need for sustainable alternatives. "Yeast oil" produced by Lipomyces starkeyi, an oil-producing yeast, is expected to solve these problems because its fatty acid composition is similar to that of palm oil. To date, we have successfully developed yeast oil as an edible alternative to palm oil. However, conventional processes, including cell collection and lyophilization, are difficult to industrialize in terms of equipment and cost. Therefore, a method for extracting yeast oil from the emulsified liquid generated by crushing the culture was investigated. It is presumed that the emulsified state is stable owing to the components derived from yeast cells and metabolites; thus, solid-liquid filtration separation was attempted before extraction. The extraction recovery ratio of yeast oil was 98.2% when a hexane/ethanol mixture (3:1) was added to the residue after filtration. Furthermore, the energy consumption and processing cost of this new process were estimated to be 26% and 34%, respectively, of that of conventional methods, suggesting that the new process has potential for practical applications.