- Publisher Summary There is a common problem of biomass recovery from the fermenter and the subsequent extraction of the oil. Therefore, for the Single Cell Oils (SCOs) that are rich in a particular Polyunsaturated Fatty Acid (PUFA), there is a need to avoid sustained high temperatures or conditions that could lead to the oxidation and rancidity of the oils during their extraction. The first commercially viable SCO process was the production of an oil rich in Gamma-Linolenic Acid (GLA) from Mucor circinelloide . Examination of the first batch of oil extracted from M. circinelloides indicated the presence of free fatty acids at about 3%–5% of the total oil, which then contributed certain undesirable characteristics to the oil. These free fatty acids were quickly realized to be artifacts of the downstream processing system, as they were not present if the oil was quickly extracted from small samples of biomass taken from laboratory level fermenters. Over 98% of the oil within the cells of M. circinelloides could be extracted directly, using hexane, in one of the speciality extractors. Once the oil is extracted, its further refinement and purification follows conventional procedures.