Changes in quality parameters at the various stages of arachidonic acid-rich oil refining

Arachidonic acid-rich oil (ARA-rich oil) is produced through the fermentation of Mortierella alpina or microalgae. However, the obtained ARA-rich crude oil has an unpleasant flavor and requires refinement. In this study, samples were collected at each refining stage and the variations in the quality characteristics were assessed with crude oil serving as the control. The results indicated that the acid and peroxide values significantly decreased from 0.973 to 0.034 mg/g and 0.055 to 0.016 g/100 g after refining, respectively. However, the lowest DPPH content (161.27 μmol TE/100 g) and the highest anisidine value (2.416) were found in the decolorized oils (DCO). Deodorization (DOO) most significantly reduced the unsaturated fatty acid content by 1.96% and the ARA content in the oil by 1.83%. Regarding hazardous substances, benzopyrene levels decreased significantly throughout refining. However, the level of 3-chloropropanol ester and glycidyl ester increased by 0.3 μg/kg and 0.53 μg/kg after deodorization, respectively. The volatile components of ARA-rich oil mainly included alcohols, aldehydes, hydrocarbons, and heterocyclic compounds, with heterocyclic compounds accounting for the largest proportion. PCA further confirmed that deodorization had the greatest effect on ARA-rich oil quality than the other refining processes.