Synthesis of Industrially Useful Phenolic Compounds Esters by Means of Biocatalysts Obtained Along with Waste Fish Oil Utilization

The purpose of the study was to utilize the waste fish oil after fish smoking process in Y. lipolytica yeast batch cultures in order to assess its valorization to whole-cell biocatalysts with lipolytic properties. Almost 90% of the waste carbon source in medium was used and batch cultures of Y. lipolytica W29 were characterized with biomass yield of 18.59 g/dm 3 and lipolytic activity of 53.41 U/g. The yeast biomass was used as a whole-cell biocatalyst in the synthesis of esters of selected phenolic compounds (acetates of 2-phenylethanol, tyrosol (2-(4-hydroxyphenyl) ethanol) and 3-phenyl-1-propanol, and ethyl esters of phenylacetic, 4-hydroxyphenylacetic, 3-phenylpropanoic, and 3-(4-hydroxyphenyl) propanoic acids). Y. lipolytica biomass was able to catalyze esterification of 3-phenylpropanoic acid (conversion of 95% after 24 h), but conversion of other acids to their esters was very weak, and in the case of transesterification of aromatic alcohols with vinyl acetate, conversions were 27%–63% after 24 h. Synthesized esters were tested prior potential activities as food additives. Esters of hydroxylated phenolic compounds showed activity of 2.5 mg/mL against Klebsiella pneumoniae and Citrobacter freundii , exhibited similar antioxidant properties to their precursors, and were better soluble in lipids, which increases the possibility of their use in the food industry.