The identification of biotransformation pathways for removing fishy malodor from Bangia fusco-purpurea using fermentation with Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae is effective in reducing the fishy malodor of sea products. However, the biotransformation pathways are still unclear. The seaweed B. fusco-purpurea was taken as an example to investigate the chemical transformation pathways for the deodorization process with S. cerevisiae fermentation. Sensory evaluation, GC-MS, GC-MS-O and odor activity value (OAV) analyses showed the fishy odorants were 1-octen-3-ol, (E)-2-nonenal, 2,4-decadienal, 2-pentylfuran, 2-octen-1-ol and nonanal. The removal of fishy malodor was related to the reactions of reduction, dehydrogenation, deformylation-oxygenation and ester syntheses via catalysis of aldehyde dehydrogenase, alcohol dehydrogenases, epoxide hydrolase, aldehyde deformylating-oxygenase, enone reductase, oxidases, dehydrogenases, aldo-keto reductases, ester synthase and acyltransferase. Interestingly, for the first time, it was found that 3,5-octadien-2-one transformed to 6-octen-2-one; and 2-pentylfuran transformed to o-cymene and hexyl acetate. Our findings enrich the knowledge for the removal of fishy malodor from sea products such as seaweeds.