Enzyme-based conversion of marine biomass to high-quality peptide ingredients is a promising strategy in bio-based industries. Despite their good nutritional profile and food grade quality, their utility in food products is limited by the fish smell. A well-known contributor to the smell is trimethylamine (TMA). Current strategies to mask or remove the odor are not effective or give rise to undesirable side effects. We have shown that trimethylamine monooxygenases (Tmms) can oxidize TMA into the odorless TMA N-oxide (TMAO) in hydrolysates.