NMR Metabolomics of Saurida tumbil Fish Treated with Formaldehyde Solution as Misconduct Food Preservation Method

The use of formaldehyde for fish preservation is common in developing countries like Indonesia, even though there are rules for food safety practices. Law enforcement has not been successfully implemented, as officials are unable to distinguish between external formaldehyde that has been added to fish as a preservative and internal formaldehyde that is naturally produced during the fish deterioration process. This study presents nuclear magnetic resonance (NMR) metabolomics of Saurida tumbil fish, a common fish that produces a relatively high amount of formaldehyde during the deterioration process, which was preserved at chilled temperature after treatment with 0% (control), 3%, and 5% formaldehyde. Results of the study showed that the average of formaldehyde residue in 0% (control), 3%, and 5% was 12, 28, and 26 mg/kg, respectively. Meanwhile, metabolomics analyses showed that trimethylamine oxide (TMAO) and trimethylamine (TMA) are the major factors (97.44%) that discriminate between the treated and untreated fish. A high amount of TMAO and low TMA indicates the addition of external formaldehyde and conversely. These results may serve as a baseline for a specific marker to develop a high throughput screening method for the detection of formaldehyde preservation in post-harvest fisheries products.