Influence of different storage conditions on production of trimethylamine and microbial spoilage characteristics of mackerel products

Gradual accumulation of the fishy-odor compound trimethylamine (TMA) from bacterial reduction of trimethylamine oxide (TMAO) is one of the characteristic chemical changes attributed to fish spoilage. Changes in TMA values were correlated with sensory testing results, storage temperature, storage time, and viable bacteria counts. TMA contents were determined under different storage conditions. Headspace solid-phase micro extraction analysis with gas chromatography using flame ionization detection was used with different storage times and temperatures. Mackerel samples were inoculated with Pseudomonas fragi to monitor changes in the TMA content and pH. The TMA content increased proportionally with time during storage, and pH values and the microbiological quality were evaluated to analyze correlations with the TMA content in fish products. The TMA content increased with an increasing number of P. fragi with good linearity (R (2)=0.997). Basic data are provided for developing a freshness indicator for fish spoilage.