Physicochemical Changes in Fermented Skate (Raja kenojei) Treated with Organic Acids During Storage

Fermented skate has a unique ammonia-like flavor. The flavor is preferred by a few lovers of skate muscle, while women and young people may be sensitive to the odor. Organic acids were used to reduce the ammonia-like odor in fermented skate and to investigate the physicochemical properties. Fermented skate muscles were sprayed with 20 mL of acetic acid or citric acid (3, 5, and 7%) for 30 seconds and stored at for 15 days. The physicochemical properties of organic acid-treated fermented skate were investigated during storage. The control, which was treated with distilled water, showed a higher pH value than the samples treated with organic acids. The value increased with increasing organic acid concentration, while the and values were not significantly different among the samples. The trimethylamine (TMA) decreased with increasing in the organic acid concentration, but it was not significantly different after 9 days of storage. Ammonia-type nitrogen and ammonia-like flavoring, decreased with increasing in the organic acid concentration, whereas ammonia-type nitrogen increased with a storage period more than 6 days. In conclusion, fermented skate treated with 7% citric acid was the best treatment to reduce the ammonia-like odor.