Effect of meat washing on the development of impact odorants in fish miso prepared from spotted mackerel.

Background: Miso, a fermented soybean paste prepared using koji (rice malt inoculated with Aspergillus oryzae) has been commonly used as a traditional seasoning for several centuries in East Asian countries. A miso-like fermented product was prepared using washed and unwashed meats of spotted mackerel (Scomber australasicus) with improved food functionality and aroma attributes. The evolution of aroma-active volatiles was further evaluated during the early stages of maturation.

Results: The newly developed fermented product was rich in flavor. The product was found to contain 98 volatile compounds, including aldehydes, alcohols, esters, ketones, furans, sulfur- and nitrogen-containing compounds, aromatics, and acids. Koji enzymes efficiently hydrolyzed protein and carbohydrate substrates in both the unwashed and washed fish meats. Significantly higher enzyme activities were observed when the unwashed meat was used as a raw material rather than when washed meat was used. The substrate specificity of koji enzymes plays an important role in the formation of volatile compounds.

Conclusion: The results confirmed that meat washing can reduce the levels of certain aldehydes, ketones, and nitrogen-containing compounds, and can thereby provide a pleasant aroma by reducing fishy odor in the finished product.