Supercritical Fluid Extraction of “Koku” Enhancing Compounds from Fish and Fishery by-Products

Abstract

The potential of supercritical carbon dioxide (SC-CO₂) extraction of “koku” enhancing compounds from dried herring fillet (“Migaki-nishin” in Japanese) and sturgeon liver was explored. “Koku” enhancing compounds from a water-soluble extract and a mixed water miscible SC-CO₂ extract were isolated and evaluated for their effects on sensory perception. Results showed that only select compounds were found in the mixed water miscible SC-CO₂ extract compared to the complicated composition of the water-soluble extract. A notable feature was that the mixed water miscible SC-CO₂ extract contained “koku” enhancing compounds, e.g., nicotinamide, glycerol and creatine. This study revealed for the first time that these compounds were extracted by SC-CO₂ extraction and that nicotinamide enhances “koku”. We also extracted “koku” enhancing compounds from sturgeon liver using the SC-CO₂ extraction technique. Instrumental analysis revealed that the sturgeon liver contained relatively large amounts of nicotinamide and glycerol. Thus, it is suggested that this technique might be applicable to the extraction of select compounds from fish and fishery by-products.