Some attmepts were made to decolorize the dark muscle of mackerel Pneumatophorus japonicus japonicus and Sardine Sardinops melanosticta which is responsible for the undesirable dead color of their meat products.
Preliminary experiments showed that mackerel myolgobin is readily dissolved in a HCl-ethanol mixture among many organic solvents tested. In the next place, the dark muscle of each fish was homogenized and extracted with HCl-ethanol mixtures of different proportions under various conditions. Results showed that the pigment present in the dark muscle can be extracted best with a HCl-ethanol mixture (1:99 by volume) for 30-60min. The amount of extracted pigment tended to increase at higher temperatures as far as the range that was covered (-20°C-+40°C) was concerned.
Color differencemetric analysis showed that the dark muscle thus decolorized elicits a Hunter's whiteness of 26.4 (mackerel) and 30.5 (sardine), clearly higher values than 11.2-11.8 (mackerel) and 13.8-17.9 (sardine) of the dark muscle washed repeatedly with water or a 0.2% NaHCO₈-0.15% NaCl mixture.