An application of cryo-shattering to low-fat meat separation from whole fish of mackerel and sardine

Collecting low-fat meat from whole fish by use of cryo-separation which consists of cryo-shattering followed by cryo-sieving was studied in an attempt to pave the way for the acceptance of sardines and mackerels for human food. The segregated portions of mackerel, i.e., the light muscle, dark muscle, and viscera were shattered one by one at selected low temperatures. The particle size distribution of shattered tissues deeply depended on the temperature of shattering. At -60°C, the light muscle, the leanest among the portions, was ground into finer particles than that of the other portions. The relationship between the particle size and the fat content of particles, obtained through cryo-shattering of whole mackerels and sardines, showed various patterns depending upon shattering temperatures. Fortunately, however, a simple relationship in which the fat content of particles decreased with the reduction in particle size was obtained at -60°C for mackerel and at -80°C for sardine. The maximum recoveries of low-fat meat (light muscle equivalent) were 95% for mackerel and 89% for sardine.