The work developed in the SEAFOODplus project PROPEPHEALTH aims at upgrading fish by-products and underutilized species by using the pH-shift methods described to produce protein isolates. For this reason, the application of the recovered proteins in different seafood products was studied.
The yields achieved from when recovering proteins from hake and blue whiting by-products using the alkali-aided process were 63 % and 51.2 %, respectively. These yields are considerably higher than those obtained by the traditional surimi process. The gels obtained with the isolated proteins may be considered of medium quality. In the case of hake by-products it was sometimes observed that the proteins obtained by the traditional process pH shift process did not gellify properly. However, by applying microbial transglutaminase (ca. 0.5 U/g protein) to the recovered proteins the gel forming capacity improved considerably.