Foaming capacity of fish minces during frozen storage

This work covers a year's study of the foaming capacity (FC) of minced muscle of three fish species-blue whiting (Micromesistius poutassou R), horse mackerel (Trachurtus trachurus L), and mackerel (Scomber scombrus L)--caught in two different seasons January and July) and stored at -18 degrees C. Periodic assays were performed to determine protein solubility, FC and dimethylamine formation. The results show that FC is initially inhibited by the presence of the species own lipids; however, during frozen storage this effect is attenuated and thus FC increases. The results corroborate the view that protein solubility is not an indispensible requisite for FC, and that mere dispersion of proteins is sufficient. However, FC is not diminished by changes in protein during frozen storage when this deficiency is offset by sufficient protein concentration. On the other hand, FC is clearly affected by the formaldehyde generated during frozen storage, so that beyond a certain level the aggregates formed as a result of formaldehyde formation are too large to disperse, and hence FC decreases drastically.