Effects of additives and thermal treatment on the content of nitrogen compounds and the nutritive value of hake meat.

Heating of minced meat from 40 to 130 degrees C for 10 min and at 120 degrees C from 15 to 60 min with potato starch (3%), soya oil (4%), salt (1.5%), and water (15%) resulted in a decrease in total amino-acid content by 6% on the average, compared to the content in meat without additives. Heating time-dependent changes involved a decrease in the lysine content, while temperature-dependent changes involved a decrease in the valine content. On the other hand, the presence of additives reduced the thermal protein hydrolysis towards the formation of low-molecular nitrogen compounds. Prolonged time of heating of minced hake meat at 120 degrees C produced a more intensive protein hydrolysis than a shorter heating up to 130 degrees C; at the same time with temperatures exceeding 100 degrees C an intensive increase in the ammonia content, decrease in -SH groups content, and a decrease in protein digestibility were observed.