Studies on the recovery of proteinaceous substances from chicken heads: II—Application of pepsin to the production of protein hydrolysate

Minced heads of broiler chickens were hydrolysed under various conditions using porcine pepsin. It was found that hydrolysis goes at an optimum rate at 55°C and pH 1.5 following the addition of 750 g water and 3 g pepsin per kg raw material. After 5 h of proteolysis, 1 kg of the raw material yielded 144 g of dry unneutralised hydrolysate containing 15.7 g total nitrogen, equivalent to a 67.8% nitrogen recovery. Neutralisation prior to drying marginally decreased nitrogen recovery and reduced the nitrogen solubility index by >30%. The final dried products were pale cream coloured, had no bitter taste, were of high microbiological quality and had a high mineral content. Both dried hydrolysates had poor emulsifying properties.