Impact of raw material and enzyme type on the physico-chemical and functional properties of fish by-products hydrolysates

To examine the impact of raw material and enzyme type on the physico-chemical and functional properties of fish by-products hydrolysates, mackerel (Scomber scombrus) and sardine (Sardina pilchardus) by-products were the raw material, and papain, pepsin and Protamex™ were the protease enzymes. Hydrolysates' physico-chemical and functional properties were affected by the fish species used as raw material and the employed enzyme type. Mackerel produced hydrolysates with higher foaming properties and solubility at pH 10 than sardines. Hydrolysis, oil retention capacity, and turbidity were higher for the hydrolysates obtained from the sardine by-products. The Papain and Protamex™ hydrolysates exhibited similar functional properties, while significant differences were observed between these and the pepsin hydrolysates. Papain and Protamex™ displayed the highest degree of hydrolysis and relevant emulsifying properties. The Pepsin hydrolysates had good foaming and oil retention capacities. These results underline the need to consider fish species and hydrolysis enzymes when protein hydrolysates and peptides with specific functions are desired.