ARTICLE FEED & ADDITIVE MAGAZINE January 2023 65 terface of the two liquids. Fish protein hydrolysates, on account of their enhanced amphiphilic nature, act as good emulsifier. Protein hydrolysis results in exposure of more hydrophilic and hydrophobic groups facilitating their orientation at the oil–water interface enabling effective adsorption. FPH with a higher DH, a higher amount of smaller peptides are formed, which may result in a drastic loss of emulsifying properties. Therefore, a low DH along with a careful choice of enzymes is a key aspect if enhanced emulsifying properties are desired. Foaming properties Similar to emulsifying properties, foaming properties also rely on protein’s surface properties. Hydrophobicity has a significant correlation to foaming formation and comparable to other functional properties, these attributes are also related to the degree of hydrolysis. Foaming properties are usually expressed as foaming capacity and foam stability. Foaming capacity is referred to as the ability of protein to form foams also described as over run, which is the excess amount of foam produced on whipping a protein solution in comparison to the initial protein solution volume. Foam stability is measured as the decrease in volume of the whipped protein solution within a specific period. Sensory properties Although enzymatic cleavage of proteins is desirable for enhanced functionality in protein hydrolysates, the disadvantage associated with this mechanism is the bitterness development. The mechanism of bitterness has been documented to be linked with the presence of bitter peptides mostly comprising of hydrophobic amino acids. In addition, the native protein, the peptide sequences, the hydrolytic conditions, extent of hydrolysis, concentration and position of bitter taste residues, number of carbons on the ‘R’ group of branched chain amino acids and amino acid conformation are also influential in bitterness generation in peptides. ROLE OF FPH IN AQUACULTURE PRODUCTION Feed intake and utilization The enzymatic hydrolysis process helps to formation of peptides with small molecular weight that may act as an attractant for fish. The availability of small molecular weight peptides and free amino acids in hydrolysed protein can improve the feed palatability which may stimulate feed intake of fish. The low molecular weight fractions of FPH reducing gluconeogenesis can increase the amino acids
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