Bitterness in Fish Protein Hydrolysates and Methods for Removal

Enzymatic hydrolysis is a processing method for recovering protein from under utilized fish biomass and fish by-products. However, the hydrolysis process often creates bitter taste in the product. The bitterness restricts the practical uses of these hydrolysates. The presence of bile in whole fish and fish viscera is shown to cause bitterness in fish protein hydrolysates. The fat and ash content could also cause bitter taste. The content of total amino acids and hydrophobic amino acids did not correlate with bitterness. Three different methods were used to eliminate or reduce bitterness from FPHs after enzymatic hydrolysis with commercial enzymes: (1) treatment with endopeptidases (Flavourzyme(®)), (2) extraction with butanol and (3) treatment with cholestyramine resin. Flavourzyme(®) did not reduce the bitterness. The use of butanol and cholestyramine resin separately or in combination reduced the bitter taste from FPH to levels barely discernible by our sensory panel in 1% concentration.