Hydrolysis bitter peptide formation

Extensive proteolysis of a protein often results in the formation of bitter peptides ( ). Therefore, a compromise between high protein yield and low bitterness has to be found when choosing the DH-value at which the hydrolysis reaction should be terminated. For the present process a DH-value of about 10% seems to be a reasonable value. The termination is performed by acid inactivation of the enzyme and the acid used should be chosen in accordance with the desired organoleptic characteristics of the final hydrolysate. A totally non-bitter product can be produced by use of an organic acid like malic or citric acid. Due to the masking effects of such acids, absolutely no bitterness can be detected even when the taste evaluation is performed at neutral pH. Such products are found most suitable for soft drinks. However, when inorganic acids, e.g. hydrochloric or phosphoric acids are used, a slight bitterness may be detected in the pure hydrolysate. However, when evaluated in for instance a meat product, no bitterness at all can be tasted even when the hydrolysate is added up to a proportion of 1 3 of hydrolyzed protein to meat protein. 

The three available industrial methods for the production of HVPs are (i) enzymatic a slow process that may result in the formation of bitter peptides and typically lacks the desired aroma/taste profile [20,21,39] (ii) alkaline hydrolysis which typically results in unacceptable flavor profile and an unbalanced amino acid content, and (iii) acid hydrolysis the most preferred method that is cost effective and yields a range of good flavors (see Chapter 11, section 11.4.1.2 Hydrolyzed Vegetable Proteins). 

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