Enzymatic hydrolysates tastes

The enzymatic hydrolysates of milk casein and soy protein sometimes have a strong bitter taste. The bitter taste is frequently developed by pepsin [9001 -75-6] chymotrypsin [9004-07-3] and some neutral proteases and accounted for by the existence of peptides that have a hydrophobic amino acid in the carboxyhc terminal (226). The relation between bitter taste and amino acid constitution has been discussed (227). 

Enzymatic hydrolysates of various proteins have a bitter taste, which may be one of the main drawbacks to their use in food. Arai el al. [90] showed that the bitterness of peptides from soybean protein hydrolysates was reduced by treatment of Aspergillus acid carboxypeptidase from A. saitoi. Significant amounts of free leucine and phenylalanine were liberated by Aspergillus carboxypeptidase from the tetracosapeptide of the peptic hydrolysate of soybean as a compound having a bitter taste. Furthermore, the bitter peptide fractions obtained from peptic hydrolysates of casein, fish protein, and soybean protein were treated with wheat carboxypeptidase W [91], The bitterness of the peptides lessened with an increase in free amino acids. Carboxypeptidase W can eliminate bitter tastes in enzymatic proteins and is commercially available for food processing. 

Schlichtherle-Cemy, H. and Amado, R. 2002. Analysis of taste-active compounds in an enzymatic hydrolysate of deamidated wheat gluten. J. Agric. Food Chem. 50, 1515—1522. 

The earliest commercial milk protein enzymatic modification dates back to the 1940s, when the first formulas for allergenic infants were made. The aims of this process were to reduce allergenicity as well as to change the functional properties of proteins while preserving their nutritional value for clinical use. Unfortunately the hydrolysates thus obtained were characterized by bitter taste, and for mainly this reason proteolysis, as a technological process, enjoyed very little popularity. 

Enzymatic hydrolysis of food proteins generally results in profound changes in the functional properties of the proteins treated. Protein hydrolysates may therefore be expected to fulfil certain of the food industry s demands for proteins with particular, well-defined functional properties. A wide-spread use of protein hydrolysates in food requires, however, a careful control of the taste and functionality of the protein during its hydrolysis and subsequent processing to obtain a reproducible product quality. 

Many workers have studied the influence of enzymatic hydrolysis on the functional properties of various food proteins, and much of this work has recently been reviewed by Richardson (2). However, there seem to be very few reports which quantitatively relate functionality to parameters which characterize the protein hydrolysates per se (e.g. molecular weight). Ricks et al. (3 ) examined the solubility and taste of a number of pure proteins (denatured pepsin, lactoblobulin, a-Sj -, K-, and 8-casein) hydrolysed with... 

In certain foods a bitter taste is definitely not desirable, therefore different debittering methods have been developed. Methods for removing the bitter taste of enzymatic protein hydrolysates (such as casein hydrolysates) are described in Section 2.3.2.2. These methods are mainly based on controlled proteolysis, plastein reaction, extraction with azeotropic mixtures of alcohols and masking of bitter substances. 

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