Analyze properties of pea protein-derived enzymatic hydrolysates.

Protein hydrolysates have become increasingly popular ingredients for the manufacture of health-promoting foods because of their excellent functional performance in different food systems. However, one major obstacle that limits the use of certain protein hydrolysates is the bitter taste that they impart to food products. So, it's desirable to reduce or even eliminate this bitterness.

Pea proteins are readily abundant ingredients, but little is known about the relationships between the actions of different proteases and the physicochemical or functional properties of the resulting protein hydrolysates. Canadian scientists believe that the properties of pea protein hydrolysates will vary according to the specificity of proteases used for hydrolysis. For this reason, they indicate it's possible to identify products with a desirable combination of a low bitterness threshold and good functional-nutritional attributes.

In experiments, commercial pea protein isolate was hydrolyzed for four hours using a variety of different enzymes. The scientists clarified the digested mixtures by centrifugation. This was followed by desalting the supernatant. Alcalase and Flavourzyme produced protein hydrolysates with a significantly higher degree of hydrolysis when compared to the other proteases.

Flavourzyme, papain and Alcalase produced hydrolysates that contained the highest levels of aromatic amino acids, while trypsin hydrolysate had the highest levels of lysine and arginine. Papain hydrolysates contained high molecular weight peptides-23 kilodaltons (kDa) to 132 kDa. Hydrolysates from the other four proteases contained low molecular weight peptides--less than 6 kDa.

Sensory analysis showed that the Alcalase hydrolysate was the most bitter. Papain and chymotrypsin hydrolysates were the least. Among the enzymes used in this research, papain and chymotrypsin appear to be the most desirable for producing high-quality pea protein hydrolysates. This is because of their low bitterness scores that combine with high levels of angiotensin to convert their enzyme inhibiting and free radical scavenging activity.

Further information. Rotimi E. Aluko, University of Manitoba, Department of Human Nutritional Sciences, H515 Duff Roblin Building, Winnipeg, Manitoba, R3T 2N2 Canada; phone: [phone]; fax: [phone]; email: [e-mail].