Enzymatically modify protein to generate flavor.

Flavor plays a major role and often determines if a consumer likes

a product enough to buy it again and again. An important mechanism for thermally generated flavors is the Maillard reaction, which is a non-enzymatic interaction between amino and carbonyl groups.

This reaction is responsible for the roasted or toasted aroma and brown color of certain foods. Protein hydrolysate is a good Maillard reactant for generating savory flavor. However, acid hydrolysis, which is commonly used to produce the hydrolysate, gives bitter compounds. It also is a potential health hazard. A better alternative involves the use of enzymes.

Deamidation also influences flavor, which is created by the ammonia released upon the loss of the amide function of glutamine-asparagine. Deamidation has been studied quite extensively as researchers seek to improve the functional properties of proteins. However, little is known about its effects on flavor. Research is even more limited on the flavor of enzymatically hydrolyzed and deamidated protein heated with reducing sugars.

Scientists at Rutgers University evaluated the flavor profile of gluten treated with a combination of protease and glutaminase and then heated with glucose. They found that optimizing the levels of enzymes can produce a flavor profile that is highly desirable for generating a savory flavor.

The researchers incubated gluten with Flavourzyme[R] (Novo Nordisk) and glutaminase. They determined the degree of hydrolysis using ninhydrin (triketohydrindane hydrate), a chemical used to detect ammonia or primary amines. They evaluated the amount of ammonia using an enzyme test kit. The researchers then reacted the hydrolysate with glucose. The flavor compounds were analyzed using gas chromatography.

Flavourzyme and glutaminase exhibited a high degree of hydrolysis and deamidation, respectively. The investigators found more volatile compounds from gluten using a double enzymatic treatment than by using just protease alone. Different combinations of enzymes altered the flavor profile of the modified gluten. The double enzymatic treatment demonstrated in gluten can also be used in other proteins that may otherwise remain as by-product waste from food processing.

Further information. C.T. Ho, Food Science Department, Cook College, Rutgers University, 65 Dudley Rd., New Brunswick, NJ 08901; phone: [phone]; fax: [phone]; email: [e-mail].