| Maillard reaction is an important mechanism involved in the thermal generation of flavors. It is responsible for the roasted, nutty, or sweet aroma and brown color of foods. Protein hydrolysate is a good source of Maillard reactants. However, the commonly used acid hydrolysis poses a possible health hazard. Another protein modification which influences flavor is deamidation, owing to the ammonia released in the process. Unfortunately, chemical deamidation is accompanied by negative side reactions. Therefore, the use of enzymes for both hydrolysis and deamidation offers a safer and milder alternative. Research on either enzymatic modification has been geared towards the improvement of functional properties of proteins. Since little is known about their effects on flavor, the overall goal of this research was to characterize the flavor profile of the Maillard reaction products of wheat gluten, which was hydrolyzed and deamidated by enzymes.; Among the proteases evaluated, Flavourzyme and Umamizyme produced the highest degrees of hydrolysis (DH). These proteases were chosen for the succeeding experiments. Gluten was treated with either Flavourzyme or Umamizyme alone and in combination with a deamidating enzyme, Glutaminase. The gluten hydrolysates were heated with glucose at 155°C for two hours. Volatile components were isolated by solid phase microextraction (SPME) using these optimized conditions: sample pH (9.0), extraction temperature (60°C), and carboxen-polydimethylsiloxane (SPME fiber). The major flavor compounds identified by gas chromatography-mass spectrometry (GC-MS) include pyrazines, furans, pyridines, and pyrroles. Although a similar profile was observed for Flavourzyme and Umamizyme systems, higher quantities of flavor compounds were obtained with Umamizyme. In general, increased levels of these volatiles were produced from gluten treated with both protease and deamidating enzyme than with protease alone. This indicates the important role of ammonia in Maillard reaction. The aroma and taste profiles of the Maillard reaction products were consistent with the organoleptic properties of the flavor compounds identified.; By optimizing the conditions for the Maillard reaction of enzymatically modified gluten, products with the desired sensory characteristics can be obtained. This double enzymatic treatment demonstrated in gluten may also be used in other proteins that may otherwise remain as a by-product waste from food processing. |
