Maillard reactions bread flavors

Many nitrogen- and sulfur-containing heterocycles have been identified in the aroma fractions of foods [214]. In roasted products (e.g., coffee) and heat-treated foods (e.g., baked bread or fried meat), these heterocycles are formed from reducing sugars and simple or sulfur-containing amino acids by means of Maillard reactions [215, 216]. Their odor threshold values are often extremely low and even minute amounts may significantly contribute to the aroma quality of many products [217, 218]. Therefore, N- and N,S-heterocyclic fragrance and flavor substances are produced in far smaller quantities than most of the products previously described. 

Maillard reactions can be involved in the manufacture of foods in at least three quite different ways. First, there is the unconscious role played in the development of flavor in such traditional processes as the roasting of coffee and cacao beans, the baking of breads and cakes, and the cooking of meats. Second, there is the deliberate use of Maillard technology in the production of artificial (or engineered) foods and flavors. Third, there are the efforts to inhibit undesirable results of Maillard reactions in food processing today. 

Fritzsche-Dodge Olcott, Inc., New York City, incorporates Maillard reaction roducts on a rather broad scale into their meat, chocolate, bread, and malt flavors. 

QHjOj, Mr 112.13 cryst. with a spicy, caramel-like odor resembling that of liquorice, mp. (monohydrate) 106 °C soluble in alcohol (25%), water (2.5%), but hardly soluble in petroleum ether it is formed from glucose by the Maillard reaction and is present in the flavor of thermally prepared foods such as maple syrup, bread, coffee, roasted nuts, and roast pork. It is mainly obtained from beech wood tar and used as a flavor compound, e. g., for the above-mentioned aromas. 

Importance Pro is able to participate in a-helices to a much lower extent than other amino acids. It is thus a helix breaker of particular importance for the structure of proteins. Rotation about the amino peptide bond of proline is especially hindered the correct folding of Pro-containing proteins thus appears to be catalyzed by peptidylprolyl cis-fra/u-isomerases (rotamases, EC 5.2.1.8 see FK-506). On account of its presence in gluten, Pro is involved in the Maillard reaction resulting in the typical bread flavor. The inner salt (betaine) of I, l-dimethyl-P. is a widely distributed pyrrolidine alkaloid in plants, e.g., in woundwort (Stachys spp., stachydrin). 

Nearly all foods are made up of a complex mixture of components, including carbohydrates, amino acids, and proteins. When these foods are heated, the Maillard reaction occurs resulting in the formation of a large variety of volatile flavor compounds (1-3). The Maillard reaction is responsible for both desirable and undesirable aromas in foods. The aroma of bread, chocolate, coffee, and meat are all examples of desirable aromas resulting from the Maillard reaction. The aromas of burned food, canned products, stale milk powder, cereal, and dehydrated potatoes are typical examples of the undesirable aspects of this reaction. 

An alternative source of characteristic heated flavor compounds is via the Maillard pathway, the thermally induced reaction between amino acids and reducing sugars. Aroma constituents in chocolate, coffee, toasted bread, and popcorn are products of Maillard reactions, in addition to flavors in roasted nuts and meats, which are discussed in Sec. II.E and 11.E. Guaiacols occur as pyrolysis products of carbohydrates or lipids in smoked or char-broiled meats. 

It should be mentioned here that a side reaction of the Maillard browning results in the formation of flavorful compounds, such as those associated with the roasting of meat, coffee, or nuts and the baking of bread. This... 

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