Sugar, reactions caramelization

Cystine and other sulfur-containing amino acids are recognized as important precursors of food flavors, especially meat flavors (3, 11-12). DMHF, a cyclic-a-dicarbonyl, possesses a sweet, caramel and fruity aroma (13). It is found in many food sources (14-17) and is used extensively in many flavor applications (18-19). DMHF can be formed from sugar via either sugar enolization (caramelization) by a Maillard reaction then cyclization (20). 

Under strong alkaline conditions sugar undergo caramelization reactions. 

When the caramels are pulled and air is incorporated into the candy mass, flavourings resistant to oxidation are required. The most popular taste directions are caramel, cream, butter, coffee, cocoa, vanilla. In the case of products where dairy ingredients and sugars are used, a browning reaction (caramelization) takes place. The flavour type has to harmonize with the inherent flavour of the candy. In caramels with a fruity taste, oil-soluble fruit flavourings can be used. Flavour types such as orange, lemon, raspberry, cherry, strawberry, blackcurrant and tropical fruits are typical. 

In addition to Maillard reactions, caramelization reactions, involving the dehydration and decomposition of sugars, can form a variety of volatile compounds found in roasted tree nuts such as heterocyclic oxygen-containing furan derivatives and maltol. 

For chocolate production, the raw cocoa is stored, shipped, and processed. The processing steps are roasting and liquor production. The heat treatment induces Maillard reactions, caramelization of sugars, protein degradation, and formatiiMi of volatile aroma components [85, 89]. An often applied step to cocoa is the dutching, the alkali treatment of cocoa powder in order to modify the color, and other physiochemical properties. The pH values of cocoa powders are adjusted from ph 5.3-5.8 in natural powders to higher than 7.6 in heavily dutched materials. The total flavanol contents are reduced from more than 34 to 3.9 g kg In the same way, the antioxidative properties of the powders are diminished [90]. 

Monosaccharides are probably involved in the browning reactions that occur during the roasting of coffee. Caramelization involving the sugars alone, and Maillard reactions, between sugars and free amino acids, produce polymeric yellow to dark brown substances, known as melanoidins. These melanoidins can be extracted into hot water, separated and characterized.105... 

Pyrroles are found in the volatiles of most heated foods [29], although they have received less attention than some other classes of aroma volatiles. Some pyrroles may contribute desirable aromas, e.g. 2-acetylpyrrole has a caramel-like aroma, and pyrrole-2-carboxaldehyde is sweet and corn-like, but alkylpyrroles and ac-ylpyrroles have been reported to have unfavourable odours [22]. Many more volatile pyrroles have been found in coffee than in other foods [30], and they are common products of amino acid-sugar model systems. Pyrroles are closely related in structure to the furans, and they are probably formed in a related manner from the reaction of a 3-deoxyketose with ammonia or an amino compound followed by dehydration and ring closure (cf Scheme 12.2). 

All the fabulous success stories and the terrible disasters that can occur in kitchens around the world can be blamed on chemical reactions. Cakes are light and fluffy because the baking soda in the batter reacts with an acid to produce carbon dioxide, a gas. When sugar is heated, it turns into dark brown, gooey caramel. The cut surfaces of apples and bananas turn brown because they react with oxygen in the air. All of these are examples of chemical reactions in the kitchen. 

Browning of breads, as induced by baking, is a complex process consisting mainly of the Maillard reaction between flour starch or other carbohydrates and flour protein or other protein-rich additives, and the caramelization of sugar and other carbohydrates. 

Perhaps one of the most fascinating and complex chemical reactions involving carbohydrates is caramelization. For example, granulated sugar heated at a high temperature in the dry state eventually produces a dark, viscous mass which has a strong and characteristic flavor totally different from the sweet taste of sucrose. 

Furans are the most abundant products of the Maillard reaction and they account for the caramel-like odor of heated carbohydrates (8). Some sugar degradation compounds, such as maltol, isomaltol, 4-hydroxy-5-methyl-3(2H)-furanone, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and 2-hydroxy-3-methyl-2-cyclopentene-l-one (cyclotene), have odors usually described predominantly... 

Theoretically, caramelisation is the browning reaction undergone by sugars on heating by themselves or, at least, in the absence of amino compounds. Cooks consider the product to be caramel. 

Caramel in this context means a brown colour that is produced either traditionally by heating sugar or as a very intense product that is made by heating carbohydrate, usually glucose syrup, with ammonia. Caramel colour is the product of the Maillard reaction, i.e. the reaction of a reducing sugar with an amino group. Chemically the colour is a melanoidin - these substances are extremely stable and can be used in any type of confectionery. 

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