Carbohydrate when heated results to a complex group of reactions in absence of nitrogen containing compounds. Such reaction is commonly known as caramelization. Sugars will show caramelization to a relatively high temperature. The browning of these carbohydrates is further facilitated by the presence of small amount of acid, salts of this acids, phosphates and metallic ions. Lack of moisture in the sugar molecule with formation of anhydro rings are actually caused by thermolysis. When double bonds are produced this leads to the development of unsaturated rings such as furans. The conjugated double bonds will then absorb light producing the brown color. Specific types of caramel colors, solubility and acidities are directed by some catalysts to increase the reaction. Mostly some of the unsaturated rings condense into polymers yielding the different colors. One of the commonly used sugars during caramelization is sucrose solution. The brown caramel color produced in its reaction with ammonium bisulfate is used in cola soft drinks, syrups, candies, pet foods and dry seasonings. Solutions of it are acidic with pH ranges from 2-4.5 and with colloidal particles having negative charges. The non-enzymatic browning caramel pigments are large polymeric molecules with complex, uneven, and indefinite structures. It is these polymers that form the colloidal particles. Their rate of formation increases with increasing temperature and pH. (Fennema, 1996) The diagram below shows a summary of the caramelization process in the experiment “effects of heating to properties of sugar”.(deMan, 1999)
There are three general types of browning, a.) Reaction of ketones and aldehydes among the reducing sugars with amino compounds like amino acids, peptides and proteins. This reaction is not dependent on the presence of oxygen b.) Caramelization which takes place in polyhydroxy carbonyl compounds such as reducing sugars when heated at high...
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