Reductones

Another mechanism for browning in food products involves reactions of vitamin C. The following set of reactions is known as ascorbic acid browning:

+ H2O and Heat

- H2O and CO2

- H2O

This can lead to off flavors and to first red and then brown colors in food products.

Another set of reactions important in the chemistry of carbohydrate involves the reaction of aldehydes with amino acids and the subsequent decarboxylation and hydrolysis of the products. This reaction is known as the Strecker Degradation.

The following are a number of types of compounds that can be isolated from carbohydrate reaction mixtures. Most of these should be familiar to you. You should have a general idea of what the structure of these compounds is as we will be referring to them when we discuss the reaction products of Non Enzymatic Browning (NEB).


A number of compounds that add flavor to foods can be derived from further reactions of the deoxyhexosones derived from carbohydrates, from reaction of Strecker products and from aldol condensations of the above. For example the compound, 2-hydroxyacetyl furan, can be derived as follows:

The formation of these types of compounds from sugars can occur either through reactions that involve amino acids or reactions that only involve sugars. When only sugars are present, the temperatures required for formation of deoxyhexosones are much higher than when amino acids are present. If sugar is heated to a high enough temperature, deoxyhexosones will form. Further heating will lead to dehydration of the deoxyhexosones, to aldol condensations and to further reactions. This set of reactions is known as caramelization. This is one means of obtaining brown pigments from carbohydrates. Proper temperature control during caramelization will yield to the formation of compounds that can impart desirable flavors to the mixture.