Melanoidin reaction mechanism

A somewhat different mechanism for the browning reaction has been proposed by Burton and McWeeney (1964) and is shown in Figure 3-13. After formation of the aldo-sylamine, dehydration reactions result in the production of 4- to 6-membered ring compounds. When the reaction proceeds under conditions of moderate heating, fluorescent nitrogenous compounds are formed. These react rapidly with glycine to yield melanoidins. 

Studies on the non-enzymatic browning of carbohydrates and amino acids evidenced that, besides ionic condensation reactions (3,4), also mechanisms involving free radical formation produce browning compounds in the Maillard reaction (5-7). Because radicals have been detected in model melanoidins (8,9), similar reactions might be involved in the formation of melanoidins during thermal food processing. 

Unsaturated fatty acids bound in phospholipids can be oxidised by oxygen, similarly to fatty acids in triacylglycerols. Phospholipid hydroperoxides may react with amino groups of other phospholipids and other amino compounds to form dark brown macromolecular products similar to melanoidins (see Section 4.7.5.7) formed in the Maillard reaction. Therefore, phospholipids act as synergists (among other mechanisms) of... 

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