Studies on potent aroma compounds generated in Maillard-type reactions using the odor-activity-value concept

The Maillard reaction between free amino acids and reducing carbohydrates is an important tool used in the industrial production of reaction or processed flavors. However, although certain potent odorants are known to be formed from distinct precursor amino acids, e.g., 2-furfurylthiol from cysteine or 2-acetyl-1-pyrroline from proline, systematic studies correlating the overall odor of a given flavoring with the odor activity values (OAV: ratio of concentration to odor threshold) of the key odorants are scarcely performed. Extended knowledge on the structures and concentrations of key odorants formed, in correlation with the amounts of precursor present or the processing conditions, are other prerequisites enabling the manufacturer to optimize the flavor formation more towards the food flavor to be intensified or even to be mimicked. This publication summarizes own results aimed at characterizing potent aroma compounds in Maillard-type reactions using the odor-activity-value concept. Starting with data on the identification of the aroma compounds formed in binary mixtures containing one amino compound (cysteine, glutathione, proline) and one carbohydrate (ribose, rhamnose), the influence of the processing conditions on the yields of certain key odorants is discussed, based on knowledge about precursors and reaction pathways. Results obtained by thermal treatment of more complex precursor mixtures, such as yeast extracts, are presented with special emphasis on elucidating correlations between the concentrations of precursor amino acids present with the yields of key odorants formed.