Maillard volatile compound

The aroma volatiles produced in the Maillard reaction have been classified into three groups by Nursten [6], and this provides a convenient way of viewing the origin of the complex mixture of volatile compounds derived from the Maillard reaction in foods ... 

The volatile compounds formed by the Maillard reaction are only one group of flavor compounds in foods. Schutte (1) presents a brief summary of the major classes and their modes of formation from precursors. Some of them can be formed by different pathways. An example is the furans, which can be formed by non-enzymatic browning reaction but also by biotransformation. 

Evershed, R. P., Bland, H. A., van Bergen, P. F., Carter, J. F., Horton, M. C., and Rowley-Conwy, R. P. (1997). Volatile compounds in archeological plant remains and the Maillard reaction during the decay of organic matter. Science 278,432-433. 

The Maillard reaction commonly occurs in food products and during food processing. A typical or pure Maillard reaction is simply the reaction of a sugar and an amino acid. Strictly speaking, the sugar must be a reducing carbohydrate and the amino acid can be either free or bound, as a peptide or protein. The reaction generates not only volatile compounds, which provide odor, but also odorless nonvolatile compounds, some of which are colored. 

The flavor industry has introduced, over the years, methods of developing meat flavors by processing appropriate precursors under carefully controlled reaction conditions. As a result, meat flavors having a remarkably genuine meat character in the beef, chicken and pork tonalities are available for the food industry. It has repeatedly been stated that the Maillard reaction is particularly important for the formation of meat flavors. However, of the 600 volatile compounds isolated from natural beef aroma, only 12% of them find their origin in sugar/amino acid interactions and of these 70% are pyrazine derivatives. 

Volatile compounds generated by model systems of zeln, corn amylopectin and corn oil extruded at barrel temepratures of 120°C and 165°C were analyzed by GC and GC/MS. The largest quantities of lipid oxidation products were detected in systems containing all three components. In each system, the quantity of 2,4-deca-dienal was low relative to the quantities of hexanal, heptanal and benzaldehyde. Identification of the Maillard reaction products, 2-methyl-3(or 6)-pentyl-pyrazine, 2-methyl-3(or 6)-hexylpyrazine and 2,5-di-methyl-3-pentylpyrazine, suggested that lipid-derived aldehydes might be involved in the formation of substituted pyrazines. 4-Methylthiazole was identified as a major decomposition product of thiamin when corn meal containing 0.5% thiamin was extruded at a final temperature of 180°C. 

Flavour is a complex sensation, made up principally of smell and taste, but touch and hearing contribute as well. The human senses of smell and taste differ in sensitivity, between each other and depending on the nature of the component eliciting the sensation. Substances may have no impact at all (such as oxygen or carbon monoxide) or exhibit very low thresholds (such as 2 X 10 14g mL 1 water for the odour of bis-2-methyl-3-furyl disulfide).204 In general, odour thresholds are much lower than taste thresholds and so flavour tends to be dominated by odorous components, by substances able to reach the olfactory epithelium high up in the nose, that is, substances with at least some volatility. Hence, the emphasis on the volatile compounds derived from the Maillard reaction. 

The formation of volatile compounds by the Maillard reaction has been most recently reviewed by Mottram152 and Tressl and Rewicki.30... 

J. M. Ames and A. Apriyantono, Effects of pH on the volatile compounds formed in a xylose-lysine model system, in Thermally Generated Flavors Maillard, Microwave, and Extrusion Processes, T. H. Pariimenl, M. J. Morello, and R. J. McGorrin (eds), American Chemical Society, Washington, DC, 1994, 228-239. 

C.-T. Ho and J. Chen, Generation of volatile compounds from Maillard reaction of serine, threonine, and glutamine with monosaccharides, in Flavor Chemistry Thirty Years of Progress, R. Teranishi, E. L. Wick, and I. Homstein (eds), Kluwer/Plenum, New York, 1999, 327-333. 

Figure 15. Formation of volatile compounds with toasty aromas by Maillard reactions between sugar molecules and amino acid residues when wood is heated...

The major precursors in meat flavors are die water-soluble components such as carbohydrates, nucleotides, thiamine, peptides, amino acids, and the lipids, and Maillard reaction and lipid oxidation are the main reactions that convert these precursors in aroma volatiles. The thermal decomposition of amino acids and peptides, and the caramelization of sugars normally require temperatures over 150C for aroma generation. Such temperatures are higher than those normally encountered in meat cooking. During cooking of meat, thermal oxidation of lipids results in the formation of many volatile compounds. The oxidative breakdown of acyl lipids involve a free radical mechanism and the formation of... 

FARMER, L.J., MOTTRAM, D.s. and WHITFIELD, F.B. (1989). Volatile compounds produced in Maillard reactions involving cysteine, ribose and... 

The effect of lipids in the Maillard reaction has been studied by many authors who cooked or roasted mixtures of amino acids and reducing sugars in various vegetable oils. The thermal oxidative degradation of lipids generates lower molecules, for instance aldehydes, that contribute to the formation of heterocyclic volatile compounds. 

In the volatile fraction of heated glucose, Walter and Fagerson (1968) identified the unsaturated lactone, 2-buten-4-olide (G.7) for the first time in this reaction. In a study of model reactions (see Maillard reaction in Section 3.1), Baltes and Bochmann (1987a) identified G.l, G.7, G.8, G.9 and G.ll (MS data given), among more than 100 monocyclic furans (and ca 350 volatile compounds) in the reactions of serine and threonine with sucrose under conditions similar to coffee roasting. 

Ferretti A. and Flanagan V.P. (1971a) The lactose-casein (Maillard) browning system-volatile compounds. J. Agric. Food Chem. 19, 245-9. 

The reaction products of the Maillard reaction, such as l-amino-l-deoxy-2-ketose (Amadori product) or 2-amino-2-deoxyaldose (Heyns product), do not contribute to flavor directly but they are important precursors of flavor compounds [48]. These thermally unstable compounds undergo dehydration and deamination reactions to give numerous rearrangement and degradation products. The thermal degradation of such intermediates is responsible for the formation of volatile compounds that impart the characteristic burnt odor and flavor to various food products. For example, at temperatures above 100 C, enolization products (such as l-amino-2,3-enediol and 3-deoxyosone) yield, upon further dehydration, furfural from a pentose and 5-hydroxy methylfurfural and 5-meth-ylfurfural from a hexose [2]. 

The Maillard reaction between reducing sngars and amino acids under specific conditions (pH, water activity, and temperature) is primarily responsible for the production of heterocyclic volatile compounds such as pyrazines, pyridines, pyrroles, furans, and the Strecker aldehydes. Maillard reactions produce many potent aroma compounds identified in some roasted tree nuts, including 3-methylbutanal, 2,3-butanedione, methional, phenylacetaldehyde, 2-ethyl-3,5-dimethylpyrazine, and 2,5-dimethyl-4-hydroxy-3(2//)-furanone, among others. 

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. 

Severini, C., Gomes, T., De Pilli, T., Romani, S., and Massini, R., Autoxidation of packed almonds as affected by Maillard reaction volatile compounds derived from roasting, J. Agric. Food Chem., 48,... 

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