Thermal generation of flavor

Guntert, M. et al., New aspects of the thermal generation of flavor compounds from thiamine, in Progress in Flavor Precursor Studies, Schreier, P. and Winterhalter, P., Eds., Allured Publishing Corp., Carol Stream, IL, 1992, p. 361. 

The thermal generation of flavor is a very essential process for the "taste" of many different foodstuffs, e.g. cocoa, coffee, bread, meat. The resulting aromas are formed through non-enzymatic reactions mainly with carbohydrates, lipids, amino acids (proteins), and vitamins under the influence of heat. Thiamin (vitamin B ) and the amino acids, cysteine and methionine, belong to those food constituents which act as flavor precursors in thermal reactions. The role of thiamin as a potent flavor precursor is related to its chemical structure which consists of a thiazole as well as a pyrimidine moiety. The thermal degradation of this heterocyclic constituent leads to very reactive intermediates which are able to react directly to highly odoriferous flavor compounds or with degradation products of amino acids or carbohydrates. 

Giintert, M. Bertram, H.-J. Hopp, R. Silberzahn, W. Sommer, H. Werkhoff, P. "Thermal Generation of Flavor Compounds from Thiamin and Various Amino Acids". In Recent Developments in Flavor and Fragrance Chemistry Hopp, R. Mori, K., Eds. VCH Verlagsgesellschaft Weinheim, Germany, 1993,pp 215-240. 

M. Giintert, H. J. Bertram, R. Hopp, W. Silberzahn, H. Sommer, and P. Werkhoff, Thermal generation of flavor compounds from thiamin and various amino acids. Recent Developments in Flavor and Fragrance Chemistry (R. Hopp and K. Mori, eds.), VCH, Weinheim, 1993, p. 215. 

In addition to simple model systems, more complex systems which are closer to actual foodstuffs have been used to investigate the formation of flavor chemicals in the Maillard reaction. Sixty-three volatile chemicals were isolated and identified from starch heated with glycine (4). When beef fat was used as a carbonyl compound precursor in a Maillard model system with glycine, 143 volatile chemicals were identified (6). These included fifteen n-alkanes, twelve n-alkenes, thirteen n-aldehydes, thirteen 2-ketones, twelve n-alcohols, and eleven n-alkylcyclohexanes. Recently, the effect of lipids and carbohydrates on the thermal generation of volatiles from commercial zein was studied (7). 

Thermal Generation of Sulfur-Containing Flavor Compounds in Beef... 

Soy Proteins and Thermal Generation of Alkylpyrazines in Meat Flavor... 

Concentrations of thermally generated meat flavor components are diminished by protein adsorption when soy extenders are added to fresh meat products before heating. The amounts of individual alkyl pyrazines, thermally generated by heating beef diffusate, decreased linearly as the amount of whole soy, soy 7S or soy 11S proteins were increased in a model system. Similar recoveries were obtained when pyrazines were mixed with soy either as chemical standards or from diffusate. Stoichiometry and energetics of interaction were determined for methyl pyrazine congeners with soy proteins at 120° and 145°C. Results of this study suggest that flavorants can be added in readily determined amounts to compensate for losses due to adsorption in meat-soy products. 

Mottram, D.S., Salter, L.J. Flavor formation in meat-related Maillard systems containing phospholipids. In Thermal generation of aromas, ParUment, T.H., McGorrin, R.J., Ho, C.T. (Eds.), American Chemical Society, Washington, DC, 1989, 442-451. 

Severe heating of proteinaceous foods leads not only to generation of flavor compounds due to the Maillard reaction, but also to thermal degradation of Met and Cys residues in proteins, as well as of different low-molecular-weight compounds. These reactions are discussed in Chapter 10 of this volume. 

Ouweland, G.A.M., Demole, E.P., and Enggist, P, Process meat flavor development and the Maillard reaction, in Thermal Generation of Aromas, Parliment, H., McGorrin, J.M., and Ho, C.T., Eds., American Chemical Society, Los Angeles, 1988, p. 433. 

Effect of Amide Content on Thermal Generation of Maillard Flavor in EnzymaticaUy Hydrolyzed Wheat Protein... 

CHEN HO Amide Content Thermal Generation of MaUlard Flavor... 

Alkylpyrazines, effect of amide content on thermal generation of Maillard flavor, 90,92/... 

Maillard reaction is known to occur in foods and biological systems (Eriksson, 1981 Waller and Feather, 1983 Fujimaki et aL, 1986 Baynes et al, 1989 Finot, 1990 Finot et al, 1990 Labuza et aL, 1994 Lee and Kim, 1996 Ikan, 1996). Recently, food browning and its prevention (Friedman, 1996) and the thermal generation of Maillard aromas (Ho, 1996) have been reviewed. Therefore, this overview, will concentrate on application aspects of the Maillard reaction relating to the generation of flavor, antioxidant properties, desmutagenic effects, protein-polysaccharide conjugates and other major reaction products. 

Rizzi, G.P. Heat-induced flavor formation from peptides. In Thermal Generation of Aromas, Parliment, T.H. McGorrin, R.J. Ho, C.-T., Eds. ACS Symp. Ser. 409 American Chemical Society Washington D.C., 1989 pp 172-181. 

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