Flavor compounds, interactions with

The Maillard reaction and the oxidation of lipids are two of the most important reactions for the formation of aromas in cooked foods. Interactions between lipid oxidation and the Maillard reaction have received less attention, despite the fact that lipids, sugars, and amino acids exist in close proximity in most foods. Lipids, upon exposure to heat and oxygen, are known to decompose into secondary products, including alcohols, aldehydes, ketones, carboxylic acids, and hydrocarbons. Aldehydes and ketones produce heterocyclic flavor compounds reacting with amines and... 

Sugars and carbonyl compounds interact with amino acids or proteins in a sequence of complex reactions known as the Maillard reaction or as non-enzymatic browning. The browning products from this reaction have a marked influence on lipid oxidation. They generally retard lipid oxidation in foods, and contribute to meat flavors. Lipid oxidation products can also react with proteins and amino acids, leading to the loss of essential amino acids with impact on the oxidative stability and the nutritional quality of foods. 

It is not yet possible to design a molecule with specific odor (or taste) characteristics because the relations between sensory properties of flavor compounds and their molecular properties are not well understood. As a consequence, the development of compounds with desired flavor qualities has had to rely on relatively tedious synthetic approaches. Recent advances, however, in computer-based methods developed by the pharmaceutical industry to study QSAR (quantitative structure-activity relationships) may ultimately be helpful in the rational design of new flavor-structures with predictable sensory attributes. Results from QSAR studies may also provide insight into the mechanism of the molecule-receptor interaction. 

Food flavor is governed by many factors, including lipid oxidation and protein degradation. Enzyme-catalyzed oxidation ( ) and autoxidation (2) can substantially alter the flavor q ality of foods. In "addition, protein degradation, whether caused by enzymes, heat, or interactions with other compounds, can also affect flavor characteristics of certain foods (3, 4, ... 

The importance of direct gas chromatography and combined direct GC/MS to the food industry is demonstrated by the analysis of volatile flavor components and contaminants in experimental samples of rice, food blends, and raw and roasted peanuts. By examining these samples, we are able to investigate flavor systems that are probably associated with lipid oxidation, thermal degradation of protein, or protein interactions with other compounds. 

The major cause of deterioration of food products is lipid oxidation, from which low-molecular-weight, off-flavor compounds are formed. This deterioration is often caused by the oxidation of the unsaturated lipids present in foods. Off-flavor compounds are created when the hydroperoxides, formed during the initial oxidation, are degraded into secondary reaction compounds. Free radicals are also formed which can participate in reactions with secondary products and with proteins. Interactions with the latter can result in carbonyl amino... 

Equilibrium concentrations describe the maximum possible concentration of each compound volatilized in the nosespace. Despite the fact that the process of eating takes place under dynamic conditions, many studies of volatilization of flavor compounds are conducted under closed equilibrium conditions. Theoretical equilibrium volatility is described by Raoulf s law and Henry s law for a description of these laws, refer to a basic thermodynamics text such as McMurry and Fay (1998). Raoult s law does not describe the volatility of flavors in eating systems because it is based upon the volatility of a compound in a pure state. In real systems, a flavor compound is present at a low concentration and does not interact with itself. Henry s law is followed for real solutions of nonelectrolytes at low concentrations, and is more applicable than Raoult s law because aroma compounds are almost always present at very dilute levels (i.e., ppm). Unfortunately, Henry s law does not account for interactions with the solvent, which is common with flavors in real systems. The absence of a predictive model for real flavor release necessitates the use of empirical measurements. 

Aspartame contains a free Af-terminal amino group. In its deprotonated form, this could be expected to react with carbonyl compounds, forming Schiff base compounds. Some evidence has been obtained for this type of reaction, involving aspartame and flavoring agents [41]. A similar explanation might also apply to the interactions with ascorbic acid and carbohydrate sweeteners described in the previous paragraph. 

Interactions with Hexanal and Pentanal. Various compounds identified in French-fried potato flavor, e.g., 2-hexyl-4,5-dimethyloxazole and... 

Clearly, the flavor impact of any given compound at any given time depends not only on its chemical nature, but also on its quantitative level, its threshold value and its interaction with the other components present. The purpose of the present work was to study the various parameters which influence the quantitative pattern of volatiles produced from butteroil by heating. 

Heterocyclic compounds are dominant among the aroma compounds produced in the Maillard reaction, and sulfur-containing heterocyclics have been shown to be particularly important in meat-like flavors. In a recent review, MacLeod (6) listed 78 compounds which have been reported in the literature as possessing meaty aromas seven are aliphatic sulfur compounds, the other 71 are heterocyclic of which 65 contain sulfur. The Strecker degradation of cysteine by dicarbonyls is an extremely important route for the formation of many heterocyclic sulfur compounds hydrogen sulfide and mercaptoacetaldehyde are formed by the decarboxylation and deamination of cysteine and provide reactive intermediates for interaction with other Maillard products. 

The volatiles from cooked meat contain large numbers of aliphatic compounds including aldehydes, alcohols, ketones, hydrocarbons and acids. These are derived from lipids by thermal degradation and oxidation (J7) and many may contribute to desirable flavor. In addition, the aldehydes, unsaturated alcohols and ketones produced in these reactions, as well as the parent unsaturated fatty acids, are reactive species and under cooking conditions could be expected to interact with intermediates of the Maillard reaction to produce other flavor compounds. 

The problem of developing desirable meat flavor in the presence of vegetable protein has been clearly demonstrated in the literature. Physical measurements after heating a meat model system with soy proteins have shown a dramatic reduction in the concentration of alkyl pyrazine compounds due to interaction with the soy proteins. These interactions have been defined in terms of stoichiometry and binding energies from measurements on pure standards of the methyl pyrazines. 

The extruder is a continuous high-temperature short-time reactor. Ingredients, moisture, temperature, pressure, and shear can interactively produce many Mail lard-type flavor compounds. As the extrudate exits the extruder, many of the volatile reaction products may be lost with steam since the extrudate passes from a zone of relatively high pressure within the extruder to atmospheric pressure. By controlling formulation variables, the extruder can serve as a useful tool to thermally produce volatile and nonvolatile compounds which make significant contributions to overall flavor. 

Roasting cocoa beans results in the production of volatile and non-volatile compounds which contribute to the total flavor complex. 5-Methyl-2-phenyl-2-hexenal, which exhibited a deep bitter persistant cocoa note, was reported in the volatile fraction (53). It was postulated to be the result of aldol condensation of phenylacetaldehyde and isovaleraldehyde with the subsequent loss of water. The two aldehydes were the principal products of Strecker degradation products of phenylalanine and leucine, respectively. Non-volatiles contained diketopiperazines (dipeptide anhydride) which interact with theobromine and develop the typical bitterness of cocoa (54). Theobromine has a relatively stable metallic bitterness, but cocoa bitterness is rapidly noticed and disappears quickly. 

Letinski, J., and Halek, G. W. (1992). Interaction of citrus flavor compounds with polypropylene films of varying crystallinities.. Food Sci. 57, 481M84. 

Food flavor is a very important parameter influencing perceived quality. The volatile compounds contributing to the aroma of foods possess different chemical characteristics, such as boiling points and solubilities and the sensory properties of food cannot be understood only from the knowledge of aroma composition. This can be explained by interactions between flavor compounds and major constituents in food such as fat, proteins and carbohydrates (1). A number of different interactions has been proposed to explain the association of flavor compound with other food components. This includes reversible Van der Waals interactions and hydrogen bonds, hydrophobic interactions. The understanding of interactions of flavor with food is becoming important for the formulation of new foods or to... 

This paper reviews the interactions between aroma compounds and other components of a wine matrix colloids, fining agents and ethanol. Studies are carried out with model systems and instrumental methods to investigate flavor-matrix interactions. 

The knowledge of the composition of volatile compounds in food has greatly increased during the past decade. Many studies continue to report the identity and the concentration of volatile compounds in food matrices. However concentration alone appears insufScient to explain flavor properties of food. The lack of our knowledge concerning the influence of non-volatile constituents of food on the perception of aroma has to be filled by studies such as those presented in this paper. Data on interactions between aroma and matrix in wine are scarce compared with other food matrices studied. Flavor-matrix interactions in wine have generally been obtained in model systems and with instrumental experiments. However it is possible to develop some hypotheses on the possible sensory contribution of some non-volatile compounds of wine on overall aroma. 

All possible combinations of methyl, propyl, allyl, and 1-propenyl disulfides (primarily), monosulfides, and trisulfides have been found among the volatile flavor components of onion (28,29, 30,31), garlic (32), caucas Allium victorialis) (33), and other Allium species 28) although proportions vary with species. These compounds are presumably derived from the corresponding thiolsulfinates. This is accomplished either by direct decomposition by an unknown mechanism with evolution of SO2 (32) or by interaction with cysteine to produce a mixed disulfide (15),... 

Most of the flavor compounds in fats and oils are produced by the reaction of oxygen with unsaturated fatty acids in triacylglycerols or polar lipids. On the other hand, some flavor compounds such as those present in cocoa butter, roasted sesame oil, or roasted peanut oil are generated by the interaction of reducing sugars with amino compounds during thermal processing. 

Numerous studies have shown that the off-flavor intensity of soybean oil is correlated with its concentration of linolenate. Although the concentrations of both linoleate and linolenate, which can reach 60-65% in typical soybean oil, undoubtedly contribute to soybean oil s instability, it is not clear why the much smaller amount of linolenate has such a strong effect on soybean oil flavor. Linolenate is expected to oxidize about twice as fast as linoleate, but there is seven to eight times more linoleate than linolenate in typical soybean oil. The flavor compounds produced by linolenate do not seem to have much lower thresholds than those produced from linoleate. Possibly flavor interactions in olfaction may account for these effects. 

In summary, phospholipids affect the sensory properties of appearance, color, flavor, taste, and texture of foods, the key attributes that determine consumer acceptance. The flavor of phospholipids, and their interaction with both desirable and undesirable flavors, is extremely critical and contributes to the acceptability of foods containing these preparations. As various phospholipids have different physical and chemical properties, they can affect food quality to different degrees. This depends on the phospholipid s nature and content in the oil, the presence of other compounds, and the oil system in which phospholipids exist (301). 

Schirle-KeUer, J.-P, Reineccius, G.A. and HatchweU, L.C. The Interaction of Flavors with Fat Replacers Effect of Oil Level on Flavor Interactions and Data on Homologous Series of Flavor Compounds. Presented at IFT Meeting in New Orleans, June 19-23, 1992... 

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