Flavor methional

Sulfur Compounds of Beef Flavor. Methional, which results from the degradation of methionine, is an important contributor to flavor in meat. Thiolanes, formed during the cooking of beef, have peculiar oniony flavors that also augment the quality of the meaty flavor. Thiophenes and thiofurans are also important to meaty flavors. Sulfides, such as methyl sulfide, are oxidized to methyl sulfoxide and methyl sulfone. Condensation reactions of Maillard browning products also result in thiazoles such as benzothiazole, an important component of meat flavor. 

Other examples are glycine — formaldehyde, alanine — acetaldehyde, valine — isobutyraldehyde, phenylalanine — phenylacetaldehyde, and methionine — methional (106). Products such as dried skim milk, dried eggs, and dehydrated vegetables and fmits are particularly susceptible to deteriorative flavor changes ascribed to this reaction (Table 10). 

Methional, formed by the degradation of the amino acid methionine, has been reported (Patton 1954 Velander and Patton 1955) to be the principal contributor to the activated flavor. Samuelsson (1962) reported, in studies of dio- and tripeptides containing methionine, that irradiation did not result in any hydrolysis of the peptides, and the... 

In an headspace extract of fresh rye bread crust, 3-methylbutanal, (E)-2-nonenal and methional showed the highest FD-factors (Table 4), while 2-acetyl-1-pyrroline, the key odorant of wheat bread crust (cf. Table 3), did not significantly contribute to the rye (rust flavor. Quantitative measurements established [45, 55] that especially the higher odor activity (cf. 3, this chapter) of the boiled potato-like smelling methional in the rye bread crust in combination with the much lower odor activity of the roasty-smelling 2-acetyl-l-pyrroline mainly contribute to the overall flavor differences in rye and wheat bread crusts. 

Knowledge of the volatile components of irradiated and nonir-radiated beef is reviewed. Concurrent and nonconcurrent irradiation procedures produce the same compounds but in different relative quantities. Storage of irradiated beef decreases irradiation flavor and the quantity of volatile constituents. Methional, 1-nonanal, and phenylacetaldehyde are of primary importance in beef irradiation off-flavor produced under the conditions described. 

A problem associated with beef sterilized by irradiation at approximately room temperature is the production of an unpleasant flavor and aroma. This paper summarizes knowledge of the volatile components of enzyme-inactivated irradiated and nonirradiated beef, reviews the effects of concurrent and nonconcurrent irradiation procedures and of storage on these components, and presents evidence that methional (3-methylmercaptopropion-aldehyde), 1-nonanal, and phenylacetaldehyde are of primary importance to irradiation off-odor in beef thus processed. 

Merritt, as a result of elegant analytical work on raw beef, has suggested (8,10,12) that the series of n-alkanes and 1-alkenes produced during irradiation are responsible for irradiation flavor. In our work no evidence has been found which supports this suggestion. The reason for this contradiction may be the different conditions used during irradiation. Merritt worked with raw beef which was irradiated in vacuum or an inert atmosphere. Our beef, on the other hand, had been partially cooked during enzyme-inactivation and then irradiated in the presence of air. It may also be that 1-nonanal, methional, and phenylacetaldehyde are not the only substances which when mixed in correct proportions give rise to typical irradiation odor. 

A number of investigators (2, 5, 15, 21, 34, 41, 42, 48, 82, 53) have tried to isolate and to characterize the chemical compound or compounds which give rise to irradiation flavor in meat or to correlate irradiation flavor scores with the production of specific compounds or types of compounds during the irradiation of meat or meat fractions (3,4,32,44> 49,50). These investigations have indicated some probable and some improbable sources of irradiation flavor and the order of magnitude of the concentration of the compounds responsible for irradiation flavor. Wick et al. (53) have offered impressive chemical and organoleptic data connecting the 20 2 1 ratio of methional, 1-nonanal, and phenylacetaldehyde found in irradiated beef at the parts per million level with typical irradiation odor. 

A flame photometric detector specific for sulfur compounds revealed a mixture of sulfur compounds in the cooked meat extract which quantitatively changed with storage. Three nuyor sulfur compounds were identified as markers for flavor changes, namely methional, methyl sulfone, and benzothiazole. 

Volatile profiles of raw and cooked-beef flavor samples, prepared by the procedures of Figure 1, were obtained after capillary GC and FPD. Although the identification of these sulfur containing compounds is as yet incomplete, the chromatograms demonstrated that there were a number of new sulfur compounds produced on cooking that were not present in the raw beef. Three prominent sulfur compounds were identified as markers in subsequent meat flavor deterioration experiments, namely, methional (13.2 min), methyl sulfone (13.8 min), and benzothiazole (25.3 min). Each compound produced an adequate mass spectrum for spectral library search and positive identification. 

A typical cooked-beef flavor deterioration sample was prepared as described in Beef Preparation section to observe changes in key sulfur marker compounds over a period of 0-, 2-, 4-, and 7-day storage. Sulfur markers, methional, methyl sulfone, and benzothiazole were compared with benzothiophene as internal standard to follow the course of free radical reactions taking place in the stored cooked-beef. Results are plotted in... 

Light-induced oxidation of proteins has been shown to lead to off-flavors and destruction of essential amino acids in milk. Patton (1954) demonstrated that sunlight attacks methionine and converts it into methional (( -methylmercaptopropionaldehyde), which can cause a typical sunlight off-flavor at a level of 0.1 ppm. It was later demonstrated by Finley and Shipe (1971) that the source of the light-induced off-flavor in milk resides in a low-density lipoprotein fraction. 

C. Lumiflavin and lumichrome edso catalyze oxidation of lipids (to Upid peroxides) md methionine (to methional), resulting in the development of an unpleasant flavor - the so-called sunlight flavor. 

These results indicate that compounds with malty (3-methylbutanal), sulfurus (methional), coconut-like (whiskey lactone) and phenolic (ethylguaiacol, guaiacol) odor qualities contribute to the overall flavor of barrel aged wines. 

Investigation of the reaction mechanism (Maujean and Seguin, 1983) showed that sunlight flavor was mainly due to the oxidative photodegradation of methionine (Figure 8.30). It was observed that methional was the primary product of oxidative photolysis of the amino acid. 

Bread flavor. White bread During the baking process the impact substances 2-acetyl-1 -pyrroline and 2-ace-tyl-A (A )-tetrahydropyridine form in the crust, on storage their concentrations decrease rapidly. Precursors are metabolites of yeasL Also of importance are ( )-2-nonenal (see alkenals), 3-methylbutanal (see al-kanals), 2,3-butanedione, and methional. In bread crumbs, degradation products of linolic acid such as ( )- and (Z)-2-nonenaJ and ( , )- 2,4-decadienal predominate. 

Cheese flavor. C. f. is formed from milk fat, milk protein, lactose during the maturation of cheese mainly through enzymatic and microbial processes. Quantitative and, sometimes, qualitative differences are responsible for the diversity of cheese flavors. Typical aroma substances are the free C4-C,2 fatty acids, C7, C and C, 2-alkanones (also in Roquefort cheese), the butter aroma substances acetoin, 2,3-butanedione, and 5- alkanolides, (-)-(R)-l-octen-3-ol (fungus note in Camembert), 4-alkanolides and alkylpyrazines with nut-like nuances, indole, skatole, and phenols with stable-like odors, as well as numerous sulfur compounds such as methional, methyl mercaptan (moldy, coal-like), dimethyl sulfide and dialkyl polysulfides with, in part, onion- and garlic-like nuances. Furaneol" and homofuraneol (see hydroxyfura-nones) are responsible for the sweetish odor of Em-mental cheese. 

Potatoes 2-Isopropyl-3-methoxypyrazine together with 2,5-dimethylpyrazine (see pyrazines) dominate in raw potatoes. Key compounds in boiled potatoes are meAional and 2-ethyl-3,6-dimethylpyrazine. Tomatoes The highest flavor values in fresh tomatoes are exhibited by (Z)-3- and ( )-2-hexenals (see alkenals), j3- ionone, hexanal (see alkanals), 8-damascenone, I-penten-3-one (CsHgO, Mr 84.12, CAS [1629-58-9], 3-methylbutanal (see alkanals), and 2-isobutylthiazole. The most important flavor components in tomato pulp are dimethyl sulfide, )8-damascenone, )5-ionone, 3-methylbutanal, I-nitro-2-phenylethane (CgH,N02, Mr 151.16, CAS [24330-46-91), eugenol, methional, and 3-methylbutanoic acid. ... 

Methional used in model flavor system contained 48% dimer. 

Strecker aldehydes are quantitatively the major products of the Maillard reaction. In addition to their intrinsic flavor, they are very reactive and participate in numerous reactions that make additional contributions to flavor development in foods. There is a lack of information on the reaction kinetics of these Strecker aldehydes as well as other flavor compounds. Thus a kinetic study on the formation of methional and two secondary products (dimethyl disulfide and 2-acetylthiophene) from the reaction of amino acids (0.075 mole) and glucose (0.5 mole) in aqueous model systems was conducted. Systems were heated at temperatures from 75 to 115°C at times from 5 min. to 7.5 h and pH s of 6, 7, and 8. Kinetic data are presented and discussed. 

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