Malty flavor

Sheldon, R. M., Lindsay, R. C., Libbey, L. M. and Morgan, M. E. 1971. Chemical nature of malty flavor and aroma produced by Streptococcus lactis var. maltigenes. Appl. Microbiol. 22, 263-266. 

The production of aldehydes and alcohols from the hydrophobic amino acids has been studied primarily in yeast (147,148,149,154) since the fusel oils produced are significant secondary products of alcoholic fermentation (149). Also important are the studies of Morgan and coworkers on the malty flavor defect in milk which is produced by Streptococcus lactis var. maltigenes (155-161). This flavor is principally caused by 3-methylbutanal (155) which is produced by transamination of leucine to a-ketoisocaproate and decarboxylation (157). Labeling experiments showed that this compound is produced from leucine by tomato extract (9, 162, 163). The corresponding 3-methylbutanol and 3-methylbutyl acetate are produced similarly in banana (145, 163). Similar transformations of valine and phenylalanine are also carried out by banana slices (145). 

The decarboxylation of branched chain keto acids is apparently carried out by the same decarboxylase (EC 4.1.1.1, Mg and thiamine pyrophosphate dependent) which is active on pyruvate in yeast (154, 167) and orange juice (168, 169). The latter enzyme acts on the keto acids derived from valine and isoleucine at about 15% of the pyruvate rate (169). Its activity declines rapidly (80% in 1 hour) in juice (pH 3.4). The malty flavor defect produced by S. lactis var. maltigenes, however, appears to be caused by a specific decarboxylase activity not found in other strains (158, 160) since simultaneous decarboxylation of pyruvate and a-ketoisocaproate was almost additive (163) while a-ketoisocaproate and a-ketoisovalerate competed with each other. Decarboxylation of... 

This is one dark beer. When held up to sunlight in a clear glass, I couldn t see through it at all Auktor Bock is strong. It has a thick, beige head (a bottle cap floats on it ), a pungent, malty aroma, and a rich flavor. This beer could be considered chewable. The hops add enough bitterness to balance the malty flavor. 

Q-X Zhou, CL Wintersteen, KR Cadwallader. Identification and quantification of aroma-active components that contribute to the distinct malty flavor of buckwheat honey. J Agric Food Chem 50 2016-2021, 2002. 

Pale or amber lagers with malty flavor and low bitterness (low hop character). These gold- to straw-colored lagers are noted for their smooth, well-balanced maltiness, unassertive hop bitterness, and usually contain 5% alcohol by volume. 

On the basis of high FD-factors (Table 3) the sensory significance of 3-methylbutanal and 2-acetyI-l-pyrroIine with malty, roasty odors previously identified as the key odorants in fresh wheat bread crust [21] was established. During storage for 4 days the FD-factors of both odorants decreased significantly, while especially butanoic acid (rancid) and (E)-2-nonenaI remained unchanged. The fatty, green note of the latter odorant especially contributes to the stale note detectable in the overall crust flavor of the stored wheat bread. 

A comparison of the most important aroma compounds present in the wheat bread crust (3 7) with those identified in the crumb (Table IV) revealed two striking differences 2-acetyl-l-pyrroline and 3-methylbutanal, which appeared as potent flavor compounds respectively responsible for the roasty and malty aroma note in wheat bread crust, showed low FD-factors in the wheat bread crumb and are not listed in Table IV. On the other hand, carbonyl compounds with fatty aroma notes like 2(E),4(E)-decadienal, 2(E)-nonenal and 2(Z)-nonenal predominated in the crumb (Table IV). 

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. 

Although more than 280 compounds have been identified in the volatile fiction of wheat bread, only a small number is responsible for the flavor notes in the crust and the crumb. Schieberle and Grosch (73) used aroma extract dilution analysis (AEDA) to select 32 odorants in wheat. Among the odorants, 2-acetyl-pyrroline (roasly, bread crust-like) was the most potent aroma, followed by E-2-nonenal (green, tallowy), 3-methylbutanal (malty, nutty), diacetyl (buttery) and Z-2-nonenal (green, fiitty). 

This brew has a good malty aroma and malt flavor. I probably should have cut boiling of the hops back, as it was a bit out of balance. A little light in color for the style, as well. 

Schnermann and Schieberle [54] reported 13 odorants with the highest flavor dilution factors in milk chocolate as 3-methylbutanal (malty) 2-ethyl-3,5-dimetbylpyrazine (potato chip-like) 2- and 3-methylbutanoic acid (sweaty) 5-methyl-(E)-2-hepten-4-one (hazelnut-like) l-octen-3-one (mushroom-Uke) 2-ethyl-3,6-dimethylpyiazine (nutty, earthy) 2,3-diethyl-5-methylpyrazine (potato chip-like) (Z)-2-nonenal (green, tallowy) (E,E)-2,4-decadienal (fatty, waxy) (E,E)-2,4-nonadienal (fatty) 8-decalactone (sweet, peach-like) and 2-methyl-3-(methyldithio)furan. 

A wide array of bocks exists in the market (from pale to dark). These beers have a dishnchve malty and sulfur flavor and usually contain from 6% to 8% alcohol by volume. 

Copper-colored dry beer with malty and bitter flavor and low carbonation. These popular ales have a dishnchve malty and bitter flavor and usually contain from 3% to 7.5% alcohol by volume. 

Flavor-related activities of LAB depend on the species, with some specific activities found only in a small number of species. The branched-chain a-keto acid decarboxylase activity involved in the formation of malty branched-chain aldehydes from branched-chain AA, for example, has been found only in L lactis and not in the Lactobacillus and Leuconostoc strains tested (Fernandez De Palencia et al. 2006). Most LAB, however, display a great strain-to-strain variability, on the genomic level and/or at the phenotypic level. Table 19.3 gives some examples of intra- and interspecies variability of flavor-related LAB properties, such as proteolytic activities, AA-converting enzymatic activities, ester synthesis, and autolysis. 

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