Cysteine, reactions with sugars

The Middle Notes are based on reaction flavourings to impart specific complex roasted, meaty and smoky notes roasted chicken, boiled beef, smoked ham. They improve the overall taste with a general meaty background and a good mouthfeeling. Meaty middle notes are often based on the reaction of vitamin Bl, cystein and reducing sugars. Fat included in the reaction modifies the product into a specific animal direction chicken, beef, mutton, pork. 

In search for the key intermediates to meat flavor development in heated cysteine-sugar systems, it was found that in addition to thiazolidine derivatives also the tetrahydro-l,4-thiazine derivatives are being formed. These tetrahydro-l,4-thiazines, which are the cyclic form of Amadori compounds of cysteine, have excellent meat flavor precursor properties and are likely to play a prominent part in meat flavor development. Another major pathway to meat flavor development is the reaction of cysteine with the Amadori compounds of other amino acids. Model experiments showed that both pathways are probably of about equal importance for flavor development in boiled meat and process flavorings, this in spite of the low reactivity of cysteine with sugars. It seems that the first pathway is general-acid-catalyzed by the other amino acids, whereas the second pathway is inhibited by cysteine. 

Cysteine is an important precursor of meat flavor and is therefore often being used in precursor systems for the industrial production of meat process flavorings (1-4). Meat flavor development in these systems is usually based on the Maillard reaction of cysteine (and other amino acids) with sugars. Unfortunately, there are a few complications that prevent that high yields of volatile flavor compounds are obtained from these reactions. The first... 

Reactions of cysteine with sugars - general procedure... 

Numerous publications have been dedicated to the genesis of alkylthiazoles. A model reaction based on a mixture of cysteine/xylose/tributyrin was studied by Ledl and Severin (1973), who proposed the decarboxylation of cysteine into cysteamine (2-aminoethanethiol), followed by a condensation with sugar degradation products and a subsequent oxidation. Mulders (1973c) also proposed a model based on a system of cysteine/cystine/carbohydrates, with the formation of thiazolidines subsequently oxidized into thiazoles. The same pathway has been proposed by Flament (Firmenich, 1973), thiazolidines easily being formed by the reaction of cysteamine with aldehydes. Kato et al. (1973a) also found thiazoles in the volatile compounds produced by the reaction of L-cystine with carbonyl compounds. Similarly,... 

Chromophoric markers were afforded by the synthesis, through Bt technology, of azo dye-labeled terpenes, sugars, and steroids (2009S1708), and fluorescent detection of biological thiols such as L-cysteine, glutathione, and L-penicillamine was achieved by reaction with N-coumarin-3-carbonyl benzotriazoles (2011S1494). 

Sugar degradation products were determined as benzimidazole derivatives after reaction with o-phenylenediamine. More than 120 amino-acid specific Maillard products have been isolated and identified from the reaction of L-proline, hydixn roline, < teine and methionine with monosaccharides at 150° for 1-1.5 h, in connection with studies of thermally generated aromas. Proline derived components were important constituents of bread, malt and beer, and cysteine and methionine derived components were predominant in roasted coffee and meat flavours. The effects of temperature, pH, and the relative concentration of rhamnose and proline on the quantity of specific volatiles produced in the Maillard reaction of these substrates have been studied, and the data have been analysed 1 computer methodology. The glucosylated cyclopentenone (44) was one of the products of decomposition of the Amadori product 1-deoxy-l-piperidino-maltulose in warm water. ... 

A kinetic determination of 2-ketohexoses has been based on their reactions with the cysteine-sulphuric acid reagent sorbose gave a distinct absorption spectrum, whereas o-fructose, psicose, and tagatose were distinguished from each other by differences in the rate of increase of the absorbance at 412 nm. Procedures used in colorimetric ultramicroassays of reducing sugars, and... 

Reactions of sugars with amino acids, which have more reactive functional groups (such as sulfur, hydroxy, aromatic and heterocyclic amino acids), also bypass the Amadori rearrangement and the reaction gives rise to various heterocycHc compounds. For example, glucose yields a thiazolidine derivative, 2-(d-gluco-l,2,3,4,5-pentahydroxypentyl)thiazolidine-4-carboxyHc acid (4-213), with cysteine and a P-carboline derivative, 1,2,3,4-tetra hydro-1 - o-gluco-1,2,3,4,5-pentahydroxypentyl)-P-carboline (4-214), arises from tryptophan or tryptamine. 

The OV-17 phase has been found to give improved separation of the diastereoisomerlc pertrimethylsilylated methyl 2-(polyhydroxy-alkyl)thiazolidine-(ilR)-carboxylates formed from enantiomeric pairs of nine aldoses after reaction with L-cysteine methyl ester (c.f. Vol.20, p.2il8). Although each pair of sugar enantiomers gave separate peaks, those from different sugars, e.g., D-xylose and L-arabinose, sometimes co-eluted, ... 

The reaction of A-(2,2-dimcthyl 4-oxo-thictan-3-yl)-acetamide 26 with complex heterocyclic amines 27a-d, cyanoguanidine derivatives 27e-f, or a sugar derivative, namely 1-amino-1-deoxy-D-fructopyranose 27g, in various conditions resulted in cysteine amide derivatives 28a-g in satisfactory yields (Table 2) <2000BML1347, 2001T7173, 2001T825, 2002BMC2303>. 

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