Maillard reaction formaldehyde

Many other compounds have been identified as products of the sugar-amino acid reaction. Amongst these are 2,3-butanedione,195 formaldehyde,196 pyruvaldehyde,20,195, 247, 248 3-hydroxy-2-butanone,248 hydroxy-2-propanone,248 and acetaldehyde.73 Imidazoles,196, 249-251 especially 4(5)-methylimidazole, have also been isolated from the reaction under mild conditions, and could have been formed from a-hydroxy ketones or aldehydes plus amino compounds. Following the early identification247 of pyru-valdehyde as a product of the Maillard reaction, much work was done in an attempt to show that this reactive compound plays a major role in the reaction,249 262 254 but, that this is so is by no means certain.7... 

The furanic aldehydes 5-(hydroxy-methyl)furfural and 2-furaldehyde, systematically present in the toasted wood, can be formed by the thermal degradation of 3-deoxyosone during sugar pyrolysis or Maillard reactions (27). They could also be formed from glyceraldehyde, coming from degradation of DDMP, by condensation with subsequent elimination of water or formaldehyde (24). 

Modification of protein by reductive methylation of amino groups with formaldehyde/NaBH4 retards Maillard reactions. The resultant methyl derivative, depending on the degree of substitution, is less accessible to proteolysis (Fig. 1.47). Hence, its value from a nutritional/physiological point of view is under investigation. 

Formic acid is a common degradation product of sugars and also the oxidation product of formaldehyde. It is effective as a specific reagent for reductive amination of imminium ions to give secondary amines in the Maillard reaction. The reaction is known as a Wallach or Leuckart reaction (reactions of formates or formamide) R R N+=CH-R - - H-COOH R R N-CH -R + CO,. 

Several methods have been developed for assaying non-enzymatic glycosylation. As far as biological systems are concerned, these have been extensively reviewed by A. J. Furth in 1988 (5). They include both assays on intact proteins after chemical degradation and selective detection of e.g. 5-hydroxymethylfurfural (HMF) and formaldehyde using the thiobarbituric assay (TEA), and assays on protein hydrolysates with or without previous reduction of the protein-bound Amadori compound. In this last case, the analysis is based on the determination of furosine which is specifically formed from lysine Amadori compounds with a yield of approximately 30% (6). The furosine method, originally developed for milk (7), has been the subject of several analytical improvements both for food products (8) and biological materials (9). More recently, another method has been proposed to evaluate the extent of early Maillard reaction in milk products. This method is based on direct measurement of the Amadori product lactuloselysine which is released after complete enzymatic hydrolysis (10). 

J. A. Gerrard, P. K. Brown, and S. E. Fayle, Maillard crosslinking of food proteins I The reaction of glutaraldehyde, formaldehyde and glyceraldehyde with ribonuclease, Food Chem., 2002, 79, 343-349. 

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