Amadori-Heyns compounds

As illustrated in O Scheme 65, 33 reacts with an amine to give an imine 326 that isomerizes into an aminoketose 327 (Amadori product), existing as an equilibrium mixture of cyclic hemi-acetals, whereas 40 affords, by way of 328, the hexosamine derivatives 329 and 330 (Heyns products), also in cyclic form The Amadori-He)ms compounds index Amadori-Heyns com-pounds % are at the head of the complex sequences of the Maillard reaction. The crystal structure of the Amadori product 331 between 33 and glycine has been determined more than three decades after the first proposal of its structure. Alternative preparations and X-ray analyses of Heyns products 332 and 333 have been reported [273,274]. 

As indicated previously, primary and secondary amines can also react with carbonyl compounds to form a mixture of compounds containing small molecules and polymers. The small molecule compounds obtained from an aldose and an amine have the common name Amadori products because the Amadori rearrangement is involved in their formation. The compounds generated from ketoses and amines are known as Heyns products (although the differentiation Amadori/Heyns is not always considered). The mechanism for the reaction of primary amines with a reducing sugar can be formulated as follows ... 

The origin of meat flavor has been shown to arise from the combination of two primary sources. The first is the tissue fat, both extracellular and intracellular, which produces carbonyl and other lipid and lipid-oxidation products. The fat component of meat flavor is viewed as being responsible for the species specific flavor in meat (9). The second major component of meat flavor is the lean portion. The proteins, peptides, and amino acids of the lean, add not only to the muscle food s general meaty flavor, but also undergo Maillard reactions with sugars to produce Amadori and Heyns compounds having meat flavor characteristics. 

Amadori compounds with different amino acid residues have been detected in many heated and stored foods, e. g., in dried fruit and vegetables, milk products, cocoa beans or soy sauce. Amadori compounds are also found in the blood serum, especially of patients suffering from Diabetes mel-litus. As secondary amino acids, Amadori and Heyns compounds can be analytically detected by amino acid analysis (cf. protein section). 

As in the case of the deoxyosones, the concentrations of Amadori and Heyns compounds vary, depending on the reaction conditions (pH value, temperature, time, type and concentration of the educts). As a result, there is a change in the product spectrum and, consequently, in the color, taste, odor, and other properties of the food in each case. 

Wong MW (2003) Quantum-Chemical Calculations of Sulfur-Rich Compounds. 231 1-29 Wrodnigg TM, Eder B (2001) The Amadori and Heyns Rearrangements Landmarks in the History of Carbohydrate Chemistry or Unrecognized Synthetic Opportunities 215 115-175 Wyttenbach T, Bowers MT (2003) Gas-Phase Confirmations The Ion Mobility/Ion Chromatography Method. 225 201-226... 

The first group contains compounds produced in the early stages of the reaction by the breakdown of the Amadori or Heynes intermediates, and includes similar compounds to those found in the caramelisation of sugars. Many of these compounds possess aromas that could contribute to food flavour, but they are also important intermediates for other compounds. The second group comprises simple aldehydes, hydrogen sulphide or amino compounds that result from the Strecker degradation occurring between amino acids and dicarbonyl compounds. 

Only recently have N -nitroso Amadori compounds been characterized chemically. The first description of an -nltroso derivative of an Amadori compound reported the formation of 1-deoxy-l-(N -nitroso-3,4-xylidino)-D-f ructose to confirm that a secondary amino group had been formed in an Amadori compound ( 6). Coughlin et al. ( 7) and Heyns et al. ( 8) described the formation of nitrosated Amadori compounds. Since Amadori compounds are weakly basic secondary amines and occur widely in Maillard browned foods and beverages ( 5) and unburned tobacco ( ), the genotoxic potential of these compounds is of interest. 

Heyns and Stumme260 have provided further evidence as to the widespread occurrence of this type of rearrangement for compounds in which the a-hy-droxy carbonyl group is either terminal or non-terminal, and a detailed electronic mechanism for this rearrangement has been put forward.264 Confirmatory evidence for the formation of products of the Amadori type... 

Quantitatively, the major path of degradation of the Amadori or Heyns Intermediate 1s a dehydration reaction which yields furfural and hydroxymethylfurfural. Of greater flavor significance are the minor pathways which can result in both aromatic products as well as reactive Intermediates. These Intermediates can undergo a retro-aldollzatlon reaction to produce alpha dicarbonyl compounds, such as pyruvaldehyde and diacetyl as well as reactive monocarbonyls, such as glycolaldehyde and glyceraldehyde. 

Thermal degradation of Amadori and Heyns rearrangement compounds. 

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