Degradation of Amadori compounds

The degradation of Amadori compounds, important in the browning reaction occurring during food processing, has been studied with... 

Table 3.1 Degradation of Amadori compounds under acidic and neutral conditions...

J. Hirsch, V. V. Mossine, and M. S. Feather, Detection of some dicarbonyl intermediates arising from the degradation of Amadori compounds (the Maillard reaction), Carbohydr. Res., 1995, 273, 171-177. 

In the presence of oxygen, intermediate 10 can undergo oxidation and give rise to the formation of the aminoketo compound 11 and subsequently an acid, the so-called Strecker acid [36], The formation of Strecker acid, however, is not possible if dicarbonyls such as 4 are present in form of their stable cyclic hemiacetals, as shown by Hofmann and co-workers [36]. The same group revealed also that Strecker aldehydes can be formed via an oxidative degradation of Amadori compounds, as shown for the Amadori compound of phenylalanine and glucose [37],... 

T. Hofmann and P. Schieberle, Formation of aroma-active Strecker-aldehydes by a direct oxidative degradation of Amadori compounds, J. Agric. Food Ghent., 48 (2000) 4301-4305. 

R. Badoud, L. Fay, F. Hunston, and G. Pratz, Periodate oxidative degradation of Amadori compounds. Formation of V -carboxymethyllysine and... 

An example of a radical fragmentation reaction discussed in this volume is the metal ion catalyzed degradation of Amadori compounds. This reaction provides an alternate path to osones, which are key intermediates in the formation of nitrogen heterocycles via the Maillard reaction. 

Since these autoxidative degradation of Amadori compound with participation... 

BADOUD ET AL. Oxidative Degradation of Amadori Compounds Ratio Amino acidA aline (I.S.)... 

Table I shows that an increase of Amadori compounds occurs parallel with an increase of isovaleraldehyde formed by Strecker degradation of the amino acid leucine (18 ). It becomes evident from Table I that the flavor impression "burnt arises if certain concentrations of isovaleraldehyde are exceeded this flavor change is increased by increasing isovaleraldehyde concentrations. By this means an analytical control of undesirable sensory changes caused by the Maillard reaction in carrots is available.

Thermal degradation of Amadori and Heyns rearrangement compounds. 

Weygand and Bergmann investigated the oxidation of certain derivatives (known as Amadori products) of l-amino-l-deoxy-n-fructose. The oxidation of 1-deoxy-l-p-toluidino-n-fructose in 2 V ammonium hydroxide at 50° in the presence of a platinum-on-carbon catalyst led to the degradation of the compound to n-arabinonic acid, presumably according to the following sequence. 

In this report, some results of calculations made on a simple enaminol compound, 2-amino-3-hydroxy-2-butene are given first. Then the calculation results of the enaminol form of fructoseglycine as an example of the enaminol form of Amadori compound produced in the sugar-amine reaction are described. And last, the results of the calculation made on L-scorbamic acid which is produced by the Strecker degradation of dehydro-L-ascorbic acid (DHA) with an a-amino acid are given. 

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. 

The Amadori compound may be degraded via either of two pathways, depending on pH, to a variety of active alcohol, carbonyl and dicarbonyl compounds and ultimately to brown-coloured polymers called melanoidins (Figure 2.31). Many of the intermediates are (off-) flavoured. The dicarbonyls can react with amino acids via the Strecker degradation pathway (Figure 2.32) to yield another family of highly flavoured compounds. 

In former experiments (5) we have shown that chemical analysis for Amadori compounds (mainly consisting of fructose-glutamic acid) and isovaleralde-hyde, formed by Strecker degradation of the amino acids leucine and isoleucine, can be used for an early detection of undesirable quality changes caused by the Maillard reaction. In order to demonstrate the usefulness of these compounds as indicator substances for quality improvement of dried products, we performed drying experiments with carrots as an example of plant products. 

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. 

It appears that both JL, and 3 are produced as intermediates during the decomposition of an Amadori compound. There is little evidence, based on end product isolation that the 4-deoxyosone (2) is produced to any extent in these reactions. An early isolation of 1, by Anet (6), was accomplished by decomposing an Amadori compound ("difructose glycine") in aqueous solution. Subsequent studies have shown that Amadori compounds are easily converted to HMF in dilute acid solution as well. Furthermore, Kato s (8) published preparation of 3-deoxyosone, in which glucose is reacted with N-butyl amine almost certainly involves the intermediate formation of an Amadori compound and its decomposition in situ. Thus, it can be reasonably concluded that 3-deoxyosones are produced from Amadori compounds during their degradation. 

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