Pigments melanoidin

Kalavathi D.E, Uma L., Subramanian G. Degradation and metabolization of the pigment-melanoidin in a distillery effluent by the marine cyanobacterium Oscillatoria boryana DBU 92181. Enzyme and Microbial Technology, 2001 29(4-5) 246-251. 

The importance of Strecker degradation is mainly in the formation of reactive and often sensory active aldehydes and ammonia (free or bound in reactive a-amino carbonyl compounds). Strecker aldehydes, together with a-amino carbonyl compounds, contribute significantly to the formation of many heterocyclic compounds (which are important flavour-active components of processed foods) and the brown pigments melanoidins. Aldoses simultaneously produce the corresponding 2-deoxyaldoses or 1-amino-1-deoxyalditols and 2-oxoacids. 

The initial products of the reactions between sugars and proteins may enter a cascade of reactions yielding fluorescence, browning, and polymerization of proteins ("cross-linking"). The brown pigments, so-called melanoidins, are polymers whose composition has not yet been established completely. Melanoidins bind calcium and may thus interfere with de- and remineralization in caries. 

The pigments of soy sauce, first studied by Kurono and Katsume (100), are melanoidins, which were reported by Omata, et al. (101) to be produced from the reaction of sugars and amino acids. Kato, e a l. (102) found 3-deoxyglucosone as an intermediate in browning of soy sauce (cf. 103). Oxidative browning (104,105) was again reviewed (44) with emphasis on the browning of Amadori compounds and interaction between melanoidins and iron. 

Lipid oxidation products react with proteins and other amino compounds to form brown substances, similar to melanoidins. The formation of such brown substances was reviewed already at the first Maillard Symposium.150 The pigments formed are partly soluble in chloroform-methanol and partly insoluble, whereas true melanoidins are largely water-soluble. As most brown pigments of fish muscle are soluble in benzene-methanol and only to a lesser extent in water, the implication is that here oxidised lipid-protein interactions are more important than Maillard browning due to ribose-amino acid interactions. 

Blue-Mi is the name given to a pigment isolated from D-xylose-glycine.75 It was identified as the pyrrolopyrrolium compound 30 and assumed to be a dimer of the yellow pyrrolopyrrole-2-carboxaldehyde.186 It is capable of polymerising further to melanoidins and, similar to melanoidins, it has strong antioxidant activity. There is evidence of another pigment, Blue-M2, with molecular mass (MM) = 0.942 kDa. 

The most elementary, nontechnical method of identifying a polysaccharide is to burn it, observe the yellow-to-brown color, and sniff the perfumelike aroma that should be reminiscent of the aroma of maple syrup, if the test is positive. If the caramelized residue is shaken with egg white and a visible reaction produces an insoluble, pigmented deposit (melanoidin), it is empirical proof that the sample was a polysaccharide. 

Other possible theories of stream humic substance formation are the browning reactions (the black substances produced by the action of acids on sugars) (Haworth, 1971) and the melanoidin reaction (the dark pigments produced when glucose, alanine or ammonia, and phenolic substances react with one another) (Hoering, 1973 Filip et al., 1974 Ertel and Hedges, 1983). These theories are discussed in detail by Stevenson in Chapter 2 of this book. 

Melanoidins. Brown pigments produced in Maillard reactions. 

Hodge and Rist (44) have shown the role of the Amadori rearrangement in color formation following reaction between aldoses and amino acids. The reaction can eventually lead to the development of caramel-like flavors, melanoidin pigment,... 

Because fish lipids are highly unsaturated (see Chapter 13), their interaction products are dark brown. Melanoidins partially lose nitrogen by retro-aldolization, and the remaining pigments become increasingly soluble in the lipidic phase (Pokomy et al., 1990). They form stains on the surface of white fish muscle, which... 

There have been a number of reports on the Maillard reaction. Oxidation of the melanoidins produced from D-glucose and glycine with potassium permanganate and peracetic acid yielded, among other products, furan-2,5-dicarboxylic acid, suggesting that 5-hydroxymethyl-2-furaldehyde is a precursor of the melanoidic pigments produced in the Maillard reaction. 2-(2-Formyl-5-hydroxymethyl-... 

The scavenging activity of various kinds of Amadori compounds, model melanoidins, glycated protein and its hydrolysate was investigated. However, it is necessary to elucidate the scavenging activity of brown pigments from food-stuffs since the chemical... 

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