Melanoidin

As melanoidins (from gr μέλας "black" ) yellow -brown to almost black colored, nitrogen-containing organic compounds which are present in many prepared by heating foods such as coffee, bread and beer.

Production and reserves

The melanoidins are formed as by-products of browning reactions of amino acids and reducing sugars in the so-called Maillard reaction. The carbonyl group of the sugar reacts with the amino group of the amino acid or the protein molecule and there are nitrogen -substituted glycosylamines and water. High temperatures favor the formation of melanoidins, which (up to about 30%), bread are included ( here especially in the browned crust ) and beer in many foods such as coffee beans. These substances partially determine the sensory quality such as color, smell and taste of the food.

Properties and biological effects

All melanoidins are glycosylamines, that is, Condensation products of a monosaccharide and an amine. Relatively little is known about their exact structure and chemical structure, but new findings are constantly at various universities won. One of the few defined melanoidins is the Pronyl -lysine, whose structure was elucidated in 2002. The class of low molecular weight melanoidins consists of representatives with masses less than 1,000 daltons, derived from individual amino acids, and polymers with masses of about 100,000 daltons, which arise from proteins. The fabrics are usually intense light brown to black in color.

Currently are mainly discussions about the positive and negative effects of melanoidins in the center. One of the positive effects is their antioxidant effect dar. The Pronyl - lysine is even conceded to inhibit the development of cancer. Furthermore absorb melanoidines potentially hazardous substances from the diet, such as heavy metal ions or cholesterol. One of the negative impacts is the uptake of trace elements, which are thus removed from the organism.