Mixtures glucose-amino acid browning

Figure 3. Browning intensity and mutagenicity of the glucose-amino acid mixtures on TA 100 as a function of time.

Browning of glucose and simple mixtures of amino acids did not produce authentic meaty aromas, but heating a synthetic mixture of all compounds identified in beef extract in the appropriate concentration, including alanine, glutamic acid, asparagine, taurine, carnosine, anserine, histidine, cystine, creatinine, hypoxanthine, lactic and succinic acid, produced a highly desirable meaty odor. 

The brown product or melanoidin which results from the Maillard reaction has been isolated from the products from various mixtures of reactants by numerous workers. A selection of these is given below. Maillard72, studied the interaction of D-glucose and other reducing sugars with glycine and several other amino acids at 34°, 40°, 100°, and 150°. 

To identify the natural precursors of this type of radical, several binary mixtures of mono-, di- and polysaccharides, amino acids and proteins have been thermally treated, brown colored melanoidins have been isolated by ultracentifiigation and then analyzed by EPR spectroscopy for paramagnetic behavior (Hofmann, unpublished results). In a heated mixture of bovine serum albumin (BSA), which was chosen as a model food protein, and glucose, an intense radical with a g-value of 2.0038 was detected in the melanoidins (15). The EPR signal of that radical, displayed in Figure 3, was identical widi diat detected in the coffee melanoidins (cf. Figure 2). 

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