Maillard fructoselysine

The extent of heat-induced changes in protein-rich foods can be measured by determining some early Maillard reaction products (O Brien and Morrissey, 1989). Acid treatment of protein-bound or free A -fructoselysine liberates lysine, with a yield of 50%, and two other amino acids, furosine (20%) and pyridosine (10%) (Figure 13.1). The three products that result from hydrolysis of A -lactuloselysine are formed in the proportions of approximately 5 3 to 4 1 to 2, however the yield of different derivatives is variable. Therefore, in order to use these unique amino acids as indicators of changes in lysine content, the hydrolysis should be carried out in strictly-defined conditions. Furosine is present in various food products in a very wide range of concentrations (Table 13.2). 

Erbersdobler, H. F., von Wangenheim, B., Hanichen, T. Adverse effects of Maillard products — especially of fructoselysine in the organism. Paper presented at XI Intemat. Congress of Nutrition, Rio de Janeiro, Brazil, Aug. 1978. 

S. T. Seifert, R. Krause, K. Gloe, and T. Henle, Metal eomplexation by the peptide-bound Maillard reaetion products Y -fructoselysine and iV -carboxy-methyllysine, J. Agric. Food Chem., 52 (2004) 2347-2350. 

The first main intermediates formed during the Maillard reaction in the most common food items are the Amadori compounds with the fructoselysine moiety (fructoselysine, lactuloselysine or maltuloselysine) which are degraded during the acid hydrolysis of the protein, necessaiy for amino acid analysis. However they can be estimated by analyzing for furosine which is formed during hydrolysis with strong HCL (Fig. 1). 

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