In vitro formation of Maillard reaction products during simulated digestion of meal-resembling systems.

The aim of the present research was to study the formation of Maillard reaction products (MRPs) during digestive process of meal-resembling systems. An average meal (protein, starch and oil) and sugar-containing meals (protein and glucose or fructose or high fructose corn syrup (HCFS)) were tested. Intestinal simple amino acid systems were also analyzed to gain insight into their contribution to the Maillard reaction (MR). Decrease of lysine (11.7-34%), arginine (24-35%) and other amino acids occurred after digestion of the meals. Fructosamine (42.6±4.7 and 332.9±10.4μg/ml) and fluorescent adducts (22,270±119.6 and 9283±188.3 RFU) were detected in digests of those meals containing HCFS and starch, respectively. Carboxymethyllysine (CML) (5.03±1.09μg/ml) and MGO-derivative AGEs (12.2±1.5μg/ml) were found in the meals composed of fructose and only MGO-derivative AGEs (12.2±1.6μg/ml) in presence of glucose. Physiological intestinal concentrations (43mM) of sugars in simplified systems composed by single amino acids caused formation of MRPs under digestive conditions. Arginine and fructose (314mM) showed formation of fructosamine and different AGEs. Fructose (43mM) gave rise to CML by interaction with lysine, which was observed within 1h of incubation at intestinal conditions. These conditions are possible in the intestine during fructose malabsorption. The results suggest the importance of using meal systems for better understanding of complex chemical events taking place during digestion such as MR. This is the first study proposing the formation of non-fluorescent AGEs associated to the pathogenesis of diabetes during digestion of sugar containing and average meals. This formation may be possible in conditions where sugar absorption is delayed such as fructose malabsorption or intake of a fatty meal. The occurrence of the MR during the digestion process may reduce the bioavailability of essential amino acids and increase the production of MRPs causing health disorders.