Optimization of Maillard reaction products isolated from sugar-amino acid model system and their antioxidant activity

The functional properties of soluble melanoidins from a single combination of monosaccharides (fructose or glucose) and amino acid model systems were evaluated. The selected amino acids, commonly found in apple juice and highly reactive in the Maillard reaction, were asparagine (Asn), aspartic acid (Asp) and glutamic acid (Glu). The response surface methodology (RSM) was applied to determine the optimum conditions to maximize the yield (g of obtained melanoidin) from the Maillard reaction. The effect of these conditions on the colour intensity and the absorbance of melanoidins was measured at different wavelengths (280, 325, 405 nm). Browning at 420 nm, colour and antioxidant activity were also determined. The optimum reaction conditions to maximize melanoidin production were glucose/Asn 95 degrees C for 109.7 h at 0.77 (g.kg(-1)) amino acid concentration. Antioxidant activities were evaluated through the free radical scavenging activity including 1, 1-diphenyl-2-picryl-hydrazil (DPPH) and 2, 20-azinobis (3-ethylbenothiazoline-6-sulfonic acid), diammonium salt (ABTS). The results showed that the absorbance and browning intensity of the glucose/amino acid were higher than those formed from the fructose/amino acid mixture. On the other hand, the fructose/amino acid model MRPs showed higher DPPH and ABTS radical scavenging activities than the glucose/amino acid model system.