Study On Antioxidative Activity Of Maillard Reaction Products From L-ascorbicacid/Amino Acid Model Systems

The Maillard reaction refers to non-enzymatic interaction between a reducing sugar, aldehydes or ketone and an amino acid, peptide, protein or any nitrogenous compound during storage, preparation, or processing of foods. The Maillard reaction products (MRPs) are considered natural antioxidant and have been widely investigated in food industry. L-ascorbic acid (ASA) is essential to the health of man and participated as key role in many different biological processes. It occurs naturally in most fruit juices and vegetables. The objective of this investigation was to study the method for determination of ASA in MRPs based on ASA-amino acid model systems. The relationship between of the antioxidative activity and progress of Maillard reaction were evaluated by UV-absorbance and browning intensity from MRPs. The antioxidative activity of MRPs and different molecular weight fractions from MRPs were evaluated by reducing power, DPPH radical-scavenging activity. The major content and results are as follows:1,To investigate the method for determination of ASA after Maillard reaction based on ASA-amino acid model system. A metaphosphoric acid (3%(w/v)) was found to be most suitable extraction solution. The content of ASA in MRPs was determined by second-order derivative spectrophotometry. The linear range of ASA was 1.00～12.00μg/mL. The standard addition rate of recovery was 96.50%～103.75%. The regression equation was C=6721.304A-0.0588, linear corelation coefficient was 0.9999. This method has the advantage of simplicity and little disturbance , is suitable for determination of content of ASA in Maillard reaction systems2,The objective of this investigation was to study the e ect of pH on antioxidative activity of MRPs from ASA-amino acid (L-lysine(Lys), L-methionine(Met) L-alanine(Ala), L-proline(Pro), L-arginine(Arg), L-cysteine(Cys)) model systems. The results indicated that UV-absorbance, browning intensity, reducing power and DPPH radical-scavenging activity from ASA-Lys/ Met/ Ala/ Pro reached a maximum with initial pH=5.0 UV-absorbance, browning intensity, reducing power and DPPH radical-scavenging activity from ASA-Arg/ Cys reached a maximum with initial pH=4.0. An increase in Fe2 + chelating activity of MRPs derived from ASA-amino acid model systems was observed as the initial pH increased. Moreover, reducing power of MRPs correlated well the UV-absorbance. The antioxidative activitives of MRPs from ASA-Met and ASA-Lys model systems are higher than other four model systems3,The objective of this investigation was to study the e ect of time on antioxidative activitives of MRPs from ASA-Lys/ Met model systems. The results indicated that UV-absorbance, browning intensity of all MRPs derived from ASA-Met/ Met model system sharply increased within the first 200 min and 120 min of heating, respectively Reducing power and DPPH radical-scavenging activitives of MRPs derived from ASA-Met/ Met model system reached a maximum at 200 min and 120min, respectively4,The objective of this investigation was to study the effect of ratios of the amount of the substance on antioxidative activity of MRPs from the ASA-Met/Lys model systems. The results indicated that UV-absorbance, browning intensity, reducing power and DPPH radical-scavenging activity of MRPs derived from ASA-Met/Lys model systems reached a maximum with the ratios of the amount of the substance (the ratios of the amount of the substance of Met/Lys to ASA) 1:5 and 1:3, respectively5,The objective of this investigation was to study the antioxidative activity of different molecular weight fractions of MRPs from the ASA-Lys/ Met model systems. MRPs were ultra ltrated to provide six fractions (0.5-1kDa, 1-3kDa, 3-5kDa, 5-10kDa, 10-30kDa, >30kDa). The antioxidative activity of different molecular weight MRPs from the ASA-Lys/ Met model systems were measured and compared with that of ASA. It was found that the >30kDa fractions from MRPs exhibited higher reducing power and DPPH radical-scavenging activity than those of other molecular weight fractions from MRPs. But the reducing power and DPPH radical-scavenging activity from all of six fractions were weaker than that of ASA. Results obtained from the rst fraction, analysed by Fourier transform infrared spectroscopy (FT-IR) indicated that the structure of six molecular weight fractions of MRPs from ASA-Met/ Lys possible include some functional groups such as C-O-C, C-OH-, -O-H, C-H, C-O, C=N, C=C, N-H, -OH, NH2C=O.This study helps better understanding the antioxidative activity of MRPs from ASA–amino acid model systems. It would provide references to find novel antioxidants and better utilization during storage, preparation, or processing of foods.