Studying On The Effect Of The Key Factors On Model Maillard Reaction In Physiological Temperature

The Maillard reaction, that is the reaction of carbo-hydrates with amino acids or proteins, is a complex network of chemical reactions. It is one of the main sources which formed tobacco characteristic flavor. Because Maillard reaction products contains a large number of aromatic matters and most of the aromatic matters are coordination with tobacco flavor, so it can improve low-quality tobacco, reduce wooden miscellaneous gas and increase tobacco flavor effectively. Thus Maillard reaction has been thoroughly investigated. Research on this paper study the effect of solvent composition, metal ions and Vc on the Maillard reaction between D-glucose and amino acid (L-glutamic acid, L-phenylalanine, L-proline, L-lysine, L-aspartic acid or L-alanine). The purpose of this study is to provide theoretical reference for the control of the Maillard reaction in tobacco and food processing and storage process and the catalytic synthesis of Maillard reaction aroma compounds at low temperature. The results are as follows:1. Studies were conducted to investigate the effect of metal ions such as Fe²⁺, Cu²⁺, Zn²⁺, Mg²⁺ and K⁺ on model Maillard browning by analyzing the absorbance of Maillard reaction products (MRPs), between D-glucose and amino acid (L-glutamic acid, L-phenylalanine, L-proline, L-lysine, L-aspartic acid or L-alanine) with or without metal ions at 37℃, pH6.5 for 1-35 days, at 280nm and 420nm. The results showed that:â‘ Under the same conditions, the reactivity of L-lysine was 3～6 times greater than those from the other amino acids;â‘¡In addition to the low molecular aroma compounds in the model systems of glucose and glutamic acid, lysine and aspartic acid were inhibited in the presence of Zn²⁺, other metal ions presented different degree catalytic role to each model systems;â‘¢Browning tended to be accelerated in the presence of metal ions, especially Fe²⁺ and Cu²⁺, but browning between glucose and proline was inhibited by K+.2. The effects of Vc, Fe²⁺,"Fe²⁺+ascorbic acid (Vc)"and"Fe³⁺+ ascorbic acid (Vc)"on Maillard browning between D-glucose and each amino acid described above were also monitored. Browning tended to be accelerated in the presence of Vc, Fe²⁺,"Fe²⁺+ascorbic acid (Vc)"and"Fe³⁺+ascorbic acid (Vc)", especially"Fe³⁺+ascorbic acid (Vc)", although it was affected by the property of the amino acid either. The ether-soluble compounds of the reaction products, from glucose and phenylalanine as heated for 35 days, were isolated and identified by GC-MS. Only 4 compounds in a controlled system, but 13 compounds were identified in the model system which contained"Fe³⁺+ ascorbic acid (Vc)"and the major products were benzeneacetic acid (31.41%) and other esters, ketones, pyran glucosides etc.3. In order to further exploration of the effect of solvent composition on Maillard reaction and the influence of metal ions on Maillard reaction in the different solvent composition, the effects of metal ions (Fe²⁺ and Cu²⁺) and the water content in solvent on Maillard browning of phenylalanine and glucose were monitored. The results showed that the rate of the model Maillard reaction was inversely proportional to the water content: the reaction rate increased as the reducing of the water content. Browning tended to be accelerated in the presence of Fe²⁺ and Cu²⁺ and the reaction time was shorten effectively. Its catalysis increased first and then decreased with the increasing of the concentration of metal ions. The catalysis were strongest when the concentrations of Fe²⁺ and Cu²⁺ were 0.2mmol/L and the browning reaction was promoted somewhat faster in the presence of Cu²⁺ than of Fe²⁺.