| The Maillard reaction is the most important for aroma compounds generation,which is used to thermal reaction flavor in flavor industry. The Maillard reactionrefers to non-enzymatic interaction between amino-compound (such as amino acid,peptide, protein, etc) and carbonyl compound (such as glucose, fructose, lactose,etc). L-Ascorbic acid participated as key role in many different biologicalprocesses, which is widely abounded with animals and plants. It is attracting moreand more attention as a new carbonyl compounds source. The Maillard reaction isvery complex which is affected by pH, time, temperature, molar ratio, and so on. Inthis thesis, based on L-ascorbic acid and glutathione model system, the effects ofreaction time, pH value, urea, molar ratio, moisture content were studied. The majorresearch contents and the results are as follows:1. The effects of reaction time on aroma compounds produced by heating amodel ASA-GSH model systems were investigated. The volatiles were identified tobe43different kinds. The results indicated that sulfur containing volatiles such asthiophenes, cyclic polysulfides, thiazoles, thiols and thienothiophenes were themajor aroma compounds formed in the reaction model system. Extraction quantityof thiophenes, pyrazines, sulfur alcohols, thienothiophenes and total volatilesgeneration increased gradually as reaction time prolonged, which reached amaximum at200min. In contrast, thiazoles have declined steadily.2. The effects of pH value on extraction quantity of aroma compoundsgeneration from a model ASA-GSH model systems were investigated. The resultsshowed furan compounds in a neutral partial to acid conditions to form. Neutralpartial to weak alkaline could promote to the production of pyrazines, thiophenes,thiazoles and thienothiophenes. A plausible explanation for the phenomenon isglutathione easier to degradation under the condition. Glutathione produced moremiddle product such as NH3, acetaldehyde, sulphur acetaldehyde and H2S, so as tohelp to produce pyrazines, thiophenes, thiazoles, thienothiophenes.3. The effects of urea on aroma compounds produced by heating a modeASA-GSH model systems were investigated. The volatiles were identified to be39different kinds. The addition of urea into the reaction mixture in general caused areduction in content of alicyclic S compounds. On the other hand, it facilitated thegeneration of several nitrogen-containing volatiles including methylpyrazine,2,6-Dimethylpyrazine and2-Ethyl-6-methylpyrazine. A plausible explanation for this phenomenon is that hydrogen sulfide and ammonia can be liberated fromglutathione and urea respectly upon heating. Ammonia competes with hydrogensulfide to react with Maillard reaction precursors, which resulted in the increasedformation of pyrazines and reduced formation of alicyclic S compounds.4. The influence of molar ratio on extraction quantity of aroma compoundsproduced by heating a mode ASA-GSH model systems was investigated. Forans andthiazoles significantly reduced with the decrease of glutathione’s moore ratio of totalreactants. This may be because they are mainly formed with the degradation ofglutathione. More and more pyrazines was produced with the increase of ascorbicacid mole ratio. A plausible explanation for the phenomenon is GSH degradationproducts contained excessive NH3while ascorbic acid degradation products isinsufficient. So ascorbic acid has a significant influence on the amount of pyrazines.5. The influence of moisture content on aroma compounds produced by heatinga mode ASA-GSH model systems was studied. The increase of the content of waterenhanced the generation amount of thiophenes, thiols, thienothiophenes, alicyclic Scompounds, and so on. A plausible explanation for the phenomenon is the water hasgood solubility of reactant, which promote the reaction, and glycerin sticknessinhibit the flow of reactants and reduce the reaction speed. Thiazoles generationamout reach a maximum value without water which is probably because they aremainly produced by the glutathione degradation of the heat.This paper accumulated relevant data to develop new flavor, which helped tocontrol and use the maillard reaction of the actual food production system, andoptimized the processing technology provides the theory reference and technicalsupport. |
