Study Of Changes And Regulation Of Aroma Compounds In Roasted Coffee Based On Electrominc Nose And GC-MS

Coffee was widely accepted by consumers because of characteristic flavor. High temperature roasting process was beneficial to obtain good flavor, but a series of pyrolytic reactions between carbonyl compounds and amino compounds reduce nutritional value. People need to seek a method to keep high quality and nutrition of coffee. The purpose of this study enhance flavor and nutrition of coffee after roasted. We selected sulfur-containing amino acids (Cys and Met), aromatic amino acids (Trp, Tyr and Phe) and aliphatic amino acid (Ala, Val and Leu) as the exogenous amino acids, and reducing sugars (glucose,fructose and xylose) as exogenous reducing sugar,respectively.We investigated physical and chemical character of coffee, including acidity, browning degree, degradation rate of amino acid, aroma phenotype and aroma components.The relationship between roasting process and coffee aroma was studied. It is confusion that response value of electronic nose sensors own to time gradient mode which is unfavorable for the quality control of coffee. With the increase of the temperature, the response value of sensors and the level of 4-ethylguaiacol slight increase.The volatile components of coffee contained phenols, ketone, furfural, pyrazine, pyrrole,imidazole at 160?.Amino acids significantly (p?0.05) enhance the acidity and browning degree of coffee, which lead to change the reaction mechanism of coffee inside. The optimization of sensors included W1W, W2W, W1S, W5S, W2S, W1C and W5C. The result shows that Cys, Trp, Leu is best on the improvement of coffee aroma. Besides, the aroma profiles is higher than 70 because of exogenous amino acids. Cys-treatment enhance the accumulation of ethylbenzene, 2, 5-dimethylpyrazine, 1-octen-3-ol, 3-phenylfuran and N,N-diethylaniline. Trp-treatments were considered to generate quinoline and pyrrole,Leu-treatments main affect the level of aldehyde.Reducing sugar significantly (p<0.05) increased the acidity of the coffee. Besides,glucose effectively enhanced the degree of browning and the effect is better than that of fructose and xylose. The optimization of sensors included W1W, W2W, W1S, W5S, W2S,W1C and W5C in reduce sugar-trearmrnts, meanwhile, the recognized power is maximizing. The glucose is advantageous to increase the part of alkanes, alcohols,aldehydes, olefine aldehyde, ketones content.The glucose and amino acid of composite liquid have a combined effect on coffee.This result showed that the aroma was obviously different when the ratio of glucose and amino acid is 1:2. They change the phenotype of aroma by their respective characteristic aroma in coffee.