Text Box: 9:50 AM Text Box: Microbiology Text Box: Developing methods for evaluating flavor compounds in Cheddar cheese. Text Box: Hao Hsun Chang and Dr. Harper Text Box: The flavor of Cheddar cheese has been an object research topic for almost 100 years, however, the chemical basis of the flavor remains incompletely understood. Preliminary researches suggested that more than 200 volatile compounds have been identified, including fatty acids, esters, alcohols, aldehydes, ketones, lactones, amines, phenols. Main objective is to identify chemical compounds in cheddar cheese with known functional groups which contribute to the overall flavor of Cheddar cheese. Both GC/MS and ChemSensor are applied to evaluate and analysis the flavor compound. 10 or 25 grams of aged Cheddar cheese were mixed with diethyl ether and centrifuged. The ethyl layers were pull out for further SAFE distillation and the distillate was evaporated to 100 ml. 1 or 2 ml of samples were injected onto GC/MS for analysis. For the ChemSensor approach, 1 to 3 grams of Cheddar cheese sample was directly put into vial and sealed with cap. Randomly placement of each sample vials and then analyzed by the ChemStation program of the ChemSensor. It is useful not only for a discriminating purpose, but also as a potential tool for flavor research. Both of GC/MS and ChemSensor can provide an understanding of chemical basis, also, as the most important, to be a simple and rapid analytical procedure for food aroma differentiation and identification.