Isolation of Bitter and Astringent Fractions from Cheddar Cheese

A simple, rapid, and reproducible method was developed for the isolation of bitter and astringent flavor components from Cheddar cheese. The isolated components were crude but highly concentrated. Freezedried cheese was extracted with 2:1 (v:v) chloroform-methanol. There was no bitter flavor in the residual cheese. The extract was then made biphasic with 0.2 volume of water. The lower chloroform layer contained mostly lipids and was not bitter. After removing methanol by vacuum evaporation, the upper aqueous methanolic phase yielded a nonbitter white precipitate and a clear aqueous solution that was extremely bitter and astringent. Bitter and astringent flavor components were further separated by isoelectric precipitation of astringent material at pH 6 to 7. The separation was complete as judged by taste, by elution characteristics during gelfiltration and by migration upon highvoltage paper electrophoresis. This is the first description of astringency in cheese.