Isolation of Bitter and Astringent Fractions from Cheddar Cheese

Abstract

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. Freeze- dried 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 con- tained mostly lipids and was not bitter. After removing methanol by vacuum evap- oration, the upper aqueous methanolic phase yielded a nonbitter white precipitate and a clear aqueous solution that was ex- tremely 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 gel- filtration and by migration upon high- voltage paper electrophoresis. This is the first description of astringency in cheese.