FLAVOR DEFECT REFERENCE-STANDARDS FOR BUTTER AND CHEDDAR CHEESE

Reference standards for five commercially important butter and cheddar cheese flavour defects were developed to represent slight, medium, and intensely perceived flavour intensities corresponding to Canada 1, 2, and 3 grade as judged by federal dairy inspectors. Flavour defects were produced as follows: oxidized by exposing milk to 200 Lux at 5-degrees-C for 1, 3, and 24 h; sour by adding 0.08, 0.16, and 0.24% (w/v) lactic acid; bitter by adding an equal part mixture of L-isoleucine/L-leucine at 0.4, 0.6, and 0.8% (w/v); rancid by adding 0.2% (w/v) lipase and incubating the milk at 35-degrees-C for 20, 60, and 90 min; and fruity by adding a mixture of esters and alcohols. In addition, the oxidized, sour, and bitter flavours were produced at 6 different levels and evaluated for flavour intensity by a trained panel. The perceived intensities increased with increasing treatment level and were stable over a four day period at 5-degrees-C.