NONENZYMATIC BROWNING BEHAVIOR, AS RELATED TO GLASS-TRANSITION, OF A FOOD MODEL AT CHILLING TEMPERATURES

A food model composed of maltodextrin, lysine, and xylose was developed to study nonenzymatic browning at low temperatures (5, 10, and 20 degrees C) around the glass transition temperature (T-g) region of the matrix. The extent of nonenzymatic browning at various T - T-g conditions was followed spectrophotometrically at 420 nm. Nonenzymatic browning occurred at low temperatures and intermediate water contents, showing an increasing rate with increasing water content. The rate of the reaction at each water content increased with increasing temperature. The rate was extremely low below T-g, probably because of limited diffusion. The browning reaction in a suitable matrix can be used to indicate the time-temperature history of chilled foods.