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 develope d to study nonenzymatic browning at low temperatures (5, 10, and 20 de grees C) around the glass transition temperature (T-g) region of the m atrix. The extent of nonenzymatic browning at various T - T-g conditio ns was followed spectrophotometrically at 420 nm. Nonenzymatic brownin g occurred at low temperatures and intermediate water contents, showin g an increasing rate with increasing water content. The rate of the re action at each water content increased with increasing temperature. Th e rate was extremely low below T-g, probably because of limited diffus ion. The browning reaction in a suitable matrix can be used to indicat e the time-temperature history of chilled foods.