Heat Induced Browning of Clarified Apple Juice at High Temperatures

A procedure to determine deterioration reaction kinetics of fluid foods at elevated temperatures is described. With this method the nonenzymatic browning (NEB) measured as O.D. at 420 nm of Red Delicious (RD) and Granny Smith (GS) apple juices was examined. Color development at 15°, 30°, 50°, and 70° Brix and temperatures ranging from 90–108°C were compared over 60 min. Results indicated an apparent first order reaction rate depending on temperature, apple juice composition and soluble solids. Browning occurred at a more rapid rate in GS juice. NEB reaction rate was shown to depend critically on the total amino acid content. Temperature dependence followed the Arrenhius equation and the activation energy (E a ) ranged from 22.0–24.8 Kcal/mole.