PREDICTION OF 5-HMF FORMATION IN AN INDUSTRIAL APPLE-JUICE EVAPORATOR

The rate of formation of 5-hydroxymethylfurfural (5-HMF) in apple juic e with soluble solids ranging from 15 to 69 degrees Brix at 100, 104, 108 or 112 degrees C was experimentally determined. Different mechanis ms of reaction were proposed and corresponding kinetic models were der ived. The model that provided the best fit to experimental data corres ponded to a first-order initiation step, followed by an autocatalytic period limited by consumption of reactants. The resulting kinetic equa tions were incorporated into the mathematical model of a triple-effect apple-juice evaporator. The simulation values obtained for the conten t of 5-HMF in the concentrated apple juice were in good agreement with observed industrial levels. From simulation runs 5-HMF generation was strongly related to the temperature level at the first evaporation ef fect.