Abstract
Synthetic model systems of local orange juice were prepared in concentration 13% with different concentrations of sulfur dioxide ( (SO2) 0, 100, 200, 300, 400 ppm). Samples were stored at 20,30 and 405C for 4 months. Results showed that increasing the temperature and period storage caused decreasing in ascorbic acid content. Results of kinetic parameters of ascorbic acid degradation showed that the reaction order was first order and the values of reaction constant (K) decreased with increasing the SO2 but increased with increasing the temperatures. The activation energy (Ea) increased with increasing concentration of SO2 . The temperature coefficient (Q10) increased with increasing storage temperature. The shelf life of model systems increased with increasing the SO2 concentration and decreased with increasing the temperature. It was indicated that increasing the SO2 and decreasing the temperature caused to decreasing the degradation of ascorbic acid and increasing the shelf life of these juices.
