The effects of cutting and drying medium on the vitamin C content of rosehip during drying

Kinetics of ascorbic acid degradation during air-drying of whole rosehip has been investigated. Changes of vitamin C content during drying have been affected by drying time, drying air temperature and as well as moisture content. Vitamin C degradation rates for whole fruits during drying have been satisfactorily described by first-order kinetics. Temperature dependency of the model has been described also by Arrhenius relationship. Activation energy and reaction rate constant have been determined as a function of moisture content and described as E-a = 38600 + 100M and k(0) = exp(6.32 + 0.75M). In addition, rosehip has been pre-treated by cutting into pieces and drying experiments were conducted with air and with the atmospheres prepared with various ratios of air CO2 mixtures. Cutting of the rosehips before drying accelerated the drying process and increased the retention of vitamin C. The loss of vitamin C was increased depending on the rate of the oxygen in the air-CO2 mixtures used as a drying medium. (c) 2004 Elsevier Ltd. All rights reserved.