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 Ea = 38600 + 100M and k0 = 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.