This work concerns the degradation of the nutritional compounds glucoraphanin (GR) and vitamin C
(Vc), and the inactivation of the enzyme myrosinase (MYR) in broccoli (Brassica oleracea var. italica)
during drying with air temperatures in the range of 30e60 C. Dynamic optimization is applied to find
the optimized temperature trajectories that minimize degradation and inactivation. Simulation and
experimental results for optimized temperature trajectories are compared to constant inlet air temperature
drying at 40 and 50 C. The results show that with the optimized temperature trajectories the
retention of GR, MYR and Vc improved significantly. Moreover, the experiments show that degradation
and inactivation during drying is slower than expected from kinetic studies. The deviation is explained
from the difference in the physical state of the samples used in the drying experiments, i.e. original plant
tissue versus the grounded state of the plant tissue used in the experiments for the kinetic studies. The
results indicate that besides temperature and moisture content the physical state is also an important
aspect in the degradation of nutritional compounds and enzymes