Combination Drying Processes : Influence factors on the drying behaviour of red bell pepper and assessment of the diffusional behaviour of water

Convective and microwave-vacuum drying are the two drying techniques which have been well implemented for the drying of foodstuffs since years. One interesting question is how the combination of those two drying techniques can help to improve the quality of dried foodstuffs. The combination of convective and microwave-vacuum drying was implemented with a new modular drying processor to dry red bell pepper and model food in such a way which could result in minimising the degradation of vitamin C. In three sets of combined processes, the products were convective dried up to 70 % (first set), 50 % or 40 % (second set) and 30 % (third set) of initial weight at first and followed by microwave-vacuum drying till 15 % w.b. moisture content. The determined convective drying curves were used to calculate the Fick's and self diffusion coefficients of those foodstuffs to get an overview of the diffusional behaviour of water. These analyses would help food manufacturers for implementing proper drying technique to preserve red bell pepper for different processing requirements. At the same time model food could be used for proper evaluation of the degradation kinetics of vitamin C during drying.