Fluidized bed drying characteristics of moringa leaves and the effects of drying on macronutrients

Abstract

Moringa oleifera is an important source of nutrients and phytochemicals with beneficial bioactive properties. However, its availability must be improved through processing to transform it into storage-stable products. One of the most important processing steps is drying. The aims of this study were to investigate drying behaviour of moringa leaves under fluidized bed drying conditions and the effects of fluidized bed drying at 35, 45, 55, and 65 oC on nutritional contents of dried moringa leaves. The parameters measured were moisture contents during drying, crude protein, crude fat, crude fibre, ash, and carbohydrate. Results of chemical analysis revealed that the effects of drying on these nutrients can be significant. Moisture content of moringa leaves decreased linearly with time at the early stage of drying and became non-linear after the moisture content dropped to about 60-70% dry basis. Drying process occurred mostly in the constant rate period at low temperature and in the falling rate period at high temperature and drying behavior of moringa leaves can be best fitted using Page model. The effective moisture diffusivity during falling rate period were 4.86 x 10-13 m2/s at 35 oC, 5.70 x 10-13 m2/s at 45oC, 1.07 x 10-12 m2/s at 55oC, 1.44 x 10-12 m2/s at 65 oC.