Effect of microwave power coupled with hot air drying on process efficiency and physico-chemical properties of a new dietary fibre ingredient obtained from orange peel

•Time and energy consumption are reduced by coupling microwaves to hot air drying.•Chemical composition of citrus fibre is not affected by the drying treatment.•Coupling microwaves to hot air drying increases particle size of orange fibre.•Coupling microwaves to hot air drying improves swelling capacity of orange fibre.•The gradient of water chemical potential affects fibre rehydration properties.

Orange by-products are an excellent source of dietary fibre. The main objective of this work was to compare the physico-chemical and technological properties of fibres obtained from orange by-products by applying two different drying methods: hot air (HAD) and hot air coupled with microwave drying (HAD + MW). Process efficiency was also compared. 92% reduction in processing time and 77% reduction in energy consumption was achieved with HAD + MW. The drying treatment did not affect the physico-chemical properties of the fibres; however, the shrinkage-swelling phenomena that occurred during drying changed the rehydration properties of the fibre. HAD mainly affected the mechanical energy whereas HAD + MW affected the surface tension. An increase in particle size due to an increase in porosity during HAD + MW improved the fibre swelling capacity. HAD + MW can reduce drying time resulting in a more efficient drying process that positively affects the orange fibre's technological properties.