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.