Effect of different drying processes on functional properties of industrial lemon byproduct

The aim of this work was to investigate the effects of different drying processes on drying kinetics, physico-chemical properties and antioxidants of industrial lemon by-product. Lemon byproduct was submitted to infrared drying (50-75 °C), convective drying (50-75 °C), microwave drying (90-350 W) and combined air-microwave drying (90 W/50 °C; 90 W/75 °C). Lemon byproduct is rich in water (3.18 ± 0.12 g water/g d.b), but also in phenols (5.52 ± 0.08 g GAE/100 g d.b), with a radical scavenging activity of 8.381 ± 0.400 mg Trolox Equivalent/g of extract. The drying time of industrial lemon byproduct varies between 27 min (350 W) and 480 min (infrared drying at 50 °C). Combined-air microwave drying (590 W/75 °C) and convective air drying at 75 °C allow better retention of phenols and flavonoids (more than 60%). Infrared drying of lemon byproduct at 75 °C was in favour of maximal water and oil retention capacities and radical scavenging activity; whereas color preservation is achieved after microwave drying (90 W) and convective drying (50 °C).