Drying of aloe vera puree using hot air in combination with far-infrared radiation and high-voltage electric field: Drying kinetics, energy consumption and product quality evaluation

- Novel drying system combining FIR and HVEF was proposed and applied to aloe vera.
- HVEF exhibited dominant effect on drying kinetics only at lower air velocity.
- Application of HVEF reduced specific energy consumption at lower air velocity.
- FIR, HVEF and temperatures affected drying kinetics and product quality.

In this work, aloe vera puree was subject to hot air drying with/without the application of far-infrared radiation (FIR) and high-voltage electric field (HVEF). The puree was dried at various air velocities (0.2, 0.6 and 1 m/s), drying air and controlled surface temperatures (50, 60 and 70 °C) as well as high-voltage electric field strengths (0, 1.88 and 3.75 kV/cm). Comparative evaluation of the drying kinetics, specific energy consumption (SEC) and quality (in terms of color, aloin, total polysaccharides and acemannan contents as well as microbial counts) of the products undergone different drying processes was made. Electric field strength had a significant effect on the drying kinetics, SEC and quality of the dried product. On the other hand, HVEF exhibited a dominant effect on the drying kinetics only at a lower air velocity (0.2 m/s). Application of HVEF could significantly reduce the SEC of the drying process at an air velocity of 0.2 m/s. The optimum condition for aloe vera puree drying using hot air in combination with FIR and HVEF was the use of an air velocity of 0.2 m/s, temperature of 70 °C and high-voltage electric field strength of 3.75 kV/cm.