Infrared (IR), vibratory bed assisted infrared (VIR), vacuum infrared (VC-IR), and vibratory bed assisted vacuum infrared (VC-VIR) drying of Cissus quadrangularis Linn. (CQ) were conducted. The objective was to investigate the effects of vibration, vacuum, and material thickness on IR drying of CQ. VC-VIR drying of 5-mm CQ provided the highest maximum drying rate ( DR ) of 0.258 g water/g dry matter·min. Although the vacuum operation contributed to improved effective moisture diffusivity ( D eff ), it consumed high energy and degraded active compounds of CQ. VIR drying could be a more promising technique. VIR drying of 15-mm CQ produced the greatest total phenolic content (TPC) and quercetin content of 1083.62 mg GAE/100 g dry matter and 3.472 mg/100 g dry matter, respectively. The lowest total color difference (Δ E ) of 13.69 was also obtained. It required low specific energy consumption (SEC) of 17.62 kWh/kg and provided maximum DR of 0.112 g water/g dry matter·min.

Abstract. This study aimed to investigate the effect of drying temperature (40, 60, 80, and 100C) on drying characteristics of Cissus quadrangularis Linn. (CQ) undergoing convective drying. Physical properties and phytochemicals of the dried CQ were also evaluated. CQ with the thickness of 5 mm was dried from about 10 to 0.1 g water/g dry matter. The results showed that increasing drying temperature increased drying rate (DR) and effective moisture diffusivity (D eff ) and consequently decreased drying time. The drying time, maximum DR, and D eff were in the ranges of 85-1920 min, 0.0059-0.0248 g water/g dry mattermin, and 0.7302-9.1281×10 -9 m 2 /s, respectively. Lower drying temperature could preserve quality of the dried CQ. Decreasing drying temperature resulted in greener and lower bulk density and shrinkage. The greatest total phenolic content (TPC) and quercetin content were obtained by drying the CQ at 60C.