Rice phytochemicals concentrated by molecular distillation process and their use as co-surfactant in water dispersion

This study investigated the effects of evaporating temperature during molecular distillation (MD) process employed to deodorizer distillate (DD) on the retention of rice phytochemicals in the unevaporated fraction (UMDs), which were then further used as co-surfactants in the fabrication of water-dispersible vesicles. The pilot-scale MD unit was operated at 120, 140 or 160 °C and 0.1 Pa to concentrate rice phytosterols from 1540.8 mg in 100 g DD to 3990.2-4904.8 mg in 100 g UMDs by evaporating out free fatty acids. Although γ-oryzanol content was increased from 598.9 mg in 100 g DD to 870.0-1018.1 mg in 100 g UMDs when the temperature was raised to 160 °C, such high temperature decreased tocols from 2185.7 mg in 100 g DD to 850.5 mg in 100 g UMDs and antioxidant capacity of UMDs measured as 2,2-diphenyl-1-picrylhydrazyl scavenging capacity. The UMD obtained after distillation at 140 °C was used as co-surfactant with soy lecithin, sucrose palmitate or polyoxyethylene sorbitan monooleate (Tween 80) to fabricate vesicles in pH 7.0 phosphate buffered saline (PBS). This study showed potential use of the UMD as a source of rice phytochemicals and a co-surfactant when used with Tween80 in small vesicle fabrication. The fabricated Tween 80/UMD vesicles in PBS had the size range of 200-300 nm and were stable within a temperature range of 4 to 37 °C for 96 h.