Low-temperature vacuum drying as novel process to improve papaya (Vasconcellea pubescens) nutritional-functional properties

A novel dryer operating at low temperatures under vacuum conditions was used to study the drying kinetics and resulting physical and nutritional-functional properties of papaya (Vasconcellea pubescens). Drying experiments were carried out at 10, 20, 30 and 40°C and constant vacuum (1 kPa). Proximate composition, dietary fiber content, color and non-enzymatic browning changes were determined. The drying time of the fruit was significantly influenced by the temperatures. After drying, proximate and dietary fiber compositions slightly varied in value. Dried samples were brighter and exhibited low Maillard potential. The retention percentages of dried samples at different drying temperature with respect to the fresh sample ranged from 71.8 to 131.3 % for total phenolic content (TPC), 73.7 to 137 % for β- carotene content, 76.1 to 85.5 % for vitamin C content and 48.7 to 86.9 %, for total flavonoids content (TFC). Antioxidant properties of papaya decreased significantly after drying. Overall, this study demonstrated that low temperature vacuum drying (LTVD) improved the retention of dried papaya bioactive compounds. However, the combination of this drying technique with other techniques is suggested to improve drying rate.