University Institution Colegio Mayor de Antioquia, Medellín, Colombia
Anthocyanins have a high antioxidant activity. Purple yam (Dioscorea alata) is a common plant in tropical countries and could be a valuable source of these compounds. Ultrasonic assisted extraction (UAE) allows increase the extraction yield using reduced extraction times, low temperatures and solvents considered as safe. The aim of this study was to obtain ethanolic anthocyanin-rich extracts from lyophilized purple yams. The effect of temperature (30 and 60°C), extraction time (10 and 30 min), amplitude (20 and 60%) and ethanol:water ratio (80:20 and 50:50) were evaluated through a fractional factorial design. The global extraction yield (%) and the anthocyanin concentration (ppm) were determined. The economic evaluation was performed using the SuperPro Designer® software (v. 8.5). A two extractor system with capacities of 5, 50 and 500 l was considered. Global extraction yield varied from 14.9 and 22.6%. Anthocyanin concentrations between 5.1 and 16.9 ppm were obtained. The operation factors had a statistical significant effect over the global yield and anthocyanin concentration. The results indicate that the optimum extraction conditions are 60°C, 10 min, 60% amplitude and ethanol:water ratio 80:20. UAE required three and eighteen times less extraction time than low-pressure solvent extraction and Soxhlet extraction, respectively, to produce similar extraction yields. The cost of manufacture decreased from US$ 950,52 kg-1 to US$ 124,08 kg-1 when the extractor capacity increased from 5 l to 500 l. The results show that UAE is more efficient that the conventional techniques. UAE is a feasible technique for obtaining anthocyanin-rich extracts from purple yam.
J. Felipe Osorio-Tobón holds a BS degree in Agricultural Engineering (2004) and an MSc in Biotechnology (2008), both from National University of Colombia (2004), Colombia. He holds a PhD in Food Engineering from University of Campinas (2016). Nowadays, he is a professor in the University Institution Colegio Mayor de Antioquia (Medellín, Colombia). His research is related to the extraction of bioactive compounds using emerging technologies such as pressurized liquid extraction, supercritical fluid extraction and ultrasonic assisted extraction. Currently, he is working in the valorization plant species and crop by-products through the simulation and economical evaluation of novel extraction technologies.