Optimization of the recovery of high-value compounds from pitaya fruit by-products using microwave-assisted extraction

A green microwave-assisted extraction of high value-added compounds from exotic fruits' peels was optimized by Box-Behnken design using 3 factors: solid/solvent ratio, X-1, temperature, X-2, and extraction time, X-3. By using Derringer's desirability function, optimum extraction yields are obtained with X-1 = 1/149.95 g/mL, X-2 = 72.27 degrees C and X-3 = 39.39 min (white-fleshed red pitaya) and X-1 =1/148.96 g/mL, X-2 = 72.56 degrees C and X-3 = 5.02 min (yellow pitaya) and a maximum betacyanin content is achieved with X-1= 1/150 g/mL, X-2 = 49.33 degrees C and X-3 = 5 min. None of the factors influenced the extraction of phenolic compounds. Eighteen cinnamoyl derivatives, 17 flavonoid derivatives and 4 betacyanins were identified by HPLC-DAD-ESI/MSn, 23 and 15 new compounds being described in yellow and white-fleshed red pitayas, respectively. These results indicate that it is possible to reuse these by-products to recover compounds for food and pharmaceutical industries. (C) 2017 Elsevier Ltd. All rights reserved.