Effect of air-drying temperature on extractable and non-extractable phenolics and antioxidant capacity of lime wastes

The lime industry is generating more waste due to the increasing demand of juice. In this study, extractable and non-extractable phenolics in the Gallega lime waste, dried at different temperatures were determined and their antioxidant capacities were evaluated using DPPH (2,2-diphenyl-picrylhydrazyl), ARTS (2,2'-azino-bis(3-ethylbenzothiazoline-6/sulphonic acid) and, ORAC (oxygen radical absorbance capacity) methods. The amount of non-extractable phenolics measured in lime waste dried at 60, 90, and 120 degrees C were 38.4%, 39.2%, and 33.5%, respectively higher, compared to the amount of extractable phenolics. Dried lime waste is rich in extractable and non-extractable hesperidin (213.87 and 181.32 mg/g, respectively), and eriocitrin (55.22 and 97.24 mg/g, respectively) and non-extractable gallic acid (42.45 mu g/g,). The antioxidant capacities of extractable and non-extractable phenolics were from highest to lowest: ABTS > ORAC > DPPH and ABTS >DPPH > ORAC, respectively. The information reported here may encourage lime industry operators to re-evaluate their by-products, extending the application of lime fruits and reducing waste. (C) 2016 Elsevier B.V. All rights reserved.