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

• We evaluated phenolics and antioxidant activity of dried lime waste.
• Temperature increased phenolics and antioxidant capacity.
• Dried lime wastes showed high fiber, flavonoid and phenolic acid levels.
• Information here might encourage less lime waste.

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), ABTS (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 °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 μg/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.