The development of an activated carbon from cherry stones and its use in the removal of ochratoxin A from red wine

The ability of activated carbon (AC) prepared from cherry stones (CS) by activation with H3PO4, ZnCl2 or KOH to remove ochratoxin A (OTA) from two Italian red wines has been studied. AC was characterized in terms of texture and surface chemistry. OTA was analyzed by reversed-phase high-performance liquid chromatrography, using a fluorescence detector. The content of OTA in the starting wines is 7.38 and 2.36 μg/L. The adsorption of OTA is high only for one AC, which was prepared by KOH activation at 900 °C, using the 3:1 KOH:CS impregnation ratio. It possesses a large apparent surface area (SBET = 1620 m2/g) and a high volume of large size macropores (1.84 cm3/g). It also contains narrow mesopores and intermediate size and wide micropores. Its content of acidic oxygen surface groups is low, whereas the content of basic groups is high (2.62 meq/g). The treatment of the wines with such an AC results in a decrease of the initial OTA content of more than 50%. However, the changes produced in the total polyphenolic index, color intensity, and hue are small (i.e. ∼8%, ∼5.5% and ∼1.2%, respectively).