Electrochemical determination of the antioxidant capacity of Brazilian woods as alternative materials for the aging of cachaça

Brazilian flora presents a vast biodiversity with great chemical and pharmacological potentialities. Particularly, the local industries of distilled spirits (cachaça) are actively searching for a type of wood that can substitute the oak in the aging process of those beverages. The great challenge is to find a wood with a phenolic content similar to oak and, at the same time, can furnish analogous sensorial characteristics to the final product. As a possible attempt, the antioxidant capacity of some local woods can be measured as a preliminary indicative of its phenolic composition. Therefore, the antioxidant capacity of four samples of Brazilian woods extracts, namely, cabreúva (Myrocarpus frondosus), cabreúvavermelha (Myroxylon balsamum), imbuia (Octea porosa) and pequi (Caryocar brasiliense), as well as, of the traditionally used oak (Quercus sp.) were determined using the recently developed CRAC (ceric reducing/antioxidant capacity) assay. The CRAC methodology uses chronoamperometric measurements to monitor the diminishing of the Ce4+ species concentration, using the Cottrell equation before and after four minutes of reaction between each antioxidant sample and the oxidant solution (Ce4+). Due to the high redox potential of the Ce4+/Ce3+ couple, this system allows measurements for the majority of the known antioxidant molecules using a boron-doped diamond film as the cathode. The experimental results are commonly expressed in terms of Trolox Equivalent (TE), a non-dimensional value of the relative antioxidant capacity. In the present study, the antioxidant hierarchy was determined as being: oak (1.73) > cabreúva-vermelha (1.05) > cabreúva (0.90) > imbuia (0.71) > pequi (0.31). These results show that among the analyzed woods, the cabreúva-vermelha stands out with an antioxidant capacity closer to the oak and might become a proper alternative after the necessary sensorial tests are carried out. They also show that the CRAC assay is a powerful tool in the determination of the antioxidant capacity of real samples.