Valuing Brazilian Woods: Isotopic Traceability and Antioxidant Profile of Grappa Aged in Putumuju and Ipê Chips

Aging alcoholic beverages enhances their quality, and when done using wood chips instead of barrels, offers the advantage of being considered more sustainable, economical, and enabling faster interaction with the beverage. However, the most commonly Brazilian used native tree species are at risk of extinction, which requires an urgent search for alternatives. In this context, woods such as Ipê (Handroanthus ap.), providing notes of tannins and nuts to spirits; and Putumuju (Centrolobium tomentosum), adding floral notes and sweetness; are gaining prominence, although little research has been conducted regarding the migration of antioxidant compounds, or the possibility of determining aging time using the stable isotope method. Since stable carbon isotope analyses (δ¹³C) do not allow for distinguishing between compounds present in grappa from those present in woods, the beverages were analyzed using hydrogen (δ²H) and oxygen (δ¹⁸O) isotopes. In this regard, with the aim of exploring new technological possibilities that encompass sustainability and the value-added use of Brazilian wood species that are not threatened with extinction, this study evaluated the use of Ipê (toasted and untoasted) and Putumuju (toasted and untoasted) chips in the aging of grappa (0, 60, 120, and 180 days) in terms of antioxidant content (DPPH• and total phenolic compounds—mg EAG/mL of sample), color (L*, a*, b*), and isotopic signatures (δ²H and δ¹⁸O). Aging, in the conditions of this study, increased beverage antioxidant content by up to 66.28 times when Putumuju was used and by 16.79 when using Ipê. During the first 60 aging days, all wood species resulted increased δ²H and δ¹⁸O isotopic signatures, indicating migration of compounds from the wood into the beverage. Between 60 and 180 days, however, most samples exhibited decrease in both signatures, suggesting compounds degradation or polymerization. Lower Isotopic signatures as a function of wood toasting were consistent with the results regarding DPPH and antioxidant content, which were 1.56 and 2.54 times lower in beverages aged in toasted Putumuju wood compared to un-toasted wood (aged for 60 days), and 1.29 and 1.12 times lower when Ipê wood was used, respectively. All types of wood affected sample coloration, tending toward an increase in greenish (-a) and yellowish (+b) hues; the effect being most pronounced in un-toasted woods, corroborating compounds migration. The lightness (L) remained constant (until 60 days), decreasing over the last 180 days, suggesting compound polymerization explaining the drop in the isotopic signal. Aging time, wood chip variety, and whether or not the chips were toasted affected the beverage’s antioxidant content and final color, and influenced δ¹⁸O and δ²H isotope signals. Our thanks to Vinícola Casagrande and Havana Dornas for Grappa and wood chips donation and to Cnpq for the scholarship support.