Partition Studies of Resveratrol in Low-Impact ATPS for Food Supplementation

Antioxidant-rich food supplements can effectively address widespread nutritional deficiencies in the human diet and simultaneously reduce the concentration of reactive oxygen species (ROS) due to the free radical scavenging activity of antioxidants, minimizing inflammation and oxidative stress. Resveratrol (RVT) is a very important antioxidant which can be extracted from food industry byproducts such as grape skins, contributing to a more circular economy and reducing the environmental impact of the extraction processes. In this work, RVT was successfully extracted in the aqueous two-phase systems (ATPSs) {ethyl lactate (1) + Na₃Citrate or K₃Citrate or Na₂Succinate or NaKTartrate (2) + water (3)} at 298.15 K and 0.1 MPa, which provided biocompatible and sustainable extractive media. The studied ATPS yielded partition coefficients (K) above unity, indicating a preference for the top phase (rich in ethyl lactate), which hints at a successful extraction of this phenolic compound. Larger tie-lines generally resulted in larger partition coefficients (K) and larger extraction efficiencies (E), favoring solute migration to the top phase. The most promising partition coefficients (K = 40 ± 6 and 41 ± 9) and extraction efficiencies (E/% = 98 ± 1 and 95.0 ± 0.6) were obtained for the longest tie-lines (TLL = 77.66 and 70.73 m%) for {ethyl lactate (1) + K₃Citrate (2) + water (3)} and {ethyl lactate (1) + NaKTartrate (2) + water (3)}, respectively. Additionally, the effect of pH on the UV–vis absorbance spectrum of RVT was studied to minimize errors in solute quantification, resulting in low antioxidant mass losses (<5%).