Deep Eutectic Solvents as Sustainable Media for Efficient Recovery of Phenolics From Black ( Lycium ruthenicum Murr.) and Red ( Lycium barbarum Lam.) Goji Berries: Optimization and Functional Evaluation

Deep eutectic solvents (DESs) have been frequently preferred over the past decade as alternatives to conventional solvents for the extraction of bioactive compounds from natural products. Meanwhile, black and red goji berries are widely consumed as functional foods due to their many functional properties reported in the literature. The aim of this study is to evaluate the effectiveness of different DESs in the extraction of individual phenolic compounds from goji berry (Lycium barbarum and L. ruthenicum) fruits, to determine the most suitable DES, and to optimize the extraction conditions. The DES that provided the highest yield in the extraction of individual phenolic compounds from L. barbarum was determined to be proline:citric acid (DES6 - a total of approximately 33,545 µg/kg), while for L. ruthenicum it was choline chloride:acetic acid (DES3 - a total of approximately 37,496 µg/kg). Rutin was the predominant phenolic compound in both species. DESs provided a higher phenolic yield compared to ethanol and water. In addition, L. ruthenicum exhibited higher total phenolics, flavonoids, proanthocyanidins, and antioxidant activity compared to L. barbarum. These findings reveal that DESs are a green, efficient, and sustainable alternative for the extraction of phenolic compounds from goji berries.