CHARACTERIZATION AND SELECTION OF NATURAL DEEP EUTECTIC SOLVENTS FOR THE EXTRACTION OF BIOACTIVE COMPOUNDS FROM CAMU CAMU (Myrciaria dubia) DEPULPING RESIDUES THROUGH MULTIVARIATE ANALYSIS AND A MULTICRITERIA APPROACH

Camu camu (Myrciaria dubia) depulping residues—comprising seeds, peels, and residual pulp—account for over 56% of total fruit mass and are fully discarded despite being remarkably richer in vitamin C, proanthocyanidins, and phenolic antioxidants than the commercial pulp itself. Natural deep eutectic solvents (NADES) represent a promising green, non-volatile, and biocompatible alternative for bioactive recovery. In a first stage, seven NADES formulations were synthesized using various combinations and molar ratios of hydrogen bond acceptors (choline chloride, sodium acetate, ammonium acetate) and donors (glycerol, lactic acid, malic acid, urea), incorporating 20% water to reduce system viscosity. Physicochemical characterization revealed broad operational ranges in pH (0.16–9.24), electrical conductivity (4.07–20.67 mS/cm), refractive index (1.419–1.473), density (1.0976–1.2342 g/cm³), and dynamic viscosity (0.050–0.217 Pa·s). Statistical correlation analysis demonstrated that lower viscosity (Spearman ρ = −0.929, p < 0.01) and lower density (Spearman ρ = −0.713, p < 0.05) significantly enhanced total phenolic content (TPC) recovery by minimizing diffusional resistance. For multicriteria selection, extractions with water and methanol 70%,  were included alongside the NADES formulations. Criteria weights were obtained from variable loadings across the first two principal components, weighted by the proportion of variance explained by each component, and subsequently normalized to sum to one. These weights were incorporated into TOPSIS to rank the extraction alternatives using TPC, DPPH, and ABTS as benefit criteria. The Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA), employed as exploratory multivariate methods, identified patterns of similarity and differentiation among systems, highlighting the association between NADES1 and NADES5. Within this cluster, respective values for NADES1 and NADES5 were: TPC 77.31 and 79.72 mg GAE/ d.w.; DPPH 436.68 and 555.32 µmol TE/g d.w.; and ABTS 576.18 and 430.69 µmol TE/g  d.w. The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) established the ranking of the nine extraction alternatives by simultaneously considering TPC, DPPH, and ABTS. NADES1 exhibited the highest closeness coefficient to the ideal solution" (Ci=0.819), followed by NADES5 (Ci=0.797), 70% methanol (Ci=0.773). Benchmarked against water, NADES1 extracted 2.45-fold more TPC, 1.82-fold more DPPH, and 2.77-fold more ABTS, while surpassing 70% methanol by 1.17-fold in TPC and 1.15-fold in ABTS. Replacing toxic, volatile organic solvents with biocompatible NADES eliminates chemical hazards for direct food applications. The superior performance of NADES1 stems from its balanced physical properties and supramolecular hydrogen-bonding network, demonstrating the potential of this food-grade solvent to convert Amazonian agro-industrial waste into high-value functional ingredients.

Acknowledgments

This work was supported by the Vice-Rectorate for Research of the Universidad Nacional Agraria La Molina (UNALM) through the XVIII Call for Undergraduate Thesis Financial Grants (UNALM – 2025).