GREEN EXTRACTS FROM BRAZIL NUT CAKE PRESS USING TERPENES AND THEIR ANTIOXIDANT POTENTIAL IN COSMETIC EMULSIONS

The oil extraction of Brazil nuts yields a residual semi-defatted cake rich in lipid bioactives, such as tocopherols and fatty acids. Its recovery can be achieved using eco-friendly solvents, including eutectic bio-solvents and terpene compounds. The objective of this study was to incorporate these extracted antioxidants into dermatological creams and evaluate whether their antioxidant activity is preserved in the final product. Initially, six biosolvents were formulated from specific mixtures of terpene compounds: linalool combined with DL-mentol (S1), L-carvone (S2), or β-caryophyllene (S3); and orange essential oil combined with DL-mentol (S4), L-carvone (S5), or β-caryophyllene (S6). The recovered extracts had their oil content qualified and their antioxidant capacity evaluated. Based on the lowest IC₅₀ values and statistical differences, the three best-performing extracts were selected for the cream formulations, S2, S5, and S6. The topical creams were developed in an 8.5:85.5 (O:W) ratio using commercial emulsifiers (cetearyl alcohol, cetearyl olivate and sorbitan olivate), adapted from Pegorin Brasil et al. (2022). The extract was incorporated at varying concentrations (0.5% to 5.0%) as a substitute within the oil phase. For each extract, four formulations and one extract-free control were prepared following the hot emulsification method: the oily phase was slowly poured over the aqueous phase under constant stirring using an Ultra-Turrax at 8000 rpm for 5 minutes. Subsequently, the system was kept under gentle stirring in an ice bath until cooled to room temperature. The antioxidant capacity of the solvents, pure extracts and formulated creams was evaluated using the DPPH free radical scavenging assay to determine their percentual reduction and IC₅₀ values (adapted from Valavanidis et al., 2004; Espín et al., 2000). Both pure extracts and creams exhibited effective free radical scavenging capacity. However, pure extracts presented statistically lower IC₅₀ values (higher antioxidant potential) than the emulsions. In the cosmetic emulsions, antioxidant activity exhibited an atypical behavior as a function of extract concentration. Increasing the active load to 5.0% elevated the IC₅₀ values across all series. This phenomenon probably results from the preferential partitioning of bioactives and biosolvents into the hydrophobic core of the inner phase, which restricts the proton/electron transfer rate at the oil-water interface (CHENG et al., 2022). In conclusion, these findings demonstrate the potential of terpenic solvents for extraction of antioxidant compounds from Brazil nut press cake, the great antioxidant potential of the extracts produced and the role of the emulsified matrix on the accessibility of the bioactives, boosting results for valorization of this residual product rich in lipid bioactives.

Acknowledgments: The authors thank the FAPESP (2025/18326-7) for the financial support and COOPAVAM (Juruena,MT) for the materials.