Effect of Silk Fibroin as a Sustainable Solvent on the Extraction of Bixin from Annatto Seeds (Bixa orellana L.)

Bixin, an apocarotenoid from Bixa orellana seeds, is a valuable natural pigment with industrial and pharmacological applications. Traditional extraction methods rely on organic solvents, but eco-friendly alternatives like silk fibroin solution (SFS) are emerging. This study evaluated SFS for bixin extraction from annatto seeds, optimizing conditions using Box-Behnken Design (BBD). The optimal parameters 1.5% SFS, 60 °C, and 60 min yielded 10.87 mg/mL (liquid extract of annatto seeds, LEAS + SFS) and 150.72 mg/g (solid extract of annatto seeds, SEAS + SFS). Cell viability was assessed in human dermal fibroblasts (HDFn) and RAW 264.7 murine macrophages via MTT assay. After 24 and 72 h, LEAS + SFS, SEAS + SFS, purified bixin (PB), and SFS maintained >70% viability in HDFn cells. Similarly, RAW 264.7 cells showed >70% viability after 24 h, indicating low cytotoxicity. These results highlight the biocompatibility of SFS-extracted bixin, supporting its potential in food, cosmetics, and biomedicine. The study demonstrates that SFS is an effective, sustainable alternative to traditional solvents, offering high extraction efficiency and minimal toxicity. This method aligns with green chemistry principles, providing a promising solution for bixin production.