Optimization of Oil and Tocopherol Extraction from Maqui (<i>Aristotelia chilensis</i> (Mol.) Stuntz) by Supercritical CO₂ Procedure

Abstract

This study focused on the oil extraction from freeze-dried maqui (Aristotelia chilensis) by supercritical fluid extraction with carbon dioxide (SFE-CO2). The basic objective was to optimize the oil yield and the tocopherol concentration. A Box/Behnken experimental design was developed with three processing variables: supercritical pressure (74, 187, and 300 bar), temperature (35, 48, and 60 °C), and extracting time (30, 135, and 240 min). Multiple optimizations, based on the combination of factor levels at 274 bar, 240 min, and 60 °C, led to the highest oil yield and tocopherol values. The validation of the optimized conditions of maqui oil extraction led to an oil yield of 8% and values of 735, 53, and 97 (mg·kg−1 oil) for α-tocopherol, α-tocotrienol, and γ-tocopherol, respectively. A higher concentration of tocopherol compounds was observed when compared to the employment of the conventional extracting method. The optimized SFE-CO2 method led to an oil extract exhibiting higher Hydrophilic-Oxygen Radical Absorbance Capacity (H-ORAC) assay and total phenol content (22 μmol Trolox equivalents·g−1 oil and 28 mg gallic acid equivalents·g−1 oil) than the oil obtained by the conventional procedure. A practical and accurate oil extraction is proposed for obtaining tocopherol-enriched oil including high concentrations of valuable lipophilic antioxidants.

Keywords

• freeze-dried maqui
• supercritical fluid extraction
• CO₂
• Response surface methodology (RSM) optimization
• oil yield
• tocopherols