Valorization of tamarind seeds using high-pressure extraction methods to obtain rich fractions in fatty acid and phenolic compounds

Abstract

Supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) were combined, in a biorefinery approach, to recover the nonpolar and polar fractions from tamarind seeds, which represent 25–40% of processed fruit. Total phenolic content (TPC), antioxidant capacity, and chemical composition were evaluated, and compared with values from Soxhlet (SOX) samples. The nonpolar lipid fraction, obtained by SFE with CO2, contains unsaturated and saturated fatty acids, similar to sample by SOX-hexane. The polar phenolic fraction, recovered by PLE-ethanol (60 °C / 10 MPa), presented high TPC (305.1 mg GAE·g-1) and antioxidant capacity, compared to SOX-ethanol sample. Combining SFE and PLE increased the TPC (421.8 mg GAE·g-1) and antioxidant capacity (2208.3–4412.5 µmol TEAC·g-1) of final extract. Chemical analysis confirmed high concentrations of organic acids and phenolic compounds (epicatechin, procyanidin and rutin) from ethanolic extracts. The biorefinery approach provides data for tamarind seeds fractionation, valuing this underestimated by-product by high-pressure methods.