Extraction and Analytical Characterization of Phenolic Compounds from Brazil Nut (Bertholletia excelsa) Skin Industrial by-Product
Wilson Valerio Vasquez-Rojas, Diego Martín Hernández, María Pilar Cano, Tiziana Fornari Reali
Abstract
Pressurized liquid extraction (PLE) and ultrasound assisted extraction (UAE) were applied to extract phenolic antioxidants from defatted Brazil nut skin (DBNS) industrial by-product. Water/alcohol solvents (ethanol and methanol) (0 - 50 % v/v water) were used at temperatures of 50 - 200 °C in PLE and 50 °C was set in UAE. The effect on extraction yield, total phenolic compounds content (TPC), antioxidant capacity and phenolic characterization was determined. The temperature and water/alcohol mixture affected the dielectric constant, and this in turn influenced the yield, TPC, antioxidant activity and phenolic composition. In PLE, at 200 °C and 50 % (v/v) water/alcohol (ethanol and methanol) the highest yields (33.8 and 38.4 %, respectively), TPC (4673 and 5435 mg GAE/100 g DBNS) and antioxidant capacity (397 and 502 µmol TE/g DBNS) were obtained. Furthermore, at 50 °C, PLE had better extraction efficiency than UAE. Characterization of the extracts indicated that at 50 - 100 °C the extraction of protocatechuic acid and ellagic acid derivative were predominant, while at 150 - 200 °C catechin and vanillin derivatives stand out. In general, hydroxybenzoic acids and flavonoids were the most abundant phenolics, and the addition of 25 % v/v water to ethanol resulted in extracts with their highest concentration. Then, Brazil nut skin is an interesting phenolic-rich source with potential use to produce bioactive ingredients. HIGHLIGHTS High temperature and water/alcohol mixtures improves TPC and antioxidant capacity At given temperature, TPC values are linearly correlated with water/alcohol dielectric constant Extraction temperature modifies the abundance and profile of phenolic compounds Hydroxybenzoic acids and flavanols are predominant phenolics in Brazil nut skins At 50 °C, PLE have a better extraction efficiency of phenolic compounds than UAE GRAPHICAL ABSTRACT