Ultrasound-assisted extraction of white açaí (Euterpe oleracea Mart.): fatty acids profile, antioxidant and functional characterization

Abstract

Açaí ( Euterpe oleracea ) is widely recognized as a “superfruit” due to its nutritional, functional and antioxidant compounds. Previous studies have predominantly focused on purple açaí fruit variety. In this context, the aim of this research was to obtain an ethanolic ultrasound-assisted extract from the pulp of white açaí. To this, a factorial experimental design with three factors, 2 levels and one central point, and a response surface methodology were used. The extracts were characterized by physicochemical analysis regarding their oxidation state, fatty acid profile by gas chromatography (GC), color by the CIELab system, infrared spectroscopy (FTIR), thermal degradation by thermogravimetric analysis (TGA), total phenolics and antioxidant properties through DPPH, ORAC and Folin-Ciocalteu reagent assays. Results showed that the theoretically optimized condition was the experimental run 7 [50% amplitude, 20 min in sonicator and 60 min in ultrasound bath] with 49.1% of extraction yield. This extract also exhibited relevant antioxidant properties, with ~ 546 µg of gallic acid equivalent 100 mL − 1 by Folin-Ciocalteu reagent, ~ 3234.47 µmol Trolox Equivalent 100mL − 1 by DPPH and ~ 742 µmol Trolox Equivalent 100mL − 1 by ORAC assays. The spectroscopic patterns show bands related to the presence of long-chain unsaturated fatty acids, which agrees with the fatty acids profile by GC, leading to good indices of atherogenicity, thrombogenicity and hypocholesterolemic/hypercholesterolemic ratio. These results indicate the efficiency of using a green extraction method for obtaining an improved and functional fruit extract with potential for diverse applications.