Extraction of Anthocyanins and Total Phenolic Compounds from Açai (Euterpe oleracea Mart.) Using an Experimental Design Methodology. Part 2: Ultrasound-Assisted Extraction

Abstract

Two optimized methods for ultrasound-assisted extraction were evaluated for the extraction of two types of acai bioactive compounds: Total anthocyanins (TAs) and total phenolic compounds (TPCs). For the extraction optimization, a Box Behnken factorial design of different variables in the following intervals was used: Methanol-water (25%–75%) for solvent composition, temperatures between 10 and 70 °C, amplitude in the range between 30% and 70% of the maximum amplitude −200 W), extraction solvent pH (2–7), the ratio for sample-solvent (0.5 g:10 mL–0.5 g:20 mL), and cycle between 0.2 and 0.7 s. The extraction kinetics were studied using different periods between 5 and 30 min. TA and TPC were analyzed by UHPLC and the Folin–Ciocalteu method, respectively. Optimized conditions for TA were: 51% MeOH in water, 31 °C temperature, pH 6.38, cycle 0.7 s, 65% amplitude, and 0.5 g:10 mL of sample-solvent ratio. Optimized conditions for the TPC were: 49% MeOH in water, 41 °C temperature, pH 6.98, cycle 0.2 s, 30% amplitude, and 0.5 g:10 mL of sample-solvent ratio. Both methods presented a relative standard deviation below 5% in the precision study. The suitability of the methods was tested in real samples. It was confirmed that these methods are feasible for the extraction of the studied bioactive compounds from different açai matrices.

Anthocyanins: A Comprehensive Review of Their Chemical Properties and Health Effects on Cardiovascular and Neurodegenerative Diseases

“…Other good sources of anthocyanins include purple corn, cherries, plums, pomegranate, eggplant, wine, grapes, and red/purple vegetables such as black carrots, red cabbage and purple cauliflower which may contain from a few milligrams up to 200–300 mg/100 g of product [ 72 , 73 ]. More recently, anthocyanins have been identified in numerous berries whose production and consumption is steadily increasing, such as maqui [ 74 , 75 ], myrtle [ 76 , 77 ], and açai [ 78 , 79 , 80 ].…”

Optimization of Analytical Ultrasound-Assisted Methods for the Extraction of Total Phenolic Compounds and Anthocyanins from Sloes (Prunus spinosa L.)

“…To ensure the stability of the compounds of interest, the sloe samples were ground at a low temperature (4 • C) and short milling times were performed to avoid the rise in temperature of the sample. This pre-treatment, which significantly increases the contact surface between the fruit and the solvent, is usually employed in the research group because it enhances yields during the extraction process [17,23,24]. The homogenous samples obtained were stored in a freezer at −20 • C until further use.…”

“…Methanol is a solvent with very good extraction qualities for this type of compound, due to its small size (easy penetration capacity), low density and polarity similar to the polarity of the studied compounds, even more so if it is modulated with water. These properties make methanol an excellent solvent widely used to extract phenolic compounds and anthocyanins in multiple natural matrices [23][24][25][26][27]. The methanol (Fischer Scientific, Loughborough, United Kingdom) was HPLC grade.…”

Sustainable Processing of Floral Bio-Residues of Saffron (Crocus sativus L.) for Valuable Biorefinery Products

“…Water, organic solvents, and their combination are often used to extract phenolics and vitamin C [ 2 , 3 , 27 , 28 , 29 ]. Methanol is commonly chosen for phenolic compounds due to its similar polarity, small dimension, and low density [ 30 ]. In a previous work, Caser et al [ 15 ] compared conventional maceration with ultrasound assisted extraction (UAE) on fresh saffron tepals using water and different concentrations of methanol (20%, 50%, and 80%) as solvents.…”