Ultrasound-Assisted Extraction of Polyphenols from Maritime Pine Residues with Deep Eutectic Solvents

Abstract

Deep eutectic solvents represent an important alternative in the field of green solvents due to their low volatility, non-toxicity, and low synthesis cost. In the present investigation, we propose the production of enriched polyphenolic extracts from maritime pine forest residues via an ultrasound-assisted approach. A Box–Behnken experimental design with a response surface methodology was used with six variables to be optimized: solid-to-solvent ratio, water percentage, temperature and time of extraction, amplitude, and catalyst concentration. The mixture of levulinic and formic acids achieved the highest extraction yield of polyphenols from pine needle and bark biomass. In addition, the solid-to-solvent ratio was found to be the only influential variable in the extraction (p-value: 0.0000). The optimal conditions were established as: 0.1 g of sample in 10 mL of LA:FA (70:30%, v/v) with 0% water and 0 M H2SO4 heated to 30 °C and extracted during 40 min with an ultrasound amplitude of 80% at 37 kHz. The bioactive properties of polyphenol-enriched extracts have been proven with significant antioxidant (45.90 ± 2.10 and 66.96 ± 2.75 mg Trolox equivalents/g dw) and antimicrobial activities. The possibility to recycle and reuse the solvent was also demonstrated; levulinic acid was successfully recovered from the extracts and reused in novel extractions on pine residues. This research shows an important alternative to obtaining polyphenol-enriched extracts from forest residues that are commonly discarded without any clear application, thus opening an important window toward the valorization of such residues.

On the Valorization of Arbutus unedo L. Pomace: Polyphenol Extraction and Development of Novel Functional Cookies

“…The appropriate volume of solvent, taking into account the percentage of methanol (%MeOH) and pH requirements, was added to the flask. Subsequently, the samples were placed in the temperature-controlled water bath and maintained at a fixed temperature for 15 min, with the ultrasonic frequency set at 50 Hz and power of 550 W. These parameters have been selected because they have been shown to be influential variables in the extraction of polyphenols with UAE in similar matrices in investigations previously carried out by our research group [21,25,27]. Following the extraction process, the obtained extracts were filtered using a Buchner funnel and a vacuum pump.…”

“…UAE has been extensively utilized in the extraction of phenolic compounds from various food sources, encompassing both primary products and by-products [18,19]. Notable examples include mushrooms [20], blackcurrants [21], potatoes [22], moringa leaves [23], onion bulbs [24], maritime pine residues [25], and even fresh A. unedo fruits [26]. Nevertheless, to the best of our knowledge, UAE has never been used in A. unedo pomaces.…”

Ultrasound assisted hot water extraction of polysaccharides from Taraxacum mongolicum: Optimization, purification, structure characterization, and antioxidant activity

“…Ultrasound assisted extraction (UAE) utilizes the cavitation, thermal, and mechanical effects generated by ultrasound to accelerate the rupture of plant cell walls, reduce the mass transfer resistance of polysaccharides, and thereby improve the yield of polysaccharides (Wang et al., 2023). Hence, UAE is widely used to extract active ingredients (polyphenol, saponin, and organic acid) from natural plant resources (Duarte et al., 2022; Gonzalez‐Silva et al., 2022; Yusoff et al., 2022). Ultrasound assisted hot water extraction (UAHWE) integrating UAE with HWE is a novel combination for extraction of different polysaccharides including some merits of UAE and HWE.…”

Ultrasound‐assisted deep eutectic solvent extraction of bioactive compounds from persimmon calyx

“…Ultrasonic waves accelerate the extraction process through the phenomenon of cavitation, which creates high-speed micro-jets that cause macromolecules to break down, causing erosion, sonoporation, and cell wall permeability, leading to better extraction of bioactive molecules from food matrices (Perera & Alzahrani, 2021). In the literature, there are many studies on the extraction of bioactive components with ultrasound-assisted DES (Alasalvar & Yildirim, 2021;Duarte et al, 2022;Kaltsa et al, 2020;Lanjekar et al, 2022;Wu et al, 2020).…”