REviving AgroFLOrestal RESidues: From Intermolecular Interactions in Natural Polyphenols to Novel Biomaterials of Added Value.

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Poly(butylene succinate)-based composites with technical and extracted lignins from wood residues

Publication . Melro, Elodie; Duarte, Hugo; Eivazi, Alireza; Costa, Carolina; Faleiro, Maria Leonor; Rosa Da Costa, Ana; Antunes, Filipe E.; Valente, Artur J. M.; Romano, Anabela; Norgren, Magnus; Medronho, Bruno

Poly(butylene succinate) (PBS) has been drawing attention as a reliable biodegradable and sustainable alternative to synthetic petroleum-based polymers. In this study, PBS-lignin composites were developed using a recently extracted lignin (LA-lignin) from pine wood residues employing an innovative sustainable approach. These composites were systematically compared with PBS-based composites formed with commonly used technical lignins. The molecular weight of the lignins was evaluated, along with various structural and performance-related properties. The LA-lignin/PBS composites display a remarkably low water solubility (ca. < 2%), water uptake (ca. 100 degrees). Moreover, the rigidity and thermal stability of the LA-lignin-PBS composites were higher than those of the systems formed with technical lignins. Although all composites studied present remarkable antioxidant features, the novel LA-lignin-PBS systems stand out in terms of antiadhesion activity against both Gram-positive and Gram-negative bacteria. Overall, the systematic analysis performed in this work regarding the impact of various lignins on the formed PBS composites enables a better understanding of the essential structural and compositional lignin features for achieving biobased materials with superior properties.

2024Journal article

Open Access

Sustainable extraction of polyphenols from vine shoots using deep eutectic solvents: influence of the solvent, vitis sp., and extraction technique

Publication . Duarte, Hugo; Aliaño-González, María José; Cantos-Villar, Emma; Faleiro, Leonor; Romano, Anabela; Medronho, Bruno

Vine shoots are the main by-products of grapevine pruning with no added value. In the present study, deep eutectic solvents (DESs) were used as alternatives to traditional chemical solvents, for the extraction of phyto chemicals from grapevine shoots. Three levulinic acid-based DESs were tested for the first time, and their per formance was compared to methanol (a standard chemical solvent) regarding the extraction of phenolic compounds from thirteen Vitis sp. shoots. Two extraction methods have been applied: ultrasound-assisted extraction and solid-liquid extraction. A total of eleven polyphenols which belongs to four families (proantho cyanins, stilbenes, hydroxycinnamic acids, and flavonols) have been identified and quantified in the extracts. The statistical analysis shows that the levulinic acid-based DES systems are novel and important alternatives to chemical solvents due to favourable eco-friendly properties and remarkable extraction performance of poly phenols. On the other hand, the ultrasound-assisted extraction technique has significantly increased the extraction rate in comparison to the solid-liquid extraction method with p-values lower than 0.05 for most compounds. The genetic factor has been shown to play an important role in the content of extracted polyphenols, being V. riparia pubescente the one that presented the highest concentrations of extracted polyphenols. Finally, the polyphenol-enriched extracts have proven important properties such as antioxidant activity and significant delay in bacteria growth against both gram-positive and gram-negative bacteria. It is important to note that, to the best of our knowledge, this is the first time that deep eutectic solvents have been used for the extraction of bioactive compounds from vine shoot residues.

2024Journal article

Restricted

Ultrasound-assisted extraction of Polyphenols from maritime pine residues with deep eutectic solvents

Publication . Duarte, Hugo; Gomes, Valentim; Aliaño-González, María José; Faleiro, Maria Leonor; Romano, Anabela; Medronho, Bruno

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 polyphenolenriched extracts from forest residues that are commonly discarded without any clear application, thus opening an important window toward the valorization of such residues.

2022-11-22Journal article

Open Access