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Pine Nutshells and Their Biochars as Sources of Chemicals, Fuels, Activated Carbons, and Electrode Materials

Publication . Şen, Ali Umut; Rodrigues, João F.G.; Almeida, Daiana; Fernandes, Ângela; Gonçalves, Margarida; Martins, Marta; Santos, Diogo M.F.; Pereira, Helena

Pine nutshells (PNSs) are lignocellulosic waste materials with limited use in domestic heating. However, a biorefinery approach may be applied to fractionate PNSs and produce chemicals, materials, and improved solid fuels. In this study, we fractionated PNSs and produced antioxidant extracts, lignins, polysaccharides, chars, and activated carbons and analyzed their potential applications. Pyrolytic kinetic modeling as an alternative method to chemical fractionation was also tested. The results showed that the PNS contains low amounts of extracts with weak thiobarbituric acid reactive substances (TBARS) antioxidant properties, while its lignin content is remarkable (50.5%). Pyrolytic kinetic modeling was comparable to wet chemical analysis for estimating lignin yield. Moderate-temperature pyrolysis of the PNS resulted in a 23% char yield. The PNS chars showed improved fuel characteristics, retained 36% water, and leached 151 mg/L potassium into the water. The steam activation of PNS biochars at 750 ◦C resulted in oxygen-enriched activated carbons with specific surface areas up to 467 m2/g. The overall results indicate promising biochar applications of the PNS for soil amendment and supercapacitor uses.

2024Journal article

Open access

How Does Domestic Cooking Affect the Biochemical Properties of Wild Edible Greens of the Asteraceae Family?

Publication . Liava, Vasiliki; Fernandes, Ângela; Reis, Filipa S.; Finimundy, Tiane C.; Mandim, Filipa; Pinela, José; Stojković, Dejan; Ferreira, Isabel C.F.R.; Barros, Lillian; Petropoulos, Spyridon Α.

Wild edible greens are a key ingredient of the so-called Mediterranean diet and they are commonly used in various local dishes in their raw or processed form. Domestic processing of edible greens may affect their nutritional value and chemical profile. In this work, six wild species (e.g., Cichorium spinosum L. (S1); Centaurea raphanina subsp. mixta (DC.) Runemark (S2); Picris echioides (L.) Holub (S3); Urospermum picroides (L.) Scop. ex. F.W. Schmidt (S4); Sonchus oleraceus L. (S5); and S. asper L. (S6)) were assessed for the effect of domestic processing (boiling) on chemical composition and bioactivities. Concerning the chemical composition, glucose, oxalic acid, α-tocopherol, and α-linolenic acid were the most abundant compounds, especially in P. echiodes leaves. After decoction, mainly sugars, tocopherols, and oxalic acid were decreased. The species and processing affected the phenolic compounds content and antioxidant, cytotoxicity, and anti-inflammatory activities. Specific compounds were not previously detected in the studied species, while hydroethanolic extracts contained a higher total phenolic compound content. Hydroethanolic and aqueous extracts were effective towards a range of bacterial and fungi strains. Therefore, the consumption of leaves has health-promoting properties owing to the bioactive compounds and can be integrated into healthy diets. However, domestic cooking may affect the chemical profile and bioactivities of the edible leaves, especially in the case of free sugars and phenolic compound content where a significant reduction was recorded in leaves after decoction. On the other hand, domestic processing could be beneficial since it reduces the oxalic acid content in edible leaves, which is considered an antinutritional factor.

2024Journal article

Open access

Biochemical Composition of Pumpkin Seeds and Seed By-Products

Publication . Polyzos, Nikolaos; Fernandes, Ângela; Calhelha, Ricardo C.; Petrović, Jovana; Soković, Marina; Ferreira, Isabel C.F.R.; Barros, Lillian; Petropoulos, Spyridon Α.

The goal of the current work was to assess the nutritional profile and phytochemical properties of cucurbit (Cucurbita maxima L.) seeds, seed oils and oil extraction by-products (e.g., seed-cakes). Our results suggest a high nutritional value for both cucurbit seeds and cucurbit cake, while γ-tocopherol was the richest compound, with traces of α, β and δ-tocopherol compounds also detected. Regarding the free sugars composition, there were recorded significant statistical differences between seeds and cucurbit seed-cake, although sucrose content was the highest for both matrices (1.97 and 2.9 g/100 g dw, respectively) followed by trehalose (0.26 and 0.25 g/100 g dw, respectively), fructose (0.20 and 0.34 g/100 g dw, respectively) and glucose (0.21 and 0.19 g/100 g dw, respectively). In terms of organic acids, oxalic was the only compound detected in seed cake (0.006 g/100 g dw), while in seeds only traces of oxalic and malic acid were detected. In relation to fatty acid composition, linolenic acid was the most abundant compound in both seeds and seed-cake (43.9% and 41.5%, respectively), while oleic acid (37.0% and 36.3%, respectively), palmitic acid (12.2% and 14.0%, respectively) and stearic acid (4.83% and 5.46%, respectively) were detected in lesser amounts. Moreover, polyunsaturated fatty acids (PUFA) were the major fatty acids class (44.5% and 42.3% in seeds and seed cake, respectively) compared to monounsaturated fatty acids (MUFA; 37.4% and 36.7% in seeds and seed cake, respectively) and saturated fatty acids (SFA; 18.1% and 21.0% in seeds and seed cake, respectively) which were detected in lower amounts. Furthermore, the tested extracts did not present any cytotoxic or hepatoxic activity at the maximum tested concentration (GI50 > 400 μg/mL), while seed oils presented satisfactory antimicrobial properties with inhibitory activity against the studied bacterial strains and fungi. Our findings provide valuable knowledge regarding the exploitation of pumpkin seeds and seed by-products as valuable natural sources of nutrients and phytochemicals in the food industry sector within the context of a circular economy.

2024Journal article

Open access

Phytochemical and bioactive potentials of African Annonaceae species

Publication . Rangel, Josefa; Liberal, Ângela; Catarino, Sílvia; Costa, José Carlos; Romeiras, Maria M.; Fernandes, Ângela

This review aims to gather available information on the medicinal, nutritional, and bioactive profiles of Annonaceae species in the African continent, sponsoring their use worldwide and mainly in African communities, where access to food and medicines for basic health care is scarce. >60 medicinal taxa were compiled, belonging to 22 genera, namely Annickia, Annona, Anonidium, Artabotrys, Cleistochlamys, Cleistopholis, Dennettia, Duguetia, Greenwayodendron, Hexalobus, Isolona, Lettowianthus, Monanthotaxis, Monodora, Neostenanthera, Polyceratocarpus, Sphaerocoryne, Uvaria, Uvariastrum, Uvariodendron, Uvariopsis and Xylopia; the most diverse and economically important genera were the genera Annona, Uvaria and Xylopia with 7 species each. Annonaceae species hold a valuable nutritional profile, rich in proteins, fibers, and minerals, being also good sources of a wide range of bioactive compounds of high biological relevance. These compounds are especially important in developing countries, where most of these species are available for direct use as food and/or medicines by the most deprived populations.

2024Journal article

Open access

Bioactivities of Waste Cork and Phloem Fractions of Quercus cerris Bark

Publication . Şen, Ali Umut; Almeida, Daiana; Silveira, Tayse Ferreira; Pires, Tânia C.S.P.; Añibarro-Ortega, Mikel; Mandim, Filipa; Barros, Lillian; Ferreira, Isabel C.F.R.; Pereira, Helena; Fernandes, Ângela

Recently, more and more researchers have begun to consider using waste bark fractions to produce value-added biochemicals and materials, as well as for energy production. Extraction is often the first operation in biomass biorefineries. Here we obtained hydroethanolic extracts from waste cork and phloem fractions of Quercus cerris bark and analyzed them to determine their antioxidant, antimicrobial, and nitric oxide (NO) production inhibition properties and their hepatotoxicity. The antioxidant properties were investigated by ex vivo TBARSs as well as OxHLIA antioxidant assays, the antibacterial properties against Gram-positive and Gram-negative bacteria isolated from food and clinical sources, and antifungal properties against Aspergillus brasiliensis and A. fumigatus. The NO production inhibition activity was assessed in a lipopolysaccharide (LPS)-stimulated murine macrophage (RAW 264.7) cell line, and antiproliferative activities were determined against five different cell lines, including lung (NCI-H460), gastric (AGS), breast (MCF7), and colon (CaCo2) tumor cell lines, as well as a non-tumor cell line (PLP2). The hydroethanolic maceration of waste cork and phloem yielded 4.4% and 2.4% extracts, respectively. Gallic acid glucosides, phenolic acids, and ellagic acid were identified in both extracts. The waste cork and phloem extracts showed antioxidant, antimicrobial, antifungal, and antiproliferative properties but also showed hepatotoxicity in the case of waste cork. Both bark fractions varied in terms of their bioactivity, with waste cork extracts showing, in general, higher bioactivity than phloem extracts.

2024Journal article

Open access