Percorrer por autor "Cordeiro, Ana"
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- Assessing the prebiotic potential of xylooligosaccharides produced by one-step fermentation using agro-residuePublication . Cordeiro, Ana; Fernandes, Andreia; Sousa, Joana; Cardoso, Beatriz; Alves, Joana; Silvério, Sara; Peres, António M.; Rodrigues, Lígia R.; Amorim, CláudiaA prebiotic is defined as a substrate that is selectively utilized by host microrganisms, conferring a health benefit
- Assessing the prebiotic potential of xylooligosaccharides produced by one-step fermentation using agro-residuesPublication . Cordeiro, Ana; Fernandes, Andreia; Sousa, Joana; Cardoso, Beatriz; Alves, Joana; Silvério, Sara; Peres, António M.; Rodrigues, Lígia R.; Amorim, CláudiaThe prebiotic effect is a fundamental concept in the fields of nutrition and gut health, referring to the beneficial effects of specific non-digestible dietary components on the gut microbiota, including xylooligosaccharides (XOS). These compounds function as food sources for beneficial gut bacteria, fostering their growth and activity. In this work, in vitro studies were performed to evaluate the prebiotic potential of XOS produced from olive stones (OS) and coffee silver skin (CSS) via a one step fermentation using a recombinant Bacillus subtilis 3610 harbouring the xylanase gene xyn2 from Trichoderma reesei. This potential was compared with a commercially available prebiotic oligofructose (Orafti®, BENEO, Germany). A mixture of human faeces from four healthy donors aged between 24 and 28 years old was used as inoculum. The pH variation and the production of short-chain fatty acids (SCFAs), gases, and ammonia were analysed during the 48 hours fermentations. The prebiotic supplementation resulted in a reduction of the pH value over time, with oligofructose presenting the most significant pH drop at 48 hours (ΔpH=3.65). The addition of prebiotics also significantly increased the production of beneficial SCFAs, with oligofrutose exhibiting a notable increase in the production of lactic and acetic acid production after 48 hours (28.0±0.1 and 28±1 mM, respectively), while OS-XOS and CSS-XOS demonstrated a more prominent rise towards the production of acetic acid (14.8±0.4 and 20.4±0.1 mM, respectively), butyric acid (2.5±0.3 and 3.29±0.04 mM, respectively), and valeric acid (75±1 and 110±14 mM, respectively) at 48 hours. Remarkably, the gas analysis revealed that the addition of OS/CSS-XOS fully suppressed the production of CH4 and increased the CO2 generation after 48 hours (2.6±0.7 and 5.20±0.05 mmol.L-1medium, respectively). These findings strongly suggest that the XOS produced from OS and CSS holds potential prebiotic properties for human health.
- Coffee silverskin fermentation in a single step for sustainable production of carbohydrate-based mixture rich in pectic oligosaccharidesPublication . Cordeiro, Ana; Fernandes, Andreia; Ferreira, Andreia S.; Coelho, Elisabete; Coimbra, Manuel A.; Peres, António M.; Rodrigues, Lígia R.; Amorim, CláudiaA competitive single-step fermentation using Bacillus subtilis 3610 was developed to convert coffee silverskin (CSS) into an oligosaccharide-rich carbohydrate mixture, mainly composed by pectic oligosaccharides (POS). CSS is an abundant by-product of the coffee industry, and POS are widely reported as emerging prebiotics, motivating sustainable production processes from agro-industrial by-products. In this study, OS were produced using CSS and CSS-derived pellets (CP) via a single-step fermentation leveraging the native pectinolytic activity of B. subtilis 3610. CP consistently outperformed CSS, achieving higher yields of reducing sugars at the optimal time (YRSₘₐₓ). After optimisation, a YRSₘₐₓ of 162 ± 7 mg·g⁻¹ was obtained at 8 h, 45°C and pH 7.0, with 10 g·L⁻¹ CP. The combined hydrolysis of CP with commercial xylanase and pectinase led to a synergetic activity potentially occurring during fermentation, where xylanase may disrupt cell walls to release pectin, while pectinase hydrolyses it into POS. Under optimal conditions, single-step fermentation achieved a significantly higher YRSmax than the combined enzymatic hydrolysis (141 ± 6 mg·g⁻¹ at 12 h, 1 U·mL−1 per enzyme). In aerated 3.2 L bioreactors, CP fermentation showed comparable performance to shaken-flask assays (YRSₘₐₓ 162 ± 2 vs. 162 ± 7 mg·g⁻¹; Pₘₐₓ 9.3 ± 0.1 vs. 9 ± 1 mg·g−1·h−1, respectively). The carbohydrate-based mixture obtained at optimal time contained a higher content of POS (uronic acids 78.8%mol) with a neutral xyloglucan-derived fraction. This study reinforces single-step fermentation as a simplified and competitive process for carbohydrate-based mixtures that avoid enzyme purchase. © 2026 The Author(s). Published by Elsevier Ltd on behalf of Institution of Chemical Engineers.
- Different approaches to Olive Pomace valorisationPublication . Cordeiro, Ana; Lamas, Sandra; Rodrigues, Ana; Cadavez, Vasco; Silvério, Sara; Peres, António M.; Rodrigues, Lígia R.; Amorim, CláudiaOlive pomace (OP) is a substantial by-product, rich in lignocellulosic materials and water, obtained following the extraction of olive oil. It comprises the following components: olive skins, pulp, seeds, and stones. As global olive oil production continues to rise, the management and utilisation of OP have become increasingly important from both an economic and an environmental perspective [1]. In this study, the OP was chemically characterized and its potential as a source of value-added compounds was evaluated. For this purpose, several extraction studies were preformed, namely lipid extraction using petroleum ether, phenolic compound extraction with ethanol, and free sugar extraction with water using a Soxhlet system (Figure 1). These extractions allowed to recover 11.1 ± 0.3 % (w/w) of lipids, different types of phenolic compounds and oligosaccharides. Phenolic compounds are widely recognized for their health-promoting properties (e.g. antioxidant, anti-inflammatory, cancer prevention or antimicrobial activity) and have been the subject of extensive research. Oligosaccharides (OS) are short chains of monosaccharide units linked by glycosidic bonds. The ingestion of these compounds has been demonstrated to confer a multitude of salutary effects, predominantly due to their function as prebiotics and their capacity to regulate gut health and influence overall metabolic processes. Enzymatic hydrolysis was also performed using commercial xylanase from Trichoderma reesei, under optimal conditions (pH 4.5, 40°C, 150 rpm) to evaluate the potential of OP to produce xylo-based oligosaccharides [2]. The hydrolysis process was monitored through Thin Layer Chromatography (TLC), High-Performance Liquid Chromatography (HPLC) using different columns, and the Dinitrosalicylic acid (DNS) method (Figure 2). The results indicated the production of xylo-based oligosaccharides, validating the proposed bioprocess as a viable method for XOS production from OP. This approach not only provides value-added to OP but also aligns with sustainable waste management practices.
- Olive oil by-products as potential alternative substrates for xylooligosaccharides productionPublication . Cordeiro, Ana; Fernandes, Andreia; Peres, António M.; Rodrigues, Lígia R.; Amorim, CláudiaOlive pomace (OP) and olive stones (OS) are industrial by-products from the olive oil production. These residues have a high percentage of cellulose, hemicellulose, and lignin, which makes them a good source of fermentable sugars and xylan, as well as a potential alternative substrate for xylooligosaccharides (XOS) production. In this work, OP and OS were chemically characterized and used for the first time as a xylan source to produce XOS through direct fermentation by Bacillus subtilis 3610 containing the xylanase gene xyn2 from Trichoderma reesei. OS presented the highest potential for XOS production. The fermentation process was further optimized for this residue in terms of residue concentration (5, 10, 20, 40 and 60 g L-1), pH (5.0, 6.0, 7.0 and 8.0), and temperature (30, 37, 45 and 50°C). The highest total sugars yield (27 ± 2 mg g-1) was achieved after 12 h, using 20 g L-1 of OS at pH 7.0 and 45°C.
- Valorisation of olive oil by-products into pectic- and glucuronoxylo-oligosaccharides via one-step fermentationPublication . Cordeiro, Ana; Fernandes, Andreia; Ferreira, Andreia S.; Coelho, Elisabete; Coimbra, Manuel A.; Silvério, Sara C.; Cadavez, Vasco; Peres, António M.; Rodrigues, Lígia R.; Amorim, CláudiaOlive pomace (OLP) and stones (OLS) are key by-products of olive oil production, rich in lignocellulose and pectin, making them viable substrates for prebiotic oligosaccharide (OS) production. This study evaluated the chemical composition of OLP and OLS powders (OLPp and OLSp) and their potential for OS production through one-step fermentation using recombinant Bacillus subtilis 3610. Both substrates had comparable xylan and pectin levels, but OLSp showed greater potential, achieving a maximum total sugar yield of 60 +/- 3 mg.g- 1 after 12 h under optimal conditions (20 g.L- 1 OLSp, pH 7.0, 45 degrees C). The resulting OS mixture from OLSp was predominantly composed of pectic oligosaccharides (72.1 %mol) and glucurono-xylooligosaccharides (11.6 %mol). This innovative process, competitive with commercial enzymes, highlights the potential of by-product valorisation for producing value-added food compounds. The findings provide insights into low-cost bioprocesses and underscore the importance of sustainable approaches in the industry of functional food ingredients.