Percorrer por autor "Ferreira, Andreia S."
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- 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.
- 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.