Biblioteca Digital do IPB
Publications Repository of the Polytechnic Institute of Bragança
Recent Submissions
Banana Peels as Substrate for Lactic Acid Production: Upstream Fermentation Bioprocess
Publication . Pedrosa, Mariana C.; Heleno, Sandrina A.; Alvarez, Cristina; Susmozas, Ana; Ballesteros, Ignacio; Pintado, Manuela; Barros, Lillian; Carocho, Márcio
Purpose Banana peels account for around 30-40% of the banana's weight and represent an industrial waste. This biomass can be used as an eco-friendly solution for biotechnological bioprocesses. Still, due to the fibrous nature of banana peels, pretreatment becomes essential to enhance the effectiveness of enzymes on the hydrolysis of complex carbohydrates. This study aims to determine the best pretreatment and enzymatic hydrolysis conditions to produce a fermentation substrate suitable for producing lactic acid from the peels.MethodsA diluted H2SO4 (0.5% and 0.25%) was used in an autoclave for 10 min at 121 degrees C. The pretreated material was subjected to several enzymatic hydrolysis tests in which two variables were evaluated for their influence: solid load (10, 15 and 20%), and H2SO4 concentration (0.5 and 0.25% v/v). Commercial enzymes (cellulolytic enzyme mixtures and pectinase) were used.ResultsAll enzymatic hydrolysis yields of cellulose referring to glucose released in the hydrolysates surpassed 60% in all the conditions tested after pretreatment. After evaluating the pretreatment efficiency, the ideal parameters were defined as 0.25% H2SO4, and cellulolytic enzyme mixtures with 15 and 20% solid load. Subsequently, a screening was carried out in MRS + broth with the most suitable pH and temperature conditions for lactic acid production by Lacticaseibacillus rhamnosus.ConclusionsThe results showed the potential of BP medium for lactic acid production, with yields of 0.91 g/g sugar in sugar-containing media from enzymatic hydrolysis at 15% solid load and 0.82 g/g sugar in media from 20% solid load assays.
Valorisation of olive oil by-products into pectic- and glucuronoxylo-oligosaccharides via one-step fermentation
Publication . Cordeiro, Ana; Fernandes, Andreia; Ferreira, Andreia S.; Coelho, Elisabete; Coimbra, Manuel A.; Silvério, Sara C.; Cadavez, Vasco; Peres, António M.; Rodrigues, Lígia R.; Amorim, Cláudia
Olive 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.
Development of a new method for characterizing olive cultivar resistance to Verticillium dahliae, the causal agent of Verticillium wilt
Publication . Antón-Domínguez, Begoña I.; Valverde, Pedro; Agustí-Brisach, Carlos; Trapero, Carlos
Verticillium wilt of olive (Olea europaea L.), caused by the soil-borne fungus Verticillium dahliae Kleb., is one of the most important diseases affecting this crop. Using resistant cultivars is among the most effective control measures. Various inoculation methods have been used to assess olive cultivars resistance to Verticillium wilt under controlled conditions, but significant discrepancies often arise when comparing results with field conditions. This study aimed to develop a new method capable of detecting subtle differences in resistance or susceptibility among olive cultivars. Olive cultivars 'Picual', 'Arbequina', 'Koroneiki' and 'Frantoio' were inoculated using an artificial substrate containing V. dahliae microsclerotia at two doses (20 and 80%). For comparison, root seedlings were also immersed in a conidial suspension of the pathogen. The 20% substrate dose allow distinguished close levels of susceptibility ('Picual' and 'Arbequina'), while the 80% dose can distinguish between close variations of resistance ('Koroneiki' and 'Frantoio'). To validate these findings under real conditions, a field experiment was conducted over 4 years, demonstrating alignment with the controlled environment results. 'Frantoio' consistently showed the highest resistance, 'Picual' the greatest susceptibility, and 'Arbequina' exhibited intermediate levels, thus confirming the differentiation achieved using the artificial inoculation method. Consequently, this newly developed method offers a significant advancement in the accuracy and reliability of resistance assessments for olive cultivars against Verticillium wilt within breeding programs.
Assessing the prebiotic potential of xylooligosaccharides produced by one-step fermentation using agro-residues
Publication . Cordeiro, Ana; Fernandes, Andreia; Sousa, Joana; Cardoso, Beatriz; Alves, Joana; Silvério, Sara; Peres, António M.; Rodrigues, Lígia R.; Amorim, Cláudia; UNIVERSIDADE DA BEIRA INTERIOR
The 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.
Optimisation of stability and colouring power of double emulsion systems loaded with Daucus carota L.
Publication . Teixeira, Liandra Gracher; Silva, Samara Cristina; Colucci, Giovana; Santamaria-Echart, Arantzazu; Peres, António M.; Dias, Madalena M.; Barreiro, Filomena
Anthocyanins (ACNs) are water-soluble bioactive flavonoids found in flowers, roots, leaves, seeds, and stalks. ACNs cover a wide palette of colours, from blue and purple through orange to red1,2. They are used in the food industry (food colourant with E163 code), namely in fruit juice concentrates, nectars, jellies, yoghurts, marmalades, potato chips, ice creams, and soft drinks, replacing the synthetic Red 40 colourants. They also have diversified pharmaceutical and cosmetic uses due to their colouring and antioxidant attributes. However, their instability due to pH, light, and temperature is a major concern. This study used a double water-in-oil-in-water (W1/O/W2) emulsion technique to prevent rapid colour loss and colour variability with pH of a commercial black carrot extract (Fig. 1). A Central Composite Rotatable Design (CCRD) 22 was used to examine the effects of colourant concentration (wt%) and emulsion ratio ((W1/O)/W2) on stability
parameters (droplet size (D4,3), creaming index (CI), and colourimetric values (L*, a*). The main objective was to find an optimised formulation in terms of colourant potential and emulsion stability. Measurements were taken at 1, 7, 15, and 30 days. The optimal experimental design revealed two optimal solutions: 1) 48/52 (W1/O)/W2 ratio with 6 wt.% colorant, and 2) 41/59 (W1/O)/W2 ratio with 11 wt.% colourant. These formulations showed lower creaming index and droplet sizes with higher colourant potential. After accounting for the effect of time, the optimal condition was 6 wt% colourant concentration and 48/52 v/v (W1/O)/W2 emulsion ratio. A stable colour was maintained after 30 days (L*: 44.11±0.03, a*: 25.79±0.01, D4;3: 9.62 ± 0.1 µm, and CI: 14.55±0.99%). These findings are promising and might be applicable to produce novel colourants to be applied in several industries, such as food and cosmetics.