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- Opuntia ficus indica waste as a cost effective carbon source for lactic acid production by Lactobacillus plantarumPublication . Derabli, Besma; Nancib, Aicha; Nancib, Nabil; Aníbal, Jaime; Raposo, Sara; Rodrigues, Brígida; Boudrant, JosephOpuntia ficus indica (OFI) waste was evaluated as a fermentation feedstock for lactic acid production using Lactobacillus plantarum. Dilute acid pretreatment of the OFI cladodes (OFIC) was performed for extracting maximum fermentable sugars by optimizing process parameters using statistical optimization method. The best results were obtained with HCl 1% (v/v), temperature 120 ◦C, residence time 40 min, granulation 350 μm and substrate loading 5% (w/v), the sugar concentration reached 24 g/L with low concentration of hydroxymethylfurfural. The feasibility of producing lactic acid from OFI fruit peel (OFIFP) as a source of carbon was also investigated. Lactobacillus plantarum was shown to have a capacity for lactic acid production from OFIC350 (granulation 350 μm) hydrolysate and OFIFP extract without detoxification. The highest lactic acid yields of 0.46 and 0.78 g/g were obtained from enzymatic hydrolysate of pretreated OFIC350 and OFIFP extract, respectively.
- Cost-effective bioethanol production at low content of nitrogen source from carob syrupPublication . Raposo, Sara; Sousa, Catarina; Rodrigues, B.; Lima-Costa, Maria Emília; Quintas, Célia; Rodrigues, F.Ethanol, as biofuel, has received great interest in the latest decades due to its potential as an alternative transport fuel. Nowadays, ethanol can be produced through fermentative processes, using sugar rich agricultural raw material and it may have a significant role in reducing environmental impact of fossil fuels.
- Natural antioxidants in emulsions O/WPublication . EL-GEUNDOUZ, Soukaina; Azza, S.; Dandlen, Susana Anahi; MAJDOUB, Nesrine; Lyoussi, Badiaa; Raposo, Sara; Gomes, Vera; Bankova, Vassya; Popova, Milena; Antunes, Maria Dulce; Miguel, Maria GracaThis study compared the capacity of propolis extract (PE) and thyme waste extract (TWE) to prevent the oxidation of oil in water (O/W) emulsion, as well as their impact on emulsion apparent viscosity (AV) in the presence of wheat germ and almond oils as lipid phase. For this, central composite design (CCD) and principal component analysis (PCA) were performed. Oxidation process was monitored by evaluating the formation of primary and secondary lipid oxidation products, at the same time the AV behavior was determined evaluating consistency index and flow behavior index. The results revealed that the increase of PE% and TWE% decreases TBARS (Thiobarbituric Acid Reactive Substances) and hydroperoxides formation. Viscosity increases with the rise of TWE% over (0.04%), whereas lower concentrations of PE% decreases it. Those results have been confirmed in the PCA analysis. TWE showed higher resistance to oxidation, although PE was more effective as antioxidant than TWE.
- Purification and characterization milk-clotting aspartic proteinases from Centaurea calcitrapa cell suspension culturesPublication . Raposo, Sara; Domingos, AnaPlant aspartic proteinases (APs) were isolated from several sources and studied for milk-clotting ability. Extraction of milk-clotting proteinases from intact plants is labor intensive and so, plant cell cultures is a viable alternative to obtain clotting enzymes. The aim of this work was to isolate APs from established suspension cell cultures of Centaurea calcitrapa and evaluate it's the potential interest for milk clotting. Plant cell extract was purified by ionic-exchange and hydrophobic-interaction chromatographies. Results suggest that the milk-clotting proteinases from cell cultures are synthesized as a 66-kDa proenzyme which originates a 50-kDa mature enzyme. The enzyme inhibition of 92% by pepstatin at 10 μM proved it to be an aspartate proteinase. The clotting time for purified APs suggests that these extracts may be used in the production of dairy products of weak paste or conjugated with other commercial rennets.
- Biogas production from microalgal biomass produced in the tertiary treatment of urban wastewater: assessment of seasonal variationsPublication . Barros, Raúl; Raposo, Sara; Morais, Etiele; Rodrigues, Brígida; Lourenço Afonso, Valdemira; Gonçalves, Pedro; Marques, José; Cerqueira, Ricardo; Varela, João; Ribau Teixeira, Margarida; Barreira, LuísaThe valorization of microalgal biomass produced during wastewater treatment has the potential to mitigate treatment costs. As contaminated biomass (e.g., with pharmaceuticals, toxic metals, etc.) is often generated, biogas production is considered an effective valorization option. The biomass was obtained from a pilot facility of photobioreactors for tertiary wastewater treatment. The pilots were run for one year with naturally formed microalgal consortia. The biogas was generated in 70 mL crimp-top vials at 35 °C, quantified with a manometer and the methane yield measured by gas chromatography. A maximum biogas production of 311 mL/g volatile solids (VS) with a methane yield of 252 mL/g VS was obtained with the spring samples. These rather low values were not improved using previous thermo-acidic hydrolysis, suggesting that the low intrinsic biodegradable organic matter content of the consortia might be the cause for low yield. Considering the total volume of wastewater treated by this plant and the average amount of methane produced in this study, the substitution of the current tertiary treatment with the one here proposed would reduce the energy consumption of the plant by 20% and create an energy surplus of 2.8%. The implementation of this system would therefore contribute towards meeting the ambitious decarbonization targets established by the EU.
- Bioethanol production using carob pod, as carbon source on submerged fermentationPublication . Lima-Costa, Maria Emília; Sousa, Catarina; Rodrigues, B.; Quintas, Célia; Raposo, SaraIn the latest years the research for new sources of carbon sources, among industry by-products as potential raw material for bioethanol production is a needful and a sustainable strategy for the success of 2nd generation biofuels.
- Effect of poplar-type propolis on oxidative stability and rheological properties of O/W emulsionsPublication . EL-GEUNDOUZ, Soukaina; AAZZA, Smail; Lyoussi, Badiaa; MAJDOUB, Nesrine; Bankova, Vassya; Popova, Milena; Raposo, Sara; Antunes, Maria Dulce; Miguel, MariaPropolis is known to possess antioxidant activity. However, there is no information on this activity in emulsions O/W. The protective effect of propolis on the oxidation and rheological properties of emulsions O/W containing wheat germ and almond oils was evaluated. Emulsions O/W were prepared with different concentration of propolis extract, almond oil and wheat germ oil. All emulsions physically stable without phase separation were stored at 37 °C for 9 weeks. Chemical composition of propolis was established by Gas chromatography coupled to mass spectrometry. Rheological characterization of different emulsions was performed evaluating consistency index and flow behavior index. The oxidation was monitored by measuring the lipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS) methods. Flavonoids, phenolic acid esters, and aromatic acids were the main groups of compounds found in propolis. The results showed that popolis was good antioxidant in the concentration of 0.02 and 0.04% when lipid phase was constituted by almond oil. The rheological behavior is typical of a non-Newtonian fluid, being almond oil more adequate for having a higher stable O/W emulsion.
- Comparative study of the antioxidant and enzyme inhibitory activities of two types of Moroccan Euphorbia entire honey and their phenolic extractsPublication . Boutoub, Oumaima; EL-GUENDOUZ, Soukaina; Manhita, Ana; Dias, Cristina Barrocas; Estevinho, Letícia M.; Paula, Vanessa B.; Carlier, Jorge; Costa, Maria Clara; Rodrigues, Brígida; Raposo, Sara; Aazza, Smail; El Ghadraoui, Lahsen; Miguel, Maria GraçaHoney is a natural food product very famous for its health benefits for being an important source of antioxidant and phenolic compounds. Euphorbia honeys obtained from different regions of Morocco were evaluated for their ability to inhibit acetylcholinesterase, lipoxygenase, tyrosinase and xanthine oxidase activities. Their antioxidant properties were evaluated using the: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity, nitric oxide scavenging activity (NO) and scavenging ability of superoxide anion radical. Then, the phenolic extracts of the same entire honey samples were evaluated by liquid chromatography coupled to diode array detection and mass spectrometry (LC-DAD-MS) and tested for the biological activities previously evaluated on the entire honeys, in order to conduct a comparative study between both (honey and phenolic extracts). The chromatographic profiles for the studied Euphorbia honey extracts were different. Phenolic compounds gallic acid, 4-hydroxybenzoic acid and p-coumaric acid were detected in all samples, whereas kampferol was only present in two samples. Physicochemical parameters and total phenolic content were also determined. Entire honey that recorded the highest rate of phenols was sample M6 (E. resinifera) = 69.25 mg GAE/100 g. On the other hand, the phenolic extracts had better antioxidant and enzyme inhibitory activities than the entire honeys, regardless the monofloral honey type. In conclusion, the studied Euphorbia honeys may have a great potential as antioxidant, anti-inflammatory and anti-tyrosinase sources for pharmaceutical and cosmetic applications.
- Development of an empirical correlation for Newtonian and non-Newtonian fluids in a stirred tank reactor, to predict oxygen mass transfer ratesPublication . Raposo, Sara; Azevedo, F.; Lima-Costa, Maria EmíliaMost of animal and plant cell cultures present a non-Newtonian behaviour that has a deep effect on the technological performance of bioreactors, affecting the pattern of mixing, the power input required and on the mass and energy transfer as well. In aerobic cultures, the oxygen mass transfer is still a bottleneck, particularly at industrial scale-up, where the high-cell-density biomass and production of metabolites provoke the increase on the viscosity culture, lowering the production yield and eventually losing economical process viability.
- Application of the focused beam reflectance measurement method (FBRM) to the characterization of plant cells in suspension culturePublication . Jeffers, Paul; Raposo, Sara; Lima-Costa, Maria Emília; Kieran, Patricia; Glennon, BrianThe ability to determine biomass levels and organism morphological characteristics is of importance in many bioprocesses.