Patrícia Moura

Assessment on the fermentability of xylooligosaccharides from rice husks by probiotic bacteria.

Liquors from rice husk autohydrolysis, containing xylooligosaccharides (XOS), other saccharides, and nonsaccharide compounds, were refined by membrane processing to increase the proportion of substituted XOS in refined liquors. XOS were assayed for composition and degree of polymerization (DP) distribution and hydrolyzed with commercial enzymes for obtaining XOS with DP in the range of 2-6. Nanofiltered, hydrolyzed liquors were subjected to ion exchange processing to yield a final product containing monosaccharides, XOS (accounting for 55.6% of the nonvolatile solutes), and other nonvolatile compounds. The solution obtained after enzymatic hydrolysis with commercial xylanases (in which 82.8% of XOS were in the DP range of 2-6) was examined as a medium for promoting the growth of Bifidobacterium adolescentis CECT 5781, B. longum CECT 4503, B. infantis CECT 4551, and B. breve CECT 4839. The growth rate of B. adolescentis (0.58 h(-1)) was higher than the ones determined for B. longum, B. infantis, and B. breve (0.37, 0.30, and 0.40 h(-1), respectively). The percentage of total XOS consumption by B. adolescentis was 77% after 24 h, the highest percentage of utilization corresponding to xylotriose (90%), followed by xylobiose (84%), xylotetraose (83%), and xylopentaose (71%).

Biohydrogen production from microalgal biomass: Energy requirement, CO2 emissions and scale-up scenarios

This paper presents a life cycle inventory of biohydrogen production by Clostridium butyricum through the fermentation of the whole Scenedesmus obliquus biomass. The main purpose of this work was to determine the energy consumption and CO2 emissions during the production of hydrogen. This was accomplished through the fermentation of the microalgal biomass cultivated in an outdoor raceway pond and the preparation of the inoculum and culture media. The scale-up scenarios are discussed aiming for a potential application to a fuel cell hybrid taxi fleet. The H2 yield obtained was 7.3 g H2/kg of S. obliquus dried biomass. The results show that the production of biohydrogen required 71-100 MJ/MJ(H2) and emitted about 5-6 kg CO2/MJ(H2). Other studies and production technologies were taken into account to discuss an eventual process scale-up. Increased production rates of microalgal biomass and biohydrogen are necessary for bioH2 to become competitive with conventional production pathways.

Microalgae – source of natural bioactive molecules as functional ingredients

AbstractMicroalgae can provide an untapped number of important bioactive molecules (functional ingredients), and their incorporation in traditional foods (e.g. breakfast cereals, spreads, breads, cookies, brownies, energy bars, mayonnaises, gelled desserts, pastas, emulsions, ice creams, and beverag

Bifidobacterial growth stimulation by oligosaccharides generated from olive tree pruning biomass

This work aims to evaluate the prebiotic potential of oligosaccharides (OS) obtained from autohydrolysis of olive tree pruning biomass (OTPB). Two selected fractions (F1 and F2) were characterized and used in in vitro fermentations by two Bifidobacterium spp. (B. adolescentis and B. longum) and one fecal inoculum. The fraction F1 presented a lower average degree of polymerization (DP) mainly with OS ranging from 3 to 6 DP, whereas the fraction F2 corresponded to a pool of unsubstituted and acetylated oligomers with DP between 4 and 19. In the fermentation by Bifidobacterium, F1 supported a higher biomass formation, OS consumption and organic acids production than F2. With the fecal inoculum, the accumulation of organic acids, as the sum of acetate, propionate and butyrate, was similar for F1 and F2 (107 and 101mM, respectively). The bifidobacteria counts also increased during the incubation time for both OS fractions.

Biorefineries in the World

This chapter intends to give a brief overview of current conventional and advanced biomass-based biorefineries in the World. While the conventional biorefineries use mature and commercial technology , the advanced biorefineries (e.g., lignocellulosic-based biofuel biorefineries , microalgae-based biorefineries ) have different degrees of technology-readiness level and regardless the process technology, only a few of them have reached the commercial scale although the profitability remains a quest. The most representative’s examples of biorefineries in the World are reviewed in this chapter with special emphasis on thermochemical - and biochemical -based biomass processing technologies for advanced biofuel biorefineries at pilot, demo or commercial stage. Few examples of product (non-energetic)-driven biorefineries are also discussed, such as pulp and paper biorefineries and lactic acid-producing biorefineries, mainly because only a limited number are in operation because their key technologies are still in the R&D, pilot or demo stage.