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The aim of this paper was to develop broccoli soups enriched in Spirulina sp., Chlorella sp., or Tetraselmis sp., at concentrations ranging from 0.5 to 2.0% (w/v), and to assess the effect of microalgae incorporation on their quality and acceptance. Incorporation of freeze-dried microalgae biomass into the broccoli soup resulted in lower L* values, especially after incorporation of Spirulina sp. and Chlorella sp. Microalgae incorporation also led to an increased content of polyphenols and to a higher antioxidant capacity. Microalgae-containing soups showed a higher amount of bioaccessible polyphenols, calculated after a simulated gastrointestinal digestion (ranging between 32.9 ± 1.1 and 45.6 ± 0.5 mg/100 mL). The acceptability index of soups formulated using lower microalgae concentrations was over 70% suggesting that the soups would be well accepted. Indeed, the purchase intention of the soups containing microalgae at 0.5% (w/v) ranged between 3.4 and 4.1 (assessed using a 5-point hedonic scale). • Microalgae incorporation into broccoli soup. • Microalgae-containing soups had a higher phenolic content and antioxidant capacity. • The content of bioaccessible polyphenols was higher in microalgae-containing soups. • High acceptability indexes were obtained for soups containing microalgae at 0.5%. • High purchase intention scores for soups containing 0.5–1.0% microalgae. [ABSTRACT FROM AUTHOR]

Microalgae-based wastewater treatment has been suggested as an alternative to polluting and energy-consuming conventional processes. The main advantage of this strategy is the dual role of microalgae: they recover nutrients from waste and simultaneously produce biomass with varied industrial applications. In the current study, biomass of Scenedesmus sp. was produced using primary wastewater in two pilot-scale thin-layer cascade photobioreactors (63 and 126 m2). The wastewater used for microalgal growth was not subjected to any conventional treatment process, besides removal of solids, and contained a variable N-NH4+ content of 83.0–210.6 mg L−1. Biomass productivity values were comparable to those obtained when operating using freshwater and commercial chemicals as nutrient sources. When operating at a dilution rate of 0.3 day−1, the average annual productivity was 24.8 g m−2 day−1 (82.0 t ha−1 year−1) with a maximum of 32.8 g m−2 day−1 in summer. Inorganic nitrogen and phosphorus removal rates varied between 695.4 − 2383.4 and 70.4 − 111.8 mg m−2 day−1, respectively. Production of Scenedesmus sp. using wastewater would allow not only to process large volumes of water that could be reused for agricultural irrigation or safely disposed into water streams, but also reduce production costs by 0.44 € kg−1, based on a preliminary economic analysis. Overall, results demonstrate that thin-layer cascade reactors can be used to effectively remove nutrients from wastewater while simultaneously produce valuable biomass with potential applications in agriculture or animal feed production. [ABSTRACT FROM AUTHOR]

Abstract In this study, the outdoor production of marine microalgae in raceway photobioreactors was investigated, modifying the centrate percentage in the culture medium (20, 30, 40 and 50%) and using two different dilution rates (0.2 day−1 and 0.3 day−1). The data obtained showed that microalgae are capable of producing biomass in addition to recovering the nutrients contained in the centrate. The best results for biomass productivity and light efficiency were obtained when the centrate was set at 20% with a dilution rate of 0.3 day−1. The biomass productivity was 32.42 g m−2·day−1 while the photosynthetic efficiency was 0.74 g biomass ·E−1 (3.66%). Regarding the nutrients, nitrogen (the majority being in the form of ammonium [NH 4 +]) and phosphorus were only fixed into biomass when optimal conditions were set; if this was not the case, they were lost to stripping or precipitation. The maximal nutrient removal capacities under the optimal conditions were 28.72 mg N ·l−1·day−1 and 3.99 mg P ·l−1·day−1. Population changes were determined by the dilution rate set whilst the centrate percentage had little effect. Four strains were present in the culture, Nannochloropsis g. being the main one. Biochemical changes did not vary greatly between the conditions set for the culture, with a composition rich in proteins and carbohydrates being observed. One can conclude that to produce marine microalgal biomass for a range of potential commodities such as feed, biofertilizers and biofuels, it is possible to use centrate from anaerobic digestion as the sole nutrient source, as a way of reducing costs. Highlights • Marine microalgae can be produced at pilot scale outdoor using centrate as sole nutrients source. • Marine microalgae are stressed at NH 4 + concentration higher than 160 mg l−1. • Marine microalgae efficiently remove N, P and C, being useful for centrate treatment. [ABSTRACT FROM AUTHOR]

In horticultural practice accelerated plant development and particularly earlier flowering, has been reported with microalgae applications. Therefore, the objective of this work was to study the effects of foliar spraying with Scenedesmus sp. and Arthrospira platensis hydrolysates on Petunia x hybrida plant development and leaf nutrient status. Three treatments were tested: T1 (foliar application with water, the control), T2 (foliar application with Arthrospira), and T3 (foliar application with Scenedesmus). Foliar spraying was applied five times (0, 14, 28, 35, and 42 days after transplanting). The concentration of both microalgae was 10 g L−1. At the end of the trial biometric parameters and nutrient concentration in photosynthetic organs (the leaves) were measured. The results of this assay show that foliar application of Scenedesmus accelerated plant development in terms of higher rates of root growth, leaf and shoot development, and earliness of flowering. Arthrospira enhanced the root dry matter, the number of flowers per plant, and the water content. Nevertheless, a reduction was found in the conductive tissue (stem + petiole) dry weight with Arthrospira compared with Scenedesmus and the control. The results also show that microalgae hydrolysate supply can improve the plant nutrient status. Based on these results, it is advisable to use Scenedesmus hydrolysates in foliar applications to increase the blooming of Petunia x hybrida. [ABSTRACT FROM AUTHOR]

There is an increasing demand for bio-based fertilizers and phytostimulants. Microalgae biomass contains a number of compounds that have positive effects on plant growth (for instance, phenolic compounds). Other valuable substances are simultaneously produced in the biomass, enabling a biorefinery approach to be applied. Downstream processing optimization for sustainable economic biostimulant production must involve the use of microalgal wet paste instead of dry biomass. The present study investigated the effect of different parameters, such as the solvent, temperature, and time, on the extraction of biostimulant molecules from Scenedesmus almeriensis microalgal biomass. The extraction process optimization was determined by calculating the germination index in the watercress seed bioassays. Since phenols and other bioactives are extracted together, and purification should be avoided, biological methods are preferred for assessing biostimulation. Water was compared to organic solvents of lower polarity such as acetone, ethanol (96%), and an ethanol:hexane:water (76:18:6 v/v/v) mixture. Different solvent extraction ratios (0.5–8 mL solvent g−1 of dry biomass), temperatures (25–50 ºC), and extraction times (0.5–6 h) were tested, after which the best combination was selected for each solvent. The optimal conditions were obtained with organic green solvents (acetone or ethanol), which resulted in a Germination Index above 120% (at least 20% above the distilled water control). Consequently, from a biorefinery perspective, this process was considered to be the most suitable for microalgal biomass exploitation. [ABSTRACT FROM AUTHOR]

Simple Summary: The world's population is expected to increase to almost 10,000 million by 2025, thus requiring an increase in agricultural production to meet the demand for food. Hence, an increase in fertilizer production will be needed, but with more environmentally sustainable fertilizers than those currently used. Traditional nitrogenous fertilizers (TNFs, inorganic compounds, for example nitrates and ammonium) are currently the most consumed. Biofertilizers concentrated in amino acids (BCAs) are a more sustainable alternative to TNF and could reduce the demand for TNFs. BCAs are widely used in intensive agriculture as growth and fruit formation enhancers, as well as in situations of stress for the plant, helping it to recover its vigor. In addition, BCAs minimize or contribute to reducing the damage caused by pests and diseases, have an immediate action, giving a full utilization and, lastly and most importantly, they produce savings in the crop. The objective of this work is to propose a process for the production of biofertilizer concentrated in free amino acids from microalgal biomass produced in a wastewater treatment plant and to carry out techno-economic evaluation in such a way as to determine the viability of the proposal. Due to population growth in the coming years, an increase in agricultural production will soon be mandatory, thus requiring fertilizers that are more environmentally sustainable than the currently most-consumed fertilizers since these are important contributors to climate change and water pollution. The objective of this work is the techno-economic evaluation of the production of biofertilizer concentrated in free amino acids from microalgal biomass produced in a wastewater treatment plant, to determine its economic viability. A process proposal has been made in six stages that have been modelled and simulated with the ASPEN Plus simulator. A profitability analysis has been carried out using a Box–Behnken-type response surface statistical design with three factors—the cost of the biomass sludge, the cost of the enzymes, and the sale price of the biofertilizer. It was found that the most influential factor in profitability is the sale price of the biofertilizer. According to a proposed representative base case, in which the cost of the biomass sludge is set to 0.5 EUR/kg, the cost of the enzymes to 20.0 EUR/kg, and the sale price of the biofertilizer to 3.5 EUR/kg, which are reasonable costs, it is concluded that the production of the biofertilizer would be economically viable. [ABSTRACT FROM AUTHOR]

Production of phytoplankton (microalgae and cyanobacteria) in commercial raceway ponds and other systems is adversely impacted by phytoplankton pathogens, including bacteria, fungi and viruses. In addition, cultures are susceptible to productivity loss, or crash, through grazing by contaminating zooplankton such as protozoa, rotifers and copepods. Productivity loss and product contamination are also caused by otherwise innocuous invading phytoplankton that consume resources in competition with the species being cultured. This review is focused on phytoplankton competitors, pathogens and grazers of significance in commercial culture of microalgae and cyanobacteria. Detection and identification of these biological contaminants are discussed. Operational protocols for minimizing contamination, and methods of managing it, are discussed. [ABSTRACT FROM AUTHOR]

In this paper the influence of irradiance and the operation modes on biomass production and biochemical composition, especially the fatty acid profile, on the diatom Nitzschia aff. pellucida was studied. Experiments were carried out under laboratory conditions, but simulating those outdoors, at irradiances ranging from 100 to 1000 µmol photons m−2 s−1, both in batch and semi-continuous mode. The data show that the growth rate increased with irradiance, following a hyperbolic relationship with the average irradiance (Eav). However, at irradiances higher than 450 µmol photons m−2 s−1, photo-inhibition was observed, with Fv/Fm values notably decreasing at irradiances above 1000 µmol photons m−2 s−1. To take account of this phenomenon, a growth model is proposed that considers the saturation constant modification (Ek) as a function of available irradiance. The data indicate that N. aff. pellucida is better adapted to low irradiances, below 300 µmol photons m−2 s−1. Regarding the biochemical composition, the highest content of lipids (~ 20%) and carbohydrates (~ 40%) was achieved at high irradiances (≥ 450 µmol photons m−2 s−1), while the highest protein content (> 8%) was found at low irradiances (≤ 200 µmol photons m−2 s−1). Elevated amounts of saturated fatty acids (SFA) (> 60%) were measured at high irradiances, while the highest content of unsaturated fatty acids (USFA) (> 35%) was found at low irradiances. Eicosapentaenoic acid (C20:5 n-3) (EPA) and arachidonic acid (C20:4 n-6) (ARA) were only detected at 200 µmol m−2 s−1 but not at higher irradiances. The results confirm the effects of irradiance and the cultivation mode on the growth and biochemical composition of N. aff. pellucida. The model is an important tool when using this valuable strain to produce compounds of biological interest. [ABSTRACT FROM AUTHOR]

The effects of water depth, operational and environmental conditions on bacterial communities were analyzed in microalgal-bacterial outdoor photobioreactors treating urban wastewaters from March to August 2014. Three raceway photobioreactors inoculated with Scenedesmus sp. and with different water depths (20, 12, and 5 cm) were used at different dilution rates (0.15, 0.3, 0.4, and 0.5 d−1). A thin-layer reactor with 2 cm water depth and operated at 0.3 d−1 was used as a control. The results showed that biomass productivity increased as water depth decreased. The highest biomass productivity was 0.196 gL−1d−1, 0.245 gL−1d−1, and 0.457 gL−1d−1 for 20, 12, and 5 cm depth raceway photobioreactors, respectively. These values were lower than the maximum productivity registered in the control reactor (1.59 gL−1d−1). Bacterial communities, analyzed by high-throughput 16S rRNA sequencing, were not affected by water depth. A decrease in community evenness was related to a decrease in nutrient removal. Hetetrotrophs and phototrophs, mainly from the family Rhodobacteraceae , dominated bacterial diversity. The community changed due to increasing temperatures, irradiance, and organic carbon, ammonia, and phosphate contents in the photobioreactor-influent as well as, microalgae inhibition and higher organic carbon in the effluent. The photobioreactors shared a core-biome that contained five clusters of co-occurring microorganisms. The bacteria from the different clusters were taxonomically and ecologically different but functionally redundant. Overall, the drivers of the community changes could be related to abiotic variables and complex biological interactions, likely mediated by microalgae excretion of organic substances and the microorganisms' competence for substrates. [Display omitted] • Biomass productivity increased as the depth of cultivation decreased. • No influence of water depth on bacterial community structure. • Strong influence of temperature, irradiance and nutrients on bacterial communities. • The PBRs core biome was dominated by heterotrophic and phototrophic bacteria. • Microalgae excretion of organic substances could modulate bacterial communities. [ABSTRACT FROM AUTHOR]

Primary urban wastewater was treated in outdoor raceways using microalgae-bacteria consortia dominated by Scenedesmus almeriensis. The current study aimed at assessing the effect of operational conditions, namely, culture depth and dilution rate, on the following: (i) biomass productivity, (ii) the nutrient removal capacity and (iii) the composition of the microalgae-bacteria consortium and the presence of unwanted microorganisms. Optimum dilution rates to process large quantities of wastewater during summer and achieve high biomass productivities were 0.3–0.5 day−1. Under the optimum operational conditions, nitrogen and phosphorus removal rates were higher than 90% while removal of chemical oxygen demand was 70%. Operating at different culture depths had a striking effect on the composition of the microalgae-bacteria consortium. The relative abundance of nitrifiers increased with culture depth and was minimised at 0.05 m: larger culture depths led to enhanced nitrifying activity and therefore to nitrate production and accumulation in the system. Results demonstrate the potential of microalgae-based wastewater treatment processes and the importance of selecting suitable operational conditions to maximise both, biomass production and nutrient removal by minimising the occurrence of nitrifying bacteria. [ABSTRACT FROM AUTHOR]

There are places in our planet where environmental conditions are beyond normal limits for growth but still harbour life. Extremophile microalgae are the candidates for large‐scale production because (i) their extreme growth conditions help to avoid unwanted contaminations, facilitating their production and (ii) in order to survive under harsh environments, these microorganisms synthesise valuable uncommon biomolecules. Extremophile microalgae include Arthrospira platensis, used as a source of phycocyanin and produced under highly alkaline conditions, and Dunaliella salina, which is industrially produced as a source of β‐carotene and can naturally resist salinity conditions exceeding 300 g L−1. Microalgae can be produced on non‐arable lands, using seawater, and within a wide range of environmental conditions, allowing their production in almost any part of the planet. The current paper aimed at highlighting the biotechnological potential of extremophile microalgae as sources for carotenoids, valuable molecules used as pigments and health‐promoters. [ABSTRACT FROM AUTHOR]

Our aim was to develop a novel medium for the large‐scale production of protein‐rich Arthrospira with potential applications as a biofertilizer. The novel culture medium, termed as FM‐II, was formulated using low‐cost commercial chemicals and specifically designed to improve protein production. Both Arthrospira platensis and Arthrospira maxima were produced using FM‐II and Arnon medium, which was used as a control. Photosynthetic status of the cells, which was checked by measuring chlorophyll fluorescence, biomass dry weight and protein content, was assessed daily. Arthrospira platensis had higher biomass and protein productivities than A. maxima when cultured in both control and FM‐II media. Incorporation of varied micronutrients into FM‐II formulation did not improve biomass productivity. Maximum biomass dry weight in FM‐II and control medium was 2.9 and 2.5 g · L−1, respectively. Total protein content of the biomass ranged between 55% and 65%, suggesting potential for being used in the development of high‐value agricultural products. As some nutrients were discarded unused, the initial content of phosphates and bicarbonates was reduced by 75% and 50%, respectively, without affecting the process productivity. Results reported herein could promote the production and utilization of Arthrospira platensis by significantly reducing productions costs and therefore increasing the feasibility of the process. [ABSTRACT FROM AUTHOR]

Extraction of carotenoids and fatty acids from microalgae is a technological bottleneck in processing. An improved extraction process was developed to scale the production of these bioproducts from Nannochloropsis gaditana. Different cell disruption methods were evaluated in terms of carotenoid release. Ethanol was substituted with isopropyl alcohol in a three-component solution of water:isopropyl alcohol:hexane (WIH), in which the extracts were separated by solution partitioning. This resulted in higher carotenoid and fatty acid recovery yields if compared with the standard method. The extraction method was replicated on a pilot scale, obtaining similar carotenoid recovery yields, higher than those of the standard method. Although fatty acid recovery was lower than that of the small-scale tests, yields above 85% were obtained. This demonstrated that the method was scalable for the extraction of high-value products from microalgae up to 10-L reactor volume. The use of isopropyl alcohol, which is cheaper than ethanol, and the separation of the solution phases by partitioning (avoiding drying) could contribute to reduce operation costs of downstream processing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Centrate is an efficient substitute for synthetic fertilizer. • Centrate biomass showed higher N than synthetic media biomass. • Dynamics and growths between media were comparable. • Centrate might lead to higher richness, diversity and N metabolism genes abundances. Centrate is a low-cost alternative to synthetic fertilizers for microalgal cultivation, reducing environmental burdens and remediation costs. Adapted microalgae need to be selected and characterised to maximise biomass production and depuration efficiency. Here, the performance and composition of six microalgal communities cultivated both on synthetic media and centrate within semi-open tubular photobioreactors were investigated through Illumina sequencing. Biomass grown on centrate, exposed to a high concentration of ammonium, showed a higher quantity of nitrogen (5.6% dry weight) than the biomass grown on the synthetic media nitrate (3.9% dry weight). Eukaryotic inocula were replaced by other microalgae while cyanobacterial inocula were maintained. Communities were generally similar for the same inoculum between media, however, inoculation with cyanobacteria led to variability within the eukaryotic community. Where communities differed, centrate resulted in a higher richness and diversity. The higher nitrogen of centrate possibly led to higher abundance of genes coding for N metabolism enzymes. [ABSTRACT FROM AUTHOR]

This work aimed to investigate the possibility of integrating microalgae production with anaerobic digestion of dairy cattle manure and subsequent digestate treatment, thus helping to reduce the cost of slurry treatment and improving the energy balance of the process. Real biogas and digestate-treatment units were monitored for energy, mass and nutrient balances. The existing system produces electrical energy (2182 ekWh d −1 ) and organic fertilizers/amendments (11,655 t y −1 ), among others. Microalgae production was integrated with this system by using untreated ultra-filtered digestate as the growth medium for the production of Scenedesmus sp. The tolerance of this strain to digestate was evaluated and results demonstrated that a percentage of digestate of over 10% inhibited the growth of this microalga, but below this value productivity of up to 124 mg L −1 d −1 could be obtained. The composition of the culture medium also influenced the biomass composition, with protein, carbohydrate and lipid content being direct functions of ammonia concentrations. Integrating microalgae production with anaerobic digestion, it is possible to produce 166–190 t y −1 of valuable microalgal biomass. Overall energy and mass balances of the process allow us to show that the integration of both anaerobic digestion and microalgae production steps are positive and technically feasible. [ABSTRACT FROM AUTHOR]

A coupled process combining microalgae production with direct supercritical biodiesel conversion using a reduced number of operating steps is proposed in this work. Two newly isolated native microalgae strains, identified as Chlorella sp. and Nannochloris sp., were cultivated in both batch and continuous modes. Maximum productivities were achieved during continuous cultures with 318 mg/l day and 256 mg/l day for Chlorella sp. and Nannochloris sp., respectively. Microalgae were further characterized by determining their photosynthetic performance and nutrient removal efficiency. Biodiesel was produced by catalyst-free in situ supercritical methanol transesterification of wet unwashed algal biomass (75 wt.% of moisture). Maximum biodiesel yields of 45.62 wt.% and 21.79 wt.% were reached for Chlorella sp. and Nannochloris sp., respectively. The analysis of polyunsaturated fatty acids of Chlorella sp. showed a decrease in their proportion when comparing conventional and supercritical transesterification processes (from 37.4% to 13.9%, respectively), thus improving the quality of the biodiesel. [ABSTRACT FROM AUTHOR]

Microalgae, which are promising candidates for biodiesel production, possess a robust cell wall which prevents the release of intracellular lipids in the medium. The breaking of the algal cell wall for lipid releasing can be energy-intensive. The direct or in situ supercritical transesterification method is considered to have the potential to disrupt the rigid algal cell wall and convert the extracted lipids into biodiesel in only one step, thus reducing significantly the process energy consumption. In this work, wet (∼80 wt.% moisture) and dry unwashed marine microalgae Nannochloropsis gaditana were used directly to synthesize biodiesel in a single-step process by direct transesterification with no added catalysts using supercritical methanol. The effect of main process parameters (methanol to dry algae ratio, reaction time and temperature) was studied. Initially, the methanol to dry algae ratio (6:1–12:1 vol./wt.) was investigated and then the synergic effect between reaction time (10–50 min) and temperature (245–290 °C) was studied using a factorial experimental design. In addition, the effect of the supercritical process on the structure of the algal cell walls was studied by scanning electron microscopy observations. Maximum biodiesel yields of ∼0.46 and ∼0.48 g/g of lipids were reached from wet and dry unwashed algal biomass, respectively, at 255–265 °C, 50 min reaction time, and using a methanol to dry algae ratio of 10:1 (vol./wt.). The highest biodiesel yields obtained from dry microalgae were only between 2% and 9% higher than those reached from wet microalgae, indicating that a high content of water in the unwashed algal biomass did not significantly affect the supercritical process. [ABSTRACT FROM AUTHOR]

One of the main social and economic challenges of the 21st century will be to overcome the worlds' water deficit expected by the end of this decade. Microalgae based wastewater treatment has been suggested as a strategy to recover nutrients from wastewater while simultaneously producing clean water. Consortia of microalgae and bacteria are responsible for recovering nutrients from wastewater. A better understanding of how environmental and operational conditions affect the composition of the microalgae-bacteria consortia would allow to maximise nutrient recoveries and biomass productivities. Most of the studies reported to date showed promising results, although up-scaling of these processes to reactors larger than 100 m2 is needed to better predict their industrial relevance. The main advantage of microalgae based wastewater treatment is that valuable biomass with unlimited applications is produced as a co-product. The aim of the current paper was to review microalgae based wastewater treatment processes focusing on strategies that allow increasing both biomass productivities and nutrient recoveries. Moreover, the benefits of microalgae based agricultural products were also discussed. [Display omitted] • Microalgae based wastewater treatment is sustainable and economically viable. • Raceway reactors allow processing large volumes of wastewater. • Operational conditions can influence the microalgae-bacteria consortia. • Up-scaling of current processes to over 100 m2 reactors is required. • Microalgal biomass can be used to produce high-value agricultural products. [ABSTRACT FROM AUTHOR]

High concentration of dissolved oxygen within microalgae cultures reduces the performance of corresponding microalgae cultivation system (MCS). The main aim of this study is to provide a reliable computational fluid dynamics (CFD)-based methodology enabling to simulate two relevant phenomena governing the distribution of dissolved oxygen within MCS: (i) mass transfer through the liquid–air interface and (ii) oxygen evolution due to microalgae photosynthesis including the inhibition by the same dissolved oxygen. On an open thin-layer cascade (TLC) reactor, a benchmark numerical study to assess the oxygen distribution was conducted. While the mass transfer phenomenon is embedded within CFD code ANSYS Fluent, the oxygen evolution rate has to be implemented via user-defined function (UDF). To validate our methodology, experimental data for dissolved oxygen distribution within the 80 meter long open thin-layer cascade reactor are compared against numerical results. Moreover, the consistency of numerical results with theoretical expectations has been shown on the newly derived differential equation describing the balance of dissolved oxygen along the longitudinal direction of TLC. We argue that employing our methodology, the dissolved oxygen distribution within any MCS can be reliably determined in silico, and eventually optimized or/and controlled. [ABSTRACT FROM AUTHOR]

This work presents an alternative for adding value to greenhouse crop residues, used for (1) heating and (2) as a CO2 source. Both options are focused on greenhouse agricultural production, but could be applied to other applications. The influence of factors, such as the air/fuel rate and turbulence inside the combustion chamber, is studied. Our results show that for pine pellets, olive pits, tomato-crop residues, and a blend of the latter mixed with almond prunings (75–25%), the thermal losses ranged from 19.5–53.1, 20.5–58.9, 39.9–95%, and 29.4–75.5%, respectively, while the NOX emissions were 30–247, 411–1792, and 361–2333 mg/Nm3, respectively. The above-mentioned blend was identified as the best set-up. The thermal losses were 39.2%, and the CO, NOX, and SO2 concentrations were 11,690, 906, and 1134 mg/Nm3, respectively (the gas concentration values were recalculated for 0% O2). Currently, no other work exists in the literature include a similar analysis performed using a boiler with a comparable thermal output (160.46 kW). The optimal configurations comply with the relevant local legislation. This optimization is important for future emission control strategies relating to using crop residues as a CO2 source. The work also highlights the importance of ensuring a proper boiler set-up for each case considered. [ABSTRACT FROM AUTHOR]

• The molecular composition of Spirulina is discussed. • The effect of incorporating Spirulina into foods is reviewed. • Spirulina is being consumed mainly in cereal-based products and snacks. • Health-benefits of consuming Spirulina are revised and discussed. • Spirulina shows potential for prevent-treat metabolic syndrome. Humans are no strangers to the consumption of microalgae as already in the sixteenth century Spirulina was harvested from Lake Texcoco and consumed in markets in Tenochtitlan (today Mexico City). Nowadays, microalgae are being incorporated into many food formulations. Most of these use microalgae as a marketing strategy or as a colouring agent. However, Spirulina (and compounds derived thereof) show potential for being used as ingredients in the development of novel functional foods, which are one of the top trends in the food industry. Several human intervention studies demonstrated the potential of Spirulina for being used in the prevention or treatment of disorders related to metabolic syndrome. The aim of the current paper was to review current and potential applications of this microalga in the food and functional food industries. Health benefits associated with consuming Spirulina and/or some of the most important compounds derived from Spirulina were also discussed. [ABSTRACT FROM AUTHOR]

The potential use of the microalgae species Tetraselmis and Nannochloropsis was investigated for the production of functional breads and crackers. Optimum flour substitution levels were 2.5% for baked crackers and 1.0 or 2.0% for breads containing Nannochloropsis or Tetraselmis , respectively. No major differences were observed in the physicochemical properties of the end products besides an expected darker and greener colour. Microalgae incorporation led to increased phenolic content and in vitro antioxidant capacity in both matrices. For example, the total phenolic content of crackers increased from 24.6 ± 1.5 mg/100 g in the control to 32.4 ± 0.4 or 34.2 ± 1.0 mg/100 g in crackers containing Tetraselmis or Nannochloropsis , respectively. The amount of bioaccessible polyphenols after a simulated gastrointestinal digestion was also higher in microalgae-containing goods than in the controls. Sensory evaluation showed that microalgae-containing products were competitive with the controls with the added advantage of having an improved nutritional value and a "trendy" ingredient. Moreover, microalgae-containing products showed an increased emission of some volatile compounds such as p-cymene and (Z)-2-heptenal, which are responsible for fresh, citrus, terpenic, woody, and spicy or fatty, oily, and fruity odours, respectively. • Optimum flour substitution levels were 2.5% for crackers and 1–2% for breads. • Microalgae incorporation led to higher phenolic content and antioxidant capacity. • The content of bioaccessible polyphenols was higher in microalgae-containing products. • High acceptability indexes were obtained for both breads and crackers. • The volatile profile of the breads was affected after microalgae incorporation. [ABSTRACT FROM AUTHOR]