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- Antioxidant potential of extracts of Chromochloris zofingiensis cultivated in pilot-scale outdoor tubular photobioreactors under nitrogen limitationPublication . CorrĂȘa, Priscila S.; M. JĂșnior, Wilson G. de; Caetano, NĂdiaChromochloris zofingiensis is known to be able to produce large amounts of astaxanthin and also to coproduce other molecules with antioxidant properties. Outdoor cultivation is the cheapest way for large-scale production; however, the unstable weather conditions can hinder the productivity of the biomass and the target product. The final biomass (0.92 g·Lâ1) and total carotenoids (0.55 mg·gâ1) concentration achieved in outdoor cultivation (i.e., during autumn in Porto, Portugal) had no statistically significant difference compared to control cultivation (i.e., constant temperature, 18 °C, and light intensity, 4000 lx) (1.36 g·Lâ1 and 0.56 mg·gâ1, respectively), however the biomass productivity was about threefold lower. Regarding the antioxidant potential, methanolic extracts from outdoor cultivation presented one of the highest values for radical scavenging ability (44.2 %) and ferrous-ion chelating ability (59.1 %), similarly to the results obtained by ethanolic extracts from indoor cultivation under nitrogen limitation. Highest total antioxidant capacities were observed in ethanolic extracts varying from 120.0 to 185.2 mg GAE·gâ1.
- Increase in antioxidant activity of Nannochloropsis sp. through stress cultivation conditionsPublication . Coimbra, R.S.T.; CorrĂȘa, P:S.; Saraiva, J.A.; Lemos, Ă. T.; Tavares, J.; Caetano, N.S.(Introduction) Nowadays, there is a great demand on the use of microalgae, or their derivatives, as novel foods or food ingredientes. Microalgal supplements provide an optimal solution to balance the diet of people who do not consume fish, promoting a healthy diet and reducing metabolic and aging pathologies with an environmentally and economically sustainable approach (1). The genus Nannochloropsis sp. has a high content of antioxidants, specific vitamins, PUFAs (in particular EPA) and is suitable for intensive culture thus being a good candidate for human consumption (1). This research work was done under the scope of the project NÂș 33784: EXTRATOTECA â High Value Added Microalgae Extracts.
- Microalgae extracts for cosmetic applications: Influence of abiotic stress on their antioxidant potentialPublication . CorrĂȘa, P.S.; Caetano, N.S.(Introduction) As society changes, industries need to make efforts to innovate, keeping up with these opportunities. For instance, the increasingly stringent health, sustainability, and safety requirements have driven the demand for natural and bioactive ingredients to replace synthetic ones in cosmetic formulations. In this regard, microalgae biomass is a rich source of biomolecules (e.g. pigments, lipids, secondary metabolites, among others) to be used for cosmetics and cosmeceuticals purposes. In order to obtain extracts with high antioxidant potential, carotenoids, chlorophylls, and phenolic compounds are biomolecules reported as likely to have a significant impact on antioxidant capacity of microalgae extracts. Carotenoids, for example, are capable of deactivating and trapping free radicals. On the other hand, the antioxidant activity of phenolic compounds is based on the transfer of hydrogen atoms and single electrons. Imposition of abiotic stress (i.e., medium composition, temperature, light irradiation, etc.) can modulate the profile and quantity of the components produced, resulting in extracts with different properties. Chromochloris zofingiensis, for instance, is known as a potential source of a powerful antioxidant, astaxanthin (approximately 50% of total carotenoid content). As for the composition of the culture medium, several compounds have been highlighted for playing an important metabolic role in biomass accumulation and composition, such as nitrate, phosphate, ferrous sulphate, and sodium chloride. Thus, this work aims to evaluate the influence of various cultivation parameters (i.e. culture medium composition, temperature, light irradiation and culture time) on the production of carotenoids, chlorophylls and phenolic compounds and to discuss the contribution of these biomolecules in the antioxidant potential of aqueous and ethanolic extracts of C. zofingiensis.
- Urea as an alternative source of notrogen for microalgae cultivation: Effect on growth and biomass compositionPublication . CorrĂȘa, P.S.; Freitas, M.M.A.; Caetano, N.S.(Excerto introdução) In the present work, C. zofingiensis was cultivated in five different media with respect to nitrogen concentration and source. Higher carotenoids content was observed in biomasses cultivated with higher nitrogen concentration, BBM (U) and BBMSTD, 1.24 and 1.17 mg·g-1, respectively. Moreover, the highest chlorophyll accumulation found in the control condition (10.32 mg·g-1). In contrast, when the nitrogen concentration was reduced, the carotenoids content was almost threefold higher using urea as nitrogen source (0.71 as opposed to 0.22 mg·g-1). Higher lipids accumulation was observed in tenfold nitrogen-reduced media, 45.1 and 40.8 % (BBM (-) and BBM (U-), respectively). Nevertheless, there was no statistical difference between the results of lipids content obtained in NaNO3 and urea media with same nitrogen concentration. Finally, replacing sodium nitrate with urea did not improve the final biomass concentration.
- Microalgae for pigments and cosmeticsPublication . Caetano, NĂdia S.; CorrĂȘa, Priscila S.; Morais JĂșnior, Wilson G. de; Oliveira, Gisela M.; Martins, Antonio A.A.; Branco-Vieira, Monique; Mata, Teresa M.Microalgae are among the most promising cell factories of the near future. Their renewable nature, and ability to rely on photosynthesis to use CO2 or nutrients from wastewater to grow and multiply, make them an emergent source of valuable natural compounds. Although in the past, a few of these microalgae have been known for their value as a source of proteins, carbohydrates, exopolysaccharides, polyunsaturated fatty acids, omega 3 and omega 6 fatty acids, recently they have also been found increasingly important sources of more valuable compounds such as carotenoids, of which astaxanthin, lutein and ÎČ-carotene are of extreme importance in food, feed and cosmeceutical industries, and phycobiliproteins, chlorophylls, that are finding their place in the commercial market. There are still various challenges to be addressed to make sustainable the production of some of these valuable bioproducts. However, the circular economy and the biorefinery approach are at the center of the whole process to make the microalgae-based industry one of the most dynamic, modern and profitable industries. In this chapter it will be presented the potential microalgae sources of these valuable compounds, existing industrial applications, as well as the major ongoing research projects, and their contribution driving the blue bioeconomy.
- Microalgae Biomolecules: Extraction, Separation and Purification MethodsPublication . CorrĂȘa, Priscila S.; Morais JĂșnior, Wilson GalvĂŁo; Martins, AntĂłnio A.; Caetano, NĂdia; Mata, Teresa M.Several microalgae species have been exploited due to their great biotechnological potential for the production of a range of biomolecules that can be applied in a large variety of industrial sectors. However, the major challenge of biotechnological processes is to make them economically viable, through the production of commercially valuable compounds. Most of these compounds are accumulated inside the cells, requiring efficient technologies for their extraction, recovery and purification. Recent improvements approaching physicochemical treatments (e.g., supercritical fluid extraction, ultrasound-assisted extraction, pulsed electric fields, among others) and processes without solvents are seeking to establish sustainable and scalable technologies to obtain target products from microalgae with high efficiency and purity. This article reviews the currently available approaches reported in literature, highlighting some examples covering recent granted patents for the microalgaeâs components extraction, recovery and purification, at small and large scales, in accordance with the worldwide trend of transition to bio-based products.
- Exploring the antioxidant potential of Lobosphaera sp. and Odontella sp. biomasses under different extraction and preservation conditionsPublication . CorrĂȘa, P.S.; Coimbra, R.S.T.; Caetano, N.S.Microalgae has aroused academic and industrial interest due to the great variety of biomolecules present in their biomasses, in addition to other products released to the extracellular medium during cultivation [1]. Lobosphaera sp. is a freshwater green alga known to accumulate large amounts of polyunsaturated fatty acids (PUFAs), especially arachidonic acid (ARA, Ï-6) [2]. In contrast, Odontella sp. is a marine diatom that has been reported as a potential source of fucoxanthin and eicosapentaenoic acid (EPA, Ï-3). Also producing chrysolaminarin (ÎČ-1,3-glucan) as a storage polysaccharide, which has a high capacity to scavenge hydroxyl radicals [3]. Nevertheless, other antioxidants can be obtained through ethanolic extraction of some polar compounds (e.g., phenols, flavonoids, chlorophylls) [4]. Under specific conditions Lobosphaera sp. and Odontella sp. were able to produce extracts with considerable amounts of phenolic compounds, 11.5 and 20.9 mg GAE·g-1, respectively. Interestingly, studies have suggested that phenolic compounds have the main effect on total antioxidant activity when compared to carotenoids and tocopherols, for example [5,6]. Finally, the ferrous-ion chelating ability (FICA) and DPPHâą radical scavenging activity (RSA) of ethanolic extracts obtained from these genera were also investigated, varying from 43 to 60 % and 1 to 9 %, respectively.
- Acid pretreatment of sugarcane biomass to obtain hemicellulosic hydrolisate rich in fermentable sugarPublication . Morais JĂșnior, Wilson GalvĂŁo; Pacheco, ThĂĄlyta F.; CorrĂȘa, Priscila S.; Martins, AntĂłnio A.; Mata, Teresa M.; Caetano, NĂdiaThe objective of this work was to find the ideal pretreatment conditions with high efficiency to obtain a hydrolyzate rich in fermentable sugars and low possible inhibitors levels. Thus, it was applied diluted phosphoric acid to pretreat the sugarcane biomass. Through a Central Composite Design, it was evaluated the influence of temperature, operating time and acid concentration. The pretreatment efficiency was verified by the concentration of total monosaccharides in the liquid fraction after the reaction. The phosphoric acid concentration of 4.95% at 80 °C, during 375 min, resulted in a hemicellulosic hydrolyzate with the highest concentration of fermentable sugars (saccharification greater than 99%), with the absence of HMF and furfural, and relatively low amounts of acetic acid.
- Avaliação de extratos de microalgas para potencial aplicação em alimentos funcionaisPublication . CorrĂȘa, P.S.; Freitas, M.M.A.; Caetano, N.S.(Introdução) Microalgas sĂŁo micro-organismos fotossintĂ©ticos, que para alĂ©m de servirem como fonte de proteĂnas, tambĂ©m sĂŁo capazes de produzir uma gama de compostos bioativos, tais como, pigmentos, lĂpidos e compostos fenĂłlicos. Tais caracterĂsticas as tornam bastante promissoras para aplicação de suas biomassas em alimentos funcionais (Pina-PĂ©rez et al., 2019). De modo geral, os alimentos funcionais alĂ©m de terem elevado valor nutricional, tambĂ©m trazem algum benefĂcio Ă saĂșde. Chromochloris zofingiensis, Koliella longiseta e Schizomeris leibleinii sĂŁo microalgas de ĂĄgua doce, relativamente pouco estudadas na literatura, mas potencialmente interessantes para produção de carotenoides, lĂpidos e compostos fenĂłlicos (Fogliano et al., 2010; Zhang et al., 2021). A imposição de condiçÔes de estresse abiĂłtico (i.e. variação na concentração de determinado nutriente no meio de cultivo, temperature, pH, etc.), Ă© uma das estratĂ©gias mais utilizadas para induzir uma maior produção de determinado composto de interesse (Suparmaniam et al., 2024). Desta forma, este trabalho se propĂŽs a estudar o impacte de diferentes condiçÔes de cultivo na produção de carotenoides, clorofilas, lĂpidos e compostos fenĂłlicos. AlĂ©m disso, foram produzidos extratos em solventes diferentes (i.e. ĂĄgua e etanol) e testado o potencial antioxidante de cada um.
- LCA: A tool to develop sustainable microalgal biorefineriesPublication . Caetano, N.S.; CorrĂȘa, P.S.; Morais JĂșnior, W. G.; Mata, T.M.; Martins, A.A.A.; Branco Vieira, M.Microalgae biorefineries, similar to oil refineries, are planned to exploit and maximize the value of microalgae biomass, producing as many products as possible. The biorefinery flowsheet can take different configurations, depending on the target products and the technologies to be applied. Due to the diversity of microalgae composition and strain phenotypic plasticity, some constraints can be faced for choosing the ideal candidate species. However, there are several alternatives to explore the potentiality of a strain that can make the biorefinery economically viable, environmentally friendly, and socially acceptable. Life cycle assessment (LCA) is a tool that allows evaluating the environmental impacts of a product, process, or system, and should be used to assess the environmental performance of a planned biorefinery. When combined with life cycle costing (LCC) evaluation and social life cycle assessment (S-LCA), LCA allows to take informed decisions on the most adequate biorefinery to implement. Nevertheless, and although many of the processes used in microalgae-based biorefineries are common to those used in other well-established industries, the biorefinery is an emerging area where usually novel technologies are required, some of them applied only on a pilot or a laboratory scale, making the available data limited or highly sensitive to variations. This chapter discusses the application of LCA to biorefineries, the potential hurdles, and limitations.