Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

With the aim to find new polysaccharides of rheological interest with innovated properties, rhamnofucans produced as exopolysaccharides (EPS) in a photobioreactor (PBR) and an airlift bioreactor (ABR) by the marine microalgae Glossomastix sp. RCC3707 and RCC3688 were fully studied. Chemical characterizations have been conducted (UHPLC - MS HR). Analyses by size-exclusion chromatography (SEC) coupled online with a multiangle light scattering detector (MALS) and a differential refractive index detector showed the presence of large structures with molar masses higher than 106 g.mol-1. The rheological studies of these EPS solutions, conducted at different concentrations and salinities, have evidenced interesting and rare behavior characteristic of weak and fragile hydrogels i.e. gel behavior with very low elastic moduli (between 10-2 and 10 Pa) and yield stresses (between 10-2 and 2 Pa) according to the EPS source, concentration, and salinity. These results were confirmed by diffusing wave spectroscopy. Finally, as one of potential application, solutions of EPS from Glossomastix sp. have evidenced very good properties as anti-settling stabilizers, using microcrystalline cellulose particles as model, studied by multiple light scattering (MLS) with utilization in cosmetic or food industry. Compared to alginate solution with same viscosity for which sedimentation is observed over few hours, microalgae EPS leads to a stable suspension over few days.

Sustainable microalgal biomass as a potential functional food and its applications in food industry: a comprehensive review

Microalgae (MA) are the most abundant seaweeds with high nutritional properties. They are accepted as potential biocatalysts for the bioremediation of wastewater. They are widely used in food, feed, and biofuel industries and can potentially be food for future generations. MA-based purification of wastewater technology could be a universal alternative solution for the recovery of resources from wastewater for low-cost biomass feedstock for industry. They provide a wide range of functional components, viz. omega-3 fatty acids, along with a plenteous number of pigments such as ß-carotene, astaxanthin, lutein, phycocyanin, and chlorophyll, which are used extensively as food additives and nutraceuticals. Further, proteins, lipids, vitamins, and carbohydrates are described as nutritional characteristics in MA. They are investigated as single-cell protein, thickening/stabilizing agents, and pigment sources in the food industry. The review emphasizes the production and extraction of nutritional and functional components of algal biomass and the role of microalgal polysaccharides in digestion and nutritional absorption in the gastrointestinal tract. Further, the use of MA in the food industry was also investigated along with their potential therapeutic applications.

Challenges in Functional Food Products with the Incorporation of Some Microalgae

Much attention has been given to the use of microalgae to produce functional foods that have valuable bioactive chemicals, including essential amino acids, polyunsaturated fatty acids, vitamins, carotenoids, fiber, and minerals. Microalgal biomasses are increasingly being used to improve the nutritional values of foods because of their unique nutrient compositions that are beneficial to human health. Their protein content and amino acid composition are the most important components. The microalgal biomass used in the therapeutic supplement industry is dominated by bio-compounds like astaxanthin, β-carotene, polyunsaturated fatty acids like eicosapentaenoic acid and docosahexaenoic acid, and polysaccharides such as β-glucan. The popularity of microalgal supplements is growing because of the health benefits of their bioactive substances. Moreover, some microalgae, such as Dunaliella, Arthrospira (Spirulina), Chlorella, and Haematococcus, are commonly used microalgal species in functional food production. The incorporation of microalgal biomass leads not only to enhanced nutritional value but also to improved sensory quality of food products without altering their cooking or textural characteristics. Microalgae, because of their eco-friendly potential, have emerged as one of the most promising and novel sources of new functional foods. This study reviews some recent and relevant works, as well as the current challenges for future research, using different methods of chemical modification in foods with the addition of a few commercial algae to allow their use in nutritional and sensory areas. It can be concluded that the production of functional foods through the use of microalgae in foods has become an important issue.

A novel co-metabolic mode with Spirulina powder in enhancing the anaerobic degradation of typical nitrogen heterocyclic compounds

Spirulina powder emerged as a novel and suitable co-metabolism substance significantly enhancing the anaerobic degradation of specific nitrogen heterocyclic compounds. On the addition of 1.0 mg/L of Spirulina powder, the reactor demonstrated optimal degradation efficiency for quinoline and indole, achieving ratios of 99.77 ± 1.83% and 99.57 ± 1.98%, respectively. Moreover, the incorporation of Spirulina powder resulted in increased concentrations of mixed liquor suspended solids, mixed liquor volatile suspended solids, proteins, and polysaccharides in anaerobic sludge. In addition, Spirulina powder led to reduced levels of Acinetobacter and enriched Aminicenantes genera incertae sedis, Levilinea, and Longilinea. The analysis of the archaeal community structure confirmed that the addition of Spirulina powder increased archaeal sequences, fostering greater richness and diversity in the archaeal community.

Neuroprotection of Truncated Peptide IIAVE from Isochrysis zhanjiangensis: Quantum Chemical, Molecular Docking, and Bioactivity Studies

Parkinson's disease (PD) is a progressive neurodegenerative disorder of the elderly for which there is no cure or disease-modifying therapy. Mitochondrial dysfunction and oxidative stress play a central role in dopaminergic neurodegeneration in PD. Therefore, antioxidants are considered a promising neuroprotective approach. In in vivo activity studies, 6-OHDA-induced oxidative stress in SH-SY5Y cells was established as a model of PD for cellular experiments. IIAVE (Ile-Ile-Ala-Val-Glu) was derived from Isochrysis zhanjiangensis octapeptide (IIAVEAGC), which has a small molecular weight. The structure and antioxidant activity of IIAVE were tested in a previous study and proved to have good antioxidant potential. In this study, the chemical properties of IIAVE were calculated using quantum chemical methods, including frontier molecular orbital (FMO), molecular electrostatic potential (MEP), natural population analysis (NPA), and global reactivity properties. The interaction of IIAVE with Bcl-2 and DJ-1 was investigated using the molecular docking method. The results showed that IIAVE promoted the activation of the Keap1/Nrf2 pathway and up-regulated the expression of the superoxide dismutase 1 (SOD-1) protein by inhibiting the level of reactive oxygen species (ROS) in cells. In addition, IIAVE inhibits ROS production and prevents 6-OHDA-induced oxidative damage by restoring mitochondrial membrane potential. Furthermore, IIAVE inhibited cell apoptosis by increasing the Bcl-2/Bax ratio and inhibiting the activation of Caspase-9 and Caspase-3. Thus, IIAVE may become a potential drug for the treatment and prevention of PD.

The potential, challenges, and prospects of the genus Spirulina polysaccharides as future multipurpose biomacromolecules

Spirulina has been widely used worldwide as a food and medicinal ingredient for centuries. Polysaccharides are major bioactive constituents of Spirulina and are of interest because of their functional properties and unlimited application potential. However, the clinical translation and market industrialization of the polysaccharides from genus Spirulina (PGS) are retarded due to the lack of a further understanding of their isolation, bioactivities, structure-activity relationships (SARs), toxicity, and, most importantly, versatile applications. Herein, we provide an overview of the extraction, purification, and structural features of PGS; meanwhile, the advances in bioactivities, SARs, mechanisms of effects, and toxicity are discussed and summarized. Furthermore, the applications, potential developments, and future research directions are scrutinized and highlighted. This review may help fill the knowledge gap between theoretical insights and practical applications and guide future research and industrial application of PGS.

Legal Aspects of Microalgae in the European Food Sector

The interest in microalgae as food in Europe is growing due to its remarkable features that can foster a sustainable economy. The lack of tradition on their use among Europeans is changing and a demand for more sustainable products is increasing. The legal framework from the microalgae stakeholders' point of view has been consistently identified as a bottleneck, regardless of its nutritional value and potential to provide added-value metabolites. Microalgae-based products have been mostly consumed as food supplements, which are characterized by some general uncertainty with regards to food security of products sourced from non-European countries. The novel foods regulation is a landmark in Europe's food law defining the conditions in which a new type of food can be commercialized. Currently, a more simplified and centralized version is in place, and around eleven microalgae-based products are on the market; however, more than half are represented by Schizochytrium sp. derived products (DHA-rich oil). Microalgae have immense potential as a sustainable food source; nonetheless, there is limited experience in assessing the safety of these microorganisms, considering the uncertainty around undesirable substances present in the way they are produced and their diverse metabolites. Here, we overview the regulatory use of microalgae as food in Europe with a focus on market introduction, highlighting the administrative procedures and scientific requirements to assess food safety. We also discuss the implications of the Transparency regulation related to microalgae as novel foods and provide considerations for a more solid interaction between academia and industry.

Resolving the dynamics of chrysolaminarin regulation in a marine diatom: A physiological and transcriptomic study

Diatom containing different active biological macromolecules are thought to be an excellent microbial cell factory. Phaeodactylum tricornutum, a model diatom, is a superb chassis organism accumulating chrysolaminarin with important bioactivities. However, the characteristic of chrysolaminarin accumulation and molecular mechanism of the fluctuated chrysolaminarin in diatom are still unknown. In this study, physiological data and transcriptomic analysis were carried out to clarify the mechanism involved in chrysolaminarin fluctuation. The results showed that chrysolaminarin content fluctuated, from 7.41 % dry weight (DW) to 40.01 % DW during one light/dark cycle, increase by day and decrease by night. The similar fluctuated characteristic was also observed in neutral lipid content. Genes related to the biosynthesis of chrysolaminarin and neutral lipid were up-regulated at the beginning of light-phase, explaining the accumulation of these biological macromolecules. Furthermore, genes involved in carbohydrate degradation, cell cycle, DNA replication and mitochondria-localized β-oxidation were up-regulated at the end of light phase and at the beginning of dark phase hinting an energy transition of carbohydrate to cell division during the dark period. Totally, our findings provide important information for the regulatory mechanism in the diurnal fluctuation of chrysolaminarin. It would also be of great help for the mass production of economical chrysolaminarin in marine diatom.

Determination of nine bioactive phenolic components usually found in apple juice by simultaneous UPLC-MS/MS

The functional food ingredients of apple juice can significantly change during processing, transportation, and storage, thus affecting the quality of the product. A simple and derivation-free analytical method based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed and optimized for the simultaneous determination of functional food ingredients in apple juice bought in the market. Cleanup steps and chromatographic conditions were optimized to remove interference and decrease the matrix effect. The nine target analytes were separated on an Acquity UPLC system equipped with a BEH C18 column and detected by electrospray ionization source (ESI) operating in positive subsection acquisition mode under multiple reaction monitoring (MRM) conditions. The results showed that p-hydroxybenzoic acid, protocatechuate, caffeic acid, chlorogenic acid, epicatechin, phloridzin, hyperoside, procyanidin B₂, and rutin could be sufficiently separated for content determination within 6 min. In the concentration range of 20 μg/L-50 mg/L, nine standard samples exhibited a good linear fit with correlation coefficients above .985.

Study on bioactive compounds of microalgae as antioxidants in a bibliometric analysis and visualization perspective

Natural antioxidants are more attractive than synthetic chemical oxidants because of their non-toxic and non-harmful properties. Microalgal bioactive components such as carotenoids, polysaccharides, and phenolic compounds are gaining popularity as very effective and long-lasting natural antioxidants. Few articles currently exist that analyze microalgae from a bibliometric and visualization point of view. This study used a bibliometric method based on the Web of Science Core Collection database to analyze antioxidant research on bioactive compounds in microalgae from 1996 to 2022. According to cluster analysis, the most studied areas are the effectiveness, the antioxidant mechanism, and use of bioactive substances in microalgae, such as carotene, astaxanthin, and tocopherols, in the fields of food, cosmetics, and medicine. Using keyword co-occurrence and keyword mutation analysis, future trends are predicted to improve extraction rates and stability by altering the environment of microalgae cultures or mixing extracts with chemicals such as nanoparticles for commercial and industrial applications. These findings can help researchers identify trends and resources to build impactful investigations and expand scientific frontiers.

Structural properties of the extracellular biopolymer (β-D-xylo-α-D-mannan) produced by the green microalga Gloeocystis vesiculosa Nägeli

Many species of microalgae produce a relatively diverse range of metabolites that are interesting for biotechnological applications, and among them exopolysaccharides attract attention due to their structural complexity, biological activities, biodegradability or biocompatibility. An exopolysaccharide of high molecular weight (M_p) of 6.8 × 10⁵ g/mol was obtained by cultivation of the freshwater green coccal microalga Gloeocystis vesiculosa Nägeli 1849 (Chlorophyta). Chemical analyses revealed a dominance of Manp (63.4 wt%), Xylp and its 3-O-Me-derivative (22.4 wt%), and Glcp (11.5 wt%) residues. The results of the chemical and NMR analyses showed an alternating branched 1,2- and 1,3-linked α-D-Manp backbone terminated by a single β-D-Xylp and its 3-O-methyl derivative at O2 of the 1,3-linked α-D-Manp residues. The α-D-Glcp residues were found mainly as 1,4-linked and to a lesser extent as the terminal sugar, indicating partial contamination of β-D-xylo-α-D-mannan with amylose (∼10 wt%) in G. vesiculosa exopolysaccharide.

Bioprocessing to Preserve and Improve Microalgae Nutritional and Functional Potential: Novel Insight and Perspectives

Microalgae are aquatic unicellular microorganisms and, although various species are approved for human consumption, Arthrospira and Chlorella are the most widespread. Several nutritional and functional properties have been bestowed to microalgae principal micro- and macro-nutrients, with antioxidant, immunomodulatory and anticancer being the most common. The many references to their potential as a food of the future is mainly ascribed to the high protein and essential amino acid content, but they are also a source of pigments, lipids, sterols, polysaccharides, vitamins, and phenolic compounds with positive effects on human health. Nevertheless, microalgae use is often hindered by unpleasant color and flavor and several strategies have been sought to minimize such challenges. This review provides an overview of the strategies so far proposed and the main nutritional and functional characteristic of microalgae and the foods made thereof. Processing treatments have been used to enrich microalgae-derived substrates in compounds with antioxidant, antimicrobial, and anti-hypertensive properties. Extraction, microencapsulation, enzymatic treatments, and fermentation are the most common, each with their own pros and cons. Yet, for microalgae to be the food of the future, more effort should be put into finding the right pre-treatments that can allow the use of the whole biomass and be cost-effective while bringing about features that go beyond the mere increase of proteins.

Bioaccessibility and Bioavailability of Diet Polyphenols and Their Modulation of Gut Microbiota

It is generally accepted that diet-derived polyphenols are bioactive compounds with several potentially beneficial effects on human health. In general, polyphenols have several chemical structures, and the most representative are flavonoids, phenolic acids, and stilbenes. It should be noted that the beneficial effects of polyphenols are closely related to their bioavailability and bioaccessibility, as many of them are rapidly metabolized after administration. Polyphenols-with a protective effect on the gastrointestinal tract-promote the maintenance of the eubiosis of the intestinal microbiota with protective effects against gastric and colon cancers. Thus, the benefits obtained from dietary supplementation of polyphenols would seem to be mediated by the gut microbiota. Taken at certain concentrations, polyphenols have been shown to positively modulate the bacterial component, increasing Lactiplantibacillus spp. and Bifidobacterium spp. involved in the protection of the intestinal barrier and decreasing Clostridium and Fusobacterium, which are negatively associated with human well-being. Based on the diet-microbiota-health axis, this review aims to describe the latest knowledge on the action of dietary polyphenols on human health through the activity of the gut microbiota and discusses micro-encapsulation of polyphenols as a strategy to improve the microbiota.

Developing algae as a sustainable food source

Current agricultural and food production practices are facing extreme stress, posed by climate change and an ever-increasing human population. The pressure to feed nearly 8 billion people while maintaining a minimal impact on the environment has prompted a movement toward new, more sustainable food sources. For thousands of years, both the macro (seaweed and kelp) and micro (unicellular) forms of algae have been cultivated as a food source. Algae have evolved to be highly efficient at resource utilization and have proven to be a viable source of nutritious biomass that could address many of the current food production issues. Particularly for microalgae, studies of their large-scale growth and cultivation come from the biofuel industry; however, this knowledge can be reasonably translated into the production of algae-based food products. The ability of algae to sequester CO₂ lends to its sustainability by helping to reduce the carbon footprint of its production. Additionally, algae can be produced on non-arable land using non-potable water (including brackish or seawater), which allows them to complement rather than compete with traditional agriculture. Algae inherently have the desired qualities of a sustainable food source because they produce highly digestible proteins, lipids, and carbohydrates, and are rich in essential fatty acids, vitamins, and minerals. Although algae have yet to be fully domesticated as food sources, a variety of cultivation and breeding tools exist that can be built upon to allow for the increased productivity and enhanced nutritional and organoleptic qualities that will be required to bring algae to mainstream utilization. Here we will focus on microalgae and cyanobacteria to highlight the current advancements that will expand the variety of algae-based nutritional sources, as well as outline various challenges between current biomass production and large-scale economic algae production for the food market.

Response surface optimization of light conditions for organic matter accumulation in two different shapes of Arthrospira platensis

Arthrospira platensis has attracted wide attention as a cyanobacteria with high nutritional value. In this research, the response surface method was used to study the effects of light cycle, light intensity and red-blue LED conditions on the growth and organic matter accumulation in spiral shaped strain A. platensis OUC623 and linear shaped strain A. platensis OUC793. The light conditions suitable for A. platensis OUC623 were as follows: growth (light time 12.01 h, light intensity 35.64 μmol/m2s, LED red: blue = 6.38:1); chlorophyll a (light time 12.75 h, light intensity 31.06 μmol/m2s, red: blue = 6.25:1); carotenoid (light time 13.12 h, light intensity 32.25 μmol/m2s, red: blue = 5.79:1); polysaccharide (light time 16.00 h, light intensity 31.32 μmol/m2s, blue: red = 6.24:1); protein (light time 12.18 h, light intensity 6.12 μmol/m2s, blue: red = 7.95:1); phycocyanin (light time12.00 h, light intensity 5.00 μmol/m2s, blue: red = 8.00:1). The light conditions suitable for A. platensis OUC793 were as follows: growth (light time 13.52 h, light intensity 40.22 μmol/m2s, red: blue = 5.98:1); chlorophyll a (light time 14.22 h, light intensity 44.96 μmol/m2s, red: blue = 5.94:1); carotenoid (light time 14.13 h, light intensity 44.50 μmol/m2s, red: blue = 6.02:1); polysaccharide (light time 16.00 h, light intensity 31.85 μmol/m2s, blue: red = 6.08:1); protein (light time12.00 h, light intensity 5.00 μmol/m2s, blue: red = 8.00:1); phycocyanin (light time12.01 h, light intensity 5.01 μmol/m2s, blue: red = 8.00:1). Under the theoretical optimal light conditions, compared with white LED, the growth rate, chlorophyll a, carotenoid, phycocyanin, protein and polysaccharide contents in strain 623 increased by 91.67%, 114.70%, 85.05%, 563.54%, 386.14%, 201.18%, and in strain 793 increased by 75.00%, 150.94%, 113.43%, 427.09%, 1284.71%, 312.38%, respectively. The two strains showed different advantages. Growth rate, chlorophyll a, polysaccharide, protein and phycocyanin content of strain 623 were higher than those of strain 793, while carotenoid was higher in strain 793. After optimization, both strains could reach a good growth state, and the growth rate and organic matter content were close. And then a 20 L photobioreactor was used to expand the culture of the two strains, validating the theoretical optimal light conditions of response surface method. This study laid the foundation for the establishment of optical conditions for organic matter accumulation in two different strains of A. platensis, which provided more options for meeting the industrialization needs of A. platensis.

Spirulina platensis Suppressed iNOS and Proinflammatory Cytokines in Lipopolysaccharide-Induced BV2 Microglia

The disease burden of neurodegenerative diseases is on the rise due to the aging population, and neuroinflammation is one of the underlying causes. Spirulina platensis is a well-known superfood with numerous reported bioactivities. However, the effect of S. platensis Universiti Malaya Algae Culture Collection 159 (UMACC 159) (a strain isolated from Israel) on proinflammatory mediators and cytokines remains unknown. In this study, we aimed to determine the anti-neuroinflammatory activity of S. platensis extracts and identify the potential bioactive compounds. S. platensis extracts (hexane, ethyl acetate, ethanol, and aqueous) were screened for phytochemical content and antioxidant activity. Ethanol extract was studied for its effect on proinflammatory mediators and cytokines in lipopolysaccharide (LPS)-induced BV2 microglia. The potential bioactive compounds were identified using liquid chromatography-mass spectrometric (LC-MS) analysis. Ethanol extract had the highest flavonoid content and antioxidant and nitric oxide (NO) inhibitory activity. Ethanol extract completely inhibited the production of NO via the downregulation of inducible NO synthase (iNOS) and significantly reduced the production of tumor necrosis factor (TNF)-α and interleukin (IL)-6. Emmotin A, palmitic amide, and 1-monopalmitin, which might play an important role in cell signaling, have been identified. In conclusion, S. platensis ethanol extract inhibited neuroinflammation through the downregulation of NO, TNF-α and IL-6. This preliminary study provided insight into compound(s) isolation, which could contribute to the development of precision nutrition for disease management.

Bioactive Compounds from Red Microalgae with Therapeutic and Nutritional Value

Red microalgae represent a natural reservoir of beneficial substances with applications in different industrial sectors. They are rich in natural biomolecules known for their antihypertensive, antioxidant, antimicrobial, antiviral, anti-inflammatory, antitumor, and anticoagulant activities. Many red microalgae are a source of vitamins, minerals, photochemicals, polyunsaturated fatty acids, and a wide spectrum of polysaccharides. The content of their valuable compounds and their activities have turned red microalgae into cellular factories of special interest in food, nutraceutical, and pharmaceutical industries. Like all microalgae, the red ones are superior to traditional crops for the aims of biotechnology as they are renewable sources widely available in great quantities and are easy to culture. Moreover, some of the most studied red microalgae are generally recognized as safe. This review summarizes the valuable biochemicals from red microalgae and highlights their health and nutritional benefits.

Regulation of Cholesterol Metabolism by Phytochemicals Derived from Algae and Edible Mushrooms in Non-Alcoholic Fatty Liver Disease

Cholesterol synthesis occurs in almost all cells, but mainly in hepatocytes in the liver. Cholesterol is garnering increasing attention for its central role in various metabolic diseases. In addition, cholesterol is one of the most essential elements for cells as both a structural source and a player participating in various metabolic pathways. Accurate regulation of cholesterol is necessary for the proper metabolism of fats in the body. Disturbances in cholesterol homeostasis have been linked to various metabolic diseases, such as hyperlipidemia and non-alcoholic fatty liver disease (NAFLD). For many years, the use of synthetic chemical drugs has been effective against many health conditions. Furthermore, from ancient to modern times, various plant-based drugs have been considered local medicines, playing important roles in human health. Phytochemicals are bioactive natural compounds that are derived from medicinal plants, fruit, vegetables, roots, leaves, and flowers and are used to treat a variety of diseases. They include flavonoids, carotenoids, polyphenols, polysaccharides, vitamins, and more. Many of these compounds have been proven to have antioxidant, anti-inflammatory, antiobesity and antihypercholesteremic activity. The multifaceted role of phytochemicals may provide health benefits to humans with regard to the treatment and control of cholesterol metabolism and the diseases associated with this disorder, such as NAFLD. In recent years, global environmental climate change, the COVID-19 pandemic, the current war in Europe, and other conflicts have threatened food security and human nutrition worldwide. This further emphasizes the urgent need for sustainable sources of functional phytochemicals to be included in the food industry and dietary habits. This review summarizes the latest findings on selected phytochemicals from sustainable sources-algae and edible mushrooms-that affect the synthesis and metabolism of cholesterol and improve or prevent NAFLD.

Freshwater Microalgae as Promising Food Sources: Nutritional and Functional Properties

A number of researchers have predicted that the current food crisis is predicted to worsen in 2050. The prediction of this crisis is aligned with climate change causing increases in some basic foodstuff prices. Therefore, everyone should prepare to consume alternative foods at an early stage. Alternative foods have been widely developed, one of which involves microalgae. However, the type of microalgae produced by some countries on a large scale consists of only oceanic/seawater microalgae. This will have an impact on and hinder development in countries that do not have these resources. Therefore, it is necessary to explore the use of microalgae derived from freshwater. Unfortunately, freshwater microalgae are still rarely investigated for use as alternative foods. However, there is considerable potential to utilize freshwater microalgae, and these algae are very abundant and diverse. In terms of nutritional properties, compared to oceanic / seawater microalgae, freshwater microalgae contain nearly the same protein and amino acids, lipids and fatty acids, carbohydrates, and vitamins. There are even more species whose composition is similar to those currently consumed foods, such as beef, chicken, beans, eggs, and corn. In addition to dietary properties, freshwater microalgae also have functional properties, due to the presence of pigments, sterols, fatty acids, and polyphenols. Given the potential of freshwater microalgae, these aquatic resources need to be developed for potential use as future food resources.

How Microalgae is Effective in Oxygen Deficiency Aggravated Diseases? A Comprehensive Review of Literature

Hypoxia can aggravate the conditions of many oxygen-deficiency-aggravated diseases (ODAD), such as cancer, ischemic heart disease, and chronic wounds. Photosynthetic microalgae can alleviate the hepatotoxicity of the local microenvironment by producing oxygen. In addition, microalgae extracts have antitumor, anti-inflammatory, antibacterial, and antioxidant effects. These properties make them attractive candidates for developing methods to treat ODAD. Although researchers have exploited the advantages of microalgae and developed a variety of microalgae-based biomaterials to treat ODAD, a comprehensive review of this topic has not been presented previously. Therefore, in this review, we summarize the development and progress made in the field of developing microalgae-based biomaterials toward the treatment of ODAD. The challenges and prospects of this field are also discussed.

A Water Extract from Chlorella sorokiniana Cell Walls Stimulates Growth of Bone Marrow Cells and Splenocytes

A water extract derived from the isolated cell walls of Chlorella sorokiniana (C. sorokiniana, Chlorella water extract, CWE) was analyzed for the presence of lipopolysaccharide (LPS)-related material via the Limulus amebocyte lysate (LAL) assay and evaluated for its growth stimulation effect on the bone marrow cells and splenocytes in vitro cell cultures. The extract contained low levels of LPS-related material, and a mass spectrum suggested that the extract contained many components, including a low level of a lipid A precursor, a compound known as lipid X, which is known to elicit a positive response in the LAL assay. Treatment with the CWE dose- and time-dependently stimulated the growth of mouse bone marrow cells (BMCs) and splenocytes (SPLs). Treatment with the CWE also increased specific BMC subpopulations, including antigen-presenting cells (CD19⁺ B cells, 33D1⁺ dendritic cells and CD68⁺ macrophages), and CD4⁺ and CD8⁺ T cells, but decreased the number of LY6G⁺ granulocytes. Treatment with the CWE also increased cytokine mRNA associated with T cell activation, including TNFα, IFNγ, and granzyme B in human lymphoblasts. The present study indicates that the cell wall fraction of C.sorokiniana contains an LPS-like material and suggests a candidate source for the bioactivity that stimulates growth of both innate and adaptive immune cells.

Methodological Optimization of Supercritical Fluid Extraction of Valuable Bioactive Compounds from the Acidophilic Microalga Coccomyxa onubensis

Microalgae grow in diverse environments and possess a great biotechnological potential as they contain useful bioactive compounds. These bioactive compounds can be obtained by selective and energy-efficient extraction methods. Various industries are using the supercritical fluid extraction (SFE) method to extract these valuable bioactive compounds. Hence, for the first time, we evaluated the effects of SFE on the recovery of bioactive and antioxidant compounds using Coccomyxa onubensis, a eukaryotic acidophilic microalga of potential relevance which can be used in the field of nutraceutical and functional foods. It was isolated from the Tinto River (Pyritic Belt, Huelva, Spain), a mining region in Spain. Variables such as extraction yield, lutein purity (LP) and recovery (LR), total phenols, and antioxidant capacity (Trolox equivalents antioxidant capacity method) were studied using a Box–Behnken design based on a response surface methodology along with the overall extraction curve fitted to a spline linear model. The effects of temperature (30, 50, and 70 °C), pressure (25, 40, and 55 MPa), and the percentage of co-solvent (0, 25%, and 50% v/v ethanol) on SFE were analyzed, resulting in the co-solvent and temperature as the most significant factors followed by the pressure. Under 70 °C, 40 MPa, and 50% v/v ethanol, C. onubensis reached a maximum of 66.98% of LR. The extracts were richest in total phenols and showed the maximum antioxidant activity (36.08 mg GAEs/g extracts and 2.237 mmol TE/g extracts, respectively) under similar pressure and co-solvent percentage values and different temperatures (30 and 70 °C, respectively). The extracts obtained in this study may have potential applications in the food, nutraceutical, and cosmetic industries. SFE is a highly efficient method to valorize microorganisms living in extreme environments, which are so far unexplored using green extraction methods.

Inertia-Acoustophoresis Hybrid Microfluidic Device for Rapid and Efficient Cell Separation

In this paper, we proposed an integrated microfluidic device that could demonstrate the non-contact, label-free separation of particles and cells through the combination of inertial microfluidics and acoustophoresis. The proposed device integrated two microfluidic chips which were a PDMS channel chip on top of the silicon-based acoustofluidic chip. The PDMS chip worked by prefocusing the particles/cells through inducing the inertial force of the channel structure. The connected acoustofluidic chips separated particles based on their size through an acoustic radiation force. In the serpentine-shaped PDMS chip, particles formed two lines focusing in the channel, and a trifugal-shaped acoustofluidic chip displaced and separated particles, in which larger particles focused on the central channel and smaller ones moved to the side channels. The simultaneous fluidic works allowed high-efficiency particle separation. Using this novel acoustofluidic device with an inertial microchannel, the separation of particles and cells based on their size was presented and analyzed, and the efficiency of the device was shown. The device demonstrated excellent separation performance with a high recovery ratio (up to 96.3%), separation efficiency (up to 99%), and high volume rate (>100 µL/min). Our results showed that integrated devices could be a viable alternative to current cell separation based on their low cost, reduced sample consumption and high throughput capability.

Polysaccharide from Spirulina platensis Evokes Antitumor Activity in Gastric Cancer Cells via Modulation of Galectin-3 and Exhibited Cyto/DNA Protection: Structure-Function Study

Polysaccharides play significant role in the management of different cancer types including gastric cancer. Here, we report the effect of spirulina polysaccharide (Sp) on galectin-3 modulatory activity in gastric cancer cells (AGS). The isolated Sp possessed an average molecular weight of 1457 kDa and galactose (42%) as a major sugar consisting of (β1-4d) units with a galactoarabinorhamnoglycan backbone. The Sp inhibited the proliferation of AGS cells by 48% without affecting normal NIH/3T3 cells as compared to doxorubicin, a known anticancer drug. Also, Sp exhibited significant (p < 0.05) galectin-3 mediated hemeagglutination inhibition with MIC of 9.37 μg/mL compared to galactose (6.25 μg/mL), a sugar specific to galectin-3. Galactose showed the highest molecular interaction with galectin-3 in the in silico study. In addition, Sp exhibited the cytoprotection in RBCs, buccal cells, and DNA exposed to oxidants. These findings suggest that Sp offers a promising therapeutic tool in the management of gastric cancer.

Structural features of biologically active extracellular polysaccharide produced by green microalgae Dictyosphaerium chlorelloides

Ion-exchange chromatography of the biologically active extracellular biopolymer produced by D. chlorelloides yielded ten fractions differing in yield, protein content, monosaccharide composition and molecular weight distribution. Their sugar compositional analyses showed rhamnogalactans, substituted to different extent by mannose and glucose, as a dominant EPS component in all fractions (91 %) except one containing arabinogalactan (7 %). In highly branched rhamnogalactans the quantity of linear (1,3-; 1,4- and 1,6-linked) and branched β-D-galactose units (1,3,6-, 1,4,6- and 1,3,4,6-linked) was nearly equal. From various α-L-rhamnose linkages the 1,2,4-linkage was dominant. Data indicate a rhamnogalactan backbone of EPS, branched by terminal mannose and glucose units, and a lot of O-methylated derivatives of galactose residues (2-O-methyl, 2,3-O-dimethyl, 3-O-methyl and 6-O-methyl). In individual fractions their content and type varied. Detail study of the arabinogalactan showed that its backbone consists of 1,3-linked β-D-Galp units; some of them are branched through O-4 by 6-OMe-α-D-Galp- (1 → 2) -α-L-Araf side chain, other through O-6 by 3-OMe-β-D-Galp, 6-OMe-β-D-Galp, β-D-Galp and β-D-Galf.

Starch-Rich Microalgae as an Active Ingredient in Beer Brewing

Microalgal biomass is widely studied for its possible application in food and human nutrition due to its multiple potential health benefits, and to address raising sustainability concerns. An interesting field whereby to further explore the application of microalgae is that of beer brewing, due to the capacity of some species to accumulate large amounts of starch under specific growth conditions. The marine species Tetraselmis chui is a well-known starch producer, and was selected in this study for the production of biomass to be explored as an active ingredient in beer brewing. Cultivation was performed under nitrogen deprivation in 250 L tubular photobioreactors, producing a biomass containing 50% starch. The properties of high-starch microalgal biomass in a traditional mashing process were then assessed to identify critical steps and challenges, test the efficiency of fermentable sugar release, and develop a protocol for small-scale brewing trials. Finally, T. chui was successfully integrated at a small scale into the brewing process as an active ingredient, producing microalgae-enriched beer containing up to 20% algal biomass. The addition of microalgae had a noticeable effect on the beer properties, resulting in a product with distinct sensory properties. Regulation of pH proved to be a key parameter in the process.

Wide Range Applications of Spirulina: From Earth to Space Missions

Spirulina is the most studied cyanobacterium species for both pharmacological applications and the food industry. The aim of the present review is to summarize the potential benefits of the use of Spirulina for improving healthcare both in space and on Earth. Regarding the first field of application, Spirulina could represent a new technology for the sustainment of long-duration manned missions to planets beyond the Lower Earth Orbit (e.g., Mars); furthermore, it could help astronauts stay healthy while exposed to a variety of stress factors that can have negative consequences even after years. As far as the second field of application, Spirulina could have an active role in various aspects of medicine, such as metabolism, oncology, ophthalmology, central and peripheral nervous systems, and nephrology. The recent findings of the capacity of Spirulina to improve stem cells mobility and to increase immune response have opened new intriguing scenarios in oncological and infectious diseases, respectively.

Involvement Theory with Market Segmentation: Effect of False Functional Food Advertising on Purchase Intention

In certain cases, people’s health can be compromised or medical treatment delayed as a result of their misplaced belief in false advertisements and purchasing of functional foods. These advertisements can be divided into three distinct types of claims: nutrition, health, and reduction in disease risk. This study analysed how, after consumers realise advertising violations, their intention to purchase functional foods with different claims are affected by the degree of consumer involvement (product, advertising, and situational involvement) and region of residence. A total of 1046 survey responses were collected for analysis. The results reveal that both product and advertising involvement influence purchase intention through the mediation of situational involvement. Residents in nonnorthern regions of Taiwan exhibited a greater effect of overall involvement on purchase intention than did those in the north. In addition, products and advertisements with health claims had a stronger effect on purchase intention than did those with nutrition and disease risk reduction claims. The results indicate that, for functional foods and advertisements with nutrition and health claims, the effects of overall involvement on nonnorthern residents’ purchase intentions were greater than those on the northern residents, but for functional foods with disease risk reduction claims, the effects were greater on the northern residents’ purchase intentions.

Algae: Study of Edible and Biologically Active Fractions, Their Properties and Applications

The beneficial properties of algae make them perfect functional ingredients for food products. Algae have a high energy value and are a source of biologically active substances, proteins, fats, carbohydrates, vitamins, and macro- and microelements. They are also rich in polyunsaturated fatty acids, proteins, mycosporine-like amino acids, polysaccharides, polyphenols, carotenoids, sterols, steroids, lectins, halogenated compounds, polyketides, alkaloids, and carrageenans. Different extraction parameters are used depending on the purpose and the substances to be isolated. In this study, the following parameters were used: hydromodule 1:10 and an extraction duration of 1-2 h at the extraction temperature of 25-40 °C. A 30-50% solution of ethanol in water was used as an extractant. Algae extracts can be considered as potential natural sources of biologically active compounds with antimicrobial activity and antiviral properties. The content of crude protein, crude fat, and carbohydrates in U. Prolifera, C. racemosa var. peltata (Chlorophyta), S. oligocystum and S. fusiforme (SF-1) was studied. It was found that C. muelleri (Bacillariophyta), I. galbana (Haptophyta), and T. weissflogii (Bacillariophyta) contain about 1.9 times more omega-3 than omega-6 fatty acids. N. gaditana (Ochrophyta), D. salina (Chlorophyta), P. tricornutum (Bacillaryophyta) and I. galbana (Haptophyta) extracts showed inhibitory activity of varying intensities against E. coli or P. aeruginosa. In addition, algae and algae-derived compounds have been proposed to offer attractive possibilities in the food industry, especially in the meat sector, to evolve functional foods with myriad functionalities. Algae can increase the biological activity of food products, while the further study of the structure of compounds found in algae can broaden their future application possibilities.

Innovative and Healthier Dairy Products through the Addition of Microalgae: A Review

In recent years, the development of healthier foods, richer in nutraceutical or functional compounds, has been in great demand. Microalgae are attracting increasing attention, as their incorporation in foods and beverages can be a promising strategy to develop sustainable foods with improved nutritional profiles and a strong positive impacts on health. Despite the increasing market demand in plant-based foods, the popularity of fermented dairy foods has increased in the recent years since they are a source of microorganisms with health-promoting effects. In this context, the incorporation of microalgae in cheeses, fermented milks and other dairy products represents an interesting approach towards the development of innovative and added-value hybrid products based on animal proteins and enriched with vegetable origin ingredients recognized as extremely valuable sources of bioactive compounds. The effect of the addition of microalgal biomass (Chlorella vulgaris, Arthrospira platensis, Pavlova lutheri, and Diacronema vlkianum, among others) and its derivates on the physicochemical composition, colorimetric and antioxidant properties, texture and rheology behavior, sensory profile, and viability of starter cultures and probiotics in yogurt, cheese and ice cream is discussed in the current work. This review of the literature on the incorporation of microalgae in dairy products aims to contribute to a better understanding of the potential use of these unique food ingredients in the development of new sustainable products and of their beneficial effects on health. Considering the importance of commercialization, regulatory issues about the use of microalgae in dairy products are also discussed.

A novel strategy to simultaneously enhance bioaccessible lipids and antioxidants in hetero/mixotrophic Chlorella vulgaris as functional ingredient

Microalgae are a promising source of polyunsaturated fatty acids as well as bioactive antioxidant compounds such as carotenoids, phenolics and tocopherols. However, the accumulation of these biomolecules is often promoted by conflicting growth conditions. In this study, a phased bioprocessing strategy was developed to simultaneously enhance the lipid and antioxidant amounts by tailoring nitrogen content in the cultivation medium and applying light stress. This approach increased the overall contents of total fatty acids, carotenoids, phenolics, and α-tocopherol in Chlorella vulgaris by 2.2-, 2.2-, 1.5-, and 2.1-fold, respectively. Additionally, the bioaccessibility of the lipids and bioactives from the obtained biomasses improved after pulsed electric field (5 μs, 20 kV cm^-1, 31.8 kJ kg^-1_sus) treatment (up to +12%) and high-pressure homogenization (100 MPa, 5-6 passes) (+41-76%). This work represents a step towards the generation of more efficient algae biorefineries, thus expanding the alternative resources available for essential nutrients.

Integrated metabolic tools reveal carbon alternative in Isochrysis zhangjiangensis for fucoxanthin improvement

This study explored the regulation of photosystem and central carbon metabolism in cell growth and fucoxanthin accumulation of Isochrysis zhangjiangensis via transcriptome analysis, targeted metabolite measurements, and flux balance analysis. High light promoted biomass accumulation but dramatically decreased fucoxanthin productivity. It suppressed the active photosystem and reduced chlorophyll content, but improved metabolic flux of Calvin-Benson-Bassham and tricarboxylic acid cycle for massive biomass accumulation. The CO₂ fixation was largely dependent on mitochondrial energy illustrated by the integrated metabolic tools. At a molecular level, glyceraldehyde-3-phosphate, acetyl-CoA, and pyruvate contents increased at exponential phase under high light, which tended to participate into fatty acid biosynthesis by the up-regulated ACCase. However, high light inhibited most genes involved in fucoxanthin biosynthesis and induced diadinoxanthin cycle to diatoxanthin form. Therefore, constant light at 100 μmol m^-2 s^-1 balancing biomass concentration and fucoxanthin content provided the highest fucoxanthin productivity at 3.06 mg L^-1 d^-1.

Microalgal Biorefinery Concepts’ Developments for Biofuel and Bioproducts: Current Perspective and Bottlenecks

Microalgae have received much interest as a biofuel feedstock. However, the economic feasibility of biofuel production from microalgae does not satisfy capital investors. Apart from the biofuels, it is necessary to produce high-value co-products from microalgae fraction to satisfy the economic aspects of microalgae biorefinery. In addition, microalgae-based wastewater treatment is considered as an alternative for the conventional wastewater treatment in terms of energy consumption, which is suitable for microalgae biorefinery approaches. The energy consumption of a microalgae wastewater treatment system (0.2 kW/h/m³) was reduced 10 times when compared to the conventional wastewater treatment system (to 2 kW/h/m³). Microalgae are rich in various biomolecules such as carbohydrates, proteins, lipids, pigments, vitamins, and antioxidants; all these valuable products can be utilized by nutritional, pharmaceutical, and cosmetic industries. There are several bottlenecks associated with microalgae biorefinery. Hence, it is essential to promote the sustainability of microalgal biorefinery with innovative ideas to produce biofuel with high-value products. This review attempted to bring out the trends and promising solutions to realize microalgal production of multiple products at an industrial scale. New perspectives and current challenges are discussed for the development of algal biorefinery concepts.

Future foods: Alternative proteins, food architecture, sustainable packaging, and precision nutrition

There are numerous challenges facing the modern food and agriculture industry that urgently need to be addressed, including feeding a growing global population, mitigating and adapting to climate change, decreasing pollution, waste, and biodiversity loss, and ensuring that people remain healthy. At the same time, foods should be safe, affordable, convenient, and delicious. The latest developments in science and technology are being deployed to address these issues. Some of the most important elements within this modern food design approach are encapsulated by the MATCHING model: Meat-reduced; Automation; Technology-driven; Consumer-centric; Healthy; Intelligent; Novel; and Globalization. In this review article, we focus on four key aspects that will be important for the creation of a new generation of healthier and more sustainable foods: emerging raw materials; structural design principles for creating innovative products; developments in eco-friendly packaging; and precision nutrition and customized production of foods. We also highlight some of the most important new developments in science and technology that are being used to create future foods, including food architecture, synthetic biology, nanoscience, and sensory perception.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2022.2033683.

Microalgae Biomass as a New Potential Source of Sustainable Green Lubricants

Lubricants are materials able to reduce friction and/or wear of any type of moving surfaces facilitating smooth operations, maintaining reliable machine functions, and reducing risks of failures while contributing to energy savings. At present, most worldwide used lubricants are derived from crude oil. However, production, usage and disposal of these lubricants have significant impact on environment and health. Hence, there is a growing pressure to reduce demand of this sort of lubricants, which has fostered development and use of green lubricants, as vegetable oil-based lubricants (biolubricants). Despite the ecological benefits of producing/using biolubricants, availability of the required raw materials and agricultural land to create a reliable chain supply is still far from being established. Recently, biomass from some microalgae species has attracted attention due to their capacity to produce high-value lipids/oils for potential lubricants production. Thus, this multidisciplinary work reviews the main chemical-physical characteristics of lubricants and the main attempts and progress on microalgae biomass production for developing oils with pertinent lubricating properties. In addition, potential microalgae strains and chemical modifications to their oils to produce lubricants for different industrial applications are identified. Finally, a guide for microalgae oil selection based on its chemical composition for specific lubricant applications is provided.

Influence of Different Light Sources on the Biochemical Composition of Arthrospira spp. Grown in Model Systems

Arthrospira platensis and Arthrospira maxima are prokaryotic microalgae commercially marketed as spirulina. The pigments extracted from these algae are widely used for cosmetic and nutraceutical applications. This work aimed to evaluate the influence of three light-emitting lamps (white, orange and blue) on the growth and biomass composition of two strains of A. platensis (M2 and M2M) and one of A. maxima. The obtained data show strain- and light-dependent responses of the microalgae. In addition, white and orange lights led to a similar overall effect by increasing the levels of chlorophyll a and carotenoids. However, exposure to orange light resulted in the highest dry weight (5973.3 mg L−1 in M2M), whereas white light stimulated an increase in the carbohydrate fraction (up to 42.36 g 100 g−1 in A. maxima). Conversely, blue light led to a constant increase in the concentration of phycocyanin (14 g 100 g−1 in A. maxima) and a higher content of proteins in all strains. These results provide important environmental information for modulating the growth of different spirulina strains, which can be used to address the synthesis of biochemical compounds of strategic importance for the development of new nutraceutical foods.

A Combination of Aqueous Extraction and Ultrafiltration for the Purification of Phycocyanin from Arthrospira maxima

The purification of phycocyanin (PC) from Spirulina generally involves a combination of different techniques. Here, we report the results on PC yields from a combined aqueous extraction-ultrafiltration (UF) process of a strain of Arthrospira maxima cultivated in a farm devoted to producing PC with food-grade purity. Samples optimized from different biomass/solvent ratios were purified by using a polyethersulphone (PES) membrane with a molecular weight cut-off (MWCO) of 20 kDa. The UF system was operated at 2.0 ± 0.1 bar and at 24 ± 2 °C up to a volume concentration factor (VCF) of 5. A diafiltration (DF) process was conducted after UF in order to increase the PC recovery in the retentate. Samples were collected during both UF and DF processes in order to evaluate membrane productivity and PC purity. The average permeate fluxes of about 14.4 L/m²h were measured in the selected operating conditions and more than 96% of PC was rejected by the UF membrane independently ofthe extraction yields and times. The concentration of PC in the final retentate was 1.17 mg/mL; this confirmed the observed rejection and the final VCF of the process (about 5-fold when compared to the concentration of PC in the crude extract). In addition, the combination of UF and diafiltration allowed the removal of about 91.7% of the DNA from the crude extract, thereby improving the purity of the phycocyanin in the retentate fraction.

A novel two-stage heterotrophic cultivation for starch-to-protein switch to efficiently enhance protein content of Chlorella sp. MBFJNU-17

This work aimed to firstly establish an efficient and novel two-stage cultivation process to produce microalgal biomass rich in protein using a heterotrophic Chlorella sp. MBFJNU-17 strain. In the first-stage cultivation, to reduce the glucose and urea utilization, microalga achieved a high biomass at 40 g/L glucose and 1 g/L urea; meantime, the expression from starch biosynthesis genes of microalga was up-regulated under nitrogen-starvation conditions for starch accumulation (55.01%). In the second-stage cultivation, based on the over-compensation effect, Chlorella cells after the first-stage cultivation were further treated at 5 g/L glucose and 3 g/L urea to up-regulate starch degradation, central carbon metabolism and urea absorption genes expression to drive intracellular starch-to-protein switch for biosynthetic protein (59.75%). Moreover, microalga performed similar characteristics in a 10-L fermenter by the established process. Taken together, Chlorella sp. MBFJNU-17 was the promising candidate to produce high-value biomass enriched in protein by the established two-stage cultivation.