Trends and Technological Advancements in the Possible Food Applications of Spirulina and Their Health Benefits: A Review

Comprehensive review on the potential of ultrasound for blue food protein extraction, modification and impact on bioactive properties

Food security for the increasing global population is a significant challenge of the current times particularly highlighting the protein deficiencies. Plant-based proteins could be considered as alternate source of the protein. The digestibility and PDCASS value of these proteins are still a concern. Blue proteins, the new approach of utilizing the proteins from aquatic sources could be a possible solution as it contains all the essential amino acids. However, the conjugation of these proteins with fats and glycogen interferes with their techno-functional properties and consequently their applicability. The application of power ultrasound for extraction and modification of these proteins from aquatic sources to break open the cellular structure, increase extractability, alter the protein structure and consequently provide proteins with higher bioavailability and bioactive properties could be a potential approach for their effective utilization into food systems. The current review focuses on the application of power ultrasound when applied as extraction treatment, alters the sulphite and peptide bond and modifies protein to elevated digestibility. The degree of alteration is influenced by intensity, frequency, and exposure time. The extracted proteins will serve as a source of essential amino acids. Furthermore, modification will lead to the development of bioactive peptides with different functional applications. Numerous studies reveal that blue proteins have beneficial impacts on amino acid availability, and subsequently food security with higher PDCAAS values. In many cases, converted peptides give anti-hypertensive, anti-diabetic, and anti-oxidant activity. Therefore, researchers are concentrating on ultrasound-based extraction, modification, and application in food and pharmaceutical systems.

Marine microalgae and their industrial biotechnological applications: A review

BACKGROUND

For use in specialized programs in the food, pharmaceutical, nutraceutical, cosmetic, and animal feed sectors, micro-algal biomass has been generated industrially. They can be grown in closed buildings, such as photobioreactors, or open structures. The utilization of biomass from microalgae for energy production is another crucial topic. Because of the world's diminishing petroleum sources and the greenhouse gas emissions from gasoline lines, it is now obvious that fuels generated from petroleum are not sustainable.

RESULTS

Microalgae can produce a variety of unique, sustainable biofuels. These include biodiesel made from trans-esterification of microalgal lipids, bioethanol from fermentation of carbohydrates, methane created by anaerobic digestion of algal biomass, and biohydrogen produced by photobiological processes. The idea of using microalgae as a fuel source is not entirely novel.

CONCLUSION

This analysis emphasizes the significance of recent and noteworthy advancements in the industrial usage of microalgae, with an emphasis on their biotechnological applications.

A review on algal biomass dewatering and recovery of microalgal-based valuable products with different membrane technologies

Efficient microalgae harvesting and dewatering are critical processes for a range of applications, including the production of raw materials, nutritional supplements, pharmaceuticals, sustainable biofuels, and wastewater treatment. The optimization of these processes poses significant challenges due to the need for high efficiency and sustainability while managing costs and energy consumption. This review comprehensively addresses these challenges by focusing on the development and application of various membrane filtration technologies specifically designed for the effective harvesting and dewatering of algal biomass. Membrane filtration has emerged as a predominant method due to its ability to handle large volumes of microalgae with relatively low energy requirements. This review systematically examines the different membrane-based technologies and their effectiveness in recovering valuable components from algal biomass, such as lipids, proteins, and carbohydrates. The discussion begins with an overview of the physical characteristics of microalgae and their cultivation conditions, which are critical for understanding how these factors influence the performance of membrane filtration processes. Key aspects such as the features of algal cells, the presence of algal organic matter, and transparent exopolymer particles are explored in detail. The review also delves into various strategies for improving membrane antifouling properties, which are essential for maintaining the efficiency and longevity of the filtration systems. In addition, the advantages and disadvantages of different membrane techniques are reviewed, highlighting their respective performance in separating microalgae and dewatering. Finally, the review offers insights into future research directions and technological advancements that could further enhance the efficiency and sustainability of microalgae processing. This comprehensive evaluation aims to provide a thorough understanding of current membrane technologies, their applications, and the ongoing developments necessary to overcome existing limitations and improve overall process performance.

Coupling ultrasound and membrane filtration for the fractionation of Spirulina platensis sp. and the recovery of phycocyanin and pigment-free proteins

The cyanobacterium Spirulina platensis was subjected to a fractionation process involving ultrasound-assisted extraction and membrane filtration to obtain a pure phycocyanin fraction and a clarified colorless protein fraction free of chlorophyll and carotenoids. The effects of pressure and power on total protein release were assessed. The retention of the extracted proteins was then assessed by ultrafiltration, with and without ammonium sulfate precipitation. Total protein recovery yields reached 97% in aqueous solution, at a low frequency (12 kHz), atmospheric pressure, and with an ultrasonic power of 200 Watts (W). Ammonium sulfate (25% w/v) precipitation was used to remove pigments and impurities from the crude protein extract. Finally, semi-frontal ultrafiltration resulted in high levels of C-phycocyanin recovery in the retentate: 95% and 91% with 10 and 100 kDa-cutoff membranes, respectively. However, the levels of total non-pigmented proteins in the permeate compartment did not exceed 67% with a 100 kDa-cutoff membrane. A fractionation process is proposed here for the valorization of two different protein fractions from Spirulina platensis.

Chemical Composition, Bioactivities, and Applications of Spirulina (Limnospira platensis) in Food, Feed, and Medicine

Spirulina (Limnospira platensis) is a microalga recognised for its rich nutritional composition and diverse bioactive compounds, making it a valuable functional food, feed, and therapeutic agent. This review examines spirulina's chemical composition, including its high levels of protein, essential fatty acids, vitamins, minerals, and bioactive compounds, such as the phycocyanin pigment, polysaccharides, and carotenoids, in food, feed, and medicine. These compounds exhibit various biological activities, including antioxidant, anti-inflammatory, immunomodulatory, antiviral, anticancer, antidiabetic and lipid-lowering effects. Spirulina's potential to mitigate oxidative stress, enhance immune function, and inhibit tumour growth positions it as a promising candidate for preventing chronic diseases. Additionally, spirulina is gaining interest in the animal feed sector as a promotor of growth performance, improving immune responses and increasing resistance to diseases in livestock, poultry, and aquaculture. Despite its well-documented health benefits, future research is needed to optimize production/cultivation methods, improve its bioavailability, and validate its efficacy (dose-effect relationship) and safety through clinical trials and large-scale human trials. This review underscores the potential of spirulina to address global health and nutrition challenges, supporting its continued application in food, feed, and medicine.

Spirulina-An Invaluable Source of Macro- and Micronutrients with Broad Biological Activity and Application Potential

With population growth expected in the near future and the planet's limited resources, alternative food sources are already being looked for. In this context, spirulina is called the food of the future due to its rich nutritional composition. This blue-green alga is primarily a valuable source of protein (55-70%) containing all essential amino acids. In its composition, it also contains unsaturated fatty acids, minerals, vitamins, and pigments, including the valuable protein-pigment complex-phycocyanin. Due to its high content of complete protein and minerals such as iron and calcium, it is an excellent addition to diets, especially those of vegans and vegetarians. Despite several limitations to the use of spirulina, including its distinctive marine flavour, low consumer awareness, or relatively high price, scientists are attempting to enrich many food products with the microalga. This is supported not only by the improved nutritional composition of the fortified product but also by spirulina's impact on sustainable food production. Therefore, this review aims to create consumer attention by presenting spirulina as a valuable and sustainable food source with health-promoting potential and great future significance.

Spirulina Unleashed: A Pancreatic Symphony to Restore Glycemic Balance and Improve Hyperlipidemia and Antioxidant Properties by Transcriptional Modulation of Genes in a Rat Model

Hyperlipidemia is the root cause of numerous chronic conditions, leading to high mortality rates around the globe. Spirulina (Arthrospira platensis) microalgae serve as a promising reservoir of bioactive compounds with diverse pharmacological properties. The current study examined the nutritional profile of spirulina powder in relation to strict glycemic control, specifically focusing on its potential to lower lipid levels. In an in vivo investigation, normal healthy male Wistar albino rats (n = 60) were divided into two groups: a negative control group (NC) of ten rats and a high-fat diet group (n = 50) that were fed a cholesterol-rich diet until their cholesterol levels reached or exceeded 250 mg/dL. Subsequently, the hypercholesterolemic rats were then randomly allocated to several treatment groups: a positive control (PC); a standard treatment diet (STD) involving fenofibrate at a dose of 20 mg/kg body weight; and three experimental groups (T1, T2, and T3) that received spirulina powder supplementation at doses of 300, 600, and 900 mg per kg body weight, respectively, for the period of 12 weeks. Blood samples were analyzed for oxidative stress biomarkers, insulin levels, lipid profiles, liver function, and expression of gene levels in the diabetogenic pathway. The study utilized spectrophotometric colorimetric methods to identify oxidative stress biomarkers, serum kit methods to measure lipid profiles and liver enzymes, and the assessment of qPCR for mRNA quantity. According to the research findings, spirulina powder has certain noteworthy features. It had the greatest quantity of chlorogenic acid (4052.90 µg/g) among seven phenolics and two flavonoid compounds obtained by HPLC-UV analysis. Furthermore, the proximate analysis demonstrated that spirulina is high in protein (16.45 ± 0.8%) and has a significant energy yield of 269.51 K-calories per 100 g. A maximal spirulina dose of 900 mg/kg/wt significantly lowered oxidative stress, cholesterol, triglyceride, low-density lipoproteins (LDL), and insulin levels (p ≤ 0.05). In contrast, high-density lipoprotein (HDL) and total antioxidant capacity (TAC) levels increased significantly (p ≤ 0.05) compared to all other groups, except the NC group. The study provides remarkable proof about the pharmacological impact of spirulina powders. Significant reductions (p ≤ 0.05) in liver enzymes {alanine aminotransferase (ALT) and aspartate aminotransferase (AST)} were observed across all treatment groups, with the exception of the NC, compared to the positive control. The treatment groups had significantly greater gene expression levels of INS-1, PDX-1, IGF-1, and GLUT-2 than the positive control group (p ≤ 0.05). These findings highlight spirulina's potential as a long-term regulator of hyperglycemia in rat models with induced hyperlipidemia, owing to its phenolic bioactive components that serve as antioxidants.

Optimization of the preparation process of Spirulina blended liquor and Spirulina fermented wine, analysis of volatile components and in vitro antioxidant study

The optimal conditions were explored for the preparation of Spirulina blended liquor (SBL) and Spirulina fermented wine (SFW), respectively. The parameters obtaining highest alga polysaccharide were calculated by response surface methodology. The optimal conditions for SBL preparation were base liquor of 42% vol, ultrasonication time of 37-min and ultrasonic power of 80 W with polysaccharide content (PC) and alcohol content (AC) of 0.2181 g/L and 39.7% vol, respectively. In the case of SFW, optimum fermentation occurred at 22°C, with a 4% inoculum and 6-day period with PC and AC of 8.533 g/L and 11.2% vol, respectively. Headspace solid-phase microextraction-gas chromatography-mass spectrometry was used to quantitatively analyze the volatile components of SBL and SFW. There were 32 and 40 main aroma compounds in SBL and SFW, respectively. Volatile organic compounds, including α-ionone and β-ionone, produced by Spirulina were detected in both SBL and SFW. Comparative evaluation of scavenging activity and total reducing power revealed the antioxidant capacity of SFW significantly outperformed that of SBL.

Bioactive compounds and in vitro biological properties of Arthrospira platensis and Athrospira maxima: a comparative study

Cyanobacteria, especially Arthrospira, are valuable resources of nutrients and natural pigments with many beneficial health-related properties. This study optimized the extraction conditions of Arthrospira to achieve high phenolic contents and antioxidant activities. Under optimized extraction conditions, the bioactive compounds (phenolics and pigment components), antioxidant activities, and inhibitions of the key enzymes relevant to some non-communicable diseases were compared between Arthrospira platensis and Arthrospira maxima. Optimized extraction conditions were determined as 2 h shaking time, 50 °C extraction temperature, and 1% (w/v) solid-to-liquid ratio, giving effective phenolic and phycocyanin contents using aqueous extraction, while 80% (v/v) aqueous ethanolic extraction provided high total chlorophyll content. Most antioxidant activities were higher using 80% (v/v) aqueous ethanolic extracts. Both Arthrospira species inhibited the key enzymes involved in controlling non-communicable diseases including hyperlipidemia (lipase), diabetes (α-amylase, α-glucosidase, and dipeptidyl peptidase-IV), Alzheimer's disease (acetylcholinesterase, butyrylcholinesterase and β-secretase), and hypertension (angiotensin-converting enzyme). High inhibitory activities were detected against β-secretase (BACE-1), the enzyme responsible for β-amyloid plaque formation in the brain that acts as a significant hallmark of Alzheimer's disease. Arthrospira extract and donepezil (Alzheimer's disease drug) synergistically inhibited BACE-1, suggesting the potential of Arthrospira extracts as effective BACE-1 inhibitors. Interestingly, A. maxima exhibited higher bioactive compound contents, antioxidant activities, and key enzyme inhibitions than A. platensis, indicating high potential for future food and medicinal applications.

Antiviral potential of spirulina in individuals with human immunodeficiency virus or Hepatis C virus infections: A systematic review and meta-analysis

BACKGROUND

Spirulina, a cyanobacterium or blue-green algae that contains phycocyanin, nutritional supplementation has been evaluated in patients living with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) due to its antiviral properties. This supplementation may be beneficial in low resource settings when awaiting antiretroviral therapy (ART) for HIV. This review aimed to evaluate the effectiveness of Spirulina supplement in antiviral-naïve HIV- and HCV-infected patients by assessing its immunological effect (Cluster of Differentiation 4 or CD-4 T-cell count) and disease progression (viral load).

METHODS

We searched PubMed, Cochrane Library, Scopus, and Web of Science from inception through January 23, 2024. Two authors independently performed the study selection, data extraction, and risk of bias assessment. We pooled data by using a random-effects model and evaluated publication bias by a funnel plot.

RESULTS

We identified 5552 articles, 5509 excluded at the title and abstract stage with 44 studies making it to the full text review. Of these 6 studies met the eligibility for inclusion in the final analysis as follows: 4 randomized controlled trials (RCTs) and 2 non-RCTs. The pooled results of the Spirulina intervention found significant improvements in biomarkers of clinical outcomes, viral load (VL) and CD4 T-cell (CD4) counts, in participants of the treatment group compared to controls; the VL had an overall Cohen's d effect size decrease of -2.49 (-4.80, -0.18) and CD4 had an overall effect size increase of 4.09 (0.75, 7.43). [Cohen's d benchmark: 0.2 = small effect; 0.5 = medium effect; 0.8 = large effect].

CONCLUSIONS

Findings from this systematic review showed a potential beneficial effect of Spirulina supplementation in HIV- and HCV-infected patients by increasing CD4 counts and decreasing viral load. However, further research in larger controlled clinical trials is needed to fully investigate the effect of this nutritional supplement on clinically relevant outcomes, opportunities for intervention, optimal dose, and cost-benefit of Spirulina supplementation.

Spirulina/Arthrospira/Limnospira-Three Names of the Single Organism

Recent advances in research techniques have enabled rapid progress in the study of spirulina, an ancient edible cyanobacteria. Nowadays, spirulina species are classified into three genera: Spirulina, Arthrospira, and Limnospira. The latter now refers to industrially manufactured spirulina strains. Whole-genome sequencing revealed gene clusters involved in metabolite production, and the physiology of spirulina. Omics technologies demonstrated the absence of hazardous compounds in spirulina cells, confirming the safety of this biomass as a food product. Spirulina is a good source of different chemicals used in food manufacturing, food supplements, and pharmaceuticals. Spirulina's enrichment with inherent biologically active substances makes it a potential supplier of natural products for dietary and pharmaceutical applications. Spirulina is also a prospective component of both terrestrial and space-based life support systems. Here, we review current breakthroughs in spirulina research and clarify fallacies that can be found in both professional literature and public media.

An Exopolysaccharide from the Cyanobacterium Arthrospira platensis May Utilize CH-π Bonding: A Review of the Isolation, Purification, and Chemical Structure of Calcium-Spirulan

The CH-π bonding potential of a saccharide is determined primarily by the number of hydrogen atoms available for bonding and is reduced by side groups that interfere with the CH-π bond. Each hydrogen bond increases the total bond energy, while interfering hydroxyl groups and other side groups reduce the bond energy by repulsion. The disaccharide repeating units of Calcium-Spirulan (Ca-SP), a large exopolysaccharide sub fractionated from the supernatant of the cyanobacterium Arthrospira platensis, contain a unique monosaccharide that is completely devoid of hydroxyl groups and side groups on its entire beta surface, leaving five hydrogen atoms available for CH-π bonding in the planar conformation. While planar conformations of independent pyranose rings are rare-to-nonexistent, due to ring strain associated with that conformation, the binding site of a protein could provide the conformational energy needed to overcome that energy barrier. By enabling a planar conformation, a protein could also enable the sugar to form a novel 5-hydrogen CH-π bond configuration. One study of the anticoagulant property of Ca-SP shows that the molecule acts as an activator of Heparin Cofactor II (HC-II), boosting its anticoagulant kinetics by 104. In comparison, the longstanding anticoagulant drug Heparin boosts the HC-II kinetics by 103. The difference may be explained by this unique CH-π configuration. Here, we review current knowledge and experience on the isolation techniques, analytical methods, and chemical structures of Ca-SP. We emphasize a discussion of the CH-π bonding potential of this unique polysaccharide because it is a topic that has not yet been addressed. By introducing the topic of CH-π bonding to the cyanobacterial research community, this review may help to set the stage for further investigation of these unique molecules, their genetics, their biosynthetic pathways, their chemistry, and their biological functions.

Multi-Omics Reveals the Effects of Spirulina platensis Powder Replacement of Fish Meal on Intestinal Metabolism and Stress in Zig-Zag Eel (Mastacembelus armatus)

The booming aquaculture industry has created a strong demand for fishmeal and increased environmental pressures. Spirulina, as a potential alternative to fishmeal, has been shown to have growth-promoting and animal health-enhancing properties. In this study, 600 large spiny loaches, divided into five experimental groups, F0, F1, F2, F3, and F4, were reared for 10 weeks using Spirulina platensis powder (SPP) as a substitute for 0%, 5%, 10%, 15%, and 20% of fishmeal, respectively. The results of intestinal physiological indexes showed that superoxide dismutase was lower than F0 in all treatment groups, and the activity of F3 was significantly lower than F0 (p < 0.05). The activity of malondialdehyde was significantly higher than that of F0 in all groups except F3 (p < 0.05). The addition of SPP also led to a decrease in the activity of acid phosphatase in the intestine, which was significantly lower in all treatment groups compared to the F0 group (p < 0.05). The results of serum physiology showed that the activity of superoxide dismutase in serum gradually increased with the increase in the percentage of SPP addition, and the F3 group produced a significant difference from the F0 group (p < 0.05). The transcriptomics results showed that DEGs in the low percentage substitution group (<15%) were mostly enriched in metabolism-related pathways, such as bile secretion; DEGs in the high percentage substitution group (>15%) were mostly enriched in inflammation-related pathways, such as complement p and coagulation cascades. Metabolomics confirmed that nicotinate and nicotinamide metabolism and glycerophospholipid metabolism were the two pathways that were significantly enriched in the treatment groups of fishmeal replacement by SPP. The present study demonstrated that a low percentage (<15%) of fishmeal replacement by SPP in feed mobilized MA digestive metabolism, whereas a high percentage (>15%) of replacement induced intestinal stress. Considering the health and farm efficiency aspects, the proportion of SPP in feed formulation for MA should be less than 15%.

Investigation of the Elemental Contents, Functional and Nutraceutical Properties of Kefirs Enriched with Spirulina platensis, an Eco-friendly and Alternative Protein Source

In this study, the effect of the use of S. platensis, which is presented as an eco-friendly and alternative protein source, in the production of kefir, a probiotic dairy product, on various physicochemical properties as well as FAA, ACE inhibitory activity, proteolysis, TPC, DPPH, ABTS+, and mineral values was investigated. It was observed that the addition of S. platensis at different ratios to the kefir samples had a statistically very significant (p < 0.01) effect on all physicochemical analyses; L. mesenteroides count; all amino acids except isoleucine, aspartic acid, and glutamic acid; ACE inhibitory activity, TN, TCAN, TCAN/TN, mM Gly, TPC, DPPH, ABTS+, Na, Mg, K, and Fe. In plain kefir samples, mineral contents were determined by order of K > P > Na > Ca > Mg > Zn >> Fe > Cr > Cr > Mn. Furthermore, a general increase was observed in FAA, ACE inhibitory activity, TPC, DPPH, ABTS+, and mineral values, as well as in the counts of Lactococcus spp. and L. mesenteroides in the samples, depending on the proportion of S. platensis added, compared to plain kefir samples. In this context, it was concluded that the addition of S. platensis to kefir at different rates could meet various components required by the body on a daily basis and result in a nutraceutical product.

Determinants of Consumers' Acceptance and Adoption of Novel Food in View of More Resilient and Sustainable Food Systems in the EU: A Systematic Literature Review

This review article aims to provide an up-to-date overview of the main determinants of consumers' acceptance of novel foods (new foods and ingredients) in the EU with emphasis on product's intrinsic properties (sensory characteristics) and individual factors (socio-demographics, perceptive, psychological) by adopting a systematic approach following the PRISMA methodology. Case studies on terrestrial (i.e., insects, cultured meat and other animal origin products, plant-based food including mushrooms, plant-based analogues, pulses, and cereals) and aquatic systems (i.e., algae and jellyfish) are included focusing on age-related and cross-national differences in consumer acceptance of novel foods and ingredients. General trends have emerged that are common to all the novel foods analysed, regardless of their aquatic or terrestrial origin. Aspects such as food neophobia, unfamiliarity, and poor knowledge of the product are important barriers to the consumption of novel foods, while healthiness and environmental sustainability perception are drivers of acceptance. Sensory properties are challenging for more familiar ingredients such as plant-based food (e.g., novel food made by pulses, mushrooms, cereals and pseudocereals). Results are discussed in terms of feasibility of introducing these products in the EU food systems highlighting strategies that can encourage the use of new ingredients or novel foods.

Characterization of halotolerant microalga isolated from waterlogged habitats: Deciphering the biochemical profiling and unraveling the molecular identity

The primary objective of this study was to comprehensively explore the biochemical profile of the novel halotolerant microalgae strain, biogas laboratory scenedesmus (BGLRS), previously isolated from waterlogged regions in the southwest zone of Punjab, India. To achieve this, three distinct drying methods viz. freeze-drying, oven-drying, and shade-drying were employed and biochemical composition and antioxidant analyses on the microalgal biomass were conducted. Utilizing advanced analytical techniques, including high-performance liquid chromatography (HPLC), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and gas chromatography-mass spectroscopy (GC-MS) on freeze-dried biomass, its carbohydrate profile, micronutrient composition, and presence of bioactive compounds with potential therapeutic and nutraceutical significance were sought to unravel. Among the drying methods evaluated, freeze-drying exhibited the most promising experimental results, prompting its selection for further investigation. Notably, ICP-AES unveiled elevated concentrations of essential elements such as calcium, iron, magnesium, and phosphorus in BGLRS, with negligible traces of heavy metals, underscoring its safety for human consumption. GC-MS analysis further divulged the existence of numerous biologically active compounds, indicating potential applications in medical and nutraceutical fields. Through molecular identification using sequencing of the internal transcribed spacer (ITS) region, a close taxonomic resemblance between BGLRS and Scenedesmus sp. MKB was established, solidifying its unique position within the microalgal taxonomy. The deposition of ITS sequences into the NCBI GenBank, obtaining accession number MN796425, attests to the rigor and transparency of this research. Overall, these findings strongly suggest that microalgae BGLRS possesses high-quality biochemical attributes of significant therapeutic and nutraceutical importance.

Purification of thioredoxin reductase from Spirulina platensis by affinity chromatography and investigation of kinetic properties

The thioredoxin system consists of thioredoxin (Trx), thioredoxin reductase (TrxR) and nicotinamide adenine dinucleotide phosphate (NADPH). Spirulina platensis, which is one of the blue-green algae in the form of spiral rings, belongs to the cyanobacteria class. Spirulina platensis can produce Trx under stress conditions. If it can produce Trx, it also has TrxR activity. Therefore, in this study, the TrxR enzyme was purified for the first time from Spirulina platensis, an algae the most grown and also used as a nutritional supplement in the world. A two-step purification process was used: preparation of the homogenate and 2',5'-ADP sepharose 4B affinity chromatography. The enzyme was purified with a purification fold of 1059.51, a recovery yield of 9.7 %, and a specific activity of 5.77 U/mg protein. The purified TrxR was tested for purity by SDS-PAGE. The molecular weight of its subunit was found to be about 45 kDa. Optimum pH, temperature and ionic strength of the enzyme were pH 7.0, 40 °C and 750 mM in phosphate buffer respectively. The Michaelis constant (Km) and maximum velocity of enzyme (Vmax) values for NADPH and 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) are 5 μM and 2.2 mM, and 0.0033 U/mL and 0.0044 U/mL, respectively. Storage stability of the purified enzyme was determined at several temperatures. The inhibition effects of Ag+, Cu2+, Al3+ and Se4+ metal ions on the purified TrxR activity were investigated in vitro. While Se4+ ion increased the enzyme activity, other tested metal ions showed different type of inhibitory effects on the Lineweaver-Burk graphs.

Comprehensive understanding of the mutant 'giant' Arthrospira platensis developed via ultraviolet mutagenesis

Introduction

Cyanobacteria are typically of a size that can be observed under a microscope. Here, we present cyanobacteria of a size that can be observed with the naked eye. Arthrospira platensis NCB002 strain showed differentiated morphological characteristics compared to previously reported Arthrospira spp.

Methods

Arthrospira platensis NCB002 was obtained by the UV irradiation of Arthrospira sp. NCB001, which was isolated from freshwater and owned by NCell Co., Ltd. A. platensis NIES-39 was obtained from the National Institute for Environmental Studies (Tsukuba, Japan). We used various analytical techniques to determine its overall characteristics.

Results and discussion

The draft genome of strain NCB002 consists of five contigs comprising 6,864,973 bp with a G+C content of 44.3 mol%. The strain NCB002 had an average length of 11.69 ± 1.35 mm and a maximum of 15.15 mm, which is 23.4-50.5 times longer than the length (0.3-0.5 mm) of previously known Arthrospira spp., allowing it to be harvested using a thin sieve. Transcriptome analysis revealed that these morphological differences resulted from changes in cell wall formation mechanisms and increased cell division. Our results show that NCB002 has outstanding industrial value and provides a comprehensive understanding of it.

Anti-Glycation Properties of Zinc-Enriched Arthrospira platensis (Spirulina) Contribute to Prevention of Metaflammation in a Diet-Induced Obese Mouse Model

Advanced glycation end products (AGEs) exert a key pathogenic role in the development of obesity and insulin resistance. Thanks to its abundance in bioactive compounds, the microalga Arthrospira platensis (spirulina, SP) is proposed as a nutritional supplement. Here, we investigated the potential anti-glycating properties of SP enriched with zinc (Zn-SP) and the following impact on diet-induced metabolic derangements. Thirty male C57Bl6 mice were fed a standard diet (SD) or a high-fat high-sugar diet (HFHS) for 12 weeks, and a subgroup of HFHS mice received 350 mg/kg Zn-SP three times a week. A HFHS diet induced obesity and glucose intolerance and increased plasma levels of pro-inflammatory cytokines and transaminases. Zn-SP administration restored glucose homeostasis and reduced hepatic dysfunction and systemic inflammation. In the liver of HFHS mice, a robust accumulation of AGEs was detected, paralleled by increased expression of the main AGE receptor (RAGE) and depletion of glyoxalase-1, whereas Zn-SP administration efficiently prevented these alterations reducing local pro-inflammatory responses. 16S rRNA gene profiling of feces and ileum content revealed altered bacterial community structure in HFHS mice compared to both SD and HFHS + Zn-SP groups. Overall, our study demonstrates relevant anti-glycation properties of Zn-SP which contribute to preventing AGE production and/or stimulate AGE detoxification, leading to the improvement of diet-related dysbiosis and metabolic derangements.

Optimization of an Alternative Culture Medium for Phycocyanin Production from Arthrospira platensis under Laboratory Conditions

Arthrospira platensis, known as spirulina, is a cyanobacterium with multiple nutritional benefits, as it contains substantial amounts of proteins, fatty acids, and pigments. However, the production of this microalga has faced significant challenges, primarily related to the cost and composition of the required culture medium for its optimal growth. This study focused on optimizing two nitrogen sources (urea and potassium nitrate) to maximize the growth of A. platensis and the production of phycocyanin, a photosynthetic pigment of significant commercial value. Optimization was performed using the response surface methodology (RSM) with a central composite design (CCD). Analysis of variance (ANOVA) was employed to validate the model, which revealed that the different concentrations of urea were statistically significant (p < 0.05) for biomass and phycocyanin production. However, potassium nitrate (KNO3) showed no significant influence (p > 0.05) on the response variables. The RSM analysis indicated that the optimal concentrations of KNO3 and urea to maximize the response variables were 3.5 g L-1 and 0.098 g L-1, respectively. This study offers valuable perspectives for the efficient production of A. platensis while reducing production costs for its cultivation on a larger scale.

Characterization of Limnospira platensis PCC 9108 R-M and CRISPR-Cas systems

The filamentous cyanobacterium Limnospira platensis, formerly known as Arthrospira platensis or spirulina, is one of the most commercially important species of microalgae. Due to its high nutritional value, pharmacological and industrial applications it is extensively cultivated on a large commercial scale. Despite its widespread use, its precise manipulation is still under development due to the lack of effective genetic protocols. Genetic transformation of Limnospira has been attempted but the methods reported have not been generally reproducible in other laboratories. Knowledge of the transformation defense mechanisms is essential for understanding its physiology and for broadening their applications. With the aim to understand more about the genetic defenses of L. platensis, in this work we have identified the restriction-modification and CRISPR-Cas systems and we have cloned and characterized thirteen methylases. In parallel, we have also characterized the methylome and orphan methyltransferases using genome-wide analysis of DNA methylation patterns and RNA-seq. The identification and characterization of these enzymes will be a valuable resource to know how this strain avoids being genetically manipulated and for further genomics studies.

Muscle cell proliferation using water-soluble extract from nitrogen-fixing cyanobacteria Anabaena sp. PCC 7120 for sustainable cultured meat production

Muscle cell cultivation, specifically the culture of artificial meat from livestock-derived cells in serum-free media is an emerging technology and has attracted much attention. However, till now, the high cost of production and environmental load have been significant deterrents. This study aims to provide an alternate growth-promoting substance that is free from animal derivatives and lowers nitrogen pollution. We have extracted water-soluble compounds from the filamentous nitrogen-fixing cyanobacteria Anabaena sp. PCC 7120 by the ultrasonication method. The heat-inactivated and molecular weight separation experiments were conducted to identify the bioactive compound present in the extract. Finally, the compounds soluble in water (CW) containing the water-soluble pigment protein, phycocyanin as a bioactive compound, was added as a growth supplement to cultivate muscle cells such as C2C12 muscle cells and quail muscle clone 7 (QM7) cells to analyze the effectiveness of the extract. The results indicated that CW had a positive role in muscle cell proliferation. A three-dimensional (3-D) cell-dense structure was fabricated by culturing QM7 cells using the extract. Furthermore, the nitrogen-fixing cyanobacterial extract has vast potential for cultured meat production without animal sera in the near future.

The utility of algae as sources of high value nutritional ingredients, particularly for alternative/complementary proteins to improve human health

As the global population continues to grow, the demand for dietary protein is rapidly increasing, necessitating the exploration of sustainable and nutritious protein sources. Algae has emerged as a promising food source due to their high value ingredients such as proteins, as well as for their environmental sustainability and abundance. However, knowledge gaps surrounding dietary recommendations and food applications restrict algae's utilization as a viable protein source. This review aims to address these gaps by assessing the suitability of both microalgae and macroalgae as alternative/complementary protein sources and exploring their potential applications in food products. The first section examines the potential suitability of algae as a major food source by analyzing the composition and bioavailability of key components in algal biomass, including proteins, lipids, dietary fiber, and micronutrients. Secondly, the biological effects of algae, particularly their impact on metabolic health are investigated with an emphasis on available clinical evidence. While evidence reveals protective effects of algae on glucose and lipid homeostasis as well as anti-inflammatory properties, further research is required to understand the longer-term impact of consuming algal protein, protein isolates, and concentrates on metabolic health, including protein metabolism. The review then explores the potential of algal proteins in food applications, including ways to overcome their sensory limitations, such as their dark pigmentation, taste, and odor, in order to improve consumer acceptance. To maximize algae's potential as a valuable protein source in the food sector, future research should prioritize the production of more acceptable algal biomass and explore new advances in food sciences and technology for improved consumer acceptance. Overall, this paper supports the potential utility of algae as a sustainable and healthy ingredient source for widespread use in future food production.

Nutritional intervention is promising in alleviating liver injury during tuberculosis treatment: a review

Liver injury is a main adverse effect of first-line tuberculosis drugs. Current management of tuberculosis-drug-induced liver injury (TBLI) mainly relies on withdrawing tuberculosis drugs when necessary. No effective treatment exists. Various nutrients and functional food ingredients may play a protective role in TBLI. However, a comprehensive review has not been conducted to compare the effects of these nutrients and functional food ingredients. We searched Pubmed and Web of Science databases from the earliest date of the database to March 2023. All available in-vitro, animal and clinical studies that examined the effects of nutritional intervention on TBLI were included. The underlying mechanism was briefly reviewed. Folic acid, quercetin, curcumin, Lactobacillus casei, spirulina and Moringa oleifera possessed moderate evidence to have a beneficial effect on alleviating TBLI mostly based on animal studies. The evidence of other nutritional interventions on TBLI was weak. Alleviating oxidative stress and apoptosis were the leading mechanisms for the beneficial effects of nutritional intervention on TBLI. In conclusion, a few nutritional interventions are promising for alleviating TBLI including folic acid, quercetin, curcumin, L. casei, spirulina and M. oleifera, the effectiveness and safety of which need further confirmation by well-designed randomized controlled trials. The mechanisms for the protective role of these nutritional interventions on TBLI warrant further study, particularly by establishing the animal model of TBLI using the tuberculosis drugs separately.

Effect of Spirulina platensis Supplementation on Carcass Characteristics, Fatty Acid Profile, and Meat Quality of Omani Goats

In a 70-day study, 36 Jabbali and Sahrawi bucks, aged 11 months, were utilized to evaluate the effects of different levels of spirulina dietary supplement (SP) on carcass characteristics, fatty acid profile, and meat quality traits in Omani goat breeds. The goats were put into six groups of six bucks, each at random. The diet consisted of a conventional concentrate feed ration (CFR) without spirulina (CON), and the CFR diet supplemented with spirulina at the levels of 2 g/head daily (T1) and 4 g/head daily (T2). In general, Sahrawi bucks showed a highly significant response to SP feeding compared with Jabbali bucks. The treatment groups, especially T1, showed a significant increase in average daily gain and carcass traits (body length, leg length, and the rack weight) compared with the CON group of Sahrawi bucks. The weights of omental and kidney fat were also significantly higher in T1 compared with CON and T2 groups of Sahrawi goats, while they were significantly higher in T2 compared with CON and T1 groups of Jabbali goats. Carcass profile and meat quality, including ultimate ph and meat color lightness (L*) were increased significantly with dietary spirulina in both LD and SM muscles of Sahrawi goats. Most of the Sfa, Mufa, Pufa, Pufa n-6, Pufa n-3, and n-6/n-3 ratios of the LD showed significant differences in diets supplemented with SP compared with CON for Sahrawi bucks, while some of them were significant in Jabbali bucks. The LD muscle of Sahrawi goats fed diets supplemented with SP of the T1 group significantly decreased in the amounts of pentadecanoic and margaric acids compared with the T2 and CON groups. The study concluded that incorporating SP (2 g and 4 g/head daily) into the diet of Omani goats, especially Sahrawi goats, can increase growth performance, as well as improve fatty acid composition and meat quality.

Emerging Applications of Chlorella sp. and Spirulina (Arthrospira) sp

Chlorella sp. and Spirulina (Arthrospira) sp. account for over 90% of the global microalgal biomass production and represent one of the most promising aquiculture bioeconomy systems. These microorganisms have been widely recognized for their nutritional and therapeutic properties; therefore, a significant growth of their market is expected, especially in the nutraceutical, food, and beverage segments. However, recent advancements in biotechnology and environmental science have led to the emergence of new applications for these microorganisms. This paper aims to explore these innovative applications, while shedding light on their roles in sustainable development, health, and industry. From this state-of-the art review, it was possible to give an in-depth outlook on the environmental sustainability of Chlorella sp. and Spirulina (Arthrospira) sp. For instance, there have been a variety of studies reported on the use of these two microorganisms for wastewater treatment and biofuel production, contributing to climate change mitigation efforts. Moreover, in the health sector, the richness of these microalgae in photosynthetic pigments and bioactive compounds, along with their oxygen-releasing capacity, are being harnessed in the development of new drugs, wound-healing dressings, photosensitizers for photodynamic therapy, tissue engineering, and anticancer treatments. Furthermore, in the industrial sector, Chlorella sp. and Spirulina (Arthrospira) sp. are being used in the production of biopolymers, fuel cells, and photovoltaic technologies. These innovative applications might bring different outlets for microalgae valorization, enhancing their potential, since the microalgae sector presents issues such as the high production costs. Thus, further research is highly needed to fully explore their benefits and potential applications in various sectors.

Effects of Infrared and Microwave Radiation on the Bioactive Compounds of Microalga Spirulina platensis after Continuous and Intermittent Drying

Pharmaceutical, nutritional and food industries have recently become interested in the potential of Spirulina platensis, a kind of cyanobacterium with high levels of proteins, vitamins and bioactive compounds. Because of its high moisture, this microalga needs to be submitted to a preservation technique such as drying to be properly used. The aim of this work is to investigate the use of infrared and microwave radiation in the Spirulina platensis drying process. The experiments were performed in continuous and intermittent modes, evaluating different operating conditions for infrared and microwave drying, as well as their effects on the quality of the final product, expressed by the content of bioactive compounds (i.e., total phenolic, total flavonoid, citric acid and phycocyanin contents). The results proved that the use of electromagnetic radiation in the drying of spirulina is an interesting alternative for processing this material if performed under adequate operating conditions. The experiments carried out continuously at lower temperatures and powers and the combination between different temperatures and powers in the intermittent mode resulted in a final product with satisfactory levels of bioactive compounds and low operation times in comparison with conventional methodologies.

Enhancing Nutrient Recovery and Bioactive Compound Extraction from Spirulina through Supercritical Fluid Extraction: Implications for SH-SY5Y Cell Viability

This work explores the efficiency of supercritical fluid extraction (SFE) to recover minerals, pigments, and antioxidant compounds from the spirulina microalgae. Moreover, the fatty acids and phenolic profiles of the extracts obtained were also investigated, and the effect of the extracts on SH-SY5Y cell viability was tested. The extraction of phycocyanin was improved by SFE compared to conventional extraction, from 2.838 ± 0.081 mg/g dry matter (DM) (control) to 6.438 ± 0.411 mg/g DM (SFE). SFE treatment also improved chlorophyll a and carotenoid recoveries increasing from 5.612 ± 0.547 to 8.645 ± 0.857 mg/g DM and from 0.447 ± 0.096 to 0.651 ± 0.120 mg/g DM, respectively. Regarding minerals, the SFE improved Mg recovery with 77% more than the control extraction. Moreover, palmitoleic, stearic, γ-linolenic, eicosadienoic and eicosatrienoic acids recovery was improved by SFE. Phenolic profiles were identified via triple-TOF-LC-MS-MS. Considering heavy metals, a higher rate of Pb extraction was observed for the SFE extract, while no significant differences were observed for Hg between both extractions. Finally, SFE extract improved cell viability compared to the control extract. Thus, SFE constitutes an interesting tool to sustainably extract high-added-value compounds; however, potential contaminants such as Pb need to be controlled in the resulting extracts.

Mitigating Osmotic Stress and Enhancing Developmental Productivity Processes in Cotton through Integrative Use of Vermicompost and Cyanobacteria

There is an urgent demand for biostimulant amendments that can sustainably alleviate osmotic stress. However, limited information is available about the integrated application of vermicompost and a cyanobacteria extract on cotton plants. In 2020 and 2021, two field experiments were carried out in which twelve combinations of three irrigation intervals were employed every 14 days (Irrig.14), 21 days (Irrig.21), and 28 days (Irrig.28) along with four amendment treatments (a control, vermicompost, cyanobacteria extract, and combination of vermicompost + cyanobacteria extract) in salt-affected soil. The integrative use of vermicompost and a cyanobacteria extract resulted in an observed improvement in the physicochemical attributes; non-enzymatic antioxidants (free amino acids, proline, total soluble sugars, and phenolics); and antioxidant enzyme activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) and a decrease in the levels of oxidative damage indicators (H₂O₂ and MDA). Significant augmentation in the content of chlorophyll a and b, carotenoid concentration, relative water content, stomatal conductance, and K⁺ was also observed. In conjunction with these findings, noticeable decreases in the content of Na⁺ and hydrogen peroxide (H₂O₂) and the degree of lipid peroxidation (MDA) proved the efficacy of this technique. Consequently, the highest cotton yield and productivity as well as fiber quality were achieved when vermicompost and a cyanobacteria extract were used together under increasing irrigation intervals in salt-affected soil. In conclusion, the integrated application of vermicompost and a cyanobacteria extract can be helpful for obtaining higher cotton productivity and fiber quality compared with the studied control and the individual applications of the vermicompost or the cyanobacteria extract under increasing irrigation intervals within salt-affected soil. Additionally, it can also help alleviate the harmful impact of these abiotic stresses.

Multifunctional Nutraceutical Composition Based on Fermented Spirulina, Apple Cider Vinegar, Jerusalem Artichoke, and Bovine Colostrum

The main purpose of this experiment was to develop a multifunctional nutraceutical composition based on ingredients of different origins (Spirulina powder (SP), bovine colostrum (BC), Jerusalem artichoke powder (JAP), and apple cider vinegar (ACV)) which possess different health benefits through their different mechanisms of action. In order to improve the functional properties of Spirulina and bovine colostrum, fermentation with the Pediococcus acidilactici No. 29 and Lacticaseibacillus paracasei LUHS244 strains, respectively, was carried out. These LAB strains were chosen due to their good antimicrobial properties. The following parameters were analysed: for Spirulina (non-treated and fermented)-pH, colour coordinates, fatty acid profile, and contents of L-glutamic and GABA acids; for bovine colostrum (non-treated and fermented)-pH, colour coordinates, dry matter, and microbiological parameters (total LAB, total bacteria, total enterobacteria, Escherichia coli, and mould/yeast counts); for the produced nutraceuticals-hardness, colour coordinates, and overall acceptability. It was established that fermentation reduced the pH of the SP and BC and affected their colour coordinates. Fermented SP contained a greater concentration of gamma-aminobutyric and L-glutamic acids (by 5.2 times and 31.4% more, respectively), compared to the non-treated SP and BC. In addition, the presence of gamma-linolenic and omega-3 fatty acids was observed in fermented SP. Fermentation of BC reduces Escherichia coli, total bacteria, total enterobacteria, and total mould/yeast counts in samples. The obtained three-layer nutraceutical (I layer-fermented SP; II-fermented BC and JAP; III-ACV) demonstrated a high overall acceptability. Finally, our finding suggest that the selected nutraceutical combination has immense potential in the production of a multifunctional product with improved functionality and a high acceptability.

Exploring the Benefits of Phycocyanin: From Spirulina Cultivation to Its Widespread Applications

Large-scale production of microalgae and their bioactive compounds has steadily increased in response to global demand for natural compounds. Spirulina, in particular, has been used due to its high nutritional value, especially its high protein content. Promising biological functions have been associated with Spirulina extracts, mainly related to its high value added blue pigment, phycocyanin. Phycocyanin is used in several industries such as food, cosmetics, and pharmaceuticals, which increases its market value. Due to the worldwide interest and the need to replace synthetic compounds with natural ones, efforts have been made to optimize large-scale production processes and maintain phycocyanin stability, which is a highly unstable protein. The aim of this review is to update the scientific knowledge on phycocyanin applications and to describe the reported production, extraction, and purification methods, including the main physical and chemical parameters that may affect the purity, recovery, and stability of phycocyanin. By implementing different techniques such as complete cell disruption, extraction at temperatures below 45 °C and a pH of 5.5-6.0, purification through ammonium sulfate, and filtration and chromatography, both the purity and stability of phycocyanin have been significantly improved. Moreover, the use of saccharides, crosslinkers, or natural polymers as preservatives has contributed to the increased market value of phycocyanin.

Optimization of Melanin Production by Streptomyces antibioticus NRRL B-1701 Using Arthrospira (Spirulina) platensis Residues Hydrolysates as Low-Cost L-tyrosine Supplement

Melanin is a functional pigment that is used in various products. It can be produced by Streptomyces antibioticus NRRL B-1701 when supplemented with L-tyrosine. Arthrospira (Spirulina) platensis is a cyanobacterium with high protein content, including the protein phycocyanin (PC). During PC's extraction, biomass residues are generated, and these residues still contain various amino acids, especially L-tyrosine, which can be used as a low-cost supplement for melanin production. Thus, this study employed a hydrolysate of A. platensis biomass residue for L-tyrosine substitution. The effects of two drying methods, namely, lyophilization and dying via a hot air oven, on the proximate composition and content of L-tyrosine in the biomass residue were evaluated. The highest L-tyrosine (0.268 g L-tyrosine/100 g dried biomass) concentration was obtained from a hot-air-oven-dried biomass residue hydrolysate (HAO-DBRH). The HAO-DBRH was then used as a low-cost L-tyrosine supplement for maximizing melanin production, which was optimized by the response surface methodology (RSM) through central composite design (CCD). Using the RSM-CCD, the maximum level of melanin production achieved was 0.24 g/L, which is approximately four times higher than it was before optimization. This result suggests that A. platensis residue hydrolysate could be an economically feasible and low-cost alternative source of L-tyrosine for the production of melanin.

Conceptual Design of an Autotrophic Multi-Strain Microalgae-Based Biorefinery: Preliminary Techno-Economic and Life Cycle Assessments

Microalgae represent a promising solution in addressing the impacts associated with the current agricultural and manufacturing practices which are causing irreparable environmental damage. Microalgae have considerable biosynthetic potential, being a rich source of lipids, proteins, and high-value compounds. Under the scope of the H2020-BBI MULTI-STR3AM project, an innovative large-scale production system of valuable commodities for the food, feed, and fragrance sectors is being developed on the basis of microalgae, reducing costs, increasing the scale of production, and boosting value chain sustainability. In this work, we aimed to create a process model that can mimic an industrial plant to estimate mass and energy balances, optimize scheduling, and calculate production costs for a large-scale plant. Three autotrophic microalgae strains (Nannochloropsis sp., Dunaliella sp. and Spirulina sp.) were considered for this assessment, as well as the use of locally sourced CO2 (flue gas). The developed process model is a useful tool for obtaining the data required for techno-economic analysis (TEA) and life cycle assessment (LCA) of industrial biorefinery-based processes. Nannochloropsis sp. was the most economic option, whereas Dunaliella sp. was the most expensive strain to produce due to its lower productivity. Preliminary environmental assessments of the climate change impact category revealed that water recirculation and the use of flue gas could lead to values of 5.6, 10.6, and 9.2 kgCO2eq·kgAFDW−1 for Nannochloropsis sp., Dunaliella sp., and Spirulina sp., respectively, with electricity and NaCl as the main contributors. The obtained data allow for the quantification of the production costs and environmental impacts of the microalgal biomass fractions produced, which will be fundamental for future comparison studies and in determining if they are higher or lower than those of the replaced products. The process model developed in this work provides a useful tool for the evaluation and optimization of large-scale microalgae production systems.

Bio-Converted Spirulina for Nutraceutical Chewing Candy Formulations Rich in L-Glutamic and Gamma-Aminobutyric Acids

This study aimed at evaluating changes of microalgae Spirulina during its fermentation with Lactiplantibacillus plantarum No. 122 strain, and further at incorporating Spirulina bio-converted for nutraceuticals rich in L-glutamic (L-Glu) and gamma-aminobutyric acids (GABA) into sucrose-free chewing candy (gummy) preparations. Fermented Spirulina had higher b* (yellowness) coordinates than untreated (non-fermented), and fermentation duration (24 and 48 h) had a statistically significant effect on colour coordinates. The highest contents of L-glutamic and gamma-aminobutyric acids (4062 and 228.6 mg/kg, respectively) were found in 24 and 48 h-fermented Spirulina, respectively. Fermentation increased the content of saturated fatty acids and omega-3 in Spirulina, while monounsaturated fatty acids and omega-6 were reduced. The addition of fermented Spirulina (FSp) significantly affected hardness, decreased lightness and yellowness, and increased the greenness of chewing candies. All chewing candy samples (with xylitol) prepared with 3 and 5 g of FSp and 0.2 µL of Citrus paradise essential oil received the highest scores for overall acceptability, and the highest intensity (0.052) of emotion "happy" was elicited by the sample group containing xylitol, agar, ascorbic acid, 3 g of FSp, and 0.1 µL of Mentha spicata essential oil. As an outcome of this research, one may conclude that fermented Spirulina has significant potential as an innovative ingredient in the production of healthier sucrose-free nutraceutical chewing candies.

Proximate Composition and Nutritional Values of Selected Wild Plants of the United Arab Emirates

Wild plants supply food and shelter to several organisms; they also act as important sources of many nutrients and pharmaceutical agents for mankind. These plants are widely used in traditional medicinal systems and folk medicines. The present study analyzed the nutritional and proximate composition of various compounds in selected wild plants available in the UAE, viz., Chenopodium murale L., Dipterygium glaucum Decne., Heliotropium digynum Asch. ex C.Chr., Heliotropium kotschyi Gürke., Salsola imbricata Forssk., Tribulus pentandrus Forssk., Zygophyllum qatarense Hadidi. The predominant amino acids detected in the plants were glycine, threonine, histidine, cysteine, proline, serine, and tyrosine; the highest quantities were observed in H. digynum and T. pentandrus. The major fatty acids present were long-chain saturated fatty acids; however, lauric acid was only present in S. imbricata. The presence of essential fatty acids such as oleic acid, α-Linoleic acid, and linolenic acid was observed in H. digynum, S. imbricata, and H. kotschyi. These plants also exhibited higher content of nutrients such as carbohydrates, proteins, fats, ash, and fiber. The predominant vitamins in the plants were vitamin B complex and vitamin C. C. murale had higher vitamin A, whereas vitamin B complex was seen in T. pentandrus and D. glaucum. The phosphorus and zinc content were high in T. pentandrus; the nitrogen, calcium, and potassium contents were high in H. digynum, and D. glaucum. Overall, these plants, especially H. digynum and T. pentandrus contain high amounts of nutritionally active compounds and important antioxidants including trace elements and vitamins. The results from the experiment provide an understanding of the nutritional composition of these desert plant species and can be better utilized as important agents for pharmacological drug discovery, food, and sustainable livestock production in the desert ecosystem.

Submerged and Solid-State Fermentation of Spirulina with Lactic Acid Bacteria Strains: Antimicrobial Properties and the Formation of Bioactive Compounds of Protein Origin

The aim of this study was to investigate the changes in bioactive compounds (L-glutamic acid (L-Glu), gamma-aminobutyric acid (GABA) and biogenic amines (BAs)) during the submerged (SMF) and solid-state (SSF) fermentation of Spirulina with lactobacilli strains (Lacticaseibacillus paracasei No. 244; Levilactobacillus brevis No. 173; Leuconostoc mesenteroides No. 225; Liquorilactobacillus uvarum No. 245). The antimicrobial properties of the untreated and fermented Spirulina against a variety of pathogenic and opportunistic strains were tested. The highest concentrations of L-Glu (3841 mg/kg) and GABA (2396 mg/kg) were found after 48 h of SSF with No. 173 and No. 244 strains, respectively. The LAB strain used for biotreatment and the process conditions, as well as the interaction of these factors, had statistically significant effects on the GABA concentration in Spirulina (p ≤ 0.001, p = 0.019 and p = 0.011, respectively). In all cases, the SSF of Spirulina had a higher total BA content than SMF. Most of the fermented Spirulina showed exceptional antimicrobial activity against Staphylococcus aureus but not against the other pathogenic bacteria. The ratios of BA/GABA and BA/L-Glu ranged from 0.5 to 62 and from 0.31 to 10.7, respectively. The GABA content was correlated with putrescine, cadaverine, histamine, tyramine, spermidine and spermine contents. The L-glutamic acid concentration showed positive moderate correlations with tryptamine, putrescine, spermidine and spermine. To summarize, while high concentrations of desirable compounds are formed during fermentation, the formation of non-desirable compounds (BAs) must also be considered due to the similar mechanism of their synthesis as well as the possibility of obtaining high concentrations in the end products.

Changes in Spirulina's Physical and Chemical Properties during Submerged and Solid-State Lacto-Fermentation

The aim of this study was to select a lactic acid bacteria (LAB) strain for bio-conversion of Spirulina, a cyanobacteria ("blue-green algae"), into an ingredient with a high concentration of gamma-aminobutyric acid (GABA) for human and animal nutrition. For this purpose, ten different LAB strains and two different fermentation conditions (SMF (submerged) and SSF (solid state fermentation)) were tested. In addition, the concentrations of fatty acids (FA) and biogenic amines (BA) in Spirulina samples were evaluated. It was established that Spirulina is a suitable substrate for fermentation, and the lowest pH value (4.10) was obtained in the 48 h SSF with Levilactobacillus brevis. The main FA in Spirulina were methyl palmitate, methyl linoleate and gamma-linolenic acid methyl ester. Fermentation conditions were a key factor toward glutamic acid concentration in Spirulina, and the highest concentration of GABA (2395.9 mg/kg) was found in 48 h SSF with Lacticaseibacillus paracasei samples. However, a significant correlation was found between BA and GABA concentrations, and the main BA in fermented Spirulina samples were putrescine and spermidine. Finally, the samples in which the highest GABA concentrations were found also displayed the highest content of BA. For this reason, not only the concentration of functional compounds in the end-product must be controlled, but also non-desirable substances, because both of these compounds are produced through similar metabolic pathways of the decarboxylation of amino acids.

Use of Refractance Window Drying as an Alternative Method for Processing the Microalga Spirulina platensis

Microalgae such as Spirulina platensis have recently attracted the interest of the pharmaceutical, nutritional and food industries due to their high levels of proteins and bioactive compounds. In this study, we investigated the use of refractance window (RW) drying as an alternative technology for processing the microalga Spirulina biomass aiming at its dehydration. In addition, we also analyzed the effects of operating variables (i.e., time and temperature) on the quality of the final product, expressed by the content of bioactive compounds (i.e., total phenolics, total flavonoids, and phycocyanin). The results showed that RW drying can generate a dehydrated product with a moisture content lower than 10.0%, minimal visual changes, and reduced process time. The content of bioactive compounds after RW drying was found to be satisfactory, with some of them close to those observed in the fresh microalga. The best results for total phenolic (TPC) and total flavonoids (TFC) content were obtained at temperatures of around 70 °C and processing times around 4.5 h. The phycocyanin content was negatively influenced by higher temperatures (higher than 80 °C) and high exposing drying times (higher than 4.5 h) due to its thermosensibility properties. The use of refractance window drying proved to be an interesting methodology for the processing and conservation of Spirulina platensis, as well as an important alternative to the industrial processing of this biomass.

Improvement in the Sequential Extraction of Phycobiliproteins from Arthrospira platensis Using Green Technologies

Arthrospira platensis (commercially known as Spirulina) is an excellent source of phycobiliproteins, especially C-phycocyanin. Phycobiliproteins are significant bioactive compounds with useful biological applications. The extraction process plays a significant role in downstream microalga production and utilisation. The important pigments found in A. platensis include chlorophyll and carotenoids as nonpolar pigments and phycobiliproteins as polar pigments. Supercritical fluid extraction (SFE) as a green extraction technology for the high-value metabolites of microalgae has potential for trends in food and human health. The nonpolar bioactive compounds, chlorophyll and carotenoids of A. platensis, were primarily separated using supercritical carbon dioxide (SC-CO₂) solvent-free fluid extraction pressure; the temperature and ethanol as cosolvent conditions were compared. The residue from the A. platensis cells was subjected to phycobiliprotein extraction. The phosphate and water extraction of A. platensis SFE residue were compared to evaluate phycobiliprotein extraction. The SFE results exhibited higher pressure (350 bar) and temperature extraction (50 °C) with ethanol-free extraction and increased nonpolar pigment. Phycobiliprotein yield was obtained from A. platensis SFE residue by ethanol-free buffer extraction as a suitable process with antioxidant properties. The C-phycocyanin was isolated and enhanced to 0.7 purity as food grade. This developed method can be used as a guideline and applied as a sustainable process for important pigment extraction from Arthrospira microalgae.

Tendencies Affecting the Growth and Cultivation of Genus Spirulina: An Investigative Review on Current Trends

Spirulina, a kind of blue-green algae, is one of the Earth's oldest known forms of life. Spirulina grows best in very alkaline environments, although it may flourish across a wide variety of pH values. There are several techniques for growing Spirulina spp., ranging from open systems such as ponds and lakes, which are vulnerable to contamination by animals and extraterrestrial species, to closed systems such as photovoltaic reactors, which are not. Most contaminated toxins come from other toxic algae species that become mixed up during harvest, necessitating the study of spirulina production processes at home. Lighting, temperature, inoculation volume, stirring speed, dissolved particles, pH, water quality, and overall micronutrient richness are only a few of the environmental parameters influencing spirulina production. This review article covers the conditions required for spirulina cultivation, as well as a number of crucial factors that influence its growth and development while it is being grown. In addition, the article discusses harvesting processes, biomass measurement methods, the identification of dangerous algae, and the risk of contaminating algae as it grows on cultures. Spirulina's rising prospects as food for human consumption are a direct outcome of its prospective health and therapeutic advantages.

Current Status and Future Trends in Removal, Control, and Mitigation of Algae Food Safety Risks for Human Consumption

With the rapid development of the economy and productivity, an increasing number of citizens are not only concerned about the nutritional value of algae as a potential new food resource but are also, in particular, paying more attention to the safety of its consumption. Many studies and reports pointed out that analyzing and solving seaweed food safety issues requires holistic and systematic consideration. The three main factors that have been found to affect the food safety of algal are physical, chemical, and microbiological hazards. At the same time, although food safety awareness among food producers and consumers has increased, foodborne diseases caused by algal food safety incidents occur frequently. It threatens the health and lives of consumers and may cause irreversible harm if treatment is not done promptly. A series of studies have also proved the idea that microbial contamination of algae is the main cause of this problem. Therefore, the rapid and efficient detection of toxic and pathogenic microbial contamination in algal products is an urgent issue that needs to be addressed. At the same time, two other factors, such as physical and chemical hazards, cannot be ignored. Nowadays, the detection techniques are mainly focused on three major hazards in traditional methods. However, especially for food microorganisms, the use of traditional microbiological control techniques is time-consuming and has limitations in terms of accuracy. In recent years, these two evaluations of microbial foodborne pathogens monitoring in the farm-to-table chain have shown more importance, especially during the COVID-19 pandemic. Meanwhile, there are also many new developments in the monitoring of heavy metals, algal toxins, and other pollutants. In the future, algal food safety risk assessment will not only focus on convenient, rapid, low-cost and high-accuracy detection but also be connected with some novel technologies, such as the Internet of Things (artificial intelligence, machine learning), biosensor, and molecular biology, to reach the purpose of simultaneous detection.