Effect of microalgal biomass incorporation into foods: Nutritional and sensorial attributes of the end products

Green microbes: Potential solutions for key sustainable development goals

The latest assessment of progress towards the Sustainable Development Goals (SDGs) has identified major obstacles, such as climate change, global instability and pandemics, which threaten efforts to achieve the SDGs even by 2050. Urgent action is needed, particularly to reduce poverty, hunger and climate change. In this context, microalgae are emerging as a promising solution, particularly in the context of food security and environmental sustainability. As versatile organisms, microalgae offer nutritional benefits such as high-quality proteins and essential fatty acids, and can be cultivated in non-arable areas, reducing competition for resources and improving the sustainability of food systems. The role of microalgae also includes other applications in aquaculture, where they serve as sustainable alternatives to animal feed, and in agriculture, where they act as biofertilizers and biostimulants. These microorganisms also play a key role in interventions on degraded land, stabilizing soils, improving hydrological function and increasing nutrient and carbon availability. Microalgae therefore support several SDGs by promoting sustainable agricultural practices and contributing to land restoration and carbon sequestration efforts. The integration of microalgae in these areas is essential to mitigate environmental impacts and improve global food security, highlighting the need for increased research and development, as well as public and political support, to exploit their full potential to advance the SDGs.

Field Cricket (Gryllus bimaculatus) and Spirulina (Arthrospira platensis) Powders as Environmentally Friendly Protein Enrichment Ingredients in Corn Snacks

Unconventional protein sources are currently extensively studied as food ingredients. This study aimed to evaluate the effect of 1.5% and 3% field cricket powder (GB) and 2-8% of its mixture (1:1) with spirulina powder (S) on the nutritional value, physicochemical properties, and sensory characteristics of corn extrudates. Additionally, 2% baking powder (BP) was added to assess its impact on the properties of the enriched extrudates. The results showed that both GB and GB + S improved nutritional value, with protein content increasing by up to 46% and higher levels of essential amino acids, particularly leucine and valine. However, these ingredients decreased the expansion ratio (by up to 15%), colour lightness (by up to 30%), and yellowness (by up to 47%) and increased the hardness (by up to 25%) of the corn extrudates. The S addition positively influenced product storage stability but decreased its sensory acceptance, especially aroma and taste. The BP addition mitigated the negative effects of higher GB and GB + S concentrations, particularly on sensory characteristics. In conclusion, incorporating up to 6% of the GB + S mixture provides a higher protein content with only minor changes to the product's characteristics compared to GB. Ratings exceeding 4.2 points indicate the good acceptability of these snacks.

Narrative Review of the Current and Future Perspectives of Phycobiliproteins' Applications in the Food Industry: From Natural Colors to Alternative Proteins

Vivid-colored phycobiliproteins (PBPs) have emerging potential as food colors and alternative proteins in the food industry. However, enhancing their application potential requires increasing stability, cost-effective purification processes, and consumer acceptance. This narrative review aimed to highlight information regarding the critical aspects of PBP research that is needed to improve their food industry potential, such as stability, food fortification, development of new PBP-based food products, and cost-effective production. The main results of the literature review show that polysaccharide and protein-based encapsulations significantly improve PBPs' stability. Additionally, while many studies have investigated the ability of PBPs to enhance the techno-functional properties, like viscosity, emulsifying and stabilizing activity, texture, rheology, etc., of widely used food products, highly concentrated PBP food products are still rare. Therefore, much effort should be invested in improving the stability, yield, and sensory characteristics of the PBP-fortified food due to the resulting unpleasant sensory characteristics. Considering that most studies focus on the C-phycocyanin from Spirulina, future studies should concentrate on less explored PBPs from red macroalgae due to their much higher production potential, a critical factor for positioning PBPs as alternative proteins.

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.

Algae: A promising and sustainable protein-rich food ingredient for bakery and dairy products

The consumer demand for protein rich foods urges the exploration for novel products of natural origin. Algae can be considered as a gold mine of different bioactive compounds, among which protein is distributed in significant amounts i.e., around 30% and can even reach to 55-60% in some cyanobacteria. Bakery and dairy products are extensively consumed worldwide due to product diversification and innovation. However, incorporation of algae biomass can lead to the development of green colour and fishy flavour that usually is not accepted in such products. Therefore, isolation and application of algae-derived proteins opens a new door for food industry. The present review provides a comprehensive understanding of incorporation of algae as a protein-rich ingredient in bakery and dairy products. The paper provides a deep insight for all the possible recent trends related to production and extraction of algae proteins accompanied by their incorporation in bakery and dairy foods.

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.

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.

Productivity, amino acid profile, and protein bioaccessibility in heterotrophic batch cultivation of Galdieria sulphuraria

The polyextremophilic Galdieria sulphuraria is emerging as a promising microalgal species for food applications. This work explores the potential of heterotrophically cultivated G. sulphuraria as a protein producer for human consumption. To this end, the performances of four G. sulphuraria strains grown under the same conditions were compared. Amino acid profiles varied among strains and growth phases, but all samples met FAO dietary requirements for adults. The specific growth rates were between 1.01 and 1.48 day-1. After glucose depletion, all strains showed an increase of 38-49 % in nitrogen content within 48 h, reaching 7.8-12.0 % w/w. An opposite trend was observed in protein bioaccessibility, which decreased on average from 69 % during the exponential phase to a minimum of 32 % 48 h after stationary phase, with significant differences among the strains. Therefore, selecting the appropriate strain and harvesting time is crucial for successful single-cell protein production.

Recent developments and challenges in algal protein and peptide extraction strategies, functional and technological properties, bioaccessibility, and commercial applications

The burgeoning demand for protein, exacerbated by population growth and recent disruptions in the food supply chain, has prompted a rapid exploration of sustainable protein alternatives. Among these alternatives, algae stand out for their environmental benefits, rapid growth, and rich protein content. However, the widespread adoption of algae-derived proteins faces significant challenges. These include issues related to harvesting, safety, scalability, high cost, standardization, commercialization, and regulatory hurdles. Particularly daunting is the efficient extraction of algal proteins, as their resilient cell walls contain approximately 70% of the protein content, with conventional methods accessing only a fraction of this. Overcoming this challenge necessitates the development of cost-effective, scalable, and environmentally friendly cell disruption techniques capable of breaking down these rigid cell walls, often laden with viscous polysaccharides. Various approaches, including physical, chemical, and enzymatic methods, offer potential solutions, albeit with varying efficacy depending on the specific algal strain and energy transfer efficiency. Moreover, there remains a pressing need for further research to elucidate the functional, technological, and bioaccessible properties of algal proteins and peptides, along with exploring their diverse commercial applications. Despite these obstacles, algae hold considerable promise as a sustainable protein source, offering a pathway to meet the escalating nutritional demands of a growing global population. This review highlights the nutritional, technological, and functional aspects of algal proteins and peptides while underscoring the challenges hindering their widespread adoption. It emphasizes the critical importance of establishing a sustainable trajectory for food production, with algae playing a pivotal role in this endeavor.

Dairy, Plant, and Novel Proteins: Scientific and Technological Aspects

Alternative proteins have gained popularity as consumers look for foods that are healthy, nutritious, and sustainable. Plant proteins, precision fermentation-derived proteins, cell-cultured proteins, algal proteins, and mycoproteins are the major types of alternative proteins that have emerged in recent years. This review addresses the major alternative-protein categories and reviews their definitions, current market statuses, production methods, and regulations in different countries, safety assessments, nutrition statuses, functionalities and applications, and, finally, sensory properties and consumer perception. Knowledge relative to traditional dairy proteins is also addressed. Opportunities and challenges associated with these proteins are also discussed. Future research directions are proposed to better understand these technologies and to develop consumer-acceptable final products.

Microalgae Proteins as Sustainable Ingredients in Novel Foods: Recent Developments and Challenges

Microalgae are receiving increased attention in the food sector as a sustainable ingredient due to their high protein content and nutritional value. They contain up to 70% proteins with the presence of all 20 essential amino acids, thus fulfilling human dietary requirements. Microalgae are considered sustainable and environmentally friendly compared to traditional protein sources as they require less land and a reduced amount of water for cultivation. Although microalgae's potential in nutritional quality and functional properties is well documented, no reviews have considered an in-depth analysis of the pros and cons of their addition to foods. The present work discusses recent findings on microalgae with respect to their protein content and nutritional quality, placing a special focus on formulated food products containing microalgae proteins. Several challenges are encountered in the production, processing, and commercialization of foods containing microalgae proteins. Solutions presented in recent studies highlight the future research and directions necessary to provide solutions for consumer acceptability of microalgae proteins and derived products.

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.

Beneficial Effects of Spirulina Supplementation in the Management of Cardiovascular Diseases

In recent decades, as a result of rising mortality rates due to cardiovascular diseases (CVDs), there has been a growing urgency to find alternative approaches to conventional pharmaceutical treatment to prevent the onset of chronic diseases. Arthrospira platensis, commonly known as Spirulina, is a blue-green cyanobacterium, classified as a "superfood", used worldwide as a nutraceutical food supplement due to its remarkable nutritional value, lack of toxicity, and therapeutic effects. Several scientific studies have evaluated the cardioprotective role of Spirulina. This article presents a comprehensive review of the therapeutic benefits of Spirulina in improving cardio- and cerebrovascular health. It focuses on the latest experimental and clinical findings to evaluate its antihypertensive, antidiabetic, and antihyperlipidemic properties. The objective is to highlight its potential in preventing and managing risk factors associated with cardiovascular disease (CVD).

Purification and characterization of thioredoxin reductase enzyme from commercial Spirulina platensis tablets by affinity chromatography and investigation of the effects of some chemicals and drugs on enzyme activity

Thioredoxin reductase (TrxR, enzyme code [E.C.] 1.6.4.5) is a widely distributed flavoenzyme that catalyzes nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reduction of thioredoxin and many other physiologically important substrates. Spirulina platensis is a blue-green algae that is often used as a dietary supplement. S. platensis is rich in protein, lipid, polysaccharide, pigment, carotenoid, enzyme, vitamins and many other chemicals and exhibits a variety of pharmacological functions. In the present study, a simple and efficient method to purify TrxR from S. platensis tablets is reported. The extractions were carried out using two different methods: heat denaturation and 2',5'-adenosine diphosphate Sepharose 4B affinity chromatography. The enzyme was purified by 415.04-fold over the crude extract, with a 19% yield, and specific activity of 0.7640 U/mg protein. Optimum pH, temperature and ionic strength of the enzyme activity, as well as the Michaelis constant (Km ) and maximum velocity of enzyme (Vmax ) values for NADPH and 5,5'-dithiobis(2-nitrobenzoic acid) were determined. Tested metal ions, vitamins, and drugs showed inhibition effects, except Se4+ ion, cefazolin sodium, teicoplanin, and tobramycin that increased the enzyme activity in vitro. Ag+ , Cu2+ , Mg2+ , Ni2+ , Pb2+ , Zn2+ , Al3+ , Cr3+ , Fe3+ , and V4+ ions; vitamin B3 , vitamin B6 , vitamin C, and vitamin U and aciclovir, azithromycin, benzyladenine, ceftriaxone sodium, clarithromycin, diclofenac, gibberellic acid, glurenorm, indole-3-butyric acid, ketorolac, metformin, mupirocin, mupirocin calcium, paracetamol, and tenofovir had inhibitory effects on TrxR. Ag+ exhibited stronger inhibition than 1-chloro-2,4-dinitrobenzene (a positive control).

Breeding a novel chlorophyll-deficient mutant of Auxenochlorella pyrenoidosa for high-quality protein production by atmospheric room temperature plasma mutagenesis

In the present work, a novel chlorophyll-deficient mutant of Auxenochlorella pyrenoidosa named A4-1 was generated by atmospheric room temperature plasma (ARTP) mutagenesis. Compared to the green wild type (WT) strain, the A4-1 mutant cultured in the dark displayed yellow colour with a 118-fold decrease of chlorophyll a and no detected chlorophyll b. Higher contents of protein (44.22 % DW), total amino acids (AAs, 34.84 % DW) and essential AAs (17.50 % DW) were also achieved, showing 31 %, 22 % and 30 % increases compared to the WT, respectively (p < 0.05). Metabolite profile analysis revealed that the chlorophyll biosynthesis pathway in the A4-1 mutant was probably inhibited in the dark, while more carbon skeletons might be utilized for de novo AAs synthesis. These results demonstrated that the A4-1 mutant not only has extremely low chlorophyll content, but also has higher protein content, making it a very promising candidate to produce microalgal protein for future foods.

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.

The potentials and challenges of using fermentation to improve the sensory quality of plant-based meat analogs

Despite the advancements made in improving the quality of plant-based meat substitutes, more work needs to be done to match the texture, appearance, and flavor of real meat. This review aims to cover the sensory quality constraints of plant-based meat analogs and provides fermentation as a sustainable approach to push these boundaries. Plant-based meat analogs have been observed to have weak and soft textural quality, poor mouth feel, an unstable color, and unpleasant and beany flavors in some cases, necessitating the search for efficient novel technologies. A wide range of microorganisms, including bacteria such as Lactobacillus acidophilus and Lactiplantibacillus plantarum, as well as fungi like Fusarium venenatum and Neurospora intermedia, have improved the product texture to mimic fibrous meat structures. Additionally, the chewiness and hardness of the resulting meat analogs have been further improved through the use of Bacillus subtilis. However, excessive fermentation may result in a decrease in the final product's firmness and produce a slimy texture. Similarly, several microbial metabolites can mimic the color and flavor of meat, with some concerns. It appears that fermentation is a promising approach to modulating the sensory profiles of plant-derived meat ingredients without adverse consequences. In addition, the technology of starter cultures can be optimized and introduced as a new strategy to enhance the organoleptic properties of plant-based meat while still meeting the needs of an expanding and sustainable economy.

Trends and prospects in dairy protein replacement in yogurt and cheese

There is a growing demand for nutritional, functional, and eco-friendly dairy products, which has increased the need for research regarding alternative and sustainable protein sources. Plant-based, single-cell (SCP), and recombinant proteins are being explored as alternatives to dairy proteins. Plant-Based Proteins (PBPs) are commonly used to replace total dairy protein. However, PBPs are generally mixed with dairy proteins to improve their functional properties, which makes them dependent on animal protein sources. In contrast, single-Cell Proteins (SCPs) and recombinant dairy proteins are promising alternatives for dairy protein replacement since they provide nutritional components, essential amino acids, and high protein yield and can use industrial and agricultural waste as carbon sources. Although alternative protein sources offer numerous advantages over conventional dairy proteins, several technical and sensory challenges must be addressed to fully incorporate them into cheese and yogurt products. Future research can focus on improving the functional and sensory properties of alternative protein sources and developing new processing technologies to optimize their use in dairy products. This review highlights the current status of alternative dairy proteins in cheese and yogurt, their functional properties, and the challenges of their use in these products.

Differences and Similarities in Lipid Composition, Nutritional Value, and Bioactive Potential of Four Edible Chlorella vulgaris Strains

The microalga Chlorella vulgaris is a popular food ingredient widely used in the industry, with an increasing market size and value. Currently, several edible strains of C. vulgaris with different organoleptic characteristics are commercialized to meet consumer needs. This study aimed to compare the fatty acid (FA) and lipid profile of four commercialized strains of C. vulgaris (C-Auto, C-Hetero, C-Honey, and C-White) using gas- and liquid-chromatography coupled to mass-spectrometry approaches, and to evaluate their antioxidant and anti-inflammatory properties. Results showed that C-Auto had a higher lipid content compared to the other strains and higher levels of omega-3 polyunsaturated FAs (PUFAs). However, the C-Hetero, C-Honey, and C-White strains had higher levels of omega-6 PUFAs. The lipidome signature was also different between strains, as C-Auto had a higher content of polar lipids esterified to omega-3 PUFAs, while C-White had a higher content of phospholipids with omega-6 PUFAs. C-Hetero and C-Honey showed a higher content of triacylglycerols. All extracts showed antioxidant and anti-inflammatory activity, highlighting C-Auto with greater potential. Overall, the four strains of C. vulgaris can be selectively chosen as a source of added-value lipids to be used as ingredients in food and nutraceutical applications for different market needs and nutritional requirements.

Alternative Protein Sources and Novel Foods: Benefits, Food Applications and Safety Issues

The increasing size of the human population and the shortage of highly valuable proteinaceous ingredients has prompted the international community to scout for new, sustainable, and natural protein resources from invertebrates (e.g., insects) and underutilized legume crops, unexploited terrestrial and aquatic weeds, and fungi. Insect proteins are known for their nutritional value, being rich in proteins with a good balance of essential amino acids and being a valuable source of essential fatty acids and trace elements. Unconventional legume crops were found rich in nutritional, phytochemical, and therapeutic properties, showing excellent abilities to survive extreme environmental conditions. This review evaluates the recent state of underutilized legume crops, aquatic weeds, fungi, and insects intended as alternative protein sources, from ingredient production to their incorporation in food products, including their food formulations and the functional characteristics of alternative plant-based proteins and edible insect proteins as novel foods. Emphasis is also placed on safety issues due to the presence of anti-nutritional factors and allergenic proteins in insects and/or underutilized legumes. The functional and biological activities of protein hydrolysates from different protein sources are reviewed, along with bioactive peptides displaying antihypertensive, antioxidant, antidiabetic, and/or antimicrobial activity. Due to the healthy properties of these foods for the high abundance of bioactive peptides and phytochemicals, more consumers are expected to turn to vegetarianism or veganism in the future, and the increasing demand for such products will be a challenge for the future.

Tisochrysis lutea as a Substrate for Lactic Acid Fermentation: Biochemical Composition, Digestibility, and Functional Properties

Microalgae, because of their high nutritional value and bioactive molecule content, are interesting candidates for functional foods, including fermented foods, in which the beneficial effects of probiotic bacteria combine with those of biomolecules lying in microalgal biomass. The aim of this work was to evaluate the potential of Tisochrysis lutea F&M-M36 as a substrate for Lactiplantibacillus plantarum ATCC 8014 and to verify fermentation effects on functionality. Bacterium selection among three lactobacilli was based on growth and resistance to in vitro digestion. Microalgal raw biomass and its digested residue were fermented in two matrixes, water and diluted organic medium, and analysed for biochemical composition and antioxidant activity along with their unfermented counterparts. Bacterial survivability to digestion and raw biomass digestibility after fermentation were also evaluated. Fucoxanthin was strongly reduced (>90%) in post-digestion residue, suggesting high bioavailability. Raw biomass in diluted organic medium gave the highest bacterial growth (8.5 logCFU mL^-1) and organic acid production (5 mg L^-1), while bacterial survivability to digestion (<3%) did not improve. After fermentation, the antioxidant activity of lipophilic extracts increased (>90%). Fermentation appears an interesting process to obtain T. lutea-based functional foods, although further investigations are needed to optimize bacterial growth and fully evaluate its effects on functionality and organoleptic features.

Smart systems in producing algae-based protein to improve functional food ingredients industries

Production and extraction systems of algal protein and handling process of functional food ingredients need to control several parameters such as temperature, pH, intensity, and turbidity. Many researchers have investigated the Internet of Things (IoT) approach for enhancing the yield of microalgae biomass and machine learning for identifying and classifying microalgae. However, there have been few specific studies on using IoT and artificial intelligence (AI) for production and extraction of algal protein as well as functional food ingredients processing. In order to improve the production of algal protein and functional food ingredients, the implementation of smart system is a must to have real-time monitoring, remote control system, quick response to sudden events, prediction and characterisation. Techniques of IoT and AI are expected to help functional food industries to have a big breakthrough in the future. Manufacturing and implementation of beneficial smart systems are important to provide convenience and to increase the efficiency of work by using the interconnectivity of IoT devices to have good capturing, processing, archiving, analyzing, and automation. This review investigates the possibilities of implementation of IoT and AI in production and extraction of algal protein and processing of functional food ingredients.

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.

Microalgal bioactive metabolites as promising implements in nutraceuticals and pharmaceuticals: inspiring therapy for health benefits

The rapid increase in global population and shrinkage of agricultural land necessitates the use of cost-effective renewable sources as alternative to excessive resource-demanding agricultural crops. Microalgae seem to be a potential substitute as it rapidly produces large biomass that can serve as a good source of various functional ingredients that are not produced/synthesized inside the human body and high-value nonessential bioactive compounds. Microalgae-derived bioactive metabolites possess various bioactivities including antioxidant, anti-inflammatory, antimicrobial, anti-carcinogenic, anti-hypertensive, anti-lipidemic, and anti-diabetic activities, thereof rapidly elevating their demand as interesting option in pharmaceuticals, nutraceuticals and functional foods industries for developing new products. However, their utilization in these sectors has been limited. This demands more research to explore the functionality of microalgae derived functional ingredients. Therefore, in this review, we intended to furnish up-to-date knowledge on prospects of bioactive metabolites from microalgae, their bioactivities related to health, the process of microalgae cultivation and harvesting, extraction and purification of bioactive metabolites, role as dietary supplements or functional food, their commercial applications in nutritional and pharmaceutical industries and the challenges in this area of research.

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Perspective: Multiomics and Machine Learning Help Unleash the Alternative Food Potential of Microalgae

Food security has become a pressing issue in the modern world. The ever-increasing world population, ongoing COVID-19 pandemic, and political conflicts together with climate change issues make the problem very challenging. Therefore, fundamental changes to the current food system and new sources of alternative food are required. Recently, the exploration of alternative food sources has been supported by numerous governmental and research organizations, as well as by small and large commercial ventures. Microalgae are gaining momentum as an effective source of alternative laboratory-based nutritional proteins as they are easy to grow under variable environmental conditions, with the added advantage of absorbing carbon dioxide. Despite their attractiveness, the utilization of microalgae faces several practical limitations. Here, we discuss both the potential and challenges of microalgae in food sustainability and their possible long-term contribution to the circular economy of converting food waste into feed via modern methods. We also argue that systems biology and artificial intelligence can play a role in overcoming some of the challenges and limitations; through data-guided metabolic flux optimization, and by systematically increasing the growth of the microalgae strains without negative outcomes, such as toxicity. This requires microalgae databases rich in omics data and further developments on its mining and analytics methods.

Potentially Beneficial Effects on Healthy Aging by Supplementation of the EPA-Rich Microalgae Phaeodactylum tricornutum or Its Supernatant-A Randomized Controlled Pilot Trial in Elderly Individuals

Dietary supplements that promote healthy aging are mostly warranted in an aging society. Because of age-related risks, anti-inflammatory and anti-oxidative agents such as microalgae are potential candidates for intervention. In a randomized controlled trial, we tested Phaeodactylum tricornutum (PT), a microalgae rich in eicosapentaenoic acid (EPA), carotenoids, vitamins, and β-glucans, cultured in bioreactors. In this pilot trial, 19 healthy elderly received supplements for two weeks based on either the whole PT (A), the β-1,3-glucan-rich PT supernatant (SupB), the combination thereof (A+SupB), or a Comparator product (Comp). The primary outcome variable plasma interleukin-6 was reduced after treatment with A+SupB compared to the Comp group (p = 0.04). The mobility parameters 5 s sit-to-stand test (p = 0.04 in the A group) and by trend gait speed (p = 0.08 in the A+SupB diet) were improved compared to Comp. No treatment effects were observed for fatty acids, compared to Comp but omega-6 to -3 fatty acid ratio (p = 0.006) and arachidonic acid/EPA ratio (p = 0.006) were reduced within group A+SupB. Further, the SupB study product reduced faecal zonulin (p = 0.03) compared to the Comp. The data revealed an anti-inflammatory and potentially anti-oxidative effect of particular PT preparations, suggesting that they might be suitable for effects in healthy elderly.

Production and Analysis of Beer Supplemented with Chlorella vulgaris Powder

The microalgae Chlorella vulgaris is a cheap source of nutrients and bioactive compounds, and thus is used in many interventional studies. This study evaluated the potential effects of C. vulgaris powder on fermentation parameters; sensory, phytochemical, and antioxidant activity; and the abundance of volatile organic compounds (VOCs) of treated versus control beers. A German Pilsner-style lager beer (GPB) was brewed and supplemented with C. vulgaris at various levels (3.3, 5, and 10 g/L) after primary fermentation. The apparent °Brix and pH was used to monitor the progress of fermentation. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2) was used to measure the antioxidant activity of beers. Addition of C. vulgaris increased the concentration of total polyphenols, total flavonoids, and antioxidant activity of treated beers (CGB) compared to the control (GPB). Treatment had no effects (p > 0.05) on higher alcohols such as 3-methyl-1-butanol, 2-hexanol, and phenylethyl alcohol. An increase in the concentration of C. vulgaris had no significant effects on sensory perception of enriched beers. The results showed that C. vulgaris could be used as a potential ingredient for designing functional beer with improved health benefits.

Active aroma compounds assessment of processed and non-processed micro- and macroalgae by solid-phase microextraction and gas chromatography/mass spectrometry targeting seafood analogs

The odor of four algae was investigated and compared to evaluate the potential of these algae to mimic shrimp aroma. Solid-phase microextraction followed by gas chromatography analysis coupled with sensory analysis was used for performance assessment. The volatile organic compounds were determined in non-processed, raw samples (r), and processed cooked (c) and cooking water (w) samples for two microalgae [Nannochoropsis oceanica (NO) and Tetraselmis chuii (TC)], two macroalgae [Ulva rígida (UR) and Saccharina latíssima (SL)], and shrimp Vannamei cong (SH). The results showed significant differences in the composition of volatile compounds between macroalgae and microalgae. The key odorants in macroalgae were octanal, 2-octenal, nonanal, and β-ionone, and in microalgae were 1,5-octadien-3-ol, hexanal, 2,4-decadienal, 2-octenal, octanal, nonanal, 3,5-octadien-2-one, and terpenes. The PCA analysis of GC-MS data showed odor similarities between the studied samples, which were divided into five main groups: (1) TC(c) and TC(w); (2) TC(r) and NO(c); (3) NO(r), NO(w), and SL(w); (4) SL(c), UR(r), UR(c), and UR(w); and (5) SL(r). The data from the sensory analysis show bigger similarities between the macroalgae and the shrimp odor. Overall, the data provided indicate that the cooking water and cooked samples are very similar in key components of odorants. These features allow the possibility to use algae and their processed resulting products as a shrimp flavor replacement in non-animal-based food formulations, thus decreasing the pressure on seafood crops and aquaculture-associated issues leading to more sustainable livestock. Furthermore, circularity and waste reduction may be further enabled by the use of otherwise wasted cooking water as an odorant agent.

Influence of Geographical Location of Spirulina (Arthrospira platensis) on the Recovery of Bioactive Compounds Assisted by Pulsed Electric Fields

Spirulina (Arthrospira platensis) has been consumed by humans since ancient times. It is rich in high added-value compounds such as chlorophylls, carotenoids and polyphenols. Pulsed electric fields (PEF) is an innovative non-thermal technique that improves the extraction of bioactive compounds from diverse sources. PEF pre-treatment (3 kV/cm, 100 kJ/kg) combined with supplementary extraction with binary solvents at different times was evaluated to obtain the optimal conditions for extraction. In addition, the results obtained were compared with conventional treatment (without PEF pre-treatment and constant shaking) and different strains of Spirulina from diverse geographical locations. The optimal extraction conditions for recovering the bioactive compounds were obtained after applying PEF treatment combined with the binary mixture EtOH/H2O for 180 min. The recovery of total phenolic content (TPC) (19.76 ± 0.50 mg/g DM (dry matter) and carotenoids (0.50 ± 0.01 mg/g DM) was more efficient in the Spirulina from Spain. On the other hand, there was a higher recovery of chlorophylls in the Spirulina from China. The highest extraction of total antioxidant compounds was in Spirulina from Costa Rica. These results show that PEF, solvents and the condition of growing affect the extraction of antioxidant bioactive compounds from Spirulina. The combination of PEF and EtOH/H2O is a promising technology due to its environmental sustainability.

Supercritical CO2 Extraction of High-Added Value Compounds from Chlorella vulgaris: Experimental Design, Modelling and Optimization

Microalgae are well-known for their high-added value compounds and their recovery is currently of great interest. The aim of this work is the recovery of such components from Chlorella vulgaris through supercritical fluid extraction (SFE) with CO₂. The effect of the extraction temperature (40–60 °C), pressure (110–250 bar), and solvent flow rate (20–40 g/min) was tested on yield, the extract’s antioxidant activity, and the phenolic, chlorophyll and carotenoid content. Thus, data analysis indicated that the yield was mainly affected by temperature, carotenoids by pressure, while the extract’s phenolics and antioxidant activity were affected by the synergy of temperature and pressure. Moreover, SFE’s kinetic study was performed and experimental data were correlated using Sovová’s mass transfer-based model. SFE optimization (60 °C, 250 bar, 40 g/min) led to 3.37% w/w yield, 44.35 mg_extr/mg_DPPH antioxidant activity (IC50), 18.29 mg_GA/g_extr total phenolic content, 35.55, 21.14 and 10.00 mg/g_extr total chlorophyll, carotenoid and selected carotenoid content (astaxanthin, lutein and β-carotene), respectively. A comparison of SFE with conventional aq. ethanol (90% v/v) extraction proved SFE’s superiority regarding extraction duration, carotenoids, antioxidant activity and organoleptic characteristics of color and odor despite the lower yield. Finally, cosolvent addition (ethanol 10% w/w) at optimum SFE conditions improved the extract’s antioxidant activity (19.46%) as well as yield (101.81%).

Extraction of lipids from microalgae using classical and innovative approaches

Microalgae, as a photosynthetic autotrophic organism, contain a variety of bioactive compounds, including lipids, proteins, polysaccharides, which have been applied in food, medicine, and fuel industries, among others. Microalgae are considered a good source of marine lipids due to their high content in unsaturated fatty acid (UFA) and can be used as a supplement/replacement for fish-based oil. The high concentration of docosahexaenoic (DHA) and eicosapentaenoic acids (EPA) in microalgae lipids, results in important physiological functions, such as antibacterial, anti-inflammatory, and immune regulation, being also a prerequisite for its development and application. In this paper, a variety of approaches for the extraction of lipids from microalgae were reviewed, including classical and innovative approaches, being the advantages and disadvantages of these methods emphasized. Further, the effects of microalgae lipids as high value bioactive compounds in human health and their use for several applications are dealt with, aiming using green(er) and effective methods to extract lipids from microalgae, as well as develop and extend their application potential.

Drying Microalgae Using an Industrial Solar Dryer: A Biomass Quality Assessment

Microalgae are considered a promising resource of proteins, lipids, carbohydrates, and other functional biomolecules for food and feed markets. Competitive drying solutions are required to meet future demands for high-quality algal biomass while ensuring proper preservation at reduced costs. Since often used drying methods, such as freeze or spray drying, are energy and time consuming, more sustainable processes remain to be developed. This study tested an indirect and hybrid solar dryer as an alternative to conventional freeze drying of industrially produced Tetraselmis chui and Nannochloropsis oceanica wet paste. The effects of the drying method on biomass quality parameters, including biochemical profiles, functional properties, and microbial safety, were assessed. No significant differences were found between the applied drying technologies for total proteins, carbohydrates, lipids, and fatty acid profiles. On the other hand, some pigments showed significant differences, displaying up to 44.5% higher contents in freeze-dried samples. Minor differences were also registered in the mineral profiles (<10%). Analyses of microbial safety and functional properties of the solar-dried biomass appear adequate for food and feed products. In conclusion, industrial solar drying is a sustainable technology with a high potential to preserve high-quality microalgal biomass for various markets at expected lower costs.

Insights on the Bioaccessibility of Natural Pigments from Diatom Chaetoceros calcitrans

This study aimed to investigate the bioaccessibility of carotenoids and chlorophylls from the biomass of microalgae Chaetoceros calcitrans. The samples were submitted to an in vitro digestion protocol, and the compounds were determined by HPLC-PDA-MS/MS. A total of 13 compounds were identified in all tests. After in vitro digestion, the relative bioaccessibility of carotenoids and chlorophylls ranged from 4 to 58%. The qualitative profile of carotenoids reflected the initial sample, with all-E-zeaxanthin (57.2%) being the most bioaccessible compound, followed by all-E-neochrome (31.26%), the latter being reported for the first time in the micellar fraction. On the other hand, among the chlorophylls only pheophytin a (15.01%) was bioaccessible. Furthermore, a chlorophyll derivative (Hydroxypheophytin a’) was formed after in vitro digestion. Considering all compounds, xanthophylls (12.03%) and chlorophylls (12.22%) were significantly (p < 0.05) more bioaccessible than carotenes (11.22%). Finally, the considerable individual bioaccessibilities found, especially for zeaxanthin, demonstrate the bioactive potential of this bioresource. However, the large reduction in the totality of compounds after in vitro digestion suggests that additional technological strategies should be explored in the future to increase the efficiency of micellarization and enhance its bioactive effects.

Lab-scale photobioreactor systems: principles, applications, and scalability

Phototrophic microorganisms that convert carbon dioxide are being explored for their capacity to solve different environmental issues and produce bioactive compounds for human therapeutics and as food additives. Full-scale phototrophic cultivation of microalgae and cyanobacteria can be done in open ponds or closed photobioreactor systems, which have a broad range of volumes. This review focuses on laboratory-scale photobioreactors and their different designs. Illuminated microtiter plates and microfluidic devices offer an option for automated high-throughput studies with microalgae. Illuminated shake flasks are used for simple uncontrolled batch studies. The application of illuminated bubble column reactors strongly emphasizes homogenous gas distribution, while illuminated flat plate bioreactors offer high and uniform light input. Illuminated stirred-tank bioreactors facilitate the application of very well-defined reaction conditions. Closed tubular photobioreactors as well as open photobioreactors like small-scale raceway ponds and thin-layer cascades are applied as scale-down models of the respective large-scale bioreactors. A few other less common designs such as illuminated plastic bags or aquarium tanks are also used mainly because of their relatively low cost, but up-scaling of these designs is challenging with additional light-driven issues. Finally, this review covers recommendations on the criteria for photobioreactor selection and operation while up-scaling of phototrophic bioprocesses with microalgae or cyanobacteria.

Nannochloropsis sp. Biorefinery: Recovery of Soluble Protein by Membrane Ultrafiltration/Diafiltration

This work proposes a way to maximize the potential of a Nannochloropsis sp. biorefinery process, through membrane technology, producing an extract enriched in soluble proteins, free from the insoluble protein fraction, with a low lipid content and eliminating the colored chlorophyll-a. This procedure, following the principles of a circular economy approach, allows for the valorization of a stream from the biorefining of Nannochloropsis sp. that, otherwise, would be considered a residue without commercial value. The process proposed minimizes fouling phenomena at the membrane surface, making it possible to achieve high permeate fluxes, thus reducing the need for membrane cleaning and, therefore, contributing to an extended membrane lifetime. Supernatant obtained after centrifugation of a suspension of ruptured Nannochloropsis sp. cells was processed by ultrafiltration using a membrane with a cut-off of 100 kDa MWCO. Two different operating approaches were evaluated—controlled transmembrane pressure and controlled permeate flux—under concentration and diafiltration modes. Ultrafiltration operated in a diafiltration mode, under controlled permeate flux conditions, led to the highest soluble protein recovery (78%) with the highest constant permeate flux (12 L·m⁻²·h⁻¹) and low membrane fouling.

Characterisation of the volatile profile of microalgae and cyanobacteria using solid-phase microextraction followed by gas chromatography coupled to mass spectrometry

Microalgae and microalgae-derived ingredients are one of the top trends in the food industry. However, consumers’ acceptance and purchase intention of a product will be largely affected by odour and flavour. Surprisingly, the scientific literature present a very limited number of studies on the volatile composition of microalgae and cyanobacteria. In order to fill the gap, the main objective of the present study was to elucidate the volatile composition of seven microalgal and cyanobacterial strains from marine and freshwaters, with interest for the food industry while establishing its potential impact in odour. Among the seven selected strains, Arthrospira platensis showed the highest abundance and chemical diversity of volatile organic compounds (VOCs). Aldehydes, ketones, and alcohols were the families with the highest diversity of individual compounds, except in Arthrospira platensis and Scenedesmus almeriensis that showed a profile dominated by branched hydrocarbons. Marine strains presented a higher abundance of sulfur compounds than freshwater strains, while the ketones individual profile seemed to be more related to the taxonomical domain. The results of this study indicate that the VOCs composition is mainly driven by the individual strain although some volatile profile characteristics could be influenced by both environmental and taxonomical factors.

Technological and Sensory Aspects of Macaroni with Free or Encapsulated Azolla Fern Powder

Azolla might be considered an alternative and promising dietary ingredient for antioxidants. There have not been any reports on the incorporation of free Azolla fern powder (FAP) or its microcapsules in foods, especially fresh pasta, yet. Microencapsulation was used to mask the undesirable taste and odour of Azolla, as well as to preserve its antioxidant potential. The current study concentrated on two major goals. The first goal was to use alginate as a wall material for FAP encapsulation, as well as to characterise the FAP microcapsule for its encapsulation efficiency, solubility, and thermal stability. The second goal was to assess the impact of integrating FAP or its microcapsules into fresh macaroni on its colour parameters, cooking quality, texture properties, and sensory characteristics. The microspheres had a high encapsulation efficiency (88.19%) and a low water solubility (85.23 g/kg), making them suitable for use in foods that require cooking in water. When compared to free Azolla powder, encapsulation reduced the antioxidant activity loss rate by 67.73%. All the cooking and textural properties of fresh macaroni were not significantly affected, except for water absorption and weight gain, but the overall acceptability index (85.13%) was not affected by microcapsule incorporation.

Culture Conditions Affect Antioxidant Production, Metabolism and Related Biomarkers of the Microalgae Phaeodactylum tricornutum

Phaeodactylum tricornutum (Bacillariophyta) is a worldwide-distributed diatom with the ability to adapt and survive in different environmental habitats and nutrient-limited conditions. In this research, we investigated the growth performance, the total lipids productivity, the major categories of fatty acids, and the antioxidant content in P. tricornutum subjected for 15 days to nitrogen deprivation (N-) compared to standard culture conditions (N+). Furthermore, genes and pathways related to lipid biosynthesis (i.e., glucose-6-phosphate dehydrogenase, acetyl-coenzyme A carboxylase, citrate synthase, and isocitrate dehydrogenase) and photosynthetic activity (i.e., ribulose-1,5-bisphospate carboxylase/oxygenase and fucoxanthin-chlorophyll a/c binding protein B) were investigated through molecular approaches. P. tricornutum grown under starvation condition (N-) increased lipids production (42.5 ± 0.19 g/100 g) and decreased secondary metabolites productivity (phenolic content: 3.071 ± 0.17 mg GAE g-1; carotenoids: 0.35 ± 0.01 mg g−1) when compared to standard culture conditions (N+). Moreover, N deprivation led to an increase in the expression of genes involved in fatty acid biosynthesis and a decrease in genes related to photosynthesis. These results could be used as indicators of nitrogen limitation for environmental or industrial monitoring of P. tricornutum.