The impact of high-pressure homogenization on thermal gelation of Arthrospira platensis (Spirulina) protein concentrate

Proteins from Microalgae: Nutritional, Functional and Bioactive Properties

Microalgae have emerged as a sustainable and efficient source of protein, offering a promising alternative to conventional animal and plant-based proteins. Species such as Arthrospira platensis and Chlorella vulgaris contain protein levels ranging from 50% to 70% of their dry weight, along with a well-balanced amino acid profile rich in essential amino acids such as lysine and leucine. Their cultivation avoids competition for arable land, aligning with global sustainability goals. However, the efficient extraction of proteins is challenged by their rigid cell walls, necessitating the development of optimized methods such as bead milling, ultrasonication, enzymatic treatments, and pulsed electric fields. These techniques preserve functionality while achieving yields of up to 96%. Nutritional analyses reveal species-dependent digestibility, ranging from 70 to 90%, with Spirulina platensis achieving the highest rates due to low cellulose content. Functionally, microalgal proteins exhibit emulsifying, water-holding, and gel-forming properties, enabling applications in baking, dairy, and meat analogs. Bioactive peptides derived from these proteins exhibit antioxidant, antimicrobial (inhibiting E. coli and S. aureus), anti-inflammatory (reducing TNF-α and IL-6), and antiviral activities (e.g., Dengue virus inhibition). Despite their potential, commercialization faces challenges, including regulatory heterogeneity, high production costs, and consumer acceptance barriers linked to eating habits or sensory attributes. Current market products like Spirulina-enriched snacks and Chlorella tablets highlight progress, but food safety standards and scalable cost-effective extraction technologies remain critical for broader adoption. This review underscores microalgae's dual role as a nutritional powerhouse and a source of multifunctional bioactives, positioning them at the forefront of sustainable food and pharmaceutical innovation.

Microalgal proteins: Unveiling sustainable alternatives to address the protein challenge

Recent breakthroughs emphasized the considerable potential of microalgae as a sustainable protein source. Microalgae are regarded as a substitute for protein-rich foods because of their high protein and amino acid content. However, despite their nutritional value, microalgae cannot be easily digested by humans due to the presence of cell walls. In the subsequent sections, protein extraction technology, the overview of the inherent challenges of the process, and the summary of the factors affecting protein extraction and utilization have been deliberated. Moreover, the review inspected the formation of proteolytic products, highlighting their diverse bioactivities, including antioxidant, antihypertensive, and immunomodulatory activities. Finally, the discussion extended to the emerging microalgal protein sourced foods, such as baked goods and nutritional supplements, as well as the sensory and marketing challenges encountered in the production of microalgal protein foods. The lack of consumer awareness about the health benefits of microalgae complicates its acceptance in the market. Long-standing challenges, such as high production costs, persist. Currently, multi-product utilization strategies are being developed to improve the economic viability of microalgae. By integrating economic, environmental, and social factors, microalgae protein can be sustainably developed to provide a reliable source of raw materials for the future food industry.

Innovative vs classical methods for drying heterotrophic Chlorella vulgaris: Impact on protein quality and sensory properties

Drying is a necessary step in the microalgae production chain to reduce microbial load and oxidative degradation of the end product. Depending on the differences in applied temperature and treatment time, the process of drying can have a substantial impact on protein quality and aroma, important characteristics determining the incorporation potential in food products. In this study, we compared the drying of heterotrophic Chorella vulgaris with both innovative (agitated thin film drying (ATFD), pulse combustion drying (PCD) and solar drying (SolD)) and commonly used drying techniques (spray drying (SprD) and freeze drying (FD)). To evaluate the impact on protein quality, we evaluated techno-functional properties, in vitro digestibility (INFOGEST) as well as protein denaturation using differential scanning calorimetry (DSC). A sensory analysis was performed by a trained expert panel, combined with headspace solid-phase microextraction (HS-SPME) - gas chromatography-mass spectrometry (GC-MS) to determine volatile organic compounds (VOCs). ATFD was found to increase techno-functional properties such as gelling, water holding and solubility as well as in vitro protein digestibility. These observations could be related to induced cell disruption and protein denaturation by ATFD. Sensory analysis indicated an increased earthy off-flavor after ATFD. Interestingly, the high-temperature PCD led to an increase in cacao odor while low-temperature FD resulted in lower flavor, odors and VOCs. These results demonstrate that protein quality and sensorial properties of C. vulgaris can be steered through the type of drying, which could help in the selection of application-specific drying methods. Overall, this work could promote the incorporation of microalgal single cell proteins in different innovative food 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.

Thermal and Modern, Non-Thermal Method Induction as a Factor of Modification of Inulin Hydrogel Properties

The aim of the study was to compare the properties of inulin hydrogels obtained with different methods, e.g., the traditional-thermal method and new, non-thermal methods, used in food production, like ultrasonic, high-pressure homogenization (HPH), and high hydrostatic pressures (HHPs). It was found that each of the compared induction methods allowed for obtaining inulin hydrogels. However, the use of non-thermal induction methods allows for obtaining a gel structure faster than in the case of thermal induction. In addition, hydrogels obtained with new, non-thermal methods differ from gels obtained with thermal treatment. They were characterized by higher stability (from 1.7 percent point-of-stability parameters for HHP 150 MPa to 18.8 for HPH II cycles) and in most cases, by improved microrheological properties-lower solid-liquid balance toward the solid phase, increased elasticity and viscosity indexes, and lowering the flow index. The gels obtained with the new, non-thermal method were also characterized by a more delicate structure, including lower firmness (the differences between thermal and non-thermal inductions were from 0.73 N for HHP at 500 MPa to 2.39 N for HHP at 150 MPa) and spreadability (the differences between thermal and non-thermal inductions were from 7.60 Ns for HHP at 500 MPa to 15.08 Ns for HHP at 150 MPa). The color of ultrasound-induced inulin gels, regarding the HPH and HHP technique, was darker (the differences in the L* parameter between thermal and non-thermal inductions were from 1.92 for HHP at 500 MPa to 4.37 for 10 min ultrasounds) and with a lower a* color parameter (the differences in the a* parameter between thermal and non-thermal inductions were from 0.16 for HHP at 500 MPa to 0.39 for HPH II cycles) and b* color parameter (the differences in the b* parameter between thermal and non-thermal inductions were from 1.69 for 5 min ultrasounds to 2.68 for HPH II cycles). It was also found that among the compared induction methods, the high-pressure technique has the greatest potential for modifying the properties of the created inulin hydrogels. Thanks to its application, depending on the amount of applied pressure, it was possible to obtain gels with very different characteristics, both delicate (i.e., soft and spreadable), using HHP at 150 MPa, and hard, using HHP at 500 MPa, the closest in characteristics to gels induced with the thermal method. This may allow the properties of hydrogels to be matched to the characteristics of the food matrix being created.

Technological readiness of commercial microalgae species for foods

Microalgae have great potential as a future source to meet the increasing global demand for foods. Several microalgae are permitted as safety sources in different countries and regions, and processed as commercial products. However, edible safety, economic feasibility, and acceptable taste are the main challenges for microalgal application in the food industry. Overcome such challenges by developing technology accelerates transition of microalgae into sustainable and nutritious diets. In this review, edible safety of Spirulina, Chlamydomonas reinhardtii, Chlorella, Haematococcus pluvialis, Dunaliella salina, Schizochytrium and Nannochloropsis is introduced, and health benefits of microalgae-derived carotenoids, amino acids, and fatty acids are discussed. Technologies of adaptive laboratory evolution, kinetic model, bioreactor design and genetic engineering are proposed to improve the organoleptic traits and economic feasibility of microalgae. Then, current technologies of decoloration and de-fishy are summarized to provide options for processing. Novel technologies of extrusion cooking, delivery systems, and 3D bioprinting are suggested to improve food quality. The production costs, biomass values, and markets of microalgal products are analyzed to reveal the economic feasibility of microalgal production. Finally, challenges and future perspectives are proposed. Social acceptance is the major limitation of microalgae-derived foods, and further efforts are required toward the improvement of processing technology.

The Effect of Storage and Pasteurization (Thermal and High-Pressure) Conditions on the Stability of Phycocyanobilin and Phycobiliproteins

The utilization of natural blue pigments in foods is difficult as they are usually unstable during processing and the commonly applied pH. The current study focuses on natural blue pigment, possessing antioxidant properties, found in Arthrospira platensis (spirulina), and phycobiliproteins (PBP). These pigments are a complex of conjugated protein and non-protein components, known as phycocyanobilin. PBP has low stability during pasteurization (high-pressure or heat treatments), resulting in protein denaturation and color deterioration that limits the application. The phycocyanobilin pigment might also be liable to oxidation during pasteurization and storage, resulting in color deterioration. Yet, the instability of the pigment phycocyanobilin during the pasteurization process and storage conditions was never studied before, limiting the comprehensive understanding of the reasons for PBP instability. In this study, the stability of phycocyanobilin under high-pressure and high-temperature conditions was compared to the stability of phycobiliproteins. We revealed that phycobiliproteins have a higher color deterioration rate at 70–80 °C than at high-pressure (300–600 MPa) whereas phycocyanobilin remained stable during high-pressure and heat processing. During storage at pH 7, phycocyanobilin was oxidized, and the oxidation rate increased with increasing pH, while at lower pH phycocyanobilin had low solubility and resulted in aggregation.

Nutritional Value and Physicochemical Characteristics of Alternative Protein for Meat and Dairy-A Review

In order to alleviate the pressure on environmental resources faced by meat and dairy production and to satisfy the increasing demands of consumers for food safety and health, alternative proteins have drawn considerable attention in the food industry. However, despite the successive reports of alternative protein food, the processing and application foundation of alternative proteins for meat and dairy is still weak. This paper summarizes the nutritional composition and physicochemical characteristics of meat and dairy alternative proteins from four sources: plant proteins, fungal proteins, algal proteins and insect proteins. The difference between these alternative proteins to animal proteins, the effects of their structural features and environmental conditions on their properties, as well as the corresponding mechanism are compared and discussed. Though fungal proteins, algal proteins and insect proteins have shown some advantages over traditional plant proteins, such as the comparable protein content of insect proteins to meat, the better digestibility of fungal proteins and the better foaming properties of algal proteins, there is still a big gap between alternative proteins and meat and dairy proteins. In addition to needing to provide amino acid composition and digestibility similar to animal proteins, alternative proteins also face challenges such as maintaining good solubility and emulsion properties. Their nutritional and physicochemical properties still need thorough investigation, and for commercial application, it is important to develop and optimize industrial technology in alternative protein separation and modification.

Dynamic high pressure treatments: current advances on mechanistic-cum-transport phenomena approaches and plant protein functionalization

Dynamic high pressure treatment (DHPT) either by high pressure homogenization or microfluidisation, is an emerging concept used in the food industry for new products development through macromolecules modifications in addition to simple mixing and emulsification action. Mechanistic understanding of droplets breakup during high pressure homogenization is used to understand how these compact and high molecular weight-sized globular plant proteins are affected during DHPTs. Plant protein needs to be functionalized for advanced use in food formulation. DHPTs brought changes in plant proteins' secondary, tertiary, and quaternary structures through alterations in intermolecular and intramolecular interactions, sulfhydryl groups, and disulfide bonds. These structural changes in plant proteins affected their functional and physicochemical properties like solubility, oil and water holding capacity, gelation, emulsification, foaming, and rheological properties. These remarkable changes made utilization of this concept in novel food system applications like in plant-based dairy analogues. Overall, this review provides a comprehensive and critical understanding of DHPTs on their mechanistic and transport approaches for droplet breakup, structural and functional modification of plant macromolecules. This article also explores the potential of DHPT for formulating plant-based dairy analogues to meet healthy and sustainable food consumption needs. HIGHLIGHTSIt critically reviews high pressure homogenization (HPH) and microfluidisation (DHPM).It explores the mechanistic and transport phenomena approaches of HPH and DHPMHPH and DHPM can induce conformational and structural changes in plant proteins.Improvement in the functional properties of HPH and DHPM treated plant proteins.HPH and DHPM are potentially applicable for plant based dairy alternatives food system.

Improved pH stability, heat stability, and functionality of phycocyanin after PEGylation

Phycocyanin (PC), a spirulina-derived protein-chromophore complex, suffers from poor techno-functional properties and is highly susceptible to aggregation and color changes upon heating and pH fluctuations. We tackled these issues by modifying PC via PEGylation. Electrophoresis and Fourier transform infrared spectroscopy proved successful conjugation of methoxy PEG (mPEG) chains on PC after PEGylation. Circular dichroism indicated highly ordered folding states adopted by PEGylated PC, which we attributed to the mPEG chains on the protein surface that sterically stabilized the protein structure. Consequently, the mPEG-PC conjugates exhibited high blue color intensity and improved thermodynamic stability. Further, benefit from an electrostatic shielding effect of mPEG chains, surface charges of PEGylated PC were neutralized over pH 2-9 and the blue hue of PC was stabilized against pH variations. Additionally, the flexible and hydrophilic mPEG polymers on the PC surface promoted protein-protein and protein-water interactions. PEGylated PC thus gained increased protein solubility, techno-functionality (emulsifying, foaming, and gelling performance), and antioxidant activities, when compared to unmodified PC. Heat-induced gels formed by mPEG-PC conjugates exhibited increased stiffness, higher water retention, and weak gel-type rheological properties. After PEGylation, the improved functional properties, bioactivity, and color stability against heat and pH fluctuations will facilitate food and pharmaceutical applications of PC.

A simple method for extracting phycocyanin from Arthrospira (Spirulina) platensis by autolysis

Phycocyanin (PC) is a natural blue pigment that has great commercial value in food and pharmaceutical industry. Arthrospira (Spirulina) platensis is a photosynthetic spiral-shaped cyanobacterium containing a rich PC pigment. Autolysis is the enzymatic digestion of cells by the action of its own enzymes. To develop an effective and economical extraction process, an autolysis process was incorporated into the conventional freezing-thawing method. In the present study, 91% of maximal extraction yield of PC with 1.194 purity (A₆₂₀/A₂₈₀) was obtained via autolysis after 3 h of incubation at 37 °C without using an extraction salt solution or a successive freezing-thawing process. In addition to temperature, the initial concentration of bicarbonate in growth medium and the concentration of wet biomass are important parameters that influence the extraction yield of PC by autolysis.

Development and Characterization of a Low-Fat Mayonnaise Salad Dressing Based on Arthrospira platensis Protein Concentrate and Sodium Alginate

The food industry is constantly reformulating different foods to fulfill the demands of the consumers (natural ingredients and good sensory quality). The present work aimed to produce low-fat mayonnaises using 30.0, 22.5, and 15.0% oil, 1% soy protein isolate (SPI) or spirulina (Arthrospira platensis) protein concentrate (SPC), and 2% sodium alginate. The physical properties (thermal stability, rheological behavior, and particle size), the sensory attributes (appearance, texture, taste, and acceptability), the purchase probability, and amino acid availability (after a simulated digestion) were evaluated. The mayonnaises demonstrated good thermal stability (>90%) using 22.5 and 15% oil, all products showed shear-thinning behavior and a consistency index of 20–66 Pa·s. The reduction of oil from 30 to 15% increased the particle size from 6–9 µm to 10–38 µm. The most acceptable product was the formulated with SPI and 22.5% oil (8.3 of acceptability and 79% of purchase probability). Finally, the addition of proteins improved the total essential amino acids compared to a commercial product (28 and 5 mg/25 g, respectively). In summary, it was possible to obtain well accepted products with high purchase probability using low concentrations of oil and vegetable proteins.

Effect of high-intensity ultrasound on the structural, rheological, emulsifying and gelling properties of insoluble potato protein isolates

The denaturation and lower solubility of commercial potato proteins generally limited their industrial application. Effects of high-intensity ultrasound (HIU) (200, 400, and 600 W) and treatment time (10, 20, and 30 min) on the physicochemical and functional properties of insoluble potato protein isolates (ISPP) were investigated. The results revealed that HIU treatment induced the unfolding and breakdown of macromolecular aggregates of ISPP, resulting in the exposure of hydrophobic and R-SH groups, and reduction of the particle size. These active groups contributed to the formation of a dense and uniform gel network of ISPP gel and insoluble potato proteins/egg white protein (ISPP/EWP) hybrid gel. Furthermore, the increase of solubility and surface hydrophobicity and the decrease of particle size improved the emulsifying property of ISPP. However, excessive HIU treatment reduced the emulsification and gelling properties of the ISPP. Meanwhile, HIU treatment changes the secondary structure of ISPP. It could be speculated that the formation of a stable secondary structure of ISPP initiated by cavitation and shearing effect might play a dominant role on gel strengthens and firmness. Meanwhile, the decrease in relative content of β-turn had a positive effect on the formation of small particle to improve emulsifying property of ISPP.

Effects of κ-Carrageenan and Guar Gum on the Rheological Properties and Microstructure of Phycocyanin Gel

The effects of two polysaccharides on the performance and microstructure of phycocyanin gels were studied by choosing anionic polysaccharides (κ-carrageenan) and neutral polysaccharides (guar gum). The linear and nonlinear rheological properties and microstructure of the phycocyanin-polysaccharide composite gel were evaluated. The results show that both κ-carrageenan and guar gum can enhance the network structure of phycocyanin gel and weaken the frequency dependence. The sample with 0.4% κ-carrageenan has the highest gel strength. All samples exhibited Type I behavior (inter-cycling strain-thinning) and mainly elastic behavior. As the concentration of κ-carrageenan increases, hydrophobic interactions and disulfide bonds play an essential role in maintaining the three-dimensional structure of the gel. Too high a concentration of guar gum hinders the formation of protein disulfide bonds. This research can provide a theoretical basis for designing and developing new food products based on phycocyanin and different polysaccharides with ideal texture in the food industry.