Spirulina platensis protein hydrolysates: Techno-functional, nutritional and antioxidant properties

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.

Advances of protein-based emulsion gels as fat analogues: Systematic classification, formation mechanism, and food application

Fat plays a pivotal role in the appearance, flavor, texture, and palatability of food. However, excessive fat consumption poses a significant risk for chronic ailments such as obesity, hypercholesterolemia, and cardiovascular disease. Therefore, the development of green, healthy, and stable protein-based emulsion gel as an alternative to traditional fats represents a novel approach to designing low-fat food. This paper reviews the emulsification behavior of proteins from different sources to gain a comprehensive understanding of their potential in the development of emulsion gels with fat-analog properties. It further investigates the emulsifying potential of protein combined with diverse substances. Then, the mechanisms of protein-stabilized emulsion gels with fat-analog properties are discussed, mainly involving single proteins, proteins-polysaccharides, as well as proteins-polyphenols. Moreover, the potential applications of protein emulsion gels as fat analogues in the food industry are also encompassed. By combining natural proteins with other components such as polysaccharides, polyphenols, or biopolymers, it is possible to enhance the stability of the emulsion gels and improve its fat-analog texture properties. In addition to their advantages in protecting oil oxidation, limiting hydrogenated oil intake, and delivering bioactive substances, protein-based emulsion gels have potential in food 3D printing and the development of specialty fats for plant-based meat.

Assessing and optimizing the bioactivities of diverse enzyme-derived protein hydrolysates from Porphyra yezoensis: unlocking the health potential

The interest in algae-derived bioactive compounds has grown due to their potential therapeutic efficacy against a range of diseases. These compounds, derived from proteins, exhibit diverse functions and profound pharmacological effects. Recent research has highlighted the extensive health benefits of algae-derived bioactive compounds, positioning them as potential natural antioxidants in the food, pharmaceutical, and cosmetic industries. This study focuses on extracting proteins from Porphyra yezoensis using innovative physical pre-treatment methods such as stirring, ball milling, and homogenization, under various acidic and alkaline conditions. Enzymatic hydrolysis, employing commercial enzymes at optimal temperature, pH, and enzyme-substrate ratios, produced distinct fractions according to molecular weight. Pepsin demonstrated the highest hydrolysis rate, with the fraction above 10 kDa identified as the most bioactive hydrolysate. Antioxidant activity was evaluated through DPPH, ABTS, ferrous ion chelation, and reducing power assays, demonstrating high antioxidant potential and the ability to mitigate oxidative stress. The 10 kDa fraction of pepsin hydrolysate exhibited 82.6% DPPH activity, 77.5% ABTS activity, 88.4% ferrous ion chelation activity, and higher reducing power potential (0.84 absorbance at 700 nm). Further exploration of mechanisms, amino acid profiles, and potential in vivo benefits is essential to fully exploit the medicinal potential of these algae-derived hydrolysates.

Euglena gracilis Protein: Effects of Different Acidic and Alkaline Environments on Structural Characteristics and Functional Properties

Due to the growing demand for human-edible protein sources, microalgae are recognized as an economically viable alternative source of proteins. The investigation into the structural characteristics and functional properties of microalgin is highly significant for its potential application in the food industry as an alternative source of protein. In this research, we extracted protein from Euglena gracilis by using alkaline extraction and acid precipitation and investigated its structural characteristics and functional properties in different acidic and alkaline environments. The molecular weight distribution of Euglena gracilis protein (EGP), as revealed by the size exclusion chromatography results, ranges from 152 to 5.7 kDa. EGP was found to be rich in hydrophobic amino acids and essential amino acids. Fourier infrared analysis revealed that EGP exhibited higher α-helix structure content and lower β-sheet structure content in alkaline environments compared with acidic ones. EGP exhibited higher foaming properties, emulsifying activity index, solubility, free sulfhydryl, and total sulfhydryl in pH environments far from its isoelectric point, and lower fluorescence intensity (2325 A.U.), lower surface hydrophobicity, larger average particle size (25.13 µm), higher emulsifying stability index, and water-holding capacity in pH environments near its isoelectric point. In addition, X-ray diffraction (XRD) patterns indicated that different acidic and alkaline environments lead to reductions in the crystal size and crystallinity of EGP. EGP exhibited high denaturation temperature (Td; 99.32 °C) and high enthalpy (ΔH; 146.33 J/g) at pH 11.0, as shown by the differential scanning calorimetry (DSC) results. The findings from our studies on EGP in different acidic and alkaline environments provide a data basis for its potential commercial utilization as a food ingredient in products such as emulsions, gels, and foams.

Performance of Azolla pinnata fern protein hydrolysates as an emulsifier and nutraceutical ingredient in an O/W emulsion system and their effect on human gut microbiota and mammalian cells

This study investigated the dual potential of Azolla pinnata fern protein hydrolysates (AFPHs) as functional and nutraceutical ingredients in an oil/water emulsion system. The AFPH-stabilised emulsion (AFPH-E) displayed a small and uniform droplet distribution and was stable to aggregation and creaming over a wide range of pH (5-8), salt concentrations ≤ 100 mM, and heat treatment ≤ 70 °C. Besides, the AFPH-E possessed and maintained strong biological activities, including antihypertensive, antidiabetic, and antioxidant, under different food processing conditions (pH 5-8; NaCl: 50-150 mM, and heat treatment: 30-100 °C). Following in vitro gastrointestinal digestion, the antihypertensive and antioxidant activities were unchanged, while a notable increase of 8% was observed for DPPH. However, the antidiabetic activities were partially reduced in the range of 5-11%. Notably, AFPH-E modulated the gut microbiota and short-chain fatty acids (SCFAs), promoting the growth of beneficial bacteria, particularly Bifidobacteria and Lactobacilli, along with increased SCFA acetate, propionate, and butyrate. Also, AFPH-E up to 10 mg mL-1 did not affect the proliferation of the normal colon cells. In the current work, AFPH demonstrated dual functionality as a plant-based emulsifier with strong biological activities in an oil/water emulsion system and promoted healthy changes in the human gut microbiota.

Protection of osteogenic peptides in nanoliposomes: Stability, sustained release, bioaccessibility and influence on bioactive properties

This study prepared osteogenic peptides (OPs) from cod meat by hydrolysis and subsequently encapsulated them in nanoliposomes (NLP) to enhance bioaccessibility. The characterization, stability, controlled release behavior and bioactivity of OPs-loaded nanoliposomes (OPs-NLP) were investigated as well. The highest loading capacity (27.32%) was achieved in NLP loaded with 6 mg/mL of OPs. The particle size, zeta potential, and encapsulation efficiency of OPs-NLP were 70.59 nm, -11.98 mV, and 75.24%, respectively. The interaction between OPs and empty NLP was through hydrogen bonding and hydrophobic. The OPs-NLP showed the greatest stability during storage at 4 °C. The in vitro release profile of OPs from OPs-NLP fitted a one-level kinetic model best. The osteogenic activity of OPs was unaffected by NLP encapsulation, and the bioaccessibility of OPs was notably improved. These findings suggest that OPs-NLP has the potential to be used in functional foods.

The effects of spirulina supplementation on serum iron and ferritin, anemia parameters, and fecal occult blood in adults with ulcerative colitis: A randomized, double-blinded, placebo-controlled trial

BACKGROUND & AIMS

The present clinical trial aimed to evaluate the efficacy of spirulina administration on serum iron, ferritin, anemia parameters, and fecal occult blood test (FOBT) in adults with ulcerative colitis (UC).

METHODS

Eighty participants with UC were randomly assigned to take, either 1 g/day (two 500 mg capsules) spirulina (n = 40) or placebo (n = 40) in a double-blinded clinical trial for eight weeks. Dietary intake, physical activity status, serum iron and ferritin levels, anemia parameters, and FOBT were assessed in each participant at baseline and following the intervention. Seventy-three participants completed the trial.

RESULTS

Our results indicated significantly increased (p = 0.04) serum iron after eight weeks of spirulina supplementation compared to the placebo group. The spirulina group also demonstrated significantly increased mean corpuscular volume (p = 0.004) whereas red blood cell count (p = 0.01) and hematocrit (p = 0.03) were significantly lowered in the placebo group. No significant changes in FOBT outcomes were seen between groups at baseline (p = 0.12) and the end of the trial (p = 0.34). Eight weeks of 1 g/day spirulina supplementation improved anemia parameters in adults with UC compared to placebo.

CONCLUSIONS

These outcomes suggest that spirulina administration may be beneficial in the management of anemia in UC. Further clinical trials of longer duration are necessary to corroborate and expand our findings. Registered at: http://www.IRCT.ir (code: IRCT20170802035460N3).

Technological, nutritional, and biological properties of apricot kernel protein hydrolyzates affected by various commercial proteases

The effect of enzymatic hydrolysis of apricot kernel protein with different proteases (Alcalase, pancreatin, pepsin, and trypsin) on the amino acid content, degree of hydrolysis (DH), antioxidant, and antibacterial characteristics of the resulting hydrolyzates was investigated in this study. The composition of amino acids (hydrophobic: ~35%; antioxidant: ~13%), EAA/TAA ratio (~34%), and PER index (~1.85) indicates the ability of the hydrolyzate as a source of nutrients and antioxidants with high digestibility. Enzymatic hydrolysis with increasing DH (from 3.1 to a maximum of 37.9%) led to improved solubility (especially in the isoelectric range) and changes in water- and oil-holding capacity. The highest free radical scavenging activity of DPPH (83.3%), ABTS (88.1%), TEAC (2.38 mM), OH (72.5%), NO (65.7%), antioxidant activity in emulsion and formation of TBARS (0.36 mg MDA/L), total antioxidant (1.61), reducing power (1.17), chelation of iron (87.7%), copper (34.8%) ions, and inhibition of the growth of Escherichia coli (16.3 mm) and Bacillus cereus (15.4 mm) were affected by the type of enzymes (especially Alcalase). This research showed that apricot kernel hydrolyzate could serve as a nutrient source, emulsifier, stabilizer, antioxidant, and natural antibacterial agent in functional food formulations.

Application of structurally modified WPC in combination with maltodextrin for microencapsulation of Roselle (Hibiscus sabdariffa) extract as a natural colorant source for gummy candy

The aim of this work was to improve the stability of Roselle extract (RE) by spray-drying using maltodextrin (MD) alone, and in combination with WPC in the forms of unmodified and modified (via ultrasonication, UWPC, or enzymatic hydrolysis, HWPC). Enzymatic hydrolysis by improving the surface activity of WPC increased spray-drying yield (75.1 %), and improved physical (flow) and functional (solubility, and emulsifying) properties of obtained microparticles. Degree of hydrolysis of the primary WPC (2.6 %) was increased to 6.1 % and 24.6 % after ultrasonication and hydrolysis, respectively. Both modifications caused a significant increase in the solubility of WPC, in a way that initial solubility (10.6 %, at pH = 5) was significantly increased to 25.5 % in UWPC, and to 87.3 % in HWPC (P < 0.05). Furthermore, emulsifying activity (20.6 m²/g) and emulsifying stability (17 %) indices of primary WPC (at pH = 5) were significantly increased to 32 m²/g and 30 % in UWPC, and to 92.4 m²/g and 69.0 % in HWPC, respectively (P < 0.05). FT-IR analysis indicated successful encapsulation of RE within carriers' matrix. According to FE-SEM study, the surface morphology of microparticles was improved when modified HWPC was used as a carrier. Microencapsulation of RE with HWPC showed the highest contents of total phenolic compounds (13.3 mg GAE/mL), total anthocyanins (9.1 mg C3G/L) as well as a higher retention of antioxidant activity according to ABTS⁺ (85.0 %) and DPPH (79.5 %) radicals scavenging assays. Considering all properties of microparticles obtained by HWPC next to their color attributes, it can be concluded that HWPC-RE powders could be used as natural colorant and antioxidant source for the fortification of gummy candy. Gummy candy obtained using 6 % concentration of the above powder gave the highest overall sensory scores.

Physicochemical, antioxidant, antimicrobial, and in vitro cytotoxic activities of corn pollen protein hydrolysates obtained by different peptidases

The applications of protein hydrolysates as food preservatives and nutraceutical ingredients have attracted much attention because of their beneficial effects. The interest in these ingredients has shifted toward their biological activities with benefits to human health. Bioactive peptides are known as antioxidant agents that could promote health-promoting effects and prolong food shelf-life beyond their basic nutritional value. Thus, the aim of this study was to investigate antioxidant, antimicrobial, and in vitro cytotoxic properties of corn pollen protein (CPP) hydrolysates obtained by different enzymes. Proteolytic activity in terms of degree of hydrolysis (DH) and SDS-PAGE analysis was measured in pancreatin (H-Pan), pepsin (H-Pep), and trypsin (H-Tri) hydrolysates. Amino acid composition, antioxidant and antimicrobial activities, and cytotoxicity of hydrolysates were evaluated. DH and SDS-PAGE revealed higher proteolytic activity of pepsin compared to other enzymes. Amino acid analysis showed that the functional amino acids such as antioxidant types were most predominant in H-Pep compared to two other samples. Antioxidant activity of hydrolysates was found to be affected by the type of enzyme and the concentration of hydrolysates. There was a significant difference (p < 0.05) between antioxidant activity of different hydrolysates. The highest antioxidant activity in terms of Trolox equivalent antioxidant capacity (0.23-2.75 mM), DPPH (33.3%-64.8%), and hydroxyl (33.7%-63.2%) radical scavenging activities, chelation of iron (33.2%-62.5%) and copper (30.2%-50.5%) metals, and total antioxidant activity (0.65-0.85) was obtained for H-Pep followed by H-Pan and H-Tri samples. Antibacterial tests showed that pepsin-hydrolyzed protein was not significantly (P > 0.05) effective against E. coli at any concentrations, however, it showed significant (P < 0.05) concentration-dependent effect against S. aureus (with inhibition zones of 15-25 mm). Cytotoxicity results revealed that CPP, as a nonhydrolyzed protein, did not generally show antiproliferative activity, however, a significant (P < 0.05) ability of H-Pep hydrolysate in decreasing HT-29 colon cancer cell line viability was seen in a concentration-dependent manner (the lowest cell viability of 32% at 5 mg/mL). Overall, investigating the application of protein-based hydrolysates is one of the possible strategies that govern their applied intentions as preservatives and nutraceuticals in the food and pharmaceutical industries.

Nanoliposomal peptides derived from Spirulina platensis protein accelerate full-thickness wound healing

Spirulina platensis is a type of blue-green algae that contains large amounts of protein with therapeutic effects. The present study was performed to investigate the effects of encapsulated Spirulina protein hydrolysates (SPH) with nanoliposomes (NLPs) in reducing wound healing period. SPH-loaded NLPs showed the size and zeta potential of 158 nm and -48 mV, respectively; as well as a uniform non-aggregated morphology. In-vitro MTT toxicity studies on the Human Foreskin Fibroblast (HFFF-2) cell line exhibited that the hydrolyzed peptides had no toxic effect and increased cell growth. The scratch test confirmed the MTT results. For in-vivo study, 162 mice were divided into nine groups, including the mice groups treated with blank gel, blank NLPs, and those treated with 2.5, 5, and 10 % SPH and SPH-loaded NLPs. The histopathological assessment was done to investigate rate of fibroblast proliferation and epithelialization. Immunofluorescence staining for bFGF, CD31, COL1A was conducted. The results showed that the mice group treated with SPH-NLPs showed higher wound contraction, epithelization, fibroblast proliferation, and higher expressions for bFGF, CD31, COL1A compared with blanks and other groups. In conclusion, the derived and encapsulated peptides showed significant effects in accelerating wound healing via angiogenesis and collagen production.

Ultrasound-Assisted Extraction of Artocarpus heterophyllus L. Leaf Protein Concentrate: Solubility, Foaming, Emulsifying, and Antioxidant Properties of Protein Hydrolysates

The impact of ultrasound-assisted extraction (UAE) was evaluated on the functionality of jackfruit leaf protein hydrolysates. Leaf protein concentrate was obtained by ultrasound (LPCU) and conventional extractions by maceration (LPCM). LPCM and LPCU were hydrolyzed with pancreatin (180 min), and hydrolysates by maceration (HM) and ultrasound (HU) were obtained. The composition of amino acids, techno-functional (solubility, foaming, and emulsifying properties), and antioxidant properties of the hydrolysates were evaluated. A higher amount of essential amino acids was found in HU, while HM showed a higher content of hydrophobic amino acids. LPCs exhibited low solubility (0.97–2.89%). However, HM (67.8 ± 0.98) and HU (77.39 ± 0.43) reached maximum solubility at pH 6.0. The foaming and emulsifying properties of the hydrolysates were improved when LPC was obtained by UAE. The IC50 of LPCs could not be quantified. However, HU (0.29 ± 0.01 mg/mL) showed lower IC50 than HM (0.32 ± 0.01 mg/mL). The results reflect that the extraction method had a significant (p < 0.05) effect on the functionality of protein hydrolysates. The UAE is a suitable method for enhancing of quality, techno-functionality, and antioxidant properties of LPC.

Digestive Constraints of Arthrospira platensis in Poultry and Swine Feeding

Microalgae have emerged as novel sources for monogastric animals' diets since they are rich in many nutrients, including proteins. Arthrospira platensis is particularly rich in proteins (up to 76% of dry matter), lipids, minerals and pigments. However, its rigid peptidoglycan cell wall interferes with the digestibility, bio-accessibility and bioavailability of nutrients for monogastric animals. The aim of the present study was to evaluate the digestibility, bio-accessibility, bioavailability and protein quality of nutrients from A. platensis for poultry and swine feeding, searching all the studies available in PubMed, Web of Science, Scopus and Google Scholar in June 2022 concerning this subject. Overall, digestibility values of A. platensis proteins or amino acids varying from 66.1 to 68.7% for poultry (microalgae at 1% feed) and from 75.4 to 80.6% for swine (10% feed) have been reported. Therefore, the extraction of microalgae components using mechanical or non-mechanical pre-treatments is required to promote cell disruption and improve digestibility and bio-accessibility. Although A. platensis is a promising feedstuff to support future needs, it is important to perform more investigation concerning digestibility, dietary inclusion level and possible treatments to disrupt microalga cell walls and increase bioavailability of nutrients.