Mass-production and biomarker-based characterization of high-value Spirulina powder for nutritional supplements

Investigation of the effects of corn flour, Spirulina powder, and buffalo yogurt on the quality characteristics of gluten-free muffins

This study aimed to investigate the properties of buckwheat flour-based gluten-free muffins formulated by using corn flour (CF), Spirulina powder (SP), and buffalo yogurt (BY) levels as the factors in the Box-Behnken experimental design. The color values, total soluble polyphenol content (TPC), radical scavenging activity (RSA), specific volume, moisture content, and baking loss results were evaluated as the response variables in the design. The buckwheat flour in the control sample was substituted with CF and SP. Cow yogurt was used in the control muffin instead of milk and was substituted with BY at different levels in other samples. Among the response variables, TPC and RSA values were selected for the optimization studies. Decreasing the CF and SP levels in the formulations resulted in observing higher TPC and RSA values. Three optimal formulations were obtained by response surface methodology. Both cow and buffalo yogurt did not change the properties of the muffins adversely compared to milk. Increasing the SP content made the muffins firmer and caused a decrease in the L*, a*, b*, and browning index values of the muffins. However, sensory scores of SP-containing muffins were also satisfactory.

Preparation and Characterization of Intracellular and Exopolysaccharides during Cycle Cultivation of Spirulina platensis

The dried cell weight (DCW) of Spirulina platensis gradually decreased from 1.52 g/L to 1.18 g/L after five cultivation cycles. Intracellular polysaccharide (IPS) and exopolysaccharide (EPS) content both increased with increased cycle number and duration. IPS content was higher than EPS content. Maximum IPS yield (60.61 mg/g) using thermal high-pressure homogenization was achieved after three homogenization cycles at 60 MPa and an S/I ratio of 1:30. IPS showed a more fibrous, porous, and looser structure, and had a higher glucose content and Mw (272.85 kDa) compared with EPS, which may be indicative of IPS's higher viscosity and water holding capacity. Although both carbohydrates were acidic, EPS had stronger acidity and thermal stability than IPS; this was accompanied by differences in monosaccharide. IPS exhibited the highest DPPH (EC₅₀ = 1.77 mg/mL) and ABTS (EC₅₀ = 0.12 mg/mL) radical scavenging capacity, in line with IPS's higher total phenol content, while simultaneously showing the lowest HO^• scavenging and ferrous ion chelating capacities; thus characterizing IPS as a superior antioxidant and EPS as a stronger metal ion chelator.

Iron Content, Iron Speciation and Phycocyanin in Commercial Samples of Arthrospira spp

Cyanobacteria are characterized by high iron content. In this research, we collected ten commercial samples of Arthrospira spp. sold as food supplement to determine iron content and assess whether iron speciation showed variability among samples and changed respect to A. platensis grown in controlled conditions. Particular attention was also paid to phycocyanin, as an iron-binding protein. In six of the ten samples, 14 essential and non-essential trace elements were analysed using ICP-MS. Iron content measured in samples using atomic absorption spectrometry (AAS) varied from 353 (sample S5) to 1459 (sample S7) µg g^-1 dry weight and was in the range of those reported by other authors in commercial supplements. Iron speciation was studied using size exclusion chromatography followed by the analysis of the collected fraction for the determination of iron by AAS and for protein separation using SDS-PAGE. Overlapping chromatographic profiles were obtained for total proteins, phycocyanin and iron, although quantitative differences were evidenced among the samples analysed. In most samples, iron was mainly bound to ligands with high molecular mass; however, in four samples iron was also bound to ligands with low molecular mass. In fractions containing the most relevant iron burden, the principal protein was phycocyanin, confirming its role as an iron-binding protein in commercial samples.

Characterization of novel euryhaline microalgal cultures from Punjab, India for bioactive compounds

Microalgae have gained recognition due to the occurrence of nutraceuticals which are sustainable reservoir to substitute the organic chemical-based health supplements. The biomass of microalgae incorporates various functional biomolecules like chlorophyll, carotenoids and phenols that exhibit therapeutic properties and act as nutraceuticals. In spite of the higher production of the microalgal biomass, difference in their biochemical composition, and lack of characterization for nutraceutical properties are the prime hindrance in upscaling these bio-factories. Two euryhaline microalgal strains viz. BGLR8 and BGLR16, isolated from water-logged areas of Punjab, India were screened for biomass production and characterized for the nutraceutical properties using biochemical estimations. Results of the study indicated that BGLR8 retained maximum amount of lipids (86 mg/g), total chlorophyll (29.42 mg/g), carotenoids (28.82 mg/g), phenols (4.46 mg/g), phycocyanin (52 mg/g), astaxanthin (19.27 mg/g) and β-carotene (5.6 mg/g) and anti-oxidant activity (31.73%) as compared to BGLR 16. The results of gas chromatography-mass spectrometry (GC-MS) study revealed the presence of 8 therapeutic compounds like Dimethyl (E)-but-2-enedioate, Hexasilacyclododecane, Heptasilacyclotetradecane, Methyl (Z)-pentadec-8-enoate, Methyl octadec-13-enoate, Methyl hexadecanoate, Methyl octadecanoate, Methyl-octadeca-9,12-dienoate in BGLR8. Molecular identification through 18S rRNA gene sequencing confirmed BGLR8 to be a member of genus Coelastrella. (GenBank accession no. MW443083.1). Microalgae can be used as an alternate and feasible source of PUFAs; however, only a few species are employed for PUFA synthesis, necessitating additional in-depth research and the isolation of novel strains.

Zinc availability from zinc-enriched yeast studied with an in vitro digestion/Caco-2 cell culture model

BACKGROUND

Organic zinc sources for the treatment of zinc deficiency or as a supplement to a specific diet are increasingly needed. Zinc-enriched yeast (ZnYeast) biomass is a promising nutritional supplement for this essential micronutrient. However, these products are not yet authorized in the European Union and a clear position from the European Food Safety Authority on the use of ZnYeast as a zinc supplement is pending, demanding more data on its bioavailability.

OBJECTIVE

The study aimed to produce a ZnYeast based on a Saccharomyces genus (S. pastorianus Rh), characterize its zinc enrichment quota, cellular distribution of zinc, and evaluate its zinc bioavailability after human digestion by comparing it to commonly used inorganic and organic zinc supplements (ZnO, ZnSO4, zinc gluconate, and zinc aspartate).

METHOD AND MAIN FINDINGS

The zinc-enriched S. pastorianus Rh contained 5.9 ± 1.0 mg zinc/g yeast, which was predominantly localized on the cell surface according to its characterization on the microscale with scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX). Combined experiments with a human in vitro digestion model and the in vitro intestinal cell model Caco-2 showed that intestinal zinc bioavailability of digested yeast biomass was comparable to the other zinc supplements, apart from ZnO, which was somewhat less bioavailable. Moreover, zinc released from digested ZnYeast was available for biological processes within the enterocytes, leading to mRNA upregulation of metallothionein, a biomarker of intestinal zinc status, and significantly elevated the cellular labile zinc pool.

CONCLUSIONS

Our findings demonstrated that ZnYeast represents a suitable nutritional source for organically bound zinc and highlighted optimization strategies for future production of dietary ZnYeast.

Effects of fluctuating temperature in open raceway ponds on the biomass accumulation and harvest efficiency of Spirulina in large-scale cultivation

It is of great significance to select strains with wide adaptability to temperature range for large-scale commercial cultivation of Spirulina. The aim of this study was to comprehend how the strain H-208 grew and whether this strain had any advantages in temperature adaptation compared with local production strain during the large-scale cultivation in Inner Mongolia. The results showed that the strain H-208 could adapt to the new environmental condition quickly, and the daily average biomass dry weight of strain H-208 was 49% and 52% more than that of production strain M-1 in first cycle (20.24 g/m2/day) and second cycle (16.90 g/m2/day) of acclimation experiment, respectively. The growth rate of strain H-208 was 0.055 and 0.066 g/L/day from July 22 to July 25 and from July 26 to July 29, respectively, while the growth rate of strain M-1 was only 0.036 and 0.032 g/L/day, respectively, during the same cultured days in 605-m2 raceway ponds before high temperature. The harvesting efficiency of H-208 and M-1 was 95.1% and 72.1% before high temperature, and that was 95.3% and 52.5% after being stressed by high temperature, respectively. Meanwhile, it was also observed that the filaments of the two strains contracted and their pitches were smaller than that before high temperature stress, especially the strain M-1. In 20-m2 raceway ponds of recovery experiment after high temperature, the percentage of daily average biomass dry weight of strain H-208 was 68% more than that of strain M-1, which demonstrated that strain H-208 could recover and grow rapidly, and its self-regulation ability was superior to that of strain M-1.

Engineering biology approaches for food and nutrient production by cyanobacteria

As photoautotrophic organisms, cyanobacteria capture and store solar energy in the form of biomass. Cyanobacterial biomass has been an important component of diet and nutrition in several regions for centuries. Synthetic biology strategies are currently being applied to increase the yield and productivity of cyanobacterial biomass by optimizing solar energy utilization and CO₂ fixation rates for carbon storage. Likewise, engineering cyanobacteria as cellular factories to synthesize carbohydrates, amino acids, proteins, lipids and fatty acids is providing an attractive way to sustainably produce food and nutrients for human consumption. In this review, we have summarized recent progress in both aspects and prospective trends under development.