Improving the shelf life of minced beef by Cystoseira compressa polysaccharide during storage.

A polysaccharide extracted from the brown alga Cystoseira compressa (CCPS) was evaluated as a food additive to extend the shelf-life of raw beef meat. The antioxidant potential of CCPS was demonstrated by its inhibition of ß-carotene bleaching (64.28 %), superoxide radicals (70.12 %), and hydroxyl radicals (93 %) at a concentration of 10 mg/ml. The polysaccharide also showed antibacterial activity with MIC values between 6.25 mg/ml and 50 mg/ml against five foodborne pathogenic bacteria. Furthermore, CCPS exhibited excellent functional, foaming, and emulsifying properties. Furthermore, microbiological and chemical effects of CCPS at concentrations equivalent to 1 MIC (CCPS-1), 2 MIC (CCPS-2), and 4 MIC (CCPS-3) were conducted. Chemical analyses showed that treated beef had significantly reduced TBARS levels below 2 mg MDA/kg at day 14. The treatment also decreased carbonyl groups, improved heme iron transformation, inhibited microbial growth (p < 0.05), and kept MetMb levels below 40 % by day 14. Moreover, two multivariate approaches, principal component analysis (PCA) and hierarchical cluster analysis (HCA), were effectively used to analyze the results characterizing the main attributes of the stored meat samples. In conclusion, these findings demonstrated that CCPS could be employed as a functional and bioactive component in the meat industry.

Enhanced growth and metabolite production from a novel strain of Porphyridium sp.

Microalgae are capable of generating numerous metabolites that possess notable biological activities and hold substantial promise for various industrial applications. Nevertheless, the taxonomic diversity of these photosynthetic microorganisms has not received thorough investigation. Using the 18S rRNA encoding gene, a recently discovered strain originating from the Tunisian coast (the governorate of Mahdia) was identified as a member of the Porphyridium genus. The growth response as well as the metabolite accumulation of Porphyridium sp. to different culture media (Pm, F/2, and Hemerick) was investigated over a period of 52 days. The highest biomass production was recorded with Pm medium (2 × 107 cell/mL). The apparent growth rates (µ) and the doubling time (Dt) were about 0.081 day-1 and 12.34 days, respectively. The highest chlorophyll a (0.678 ± 0.005 pg/cell), total carotenoids (0.18 ± 0.003 pg/cell), phycoerythrin (3.88 ± 0.003 pg/cell), and proteins (14.58 ± 0.35 pg/cell) contents were observed with F/2 medium. Cultivating Porphyridium sp. in both F/2 and Hemerick media yielded similar levels of starch accumulation. The Hemerick medium has proven to be the most suitable for the production of lipids (2.23% DW) and exopolysaccharides (5.41 ± 0.56 pg/cell).

Microalgae: A Promising Source of Bioactive Phycobiliproteins.

Phycobiliproteins are photosynthetic light-harvesting pigments isolated from microalgae with fluorescent, colorimetric and biological properties, making them a potential commodity in the pharmaceutical, cosmetic and food industries. Hence, improving their metabolic yield is of great interest. In this regard, the present review aimed, first, to provide a detailed and thorough overview of the optimization of culture media elements, as well as various physical parameters, to improve the large-scale manufacturing of such bioactive molecules. The second section of the review offers systematic, deep and detailed data about the current main features of phycobiliproteins. In the ultimate section, the health and nutritional claims related to these bioactive pigments, explaining their noticeable potential for biotechnological uses in various fields, are examined.

Expression of a Copper Activated Xylanase in Yeast: Location of the His-Tag in the Protein Significantly Affects the Enzymatic Properties.

A copper activated xylanase produced by E. coli BL21 was expressed in Pichia pastoris using the pGAPZαB expression vector. Two recombinant GH11 xylanase forms were obtained (N-His-rXAn11 and N-C-His-rXAn11). The findings revealed that the two recombinant xylanases displayed different behaviors toward the copper. In the presence of 3-mM Cu2+, the relative activity of the N-His-rXAn11 was enhanced by about 52%. However, the xylanase activity of the N- and C-terminal tagged one (N-C-His-rXAn11) was strongly inhibited by copper. In the presence of 3-mM Cu2+, the N-His-rXAn11 revealed to be thermostable at 60 °C with a half-life of 10 min. However, the N-C-His-rXAn11 was noted to be unstable since it was inactivated after 15 min of incubation at 55 °C. 3D models of the two recombinant forms showed that the created copper site in the N-His-rXAn11 was loosed in the C-terminal tagged protein. The C-terminal tag could trigger some structural changes with a notable displacement of secondary structures leading to great hindrance of the active site due to high fluctuations and probably new interactions among the N- and C-terminal amino acids.

Microalgae as feedstock for bioactive polysaccharides.

Due to the increase in industrial demand for new biosourced molecules (notably bioactive exopolysaccharides (EPS)), microalgae are gaining popularity because of their nutraceutical potential and benefits health. Such health effects are delivered by specific secondary metabolites, e.g., pigments, exopolysaccharides, polyunsaturated fatty acids, proteins, and glycolipids. These are suitable for the subsequent uses in cosmetic, nutraceutical, pharmaceutical, biofuels, biological waste treatment, animal feed and food fields. In this regard, a special focus has been given in this review to describe the various methods used for extraction and purification of polysaccharides. The second part of the review provides an up-to-date and comprehensive summary of parameters affecting the microalgae growth and insights to maximize the metabolic output by understanding the intricacies of algal development and polysaccharides production. In the ultimate part, the health and nutraceutical claims associated with marine algal bioactive polysaccharides, explaining their noticeable potential for biotechnological applications, are summarized and comprehensively discussed.

Structural Characterization and Rheological and Antioxidant Properties of Novel Polysaccharide from Calcareous Red Seaweed.

A novel sulfated xylogalactan (JASX) was extracted and purified from the rhodophyceae Jania adhaerens. JASX was characterized by chromatography (GC/MS-EI and SEC/MALLS) and spectroscopy (ATR-FTIR and 1H/13C NMR) techniques. Results showed that JASX was constituted by repeating units of (→3)-ß-d-Galp-(1,4)-3,6-α-l-AnGalp-(1→)n and (→3)-ß-d-Galp-(1,4)-α-l-Galp-(1→)n substituted on O-2 and O-3 of the α-(1,4)-l-Galp units by methoxy and/or sulfate groups but also on O-6 of the ß-(1,3)-d-Galp mainly by ß-xylosyl side chains and less by methoxy and/or sulfate groups. The Mw, Mn, D, [η] and C* of JASX were respectively 600 and 160 kDa, 3.7, 102 mL.g-1 and 7.0 g.L-1. JASX exhibited pseudoplastic behavior influenced by temperature and monovalent salts and highly correlated to the power-law model and the Arrhenius relationship. JASX presented thixotropic characteristics, a gel-like viscoelastic behavior and a great viscoelasticity character. JASX showed important antioxidant activities, outlining its potential as a natural additive to produce functional foods.

Effect of heavy metals mixture on the growth and physiology of Tetraselmis sp.: Applications to lipid production and bioremediation.

Phycoremediation of heavy metals from contaminated waters by oleaginous microalgae is an eco-friendly and emerging trend. Different concentrations of toxic metals such as nickel (Ni), chromium (Cr) and cobalt (Co) were added in Tetraselmis sp. culture media. Mixture Design was used to model the effect of these metals on cell growth, lipid production and heavy metals removal. Tetraselmis sp. was identified as an outstanding Ni, Cr and Co accumulator with bioconcentration factors of 675.17, 584.9 and 169.81 within binary mixtures (Ni × Cr), (Cr × Co) and (Cr × Co) at 6 mg/L, respectively. Optimization studies showed that the highest cell growth (9.22 × 105 cells/mL), lipid content (31% Dry Weight) and metals removal (91%) were obtained with the optimum binary mixture Ni (54.45 %) and Cr (45.45 %). This work presents interesting results revealing the potential of Tetraselmis sp. for nickel removal up to 97 % combined to its potential for biodiesel production.

In silico evidence of antiviral activity against SARS-CoV-2 main protease of oligosaccharides from Porphyridium sp.

The coronavirus pandemic (COVID-19) has created an urgent need to develop effective strategies for prevention and treatment. In this context, therapies against protease Mpro, a conserved viral target, would be essential to contain the spread of the virus and reduce mortality. Using combined techniques of structure modelling, in silico docking and pharmacokinetics prediction, many compounds from algae were tested for their ability to inhibit the SARS-CoV-2 main protease and compared to the recent recognized drug Paxlovid. The screening of 27 algal molecules including 15 oligosaccharides derived from sulfated and non-sulphated polysaccharides, eight pigments and four poly unsaturated fatty acids showed high affinities to interact with the protein active site. Best candidates showing high docking scores in comparison with the reference molecule were sulfated tri-, tetra- and penta-saccharides from Porphyridium sp. exopolysaccharides (SEP). Structural and energetic analyses over 100 ns MD simulation demonstrated high SEP fragments-Mpro complex stability. Pharmacokinetics predictions revealed the prospects of the identified molecules as potential drug candidates.

Conception of an environmental friendly O/W cosmetic emulsion from microalgae.

The development of eco-friendly cosmetic such as those from microalgae for skin regeneration and collagen synthesis has gained a great interest worldwide. Accordingly, the potential of microalgae biomass as source of anti-aging cosmetic cream with high antioxidant activity has been investigated. Stabilities and sensory characteristics of cosmetic creams supplemented with Spirulina, Tetraselmis sp. and Dunaliella sp. at 0.5, 1.5 and 2.5%, respectively, revealed a conservation of physico-chemical and preliminary stability properties of formulations. To analyze physico-chemical and textural parameters, accelerated stability study was evaluated under two thermal conditions (25 and 40 °C) during 90 days. Results showed that pH values of all formulations were within the limits of normal skin pH range under storage time at 25 and 40 °C. During this period, the colored creams showed a significant changes of a* and b* indices, reflecting the instability of microalgae colors. Microalgae modified the textural characteristics of emulsions. The Tetraselmis sp. containing-cream had the lowest (P < 0.05) values of hardness, springiness, and cohesiveness. The 0.5% Spirulina containing-cream had the best stable consistency and adhesiveness under time and temperature variations. It exhibited the best properties to be used for skin care products. Thanks to their high content in bioactive macromolecules, microalgae considerably improved the antioxidant activity of the new formulated skin creams.

SNP discovery and structural insights into OeFAD2 unravelling high oleic/linoleic ratio in olive oil.

Fatty Acid Desaturase 2 (FAD2), a key enzyme in the fatty acid biosynthesis pathway, is involved in the desaturation and conversion of oleic acid to linoleic acid. Therefore, it plays a crucial role in oleic/linoleic acid ratio and the quality of olive oil. DNA sequencing of 19 FAD2 genes from a set of olive oil varieties revealed several single-nucleotide polymorphisms (SNPs) and highlighted associations between some of the SNPs and saturated fatty acids contents. This was further confirmed by SNP-interaction and machine learning approach. Haplotype diversity analysis led to the discovery of three highly polymorphic SNPs and four haplotypes harboring differential oleic/linoleic acid ratios. Moreover, a combination of molecular modeling and docking experiments allowed a deeper and better understanding of the structure-function relationship of the FAD2 enzyme. Sequence patterns and variations involved in the regulation of the FAD2 activity were also identified. Furthermore, S82C and H213N substitutions in OeFAD2 make the Oueslati variety more interesting in terms of fatty acid profile and oleic acid level.

Apigenin analogues as SARS-CoV-2 main protease inhibitors: In-silico screening approach.

The COVID-19 new variants spread rapidly all over the world, and until now scientists strive to find virus-specific antivirals for its treatment. The main protease of SARS-CoV-2 (Mpro) exhibits high structural and sequence homology to main protease of SARS-CoV (93.23% sequence identity), and their sequence alignment indicated 12 mutated/variant residues. The sequence alignment of SARS-CoV-2 main protease led to identification of only one mutated/variant residue with no significant role in its enzymatic process. Therefore, Mpro was considered as a high-profile drug target in anti-SARS-CoV-2 drug discovery. Apigenin analogues to COVID-19 main protease binding were evaluated. The detailed interactions between the analogues of Apigenin and SARS-CoV-2 Mpro inhibitors were determined as hydrogen bonds, electronic bonds and hydrophobic interactions. The binding energies obtained from the molecular docking of Mpro with Boceprevir, Apigenin, Apigenin 7-glucoside-4'-p-coumarate, Apigenin 7-glucoside-4'-trans-caffeate and Apigenin 7-O-beta-d-glucoside (Cosmosiin) were found to be -6.6, -7.2, -8.8, -8.7 and -8.0 kcal/mol, respectively. Pharmacokinetic parameters and toxicological characteristics obtained by computational techniques and Virtual ADME studies of the Apigenin analogues confirmed that the Apigenin 7-glucoside-4'-p-coumarate is the best candidate for SARS-CoV-2 Mpro inhibition.

Ginger: a systematic review of clinical trials and recent advances in encapsulation of its bioactive compounds.

Recently, the numbers of studies on natural products have considerably increased owing to their exceptional biological activities and health benefits. Their pharmacological attributes have played an immense role in detecting natural and safe alternative therapeutics, consequently extending their industrial applications. In this line, ginger (Zingiber officinale) has been gaining wide attention owing to its bioactive compounds, such as phenolic and terpene compounds. Ginger has a great pharmacological and biological potential in the prevention and treatment of various diseases, namely colds, nausea, arthritis, migraines and hypertension. However, these bioactive compounds are unstable and susceptible to degradation, volatilization and oxidation during extraction and processing, mainly owing to their exposure to environments with adverse conditions, such as high temperature, the presence of O2 and light. In this sense, this current review covers a wide range of topics, starting from the chemical profile and biological properties of ginger bioactive compounds (GBCs), their clinical effectiveness for the treatment of diseases and the application of different encapsulation methods (molecular inclusion, spray drying, complex coacervation, ionic strength and nanoemulsions) to protect and improve their application in food products. This work summarizes the fundamental principles of, recent progress in and effectiveness of different methods regarding the physicochemical, structural and functional properties of encapsulated GBCs. The potential use of encapsulated GBCs as a promising active ingredient to be applied in different food products is discussed in detail.

Microalgae Xanthophylls: From Biosynthesis Pathway and Production Techniques to Encapsulation Development.

In the last 20 years, xanthophylls from microalgae have gained increased scientific and industrial interests. This review highlights the essential issues that concern this class of high value compounds. Firstly, their chemical diversity as the producer microorganisms was detailed. Then, the use of conventional and innovative extraction techniques was discussed. Upgraded knowledge on the biosynthetic pathway of the main xanthophylls produced by photosynthetic microorganisms was reviewed in depth, providing new insightful ideas, clarifying the function of these active biomolecules. In addition, the recent advances in encapsulation techniques of astaxanthin and fucoxanthin, such as spray and freeze drying, gelation, emulsification and coacervation were updated. Providing information about these topics and their applications and advances could be a help to students and young researchers who are interested in chemical and metabolic engineering, chemistry and natural products communities to approach the complex thematic of xanthophylls.

Sulfated exopolysaccharides from Porphyridium cruentum: A useful strategy to extend the shelf life of minced beef meat.

Sulfated exopolysaccharides (EPS) from Porphyridium cruentum strain were extracted and their antioxidant and anti-bacterial potentials were evaluated based on DPPH free radical, ABTS•+ radical cation and DNA nicking assays, and against four foodborne pathogenic bacteria, respectively. They showed also interesting functional, foaming and emulsion properties. Moreover, microbiological and chemical effects of EPS at 0.5, 1 and 2% on refrigerated minced beef meat were undertaken. Chemical analyses revealed that the treated meat underwent significant decrease (P < 0.05) of primary and secondary lipid oxidation. By the end of the storage period, exopolysaccharides at 2% reduced the metmyoglobin and carbonyl group accumulation compared to control samples and were more efficient (P < 0.05) against microflora proliferation. Furthermore, two multivariate exploratory techniques namely Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied successfully to all obtained data describing the main characteristics attributed to refrigerated meat samples. Overall, these findings indicated that EPS from P. cruentum are worthy being developed as functional and bioactive components for the meat industry.

Pistachio Hull Extract as a Practical Strategy to Extend the Shelf Life of Raw Minced Beef: Chemometrics in Quality Evaluation.

The agricultural processing industry produces a notable quantity of by-products rich in bioactive compounds, which can be exploited for agri-food applications. From pistachio industrial processing, pistachio's hull is one of the major by-products. This work aimed to evaluate the potential of pistachio hull, as a potential source of natural antioxidant, to preserve the meat quality. Here, we investigated the impact of aqueous pistachio hull extract (PHE) at 0.156% (PHE1), 0.312% (PHE2), and 0.625% (PHE3) on the quality of raw minced beef meat stored for 14 days at 4°C. At the end of storage, mesophilic total viable plate, psychotropic and Enterobacteriaceae counts, showed significantly lower (P < 0.05) microbial count in PHE samples. PHE3 revealed a powerful inhibitory effect on lipid/protein oxidation, and sensory characteristics were positively (P < 0.05) affected. Principal component analysis and heat map indicated complex and close synchronized relations among lipid/protein oxidation processes, microbial loads, and sensory attributes. Obtained results using univariate and multivariate statistical analysis underlined the importance of using different mathematical approaches, which are complementary to each other and could provide considerable information about the minced beef meat treated by PHE. Therefore, compared to synthetic antioxidants, PHE could be a clean-label alternative that can protect and enhance the quality of meat products.

Recent advancements in encapsulation of bioactive compounds as a promising technique for meat preservation.

Encapsulation is currently considered as one the most valuable methods for preserving aromatic compounds or hiding odors, enhancing their thermal and oxidative stability, and expanding their food applications. Indeed, this current article was aimed to provide an overview regarding the encapsulation of plant bioactive compounds and the spray-drying and extrusion processes with a focused discussion regarding the encountered challenges for meat and meat product preservation. Furthermore, different ranges of carbohydrates as wall materials (carriers) besides the process conditions' effects on the encapsulation effectiveness and the particle size of the encapsulated bioactive compounds have been discussed. The encapsulation of these compounds ameliorates the quality of the stored meat products by further delaying in microflora growth and lipid/protein oxidation. Therefore, the innovative technologies for plant active compounds encapsulation offer a prospective alternative for natural preservation development in the meat industry.

Production and structure prediction of amylases from Chlorella vulgaris.

Amylases are enzymes required for starch degradation and are naturally produced by many microorganisms. These enzymes are used in several fields such as food processing, beverage, and medicine as well as in the formulation of enzymatic detergents proving their significance in modern biotechnology. In this study, a three-stage growth mode was applied to enhance starch production and amylase detection from Chlorella vulgaris. Stress conditions applied in the second stage of cultivation led to an accumulation of proteins (75% DW) and starch (21% DW) and a decrease in biomass. Amylase activities were detected and they showed high production levels especially on day 3 (35 U/ml) and day 5 (22.5 U/ml) of the second and third stages, respectively. The bioinformatic tools used to seek amylase protein sequences from TSA database of C. vulgaris revealed 7 putative genes encoding for 4 α-amylases, 2 ß-amylases, and 1 isoamylase. An in silico investigation showed that these proteins are different in their lengths as well as in their cellular localizations and oligomeric states though they share common features like CSRs of GH13 family or active site of GH14 family. In brief, this study allowed for the production and in silico characterization of amylases from C. vulgaris.

Optimization of Exopolysaccharides Production by Porphyridium sordidum and Their Potential to Induce Defense Responses in Arabidopsis thaliana against Fusarium oxysporum.

Polysaccharides from marine algae are one novel source of plant defense elicitors for alternative and eco-friendly plant protection against phytopathogens. The effect of exopolysaccharides (EPS) produced by Porphyridium sordidum on elicitation of Arabidopsis thaliana defense responses against Fusarium oxysporum was evaluated. Firstly, in order to enhance EPS production, a Box-Behnken experimental design was carried out to optimize NaCl, NaNO3 and MgSO4 concentrations in the culture medium of microalgae. A maximum EPS production (2.45 g/L) higher than that of the control (0.7 g/L) was observed for 41.62 g/L NaCl, 0.63 g/L NaNO3 and 7.2 g/L MgSO4 concentrations. Structurally, the EPS contained mainly galactose, xylose and glucose. Secondly, the elicitor effect of EPS was evaluated by investigating the plant defense-related signaling pathways that include activation of Salicylic or Jasmonic Acid-dependent pathway genes. A solution of 2 mg/mL of EPS has led to the control of fungal growth by the plant. Results showed that EPS foliar application induced phenylalaline ammonia lyase and H2O2 accumulation. Expression profile analysis of the defense-related genes using qRT-PCR revealed the up-regulation of Superoxide dismutases (SOD), Peroxidase (POD), Pathogenesis-related protein 1 (PR-1) and Cytochrome P450 monooxyge-nase (CYP), while Catalase (CAT) and Plant defensin 1.2 (PDF1.2) were not induced. Results suggest that EPS may induce the elicitation of A. thaliana's defense response against F. oxysporum, activating the Salicylic Acid pathway.

Molecular and Structural Characterizations of Lipases from Chlorella by Functional Genomics.

Microalgae have been poorly investigated for new-lipolytic enzymes of biotechnological interest. In silico study combining analysis of sequences homologies and bioinformatic tools allowed the identification and preliminary characterization of 14 putative lipases expressed by Chlorella vulagaris. These proteins have different molecular weights, subcellular localizations, low instability index range and at least 40% of sequence identity with other microalgal lipases. Sequence comparison indicated that the catalytic triad corresponded to residues Ser, Asp and His, with the nucleophilic residue Ser positioned within the consensus GXSXG pentapeptide. 3D models were generated using different approaches and templates and demonstrated that these putative enzymes share a similar core with common α/ß hydrolases fold belonging to family 3 lipases and class GX. Six lipases were predicted to have a transmembrane domain and a lysosomal acid lipase was identified. A similar mammalian enzyme plays an important role in breaking down cholesteryl esters and triglycerides and its deficiency causes serious digestive problems in human. More structural insight would provide important information on the enzyme characteristics.

Effects of Ephedra alata extract on the quality of minced beef meat during refrigerated storage: A chemometric approach.

The biopreservative effect of Ephedra alata aqueous extract (EAE), used at 0.156, 0.312 and 0.624%, on minced beef meat was evaluated by microbiological, physicochemical and sensory analyses during storage at 4 °C for 14 days. The results showed that EAE significantly (P < .05) delayed the formation of thiobarbituric acid-reactive substances and carbonyls and reduced the sulfhydryl loss in a dose-dependent manner, indicating that EAE had a protective effect against lipids and protein oxidation. Concomitantly, an increase of redness and loss of lightness and yellowness was observed. Furthermore, two multivariate exploratory techniques, namely Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied to all obtained data describing the main characteristics attributed to refrigerated meat samples. During storage time, the used chemometric approaches were useful in discriminating meat samples, and therefore offers an approach to underlay connections between meat quality features. The obtained findings demonstrated the strong potential of EAE as a natural preservative in meat and meat products.