Isoelectric Point Of pH Research Articles

PH-induced interface protein structure changes to adjust the stability of tilapia protein isolate emulsion prepared by high-pressure homogenization

The pH is a crucial external factor affecting the structure and emulsification characteristics of proteins. The current study aimed to reveal the correlation between the secondary structure changes and tilapia protein isolate (TPI) emulsion stability under different pH (3.0–10.0) prepared by high-pressure homogenization. The results showed that TPI with significantly increased solubility and emulsifying properties when the pH keep away from the isoelectric point (pH 5.0). Meanwhile, TPI emulsions presented significantly enhanced stability (with decreased particle size, increased zeta potential, creaming index close to 0, and uniform dispersion of droplets) at pH 3.0 and 10.0. Interface-adsorbed protein mainly consists of a myosin-heavy chain and actin, and the secondary structure was significantly influenced by pH and high-pressure homogenization. The α-helix will be transformed into β-sheet and β-turn when pH is closer to pH 5.0. However, the high-pressure homogenization induced α-helix conversion to β-sheet. The correlation analysis revealed that emulsion stability is positively correlated with α-helix and negatively correlated with β-sheet. This work provides a deep insight into the correlation between secondary structure changes and the stability of TPI emulsion as affected by pH to offer an alternative way to enhance TPI emulsion stability.

Isolation and characterization of nettle (Urtica dioica L.) seed proteins: Conversion of underutilized by-products of the edible oil industry into food emulsifiers

This study aimed to upcycle a byproduct of the edible oil industry, cold-pressed nettle seed meal (CPNSM), into a plant-based emulsifier, thereby increasing the sustainability of the food system. The protein content of the nettle seed protein (NSP) powder was 48.3% with glutamic acid (16.6%), asparagine (10.7%), and arginine (9.7%) being the major amino acids. NSPs had a denaturation temperature of 66.6 °C and an isoelectric point of pH 4.3. They could be used as emulsifiers to form highly viscous coarse corn oil-in-water emulsions (10% oil, 4% NSP). Nevertheless, 10-fold diluted emulsions exhibited rapid creaming under different pH (2–9), salt (0–500 mM NaCl) and temperature (>40 °C) conditions, but they were relatively stable to aggregation. Our findings suggest that NSPs could be used as emulsifiers in highly viscous or gelled foods, like dressings, sauces, egg, cheese, or meat analogs.

Contributory roles of concentration and pH in CaCO3 growth inhibition for submicron particles synthesis with additive Ca2+

Excessive growth of CaCO3 precipitates is inhibited by additive Ca2+. Here, we report the influence of concentration and solution pH on the extent of growth inhibition. Equal volumes of equimolar CaCl2 and Na2CO3 solutions were mixed and continuously dispersed in Ca(OH)2 solution, where Ca2+ irreversibly adsorb on the precipitates. Compared to conditions where additive Ca2+ are absent, this method can produce more than 90% decrease in particle size. We observe the degree of growth inhibition increases as the concentration of additive Ca2+, relative to the volume of precipitates, increases. An unusual role of pH is also revealed: growth inhibition that leads to the synthesis of monodisperse submicron CaCO3 particles is only observed in high alkaline pH conditions. Additive Ca2+ adsorb on CaCO3 precipitates in pH conditions above the isoelectric point (pH ≈ 9), but their ability to limit CaCO3 growth diminishes when pH < 12.

Preparation of pH-responsive chitosan microspheres containing aminopeptidase and their application in accelerating cheese ripening

Microencapsulated enzymes have been found to effectively accelerate cheese ripening. However, microencapsulated enzyme release is difficult to control, often resulting in enzyme release during cheese processing and causing texture and flavor defects. This study aims to address this issue by developing aminopeptidase-loaded pH-responsive chitosan microspheres (A-CM) for precise enzyme release during cheese ripening. An aminopeptidase with an isoelectric point (pH 5.4) close to the pH value of cheese ripening was loaded on chitosan microspheres through electrostatic interaction. Turbidity titration measurements revealed that pH 6.5 was optimal for binding aminopeptidase and microspheres, affording the highest loading efficiency of 58.16%. Various characterization techniques, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy confirmed the successful loading of aminopeptidase molecules on the chitosan microspheres. In vitro release experiments conducted during simulated cheese production demonstrated that aminopeptidase release from A-CM was pH responsive. The microspheres retained the enzyme during the coagulation and cheddaring processes (pH 5.5-6.5) and only released it after entering the cheese-ripening stage (pH 5.0-5.5). By loading aminopeptidase on chitosan microspheres, the loss rate of the enzyme in cheese whey was reduced by approximately 79%. Furthermore, compared with cheese without aminopeptidase and cheese with aminopeptidase added directly, the cheeses made with A-CM exhibited the highest proteolysis level and received superior sensory ratings for taste and smell. The content of key aroma substances, such as 2/3-methylbutanal and ethyl butyrate, in cheese with A-CM was more than 15 times higher than the others. This study provides an approach for accelerating cheese ripening through the use of microencapsulated enzymes.

ПИЩЕВОЙ ПЕПТИД ДЛЯ ПРЕДУПРЕЖДЕНИЯ ИЗБЫТОЧНОЙ МАССЫ ТЕЛА: ВИРТУАЛЬНЫЙ СКРИНИНГ ПРОГНОЗИРОВАНИЯ ТОКСИЧНОСТИ И ВЫВЕДЕНИЯ

The aim of the research is to predict the toxicity and excretion of a biopeptide that prevents obesity. A synthesized peptide with the following sequence of amino acids was used as object of research: CHAECGAACKEFCLEG, preventing overweight. The peptide has similarities to glucagon-like peptide-1 (GLP-1), which regulates energy metabolism. Peptide characterization is the following: total hydrophobic ratio is 53 %, total charge is +0.25, hydrophobicity of the peptide according to Wimley-White in whole residue is 4.63, molecular weight 1556.826 Da, molecular formula C62H97N19O20S4, protein binding potential (Boman index) is 0.93 kcal / mol, isoelectric point pH 6.77. The peptide is highly soluble in water. The study established that the studied peptide, when ingested, does not cause acute toxicity, hepatotoxicity and cytotoxicity, does not adversely affect heart activity, does not activate heat shock protein gene receptors, does not cause DNA damage and mitochondrial dysfunction. The peptide is characterized by average half-life and low plasma clearance, which makes it effective. It should be noted that predicted characteristics do not always coincide with actual values obtained in in vitro experiments. Therefore, it is possible to recommend the peptide for inclusion in composition of specialized and preventive food products, provided that its effectiveness is proven in preclinical and clinical studies.

Emulsifying properties of O/W emulsion stabilized by soy protein isolate and γ-polyglutamic acid electrostatic complex.

In order to improve the emulsifying properties of soy protein around isoelectric point, soy protein isolate (SPI) and γ-polyglutamic acid (γ-PGA) complexes were prepared by electrostatic interaction. The formation of SPI-γ-PGA electrostatic complex and emulsifying properties were investigated by monitoring turbidity, zeta potential, intrinsic fluorophores, emulsion characterization, and microstructure observation. The results showed that the formation of SPI-γ-PGA electrostatic complex was identified through turbidimetric analysis and zeta-potential measurement. Intrinsic fluorescence spectrum indicated internal structure changes of electrostatic complexes. Furthermore, SPI-γ-PGA complex-stabilized emulsions showed better stability with small droplet sizes and slow growth as well as the uniform microstructure around the isoelectric point (pH 4.0-5.0) than SPI-formed emulsions. Under the different thermal treatments and ionic strengths, emulsions stabilized by SPI-γ-PGA-soluble complex resulted in improved emulsion stability to environmental stresses. This may be attributed to the increased steric repulsion and electrostatic repulsion by SPI-γ-PGA complexes at oil-water interfaces. The findings derived from this research would provide theoretical reference about SPI-γ-PGA electrostatic complex that can be applied in acid beverages and developed a novel plant-based sustainable stabilizer for emulsions. PRACTICAL APPLICATION: The electrostatic interaction between SPI and γ-PGA improved the emulsifying characteristics of soy protein around isoelectric point. The results derived from this research would expand applications of SPI-γ-PGA-soluble electrostatic complex that can be applied in acid beverages, as well as a novel plant-based sustainable stabilizer for emulsions.

Effect and mechanism of inorganic anions on the adsorption of Cd2+ on two-dimensional copper-based metal–organic framework

Metal-organic frameworks exhibit strong adsorption performance for Cd2+ in wastewater due to their multi-level pores and easily modified structure. In this paper, a copper based metal–organic framework: [Cu·(HL)·(DMF)]n (1) (H3L = 5-hydroxy isophthalic acid; DMF = N,N-dimethylformamide), was synthesized by hydrothermal synthesis method. The structural analysis shows that each Cu(II) in 1 is coordinated with four carboxylate O atoms from HL2− and one O atom from DMF. The two carboxylate groups in HL2− take μ2-η1:η1 to bridge two Cu(II) ions formed a two-dimensional structure. The scanning electron microscope (SEM) analysis shows that the nanomaterials prepared by the crushing method have dendritic structures and particle diameters of approximately 100 nm. The experimental results of the nano adsorbent adsorbing Cd2+ show that at an isoelectric point pH = 6, the optimal adsorbent concentration is 0.20 g/L. The maximum adsorption capacity at this time is 75.22 mg/g, which is superior to most MOFs adsorbents. At this optimal adsorbent concentration, as the solution pH increases, the adsorption capacity of the adsorbent for Cd2+ significantly increases. The thermodynamic analysis results of adsorption show that the △G < 0 and △H < 0 of the adsorbent in the range of 20–40 ℃, indicating that the adsorption of Cd2+ by the adsorbent is a spontaneous and exothermic process. The inorganic anions Cl−, HCO3−, NO3−, SO42− inhibit the adsorption of Cd2+ by nano adsorbent at a pH of 6. However, at low pH values (4, 5), it promotes the adsorption of Cd2+. This is mainly because the presence of inorganic anions changes the form of Cd2+ in solution, affecting the adsorption of it by the adsorbent.

Facile and green fabrication of algal protein/M(n+) hydrogel through coordination with cations for sustained release of vitamin B6

This study presents a facile method to prepare functional hydrogels based on spirulina algae protein/M(n+) and compares its properties with the conventional heat-induced method. Hence, algae protein isolate was extracted at the isoelectric point (pH 3.1) and hydrogels were synthesized through coordination with various cationic metals (Ca2+, Mg2+, Fe3+, Zn2+, and Cu2+) as a cross-linker. Morphological experiments (SEM) showed that the prepared hydrogels had a porous to dense and integrated structure depending on the type and concentration of metal cations. Fourier transform infrared (FTIR) spectra revealed the interaction of protein functional groups with coordinating metal ions. X-ray diffraction (XRD) patterns showed amorphous structures in algal protein/M(n+) hydrogels. The capacity of water absorption was strongly affected by pH and the type of metal cations and was much higher at pH 7.4 (490–801 %) than at acidic pH (pH 2.1, 212–419 %). The maximum release rate of vitamin B6 (83%) was obtained in Ca2+-hydrogels at pH 7.4 after 8 h. The Peppas-Sahlin model showed the best fit with the release profile of vitamin B6 (0.96–0.99), and it was also determined that the release process was based on Fickian diffusion (n ≤ 0.45) or anomalous transport (0.45 < n < 0.89). In conclusion, the study provided a new perspective on the fabrication of algal protein-based hydrogels, suggesting this matrix could be a novel delivery system for the controlled release of drugs/nutrients.

Kinetics of ester-105 degradation by La/TiO2 photocatalysis

Lanthanum-doped titanium (La/TiO2) nano-photocatalysts were prepared using the sol-gel method and characterized by X-ray diffraction (XRD), zeta potential, and low-temperature nitrogen adsorption analyses. Ester-105, a flotation collector from beneficiation wastewater, was chosen as the target pollutant. The influence of the initial ester-105 concentration, pH, and photocatalyst dosage on the photocatalytic degradation of ester-105 was investigated. To examine the kinetics of the adsorption and photocatalytic degradation of ester-105, a Langmuir adsorption model and Langmuir-Hinshelwood kinetic models were established and discussed. The synthesized photocatalyst comprised anatase-phase TiO2, with an isoelectric point of pH = 6.5, specific surface area of 56.1626 m2·g−1, and average pore size of 7.78 nm. The maximum adsorption and the adsorption equilibrium constant of La/TiO2 for ester-105 were determined as 0.338 mg·g−1 and 1.008 L·mg−1, respectively. The first-order kinetic reaction rate constant (k) exhibited a linear relationship with the initial ester-105 concentration. The optimal pH for ester degradation was theoretically determined to be 6.95, and the optimum photocatalyst dosage was found to be 0.2739 g·L−1. Experiments confirmed that the photocatalytic degradation of ester-105 using La/TiO2 followed the Langmuir-Hinshelwood kinetics model, thereby providing a theoretical foundation for the photocatalytic degradation of ester-105 for industrial application.

Influence of pH and ionic strength on the physicochemical and structural properties of soybean β-conglycinin subunits in aqueous dispersions

Understanding the impact of pH and ionic strength on the physicochemical and structural properties of soy proteins at subunit level is essential for design and fabrication of many plant-based foods. In this study, soybean β-conglycinin and its subunit fractions αα′ and β were dispersed in solutions with different pH values (3.7, 7.6, and 9.0) at low (5 mM NaCl) and high (400 mM NaCl) ionic strengths, respectively. The solubility, rheology, particle size, zeta potential, microstructure, secondary structure, and tertiary structure of the different dispersions were analyzed using a range of analytical methods. The β-conglycinin, αα′- and β-subunits aggregated near the isoelectric point (pH 3.7). Increasing the ionic strength led to the assembly of more homogeneous units. An increase in ionic strength at pH 7.6 and pH 9.0 led to electrostatic screening, which promoted dissociation of the aggregates. The β-subunit showed a greater sensitivity to pH and ionic strength than the αα′-subunits. Based on the evidence from a range of analytical methods, the highly hydrophilic extension region of the αα′-subunits played an important role in determining the stability of the β-conglycinin dispersions under different environmental conditions. Moreover, the N-linked glycans appeared to impact the conformation and aggregation state of the β-conglycinin.

Protein preparations from rapse processing waste: A review of the current status and development prospects of existing technologies

The demand for protein products is increasing due to the demographic growth of the world’s population. As an alternative to traditional sources of protein, waste from plant raw material processing is becoming increasingly popular. An important place in the global economy is occupied by oilseeds, in particular rapeseed, which production volumes are increasing in the Russian Federation every year. Rapeseed (Brassicaceae napus) is of great interest due to its high oil content (39.80–46.00%) and rich fatty acid composition, while cake and meal formed in the process of oil production are characterized by a significant content of crude protein (35.00–45.00%) and crude fiber (8.20–17.50%); however, they are used mainly as a feed additive. Recent studies on the processing of rapeseed waste indicate the value of this raw material as a source of dietary protein, which has a balanced amino acid profile and a high degree of digestibility (up to 85%). To obtain protein, rapeseed processing is envisaged: cleaning, grinding, cold pressing at a temperature of ≤ 40 °C, fat extraction with a solvent. At the next stages, the protein is extracted with 0.1–0.5 M NaCl at pH 5.3–12.0 and a temperature of 5–30 °C for 1 hour. The extracted protein is precipitated at the isoelectric point (pH 4.0) with HCl, separated from the mixture and neutralized. The result is a protein isolate with a protein content of 90.0–98.7%. It is possible to increase the quality and yield of the protein product due to the additional stage of processing the defatted cake with cellulolytic enzyme preparations. In this case, additional studies are required to determine the substrate specificity of commercial cellulase enzyme preparations and the optimal hydrolysis conditions. The parameters of extraction and precipitation of the protein in the case of using the stage of enzymatic lysis should also be specified.

PH dependence of glyphosate adsorption from aqueous solution using a cationic cellulose microfibers (cCMF) biosorbent

Abstract Currently, the agricultural sector is responsible for the contamination of groundwater and springs due to the excessive use of pesticides, which represents a risk to human and environmental health. Among pesticides, glyphosate is the most used herbicide to increase agricultural production, however, it can cause intoxication in humans and has been classified as a potentially carcinogenic agent. Alternatives for removing these contaminants from water have been studied and discussed, including biosorption, a physical-chemical process that removes substances from solutions using a natural and renewable material. In this sense, this work studied the process to obtain cationic cellulose microfibers (cCMF) from sugarcane bagasse residue, by cellulose isolation followed by cationization reaction with Girard T reagent to promote a new adsorbent for glyphosate removal from water. It was observed that cCMF structure maintains the fibrillar morphology after the microfiber production (1.375 mmol g−1 oxidation degree). Results of zero charge of cCMF microfibers showed an isoelectric point pH = 5.4 ± 0.016 and the highest adsorption capacity was reached at pH 14 (59.21 %), showing a clear pH dependence on the adsorption process. Thereby, the cCMF can be produced from sugarcane bagasse residue being applied as a potential biomaterial for removing organic compounds from water.

Investigation of the influence of pH on the properties and morphology of gelatin hydrogels

AbstractThe behavior of gelatin hydrogels is influenced by the charges located on the amino acid side chains throughout the gelatin molecules. The presence and distribution of ionisable side chains influences the surface activity of gelatin and ultimately determines the material properties. Herein, we report the influence of pH on mechanical properties as studied by texture analysis supported by data from polarimetry, zeta potential, pH titrations and NMR experiments. When adjusted to more extreme pH values (pH 2 and 12), softer gelatin blocks were observed. However, at pH values close to the isoelectric point (pH 5–10), the material is firmer. This behavior is related to the helical content. At pH 2 and pH 12 the surface of the gelatin carries a net charge, positive and negative, respectively, that inhibits the formation of tight helices and lowers the physical crosslink network density. Chemical shift perturbations were observed for the acidic amino acids glutamic and aspartic acid, under acidic pH, where their peaks shifted to higher ppm. Intense amide signals were observed at acidic pH but diminished with increasing pH. This was due to an increase in the rate of chemical exchange between the solvent and peptide amide protons as the pH increases.

Air-water interfacial and foaming properties of native protein in aqueous quinoa (Chenopodium quinoa Willd.) extracts: Impact of pH- and heat-induced aggregation

The shift from animal-based towards more sustainable plant-based food systems has increased the interest in leguminous protein such as that from the pseudo-cereal quinoa. In spite of the importance of foaming agents in a wide variety of food systems, the foaming properties of quinoa protein are still poorly understood. In this research paper, the air-water (A-W) interfacial and foaming properties of aqueous extracts from defatted quinoa wholemeal were investigated. Foams contained both albumins and 11S globulins, but no 7S globulins, despite the presence of the latter proteins in the extracts. At pH 7.0, both albumins and 11S globulins were soluble and jointly adsorbed at the A-W interface. Closer to the 11S globulin isoelectric point (pH 5.0), only albumins adsorbed at the A-W interface. Cultivar-dependent differences in protein composition and functionality allowed to hypothesize that 11S globulins foam better when present as dissociated acidic and basic subunits rather than as monomers. Heat-induced aggregation of 11S globulins led to enrichment of albumins at the A-W interface. This was associated with an increased surface tension and a decreased surface dilatational modulus. Presumably, quinoa albumins have low tendency to interact at the A-W interface resulting in a weakly elastic interfacial network. At the same time, globulin aggregates formed during heating at pH 5.0 and 7.0 lead to unstable and stable foams, respectively. As protein functional properties are important for the quality of many food products, these insights are valuable when developing novel quinoa-based food products requiring interfacial stability.

Surface Adsorption Mechanism between Lead(II,IV) and Nanomaghemite Studied on Polluted Water Samples Collected from the Peruvian Rivers Mantaro and Cumbaza.

Real water remediation is an important issue that requires the development of novel adsorbents with remarkable adsorption properties, permitting reusability. In this work, the surface and adsorption properties of bare magnetic iron oxide nanoparticles were systematically studied, before and after the application of a maghemite nanoadsorbent in two real Peruvian effluents severely contaminated with Pb(II), Pb(IV), Fe(III), and others. We were able to describe the Fe and Pb adsorption mechanisms that occurred at the particle surface. 57Fe Mössbauer and X-ray photoelectron spectroscopy results together with kinetic adsorption analyses gave evidence for two involved surface mechanisms: (i) surface deprotonation of maghemite nanoparticles (isoelectric point of pH = 2.3), forming Lewis sites bonding Pb complexes; and (ii) the formation of a thin inhomogeneous secondary layer of iron oxyhydroxide and adsorbed Pb compounds, as favored by surface physicochemical conditions. The magnetic nanoadsorbent enhanced the removal efficiency to values of ca. 96% and provided adsorptive properties with reusability due to the conserved morphological, structural, and magnetic properties. This makes it favorable for large-scale industrial applications.

The characteristics of nano-micron calcite particles/common bacteria complex and its interfacial interaction.

Based on the composite pollution of atmospheric microbial aerosol, this paper selects the calcite/bacteria complex as the research object which was prepared by calcite particles and two common strains of bacteria (Escherichia coli, Staphylococcus aureus) in the solution system. The morphology, particle size, surface potential, and surface groups of the complex were explored by modern analysis and testing methods, with an emphasis on the interfacial interaction between calcite and bacteria. The SEM, TEM, and CLSM results showed that the morphology of the complex could be divided into three types: bacteria adhering to the surface or edge of micro-CaCO3, bacteria aggregating with nano-CaCO3, and single nano-CaCO3 wrapping bacteria. The complex's particle size was about 2.07 ~ 192.4 times larger than the original mineral particles, and the nano-CaCO3/bacteria complex's particle size variation was caused by the fact that nano-CaCO3 has agglomeration in solution. The surface potential of the micro-CaCO3/bacteria complex (isoelectric point pH = 3.0) lies between micro-CaCO3 and bacteria, while the surface potential of the nano-CaCO3/bacteria complex (isoelectric point pH = 2.0) approaches the nano-CaCO3. The complex's surface groups were based primarily on the infrared characteristics of calcite particles, accompanied by the infrared characteristics of bacteria, displaying the interfacial interaction from the protein, polysaccharides, and phosphodiester groups of bacteria. The interfacial action of the micro-CaCO3/bacteria complex is mainly driven by electrostatic attraction and hydrogen bonding force, while the nano-CaCO3/bacteria complex is guided by surface complexation and hydrogen bonding force. The increase in the β-fold/α-helix ratio of the calcite/S. aureus complex indicated that the secondary structure of bacterial surface proteins was more stable and the hydrogen bond effect was strong than the calcite/E. coli complex. The findings are expected to provide basic data for the mechanism research of atmospheric composite particles closer to the real environment.

Removal of Cr(VI) from aqueous solution by Rice-husk-based activated carbon prepared by Dual-mode heating method

Rice husk-based activated carbon was prepared with the help of zinc chloride using microwave and electrical dual-mode heating. The pore characteristics and chemical properties of rice husk-based activated carbon (RH-AC) were characterized by BET, XRD, Raman spectra, FTIR and pHIEP (pH of isoelectric point). The specific surface area of RH-AC is 1719.32 m2/g with a total pore volume of 1.05 cm3/g. The performance of RH-AC for removing Cr(VI) from aqueous solution was examined considering the variation of the contact time (0–120 min), pH value (2.0–9.0), adsorbent dose (0.5–3.0 g/L), initial concentration (28–145 mg/L) and solvent temperature (15–45 °C). The ideal pH for Cr(VI) removal is between 2.0 and 3.0 with the equilibrium time of 90 min, achieving the maximum adsorption capacity of 56.82 mg/g with the pH of 3.0. Comparable study on the established kinetic models and isotherms to simulate the removal of Cr(VI) by RH-AC was carried out to sort out the inherent mechanism of the absorption. Reasonable agreements could be obtained by the pseudo-second-order kinetic model and Langmuir, Freundlich and Tempkin isothermal models. Results from Body model simulation suggest that external mass transfer was the essential cause for rate-controlling in the adsorption process of Cr(VI).

Oil Bodies from Chia (Salvia hispanica L.) and Camelina (Camelina sativa L.) Seeds for Innovative Food Applications: Microstructure, Composition and Physical Stability

Exploring and deciphering the biodiversity of oil bodies (OBs) recovered from oilseeds are of growing interest in the preparation of sustainable, natural and healthy plant-based food products. This study focused on chia (Salvia hispanica L.) and camelina (Camelina sativa L.) seed OBs. A green refinery process including ultrasound to remove mucilage, aqueous extraction by grinding and centrifugation to recover OBs from the seeds was used. The microstructure, composition and physical stability of the OBs were examined. Confocal laser scanning microscopy images showed that chia and camelina seed OBs are spherical assemblies coated by a layer of phospholipids and proteins, which have been identified by gel electrophoresis. The mean diameters determined by laser light scattering measurements were 2.3 and 1.6 µm for chia and camelina seed OBs, respectively. The chia and camelina seed OBs were rich in lipids and other bioactive components with, respectively, 64% and 30% α-linolenic acid representing 70% and 53% of the total fatty acids in the sn-2 position of the triacylglycerols, 0.23% and 0.26% phospholipids, 3069 and 2674 mg/kg oil of β-sitosterol, and lipophilic antioxidants: 400 and 670 mg/kg oil of γ-tocopherol. Phenolic compounds were recovered from the aqueous extracts, such as rutin from camelina and caffeic acid from chia. Zeta-potential measurements showed changes from about -40 mV (pH 9) to values that were positive below the isoelectric points of pH 5.1 and 3.6 for chia and camelina seed OBs, respectively. Below pH 6.5, physical instability of the natural oil-in-water emulsions with aggregation and phase separation was found. This study will contribute to the development of innovative and sustainable food products based on natural oil-in-water emulsions containing chia and camelina seed OBs for their nutritional and health benefits.

Nutritional Quality, Chemical, and Functional Characteristics of Hemp (Cannabis sativa ssp. sativa) Protein Isolate.

(1) Background: Hemp seeds are a source of plant-based protein, making them an appropriate supplement to a plant-based diet. The current work was focused on the preparation of the protein isolate from the hemp seeds with eco-friendly and cheap technology. Moreover, it evaluated the physicochemical and functional properties of hemp protein isolate for its potential application in food manufacturing. (2) Methods: The protein content of hemp seeds has been isolated through two main steps: (1) extraction of the protein content of an alkaline pH (10-12); (2) precipitation of the extracted protein on an acidic pH as an isoelectric point (pH = 4.5). (3) Results: The edastin protein is the most predominant protein in the protein profile with a molecular weight of 58.1 KDa beside albumin with a molecular weight of 31.5 KDa. The FTIR spectrum detected the absorption peaks of the amide I at 1750 and 1600 cm-1, which pointed to C=O stretching while N-H stretching at 1650-1580 cm-1. The peak at 3250 is found to be related to N-H stretching of the aliphatic primary amine (3400-3300 cm-1) and the N-H stretching for the secondary (II) amine appeared at 3350-3310 cm-1. The Hemp protein isolate (HPI) showed a high content of arginine (15.52 g/100 g), phenylalanine + tyrosine (9.63 g/100 g), methionine + cysteine (5.49 g/100 g), leucine + isoleucine (5.21 g/100 g), and valine (4.53 g/100 g). It contains a moderate level of threonine (3.29 g/100 g) and lysine (2.50 g/100 g) with tryptophan as the limiting amino acid (0.22 g/100 g). The HPI showed an appropriate water-and-oil holding capacity (4.5 ± 2.95 and 2.33 ± 1.88 mL/g, respectively). The foaming capacity of the HPI was increased with increasing the pH values to reach the maximum value at pH 11 (67.23 ± 3.20%). The highest emulsion ability index of the HPI was noted at pH 9 (91.3 ± 2.57 m2/g) with low stability (19.15 ± 2.03). (4) Conclusions: A strong positive correlation (r = 0.623) was shown between protein concentration and solubility. The current easy-to-use, cheap, and eco-friendly technology provides the industrial sector with a cheap protein isolate for manufacturing protein-rich diet and beverages. The HPI showed a good nutritional quality and functional properties that might be helpful in utilizing it in different food products such as beverages and bakery products.

Identification and characterization of antimicrobial peptide (AMP) candidate from Gonggong Sea Snail (Leavistrombus turturella) extract.

This study aimed to explore the potency of Gonggong sea snail's (GSS) extract as an antimicrobial peptide (AMP) source. The results showed that the GSS meat extracts exhibited potential antimicrobial activity against Staphylococcus aureus and Escherichia coli. A peptide band with a molecular weight < 5kDa was obtained for the characterization of AMP candidates after separating the selected extract using SDS-PAGE, and the sequences were acquired by LC-ESI-MS analysis. The results of the bioinformatics analysis showed that the AMP candidate had a molecular weight of 1.4kDa, which consisted of 12 amino acid residues (RHPDYSVALLLR), with an α-helix structure, isoelectric point pH (pI) of 9.53, net charge + 1, a total hydrophobic ratio at 49.9%, protein-binding potential (Boman index) of 2.17kcal/mol, and hydrophobicity of + 13.67kcal/mol. Furthermore, MIC and MBC values of the extract and the < 10kDa fraction on both bacteria ranged from 0.50-1.03mg/ml. The GSS meat extract could reach the intracellular site of E. coli, while in S. aureus, it was localized in the cell membrane. These results can be baseline information for developing AMPs in natural bio-preservative exploration as food additives and pharmaceuticals.