Protein Isolate Research Articles

Production of protein-epigallocatechin gallate conjugates using free radicals induced by ultrasound and their gelation behavior

In this study, free radicals generated by ultrasound were used to prepare conjugates of food proteins (soybean protein isolates, sodium caseinate and gelatin) with epigallocatechin gallate (EGCG). The changes in free amino and sulfhydryl group contents were used to confirm the occurrence of conjugation. The formation of covalent interactions on surface hydrophobicity, functional groups, structures, thermal stability, and gelation behavior of three proteins were investigated. The results showed that conjugation led to decrease in free amino and sulfhydryl group contents, reduction in the intensity of amide A and fluorescence intensity, and increase in β-fold content. The conjugation also resulted in a decrease in surface hydrophobicity and thermal stability of soybean protein isolates and sodium caseinate, but an increase in the surface hydrophobicity and thermal stability of gelatin. Furthermore, the covalent bonding between proteins and EGCG improved gel strength, water holding capacity, and resulted in a denser and more compact microstructure.

The effect of whey/soy protein fibril systems on the properties of fish gelatin stabilized emulsion gels

In this study, we investigated the effects of whey protein isolate fibril systems (WPF) and soy protein isolate fibril systems (SPF) combined with fish gelatin (FG) on the formation of emulsion gels. The aim was to evaluate how the origin and concentration of these fibril systems influence the structural, interfacial, and rheological properties of FG-stabilized emulsion gels, as well as their impact on creaming stability. FG was mixed with varying concentrations (0–2%) of WPF and SPF at pH 7, forming electrostatic complexes due to the opposite charge interactions between FG and the protein fibril dispersions. The results revealed that adding WPF and SPF increased surface hydrophobicity and enhanced interfacial activity. Increasing WPF concentrations led to a gradual decrease in emulsion droplet size owing to the increased absorbed protein content at the interface. Additionally, there was a significant improvement in the storage modulus of the emulsion gels. Conversely, introducing a small amount (0.1%) of SPF to FG increased the particle size, suggesting potential coalescence, but further increases in SPF concentration considerably reduced the particle size. Furthermore, SPF enhanced the viscoelasticity at lower concentrations, possibly due to a more uniform distribution within the continuous phase. However, excess SPF reduced the storage modulus of the emulsion gels. Our study provides valuable theoretical insights for the application of protein fibril systems in emulsion gel systems.

Incorporating κ-carrageenan regulates the gel properties and structural characteristics of corn starch-soy protein isolate based ternary system

A thorough understanding of the interactions in the starch-protein-polysaccharide ternary system is essential for the development of highly stable hydrogel systems. In this work, the effects of different κ-carrageenan (KC) incorporation on the structure and sol-gel performance of the corn starch (CS)-soy protein isolate (SPI) composite system were investigated. As the KC incorporation was raised, the gelatinization temperature increased gradually, but the enthalpy value was reduced (lower system stability, from 9.14 J/g to 8.06 J/g). The structural results show that the higher content of KC decreased the smoothness of the network structure, increased the denseness of the ternary system, and hindered the formation of nanostructures and short-range ordered structures. However, the textural properties (hardness, chewiness, gumminess) and gel strength of the composite gels increased significantly with increasing KC content (from 65.53 g to 181.90 g). This could be due to the enhancement of hydrogen bonding between KC and amylose during the cooling process, forming more stable three-dimensional network structure. This work contributes to the design of multivariate starch-based gel foods.

How Protein Depletion Balances Thrombosis and Bleeding Risk in the Context of Platelet's Activatory and Negative Signaling.

Platelets are small cell fragments that play a crucial role in hemostasis, requiring fast response times and fine signaling pathway regulation. For this regulation, platelets require a balance between two pathway types: the activatory and negative signaling pathways. Activatory signaling mediators are positive responses that enhance stimuli initiated by a receptor in the platelet membrane. Negative signaling regulates and controls the responses downstream of the same receptors to roll back or even avoid spontaneous thrombotic events. Several blood-related pathologies can be observed when these processes are unregulated, such as massive bleeding in activatory signaling inhibition or thrombotic events for negative signaling inhibition. The study of each protein and metabolite in isolation does not help to understand the role of the protein or how it can be contrasted; however, understanding the balance between active and negative signaling could help develop effective therapies to prevent thrombotic events and bleeding disorders.

A review on advancements in emerging processing of whey protein: Enhancing functional and nutritional properties for functional food applications

AbstractWhey protein (WP) isolates are widely used in food products because they improve protein content, functional properties, and health benefits. It has been observed that WP can form conjugates with essential micronutrients, improving their dietary delivery and biological availability. WP and its derived bioactive peptides have potential health benefits in preventing chronic diseases. However, the off‐flavor and bitter peptides of WP are limiting factors that can be used in the food and beverage industries. Emerging innovative processing technologies, such as high hydrostatic pressure, ultrasonication, and extrusion, improve WP gelling ability, gel strength, and storage stability, providing high‐quality and healthy functional products. The integration of technological advancements into WP‐loaded fortified food products (FFPs) has increased the uptake rate of bioactive compounds, resulting in increased bioavailability and bioaccessibility in the human body. Furthermore, WP‐based FFPs treated with advanced thermal and nonthermal processing techniques possess better rheological properties, expansion ratios, and textural properties. Therefore, WP would be a promising and sustainable ingredient for developing stable functional foods. This review explores recent advancements in the processing technologies of WP, emphasizing their role in enhancing its bioavailability and functional properties for different food applications.

Magnetic nanoparticles and quantum dots coupled immuno nano fluorescence assay for visual detection of HPV16-induced cervical cancer cells from cytology/biopsy samples

Biopsy-based histopathology and immunohistochemistry for cervical cancer detection are costly, time-consuming, and require expert personnel for data interpretation. We developed a simple magnetic nanoparticle (MNPs) and quantum dots (QD) coupled immuno nano fluorescence assay (MNPQDCINFA) for visual detection of HPV16-induced cervical cancer cells under UV light from cytology/biopsy samples exploiting host cancer cells expressing viral E7 protein as a biomarker. The E7 domain-specific polyclonal antibodies were generated against the 1–44 amino acid N-terminal (anti-domainN antibody) and 48–98 amino acid C-terminal domain (anti-domainC antibody). These antibodies were bioconjugated with nonfluorescent MNPs (60 % efficiency) and fluorescent QDs (66 % efficiency) to generate capturing (MNPs-anti-domainN antibody) and detecting (QDs-anti-domainC antibody) nano-complex, respectively. Assay conditions, such as concentration of capturing (20 μM) and detecting (50 nM) antibody nano-complexes and incubation duration (30 min), were standardized. The analytical sensitivity using pure HPV16 E7 protein was recorded up to 200 ng with very high specificity to differentiate from other HPV strains E7 proteins. The diagnostic performance characteristics with cytology samples showed 100 % sensitivity and specificity compared to immunofluorescence and biopsy-based histopathology analysis. The present invention can be effectively used for a quick, disposable, rapid cervical cancer cell detection system as an alternate test for immunofluorescence and histopathology.

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.

Engineering effects of hydrocolloids on drying kinetics, powder characteristics, and antioxidant preservation in grape powder

This study explores the preservation of bioactive compounds in grape powder via encapsulation using spray drying, focusing on the impact of hydrocolloids—whey protein isolate (WPI), gum arabic, and high methoxy pectin—on critical engineering parameters. The research analyzes the effects of these encapsulants on rheological properties, drying kinetics, droplet formation, and drying curves, all of which influence the powder's morphology and antioxidant retention. Drying times ranged from 1.05 to 1.14 s, with distinct drying curves reflecting the relationship between moisture content and time, correlating with key powder properties such as bulk and tap density, flowability, and compressibility. Dimensionless numbers, including Peclet and Reynolds numbers, showed significant correlations with both powder characteristics and bioactive retention, highlighting the role of efficient heat and mass transfer in preserving phenolic content. The study concludes that optimal formulations, particularly those combining WPI and pectin, result in uniform droplet sizes, faster drying rates, and enhanced bioactive stability, providing insights for optimizing spray drying processes to produce high-quality, stable food powders.

A cheap and straightforward method for the selective isolation of histidine-derived natural products using nickel(II) phosphate.

Nickel-based resins have long been used in biochemical studies for the purification of His-tagged proteins, but their potential in the isolation of histidine-derived small molecules has not been investigated to date. Many agriculturally-important mycotoxins incorporate histidine residues, as do natural products from both plants and bacteria. Here, a highly-selective solid-phase extraction method is described for the purification of histidine-derived natural products using the insoluble nickel salt Ni3(PO4)2. This led to the highly-selective binding and elution of two natural products, meleagrin and gartryprostatin C, from two fungal strains, Penicillium chrysogenum and Aspergillus sclerotiorum, respectively. A simple protocol involving binding, washing with water and methanol, and elution with methanolic acetate buffer, gave 65-75% recovery of both compounds directly from crude extracts of the two fungi. The procedure can easily be used as part of a multi-step isolation process in combination with HPLC to yield the purified alkaloids.

Application of flowsheet modeling for scheduling and debottlenecking analysis to support the development and scale-up of a plasma-derived therapeutic protein purification process

Plasma fractionation stands as a pivotal process for the production of therapeutic and diagnostic proteins, such as albumin and immunoglobulin G. Besides these two primary proteins in human plasma, numerous other proteins can be purified for therapeutic purposes. To support process development, a flowsheet modeling-based approach is utilized to improve production efficiency and productivity while minimizing the resource investments. The flowsheet model is first built to represent the baseline drug substance production process at pilot-scale, with operating parameters extrapolated from lab-scale experiments conducted at CSL Behring. To improve operational efficiency and save costs, throughput analysis is applied to enhance the batch throughput through new process design, scheduling, and bottleneck identification. Through implementing the strategies, the batch throughput could be increased by 47.2 % by introducing one additional operator and one buffer preparation tank into the process. Furthermore, after applying a new strategy involving multiple extractions of the initial material (paste), the batch throughput was doubled, with operating cost of goods reduced by 36.1 %. To assess the performance of the modified design and validate the model results, the pilot-scale experiments with two extractions were performed by CSL Behring and compared with model predictions, resulting in good agreement. This work demonstrates the potential of flowsheet modeling in facilitating process development from lab-scale to pilot-scale, fostering cost-effective and efficient production with limited resource investment.

Investigation of transglutaminase incubated condition on crosslink and rheological properties of soy protein isolate, and their effects in plant-based patty application

Investigation of transglutaminase incubated condition on crosslink and rheological properties of soy protein isolate, and their effects in plant-based patty application

Mechanisms of Pickering emulsion formation and stabilization by composite arabinoxylan–whey protein isolate particles

Few systematic studies were performed into the properties of arabinoxylan (AX) and protein composite particles, and their mechanisms of action in an emulsion remain largely unknown. In this study, composite particles based on different concentrations of AX and whey protein isolate (WPI) were constructed, and a systematic characterization was conducted to determine their functional properties. A good compatibility was found between WPI and AX, and the composites exhibited an enhanced thermal stability and consistent particle sizes. Molecular interactions, including hydrogen bonds, were detected between WPI and AX, and the composite particles containing 4% AX exhibited the lowest interfacial tension and the strongest emulsification ability. AX promoted protein adsorption on the oil phase surface, and the desorption energy of the composite particles at the oil/water interface increased accordingly. The stability of an emulsion stabilized by AX–WPI was confirmed by rheological and microstructural investigations. This study therefore provides theoretical support for the application of such emulsions.

A protectant for Lactobacillus rhamnosus based on whey protein isolate and isomalt: Stress resistance and underlying mechanisms

Probiotics are exposed to a variety of abiotic and biotic stresses during food fermentation and production, such as acidity, heat, osmolality, and oxidation, which affect their metabolic activity and efficiency. Therefore, it is essential to develop new protective agents to maintain the activity and stability of probiotics. This study introduces a new protectant, spray-dried whey protein isolate (WPI) and isomaltose (ISO). We evaluated the effects of four WPI-ISO ratios (1:0, 2:1, 1:1, 1:2) on the physical properties, including moisture content, water activity (aw), wettability, and glass transition temperature. In addition, we evaluated the environmental tolerance of Lactobacillus rhamnosus to different WPI-ISO ratios under thermal, storage, and simulated gastrointestinal conditions. The results showed that the moisture content (< 7 %) and water activity (< 0.3) of the protectant and probiotic powders met storage stability requirements. The moisture content, water activity, wettability index (WI), and glass transition temperature decreased significantly with the addition of isomalt, thereby improving the pressure resistance of L. rhamnosus through the synergistic effect of WPI and ISO. The WPI-ISO protectant not only improved the environmental tolerance and wettability of probiotics by reducing the moisture content and water activity but also significantly improved the survival rate of L. rhamnosus under various stress conditions such as high temperature and gastrointestinal environment. L. rhamnosus maintains good activity with a viable bacterial count of over 9 lg CFU/g after 90 days of storage, demonstrating effective protection against the environment stress. This study provides a promising new strategy to improve the stability of probiotics in the food industry.

Thermal-induced interactions between soy protein isolate and malondialdehyde: Effects on protein digestibility, structure, and formation of advanced lipoxidation end products

Thermally processed lipid- and protein-rich foods have sparked widespread concern since they may degrade food nutrition and even risk food safety. This study investigated soy protein isolate (SPI) alterations of digestibility and structure, as well as the formation of potentially hazardous chemicals, i.e., advanced lipoxidation end products (ALEs), after interacting with malondialdehyde (MDA, a lipid oxidation product) under high-temperature cooking conditions (100–180 °C, up to 60 min). In-vitro protein digestion of the SPI-MDA mixtures suggested that their room-temperature interactions damaged SPI digestibility, and increasing the temperature and the duration of the thermal treatment exacerbated the adverse effects. Protein oxidation, covalent aggregation of subunits, and changes in secondary and tertiary structures were revealed using thiol quantification, gel electrophoresis, fluorescence spectroscopy, and circular dichroism (CD) spectra, which could explain reduced protein digestibility. High-resolution mass spectrometry (HRMS) identified seven non-crosslinked ALEs and two crosslinked ALEs. Increased MDA concentrations promoted the generation of ALEs. Moreover, the acrolein-derived ALEs with reactive carbonyl groups were prone to further reacting into crosslinked ALEs, potentially responsible for the subunit aggregation.

The Temporal Change in Ionised Calcium, Parathyroid Hormone and Bone Metabolism Following Ingestion of a Plant-Sourced Marine Mineral + Protein Isolate in Healthy Young Adults.

Background: An increase in plant-sourced (PS) nutrient intake is promoted in support of a sustainable diet. PS dietary minerals and proteins have bioactive properties that can affect bone health and the risk of fracture. Methods: In a group randomised, cross-over design, this study evaluated the post-ingestion temporal pattern of change in arterialised ionised calcium (iCa), parathyroid hormone (PTH), C-terminal crosslinked telopeptide of type I collagen (CTX) and procollagen type 1 amino-terminal propeptide (P1NP) for 4 h following ingestion of a novel supplement (SUPP) containing a PS marine multi-mineral + PS protein isolate. A diurnally matched intake of mineral water was used as a control (CON). Results: Compared to baseline, the change in iCa concentration was 0.022 (95% CI, 0.006 to 0.038, p = 0.011) mmol/l greater in SUPP than CON, resulting in a -4.214 (95% CI, -8.244 to -0.183, p = 0.042) pg/mL mean reduction in PTH, a -0.64 (95% CI, -0.199 to -0.008, p = 0.029) ng/mL decrease in the biomarker of bone resorption, CTX, and no change in the biomarker of bone formation, P1NP. Conclusions: When used as a dietary supplement, or incorporated into a food matrix, the promotion of PS marine multi-mineral and PS protein isolates may contribute to a more sustainable diet and overall bone health.

Characterization of Escherichia coli as a Recombinant Protein Expression Host and its Optimization

Engineered Escherichia coli serves as an efficient platform for the production of a diverse array of recombinant proteins, thereby addressing the pharmaceutical industry's demand for high-quality biological agents. Nevertheless, challenges related to protein folding and the complexities involved in product purification must be acknowledged. This review delineates the advantages and disadvantages of utilizing E. coli as an expression host and further investigates various strategies aimed at optimizing and enhancing the E. coli expression system to elevate the yield, purity, and biological activity of recombinant proteins, ultimately supporting advancements in biopharmaceuticals and other relevant fields.

Black soldier fly (Hermetia illucens L.) whole and fractionated larvae: In vitro protein digestibility and effect of lipid and chitin removal

Protein quality, which can be defined by amino acid profile and protein digestibility, is of paramount importance when assessing a novel protein source. As the presence of chitin might impair insect protein digestion, and as there is little to no clarity as to how different insect fractions influence the overall protein digestibility, this study aimed at assessing the influence of lipids and chitin removal on the protein digestibility of black soldier fly larvae. The samples underwent an in vitro simulated gastro-intestinal digestion following the INFOGEST method, commonly used for humans, and both undigested matrices and digesta were characterized by means of amino acid composition, SDS-PAGE gel electrophoresis, and proteomic/peptidomic approaches. Protein solubilization, degree of hydrolysis (DH%) after digestion, and digestible indispensable amino acid (DIAA) contents were also determined. The results highlighted that the presence of chitin hindered protein digestion, as expected: in fact, the protein isolate showed the highest solubilized protein (84.0%), DH% (61.1%), and number of peptides and proteins detected by high resolution mass spectrometry (64 and 16, respectively), while the chitin-rich fraction the lowest (38.4% solubilized protein, 41.2% DH%, 37 peptides and 6 proteins detected, respectively). Additionally, the chitin-rich fraction had the lowest DIAAS. Interestingly, the preferred C-terminal cleavage sites for all samples were in line with the specificity of the enzymes used, meaning that insect proteins, compared to other matrices, do not change the enzymatic behavior in terms of their specificity.

Effect of green extraction techniques on the quality and functional attributes of protein isolates from cereals and pseudo cereals: a review

SummaryCereals and pseudo cereals (CPC) constitute the main staple diet of the global population. These are great source of carbohydrate, however, ignored as a potential source of protein. Cereals and Pseudo cereals can provide adequate amount of protein if taken in right quantity. Concerns over foods security, nutritional deficiencies, chronic hunger, and sustainability have brought attention to sustainable and alternative sources of protein derived from food and its byproducts. This review explains the extraction of protein from different cereals and pseudo cereals sources, novel extraction techniques, e.g., microwave assisted, ultrasound, pulsed electric field or high‐pressure processing etc., as well as pre‐treatment efficiencies of the recovery of protein, effects of process parameters on the amount of protein extractions, its isolations and possible utilisation in diversified fields. Commercial attempts have been made to extract and use the protein from CPC, but they remain largely underutilised and generally applicable to a small‐scale level. According to the current investigation, protein extraction from CPC is not only an extensive integration of extraction perspectives, process parameters, yield potential and quality, but also should focus on the nutritional aspects, functionality and bioavailability of the separated protein as a desirable dietary component is in the near future.

Improved encapsulation efficiency and storage stability of lutein by soy protein isolate nanocarriers with thermal and trypsin treatments.

Encapsulation of bioactive compounds within protein-based nanoparticles has garnered considerable attention in the food and pharmaceutical industries because of its potential to enhance stability and delivery. Soy protein isolate (SPI) has emerged as a promising candidate, prompting the present study aiming to modify its properties through controlled thermal and trypsin treatments for improved encapsulation efficiency (EE) of lutein and its storage stability. The EE of lutein nanoparticles encapsulated using SPI trypsin hydrolysates (SPIT) with three varying degrees of hydrolysis (4.11%, 6.91% and 10.61% for SPIT1, SPIT2 and SPIT3, respectively) increased by 12.00%, 15.78% and 18.59%, respectively, compared to SPI. Additionally, the photostability of SPIT2 showed a remarkable increase of 38.21% compared to SPI. The superior encapsulation efficiency and photostability of SPIT2 was attributed to increased exposure of hydrophobic groups, excellent antioxidant activity and uniform particle stability, despite exhibiting lower binding affinity to lutein compared to SPI. Furthermore, in SPIT2, the protein structure unfolded, with minimal impact on overall secondary structure upon lutein addition. The precise application of controlled thermal and trypsin treatments to SPI has been shown to effectively produce protein nanoparticles with substantially improved encapsulation efficiency for lutein and enhanced storage stability of the encapsulated lutein. These findings underscore the potential of controlled thermal and trypsin treatments to modify protein properties effectively and offer significant opportunities for expanding the applications of protein-based formulations across diverse fields. © 2024 Society of Chemical Industry.

Stabilizing emulsions by ultrasound-treated pea protein isolate - tannic acid complexes: Impact of ultrasonic power and concentration of complexes on emulsion characteristics

This work aimed to investigate the feasibility of stabilizing oil-in-water (O/W) emulsions by ultrasound-treated pea protein isolate-tannic acid (UPPI-TA) complex. The stability and microstructure of the O/W emulsions were evaluated at different ultrasonic powers (0–1000 W) and UPPI-TA complex concentrations (0.25–2.0 wt%). The contact angle (θ) of UPPI-TA was 59.6°, which was suitable for stabilizing O/W emulsions. At an ultrasonic power of 800 W, the droplet size and creaming index (CI) of emulsions decreased, and the apparent viscosity and interfacial protein adsorption content increased with increasing UPPI-TA concentration. In particular, emulsions with 1.5 % UPPI-TA showed the lowest CI, the highest interfacial protein adsorption content and viscoelasticity, as well as the best storage and thermal stability. These results showed that the suitable modifications of ultrasonic emulsification power and particle concentrations were a new potential approach to stabilize the O/W emulsions by ultrasound-treated pea protein isolated-tannic acid complex.