Protein Mass Ratio Research Articles

Fabrication and characterisation of whey–pea protein‐based emulsion gels induced by transglutaminase cross‐linking

Food industry has partially replaced animal proteins with plant‐derived alternatives, and effects of combining these two types on properties of food systems need to be elucidated. This study fabricated and characterised emulsion gels of mixed whey and pea protein, varying protein mass ratios from 100:0 to 0:100 and oil volumes from 30% to 45%, induced by transglutaminase cross‐linking. An increase in pea protein led to larger particle size and reduced surface charge in the solutions. Emulsion droplet size ranged from 0.60 to 15.17 μm, increasing with higher levels of pea protein and oil. Mixed protein gels exhibited significantly greater hardness compared to gels with individual proteins. Water‐holding capacity of pure whey protein emulsion gels exceeded 90%, while the value remained above 80% when pea protein was less than 50%. Partially replacing whey protein with pea protein may have potential applications in food products such as salad dressings and cheese.

The Potency of Maillard Conjugates Containing Whey Protein as Natural Emulsifier.

There is a continued need for the advancement of natural emulsifiers to replace synthetic emulsifiers, driven by human health concerns. This study is aimed at producing protein-polysaccharide conjugates through the Maillard reaction and at evaluating its ability as an emulsifier based on its emulsifying properties. The proteins used in this study were bovine milk whey protein and soy protein isolates, while the polysaccharides were maltodextrin and pectin. The protein-polysaccharide conjugation used a Maillard reaction under dry heating conditions. The protein and polysaccharide mass ratios were 1 : 2 and 1 : 3. The results showed that the types of proteins and polysaccharides and their mass affect the surface tension of the conjugate products. Whey protein-pectin conjugates with a mass ratio of 1 : 2 and a concentration of 1% had the lowest surface tension at 43.77 dyne/cm2. This conjugate sample also showed the highest emulsifying index at 27.20 m2/g. The conjugate powder containing pectin as a polysaccharide showed better emulsifying activity than that of those containing maltodextrin. However, the smallest droplet size of the emulsion (256.5 nm) resulted from the emulsification process using whey protein-maltodextrin conjugates as an emulsifier. The FTIR and gel electrophoresis (SDS-PAGE) analysis confirmed the conjugation formation. In general, protein-polysaccharide conjugates containing whey protein could potentially act as a natural emulsifier for food.

Formation of hydrophilic co-assemblies with improved functional properties between tilapia protein isolate and sodium caseinate

Functional enhancement of aquatic proteins still faces great challenges, resulting in their highly under-utilized applications in the field of intensive food processing. In this study, the tilapia protein isolate-sodium caseinate co-assemblies were prepared using a pH cycle strategy. The aggregation properties, component interactions, and functional properties of the formed co-assemblies were investigated. Results of particle size, zeta potential, surface hydrophobicity, and SEM indicated that tilapia protein isolates and sodium caseinate generated co-assemblies with reduced aggregation properties. Component interactions revealed that sodium caseinate binds to tilapia protein isolate mainly through hydrogen bonding and hydrophobic interactions, which inhibits the refolding of tilapia protein isolate to form more structurally ordered hydrophilic co-assemblies. Functional properties studies showed that co-assemblies with improved water solubility (reached 77.08%) and emulsification properties compared to tilapia protein isolated when the mass ratio of tilapia protein isolated to sodium caseinate was T/N = 1:1. In this experiment, the functional properties of tilapia protein isolate were enhanced by a simple, green, and efficient method, which is expected to be applied in the food industry.

Encapsulation of rutin in protein nanoparticles by pH-driven method: impact of rutin solubility and mechanisms.

The use of rutin in the food industry is limited by its poor solubility. Encapsulation can be used as an effective way to improve polyphenol solubility. Proteins with high safety, biocompatibility and multiple binding sites are known as the most promising encapsulating carriers. Therefore, the improvement of rutin solubility by pH-driven encapsulation of rutin in soy protein isolate (SPI) nanoparticles, as well as the form of rutin after encapsulation and rutin-protein binding index were investigated. SPI had a high encapsulation efficiency (87.5%) and loading amount (10.6%) for rutin. When the mass ratio of protein to rutin was 5:1, the highest concentration of rutin in solution was 3.27 g L-1 , which was a 51.57-fold increase compared to the original rutin. At this situation, rutin transformed from crystalline to amorphous form. During the formation of nanoparticles, SPI was in a dynamic change of unfolding and refolding. Rutin deprotonated in alkaline conditions increasing its solubility and bound to protein to form nanoparticles during the process of returning to neutral. Hydrophobic interactions and hydrogen bonding promoted the formation of the nanoparticles and there were at least 1-2 binding sites between rutin and each SPI molecule. The results suggested that encapsulation of rutin in protein nanoparticles can effectively increase the solubility of rutin. This study may provide important information for the effective utilization of polyphenol functional foods. © 2023 Society of Chemical Industry.

Study on properties of TGase-induced pea protein–zein complex gels

Gel systems are widely used in the food industry. However, most plant proteins are usually not gelatinous enough for industrial producrion, so studies are needed to improve the properties of and develop new protein gels. In this study, different mass ratios of pea protein and zein (from 10:0 to 5:5) were combined to form nanoparticles using a pH-driven method, after which TG enzyme was used to induce the composite protein particles to form a gel. This study analyzed the effects of different mass ratios of different protein on enzyme-induced composite gel formation and the gel properties. The stability of the complexes protein solution was evaluated using multiple light scattering. Microrheological parameters such as the mean square displacement, elasticity index, and mesh size indicated that zein had a positive effect on gel properties. The gel strength (145.39 ± 1.34 g), water-holding capacity (93.21 ± 1.59%), and sustained release performance of the composite gel were the highest when the zein content was 20%. These effects was mainly attributed to the increase in the number of disulfide bonds and formation of new covalent bonds in the gel, which stabilized the gel structure. The structure of a complex protein and its functional properties can be regulated by controlling the protein mass ratio, providing a new approach for improving gel properties.

Mixed whey and pea protein based cold-set emulsion gels induced by calcium chloride: Fabrication and characterization

The cold-set gels of oil-in-water emulsions stabilized by mixtures of whey protein isolate (WPI) and pea protein isolate (PPI) with mass ratios of 10:0, 7:3, 5:5, 3:7, and 0:10 were investigated to evaluate the possibility of pea protein to replace milk protein. Particle size and surface charge of emulsions increased and decreased with raised PPI content, respectively. The redness and yellowness of emulsion gels were strengthened with elevated pea protein percentage and independent of calcium concentration applied. Considerable differences in water holding capacity were observed between samples with different mixed proteins and high percentage of pea protein gave better water retaining ability. Gradual decreases in hardness and chewiness of emulsion gels were observed at three calcium levels with the increased PPI proportion. FT-IR spectra indicated no new covalent bonds were generated between samples with different whey and pea protein mass ratios. As PPI concentration elevated, the network structure of emulsion gels gradually became loose and disordered. The established cold-set calcium-induced whey/pea protein composite gels may have the potential to be utilized as a new material to encapsulate and deliver environment sensitive bio-active substances.

Evaluating the effect of food components on the digestion of dietary nucleic acids in human gastric juice in vitro.

Nucleic acids (NAs) were recently shown to be digested by pepsin in vitro; however, NAs digestion in human gastric juice in vivo is more complicated because of the complex gastric environment and ingestion of other food components. The purpose of this study was to investigate the digestibility of NAs in real human gastric juices after ingestion of other food components. As a result, DNA digestion was not affected when carbohydrates, proteins, and metal elements were ingested within the recommended dietary intake levels. Separately, protein exerted an inhibitory effect on DNA digestion when the mass ratio of protein:DNA was greater than 40:1. DNA exists in the nucleoprotein, which is closer to the state of DNA in real food, and was digested efficiently in human gastric juice. Meanwhile, DNA digestion was rarely affected even when the concentrations of monovalent ion (Na+) and divalent ions (Mg2+) were as high as 500 and 100 mM, respectively, and high concentration of Mg2+ ranged from 20 to 100 mM accelerated the digestion. In particular, short-stranded DNA (<100 nt) and miRNAs (19 ~ 25 nt) were not obviously degraded in human gastric juice. In conclusion, dietary NAs were digested efficiently and were not affected by other food components in human gastric juice, which may facilitate further digestion and utilization of DNA in the intestinal tract.

Development and characterization of acid-induced whey protein concentrate and egg white protein composite gel

The thermal aggregate solutions were prepared by mixing whey protein concentrate (WPC) and egg white protein (EWP) with different protein mass ratios (3:0, 3:1, 1:1, 1:3, 0:3), and then WPC/EWP composite gels were induced by glucono-δ-lactone (GDL), respectively named WPC, WE3/1, WE1/1, WE1/3, and EWP. The texture properties, water holding capacity, color, thermal stability, rheological and structure properties of the gels were investigated. The results showed that with the increase of EWP content, the hardness, adhesiveness, resilience and gumminess of WPC/EWP composite gels gradually increased. EWP gel exhibited the highest water holding capacity (96.55%). Rheological analysis showed that the storage modulus and loss modulus of the gels showed an increasing trend. EWP gel had the lowest creep flexibility and the strongest resistance to deformation. The DSC test showed the thermal stability of WE1/1 gel was the best (Td=115.84 °C). SEM results showed the three-dimensional network structure of composite gel was more denser with EWP incorporation. The self-supporting gels prepared by mixing whey and egg white protein had more excellent performance than single WPC gel. The information generated from this study may provide opportunities to develop functional food formulations enriched with whey protein and egg white protein.

Development of whey protein nanoparticles as carriers to deliver soy isoflavones

Encapsulation is an effective means to improve the stability and bioaccessibility of bioactive ingredients for food or other applications. Soy isoflavones were encapsulated in whey protein nanoparticles, using an emulsification-evaporation method. The physicochemical properties, formation, microstructure of the nanoparticles, stability, antioxidant activity, and bioaccessibility of soy isoflavones were studied. The results showed that the nanoparticles have a small particle size (54.09–59.96 nm), high zeta potential (−35.63 to −31.03 mV) and encapsulation efficiency (91.29%–92.59%) with a mass ratio of soy isoflavones and protein ranging from 1:100 to 1:40. The increased mass ratio of 1:20 resulted in aggregated particles (923.37 nm) and decreased encapsulation efficiency (82.89%). The main driving forces of nanoparticle formation have been proven to be hydrophobic interactions and hydrogen bonding. Transmission electron microscopy micrographs suggested that the nanoparticles have spherical structures. The photochemical stability, antioxidant activity, and bioaccessibility of soy isoflavones were significantly improved by encapsulation. The enhanced effectiveness of polymerized whey protein-based nanoparticles was better than that of whey protein-based nanoparticles. The results demonstrated that isoflavone-whey protein nanoparticles may be an effective nanocarrier to improve the stability, bioactivity, and bioaccessibility of soy isoflavones.

Functional characteristics and structural properties of soybean protein isolate–maltose conjugates

AbstractBackground and objectivesGlycation is a natural and green modification method and can be used to improve the functional properties of proteins. In this study, the effects of reaction conditions on structural characteristics and functional properties of soy protein isolate (SPI) conjugated with maltose (M) were investigated.FindingsWhen the mass ratio of protein and maltose was 1:2 and reaction temperature was 60°C, the degree of grafting of SPI‐M conjugates was highest and the degree of browning was moderate. The solubility of SPI‐M conjugates increased by 48.5%; after 60 hr of reaction, and the emulsification activity index and the emulsion stability index of SPI‐M conjugates increased by 79.4% and 102%, respectively. SDS‐PAGE and FT‐IR indicated that the introduction of maltose led to changes in the spatial structure of the SPI. The in vitro pancreatic digestibility of SPI‐M conjugates also was improved.ConclusionThe solubility, emulsification, and the in vitro digestibility of SPI‐M conjugates were improved. The spatial structure of SPI was changed after glycation.Significance and noveltyThe results showed that glycation can improve the functional properties of SPI and provide a theoretical basis for the development of new soybean protein products.

Revisiting the Phenomenon of Cellulase Action: Not All Endo- and Exo-Cellulase Interactions Are Synergistic

The conventional endo–exo synergism model has extensively been supported in literature, which is based on the perception that endoglucanases (EGs) expose or create accessible sites on the cellulose chain to facilitate the action of processive cellobiohydrolases (CBHs). However, there is a lack of information on why some bacterial and fungal CBHs and EGs do not exhibit synergism. Therefore, the present study evaluated and compared the synergistic relationships between cellulases from different microbial sources and provided insights into how different GH families govern synergism. The results showed that CmixA2 (a mixture of TlCel7A and CtCel5A) displayed the highest effect with BaCel5A (degree of synergy for reducing sugars and glucose of 1.47 and 1.41, respectively) in a protein mass ratio of 75–25%. No synergism was detected between CmixB1/B2 (as well as CmixC1/C2) and any of the EGs, and the combinations did not improve the overall cellulose hydrolysis. These findings further support the hypothesis that “not all endo-to exo-cellulase interactions are synergistic”, and that the extent of synergism is dependent on the composition of cellulase systems from various sources and their compatibility in the cellulase cocktail. This method of screening for maximal compatibility between exo- and endo-cellulases constitutes a critical step towards the design of improved synergistic cellulose-degrading cocktails for industrial-scale biomass degradation.

Receptor antibody time-resolved A2 phospholipase bead immunochromatography and its application in idiopathic membranous nephropathy.

ObjectiveTo detect phospholipase A2 receptor (PLA2R) antibody by established time‐resolved fluorescent bead immunochromatographic assay.MethodsThe reaction time of coupling, pH of the reaction, and coupling ratio of the label to PLA2R were determined. The EDC method was used to covalently couple PLA2R to time‐resolved fluorescent beads, which were sprayed onto a bonding pad. PLA2R and rabbit anti‐PLA2R antibody sprayed onto a nitrocellulose membrane were used as detection and quality control lines, respectively. Immunochromatographic test strips were prepared to enable rapid detection of PLA2R antibodies. Various technical indicators were evaluated, and the correlation among this method, enzyme‐linked immunosorbent assay (ELISA), and serum analysis was examined.ResultsThe pH suitable for labeling was 6.5. The optimal mass ratio of PLA2R protein to fluorescent beads was 0.08:1, and the reaction time of coupling was at least 1.5 hours. The appropriate spray film size of the coupled fluorescent bead was 5 μL/cm, and the appropriate staining concentration of the test line was 0.28 mg/mL. Further, 80 µL of sample was required for the test, and the result was obtained in only 15 minutes. The measurable range of this method was 5‐1500 RU/mL. Intra‐ and inter‐assay coefficients of variation were 7.61% and 11.07%, respectively, with an average recovery rate of 93.77%. The method showed a good correlation with ELISA, with a correlation coefficient of 0.936.ConclusionsThis method could better meet the clinical demand for idiopathic membranous nephropathy (IMN) detection.

Ectoine and Hydroxyectoine Stabilize Antibodies in Spray-Dried Formulations at Elevated Temperature and during a Freeze/Thaw Process.

Maintenance of protein stability during manufacture, storage, and delivery is necessary for the successful development of a drug product. Herein, the utility of two compatible solutes-ectoine and hydroxyectoine-in stabilizing a model protein labeled Fab2 has been investigated. Specifically, the performance of ectoine and hydroxyectoine in stabilizing Fab2 in a spray-dried formulation at elevated temperature and after multiple freeze/thaw cycles has been compared with the performance of a formulation containing trehalose and a formulation containing no excipient as controls. In the solid state at 90 and 37 °C and in freeze concentrate systems, ectoine and hydroxyectoine suppress protein aggregation. Like trehalose, hydroxyectoine also limits N-terminal pyroglutamate formation in Fab2 in the solid state. The extent of protein stabilization is dependent on the excipient concentration in the formulation, but at a 1:1 excipient to protein mass ratio, hydroxyectoine is better than trehalose in stabilizing Fab2. The results presented here suggest that ectoine and hydroxyectoine are effective excipients for stabilizing therapeutic antibodies.

Effect of redox-responsive DTSSP crosslinking on poly(l-lysine)-grafted-poly(ethylene glycol) nanoparticles for delivery of proteins.

Therapeutic proteins are utilized in a variety of clinical applications, but side effects and rapid in vivo clearance still present hurdles. An approach that addresses both drawbacks is protein encapsulation within in a polymeric nanoparticle, which is effective but introduces the additional challenge of destabilizing the nanoparticle shell in clinically relevant locations. This study examined the effects of crosslinking self-assembled poly(l-lysine)-grafted-poly(ethylene glycol) nanoparticles with redox-responsive 3,3'-dithiobis(sulfosuccinimidyl propionate) (DTSSP) to achieve nanoparticle destabilization in a reductive environment. The polymer-protein nanoparticles (DTSSP NPs) were formed through electrostatic self-assembly and crosslinked with DTSSP, which contains a glutathione-reducible disulfide. As glutathione is upregulated in various cancers, DTSSP NPs could display destabilization within cancer cells. A library of DTSSP NPs was formed with varying copolymer to protein (C:P) and crosslinker to protein (X:P) mass ratios and characterized by size and encapsulation efficiency. DTSSP NPs with a 7:1 C:P ratio and 2:1 X:P ratio were further characterized by stability in the presence proteases and reducing agents. DTSSP NPs fully encapsulated the model protein and displayed 81% protein release when incubated with 5 mM dithiothreitol for 12 hr. This study contributes to understanding stimulus-responsive crosslinking of polymeric nanoparticles and could be foundational to clinical administration of therapeutic proteins.

Interaction of Quillaja bark saponin and bovine serum albumin: Effect on secondary and tertiary structure, gelation and in vitro digestibility of the protein

The interaction of Quillaja bark saponin and bovine serum albumin was determined by isothermal titration calorimetry and correlated to the structure, gelation and in vitro digestibility of the protein. Results showed that the interactions occur at around 0.5:1.0 mass ratio of saponin to protein at 25 °C resulting in a low heat of interaction and non-specific binding. Formation of saponin and protein complexes was favored at a higher temperature (75 °C), probably due to the exposure of different groups of the protein. The saponin increased the strength of the protein gels, due to the exposure of hydrophobic regions of the protein, as well as due to crosslinking between protein molecules. The protein digestibility was not greatly affected at a saponin to protein mass ratio smaller than 2.5: 1.0. Thus, QBS can be used to increase the protein gel strength and the health benefits of food without a significant impact on protein digestibility.

Production of protein-loaded starch microspheres using water-in-water emulsion method

Protein-loaded starch microspheres were prepared by water-in-water (w/w) emulsion method. The effects of the molecular weight of starch and protein used, concentration of solutes in both dispersed and continuous phases and starch to protein mass ratio on the yield, loading capacity and encapsulation efficiency were measured. These parameters were significantly higher in Bovine serum albumin (BSA)-loaded microspheres than in lysozyme-loaded microspheres. An increase in the molecular weight of starch, solute concentration in dispersed and continuous phases increased the yield. The encapsulation efficiency was significantly improved when the starch to BSA mass ratio was increased. When the starch to BSA mass ratio was 15:1, the encapsulation efficiency reached about 100 % with a loading capacity of 7.3 g/100 g. This method is more effective when both core (protein) and shell (starch) materials with high molecular weight are used. This approach is environmentally friendly and the processing parameters can be easily optimized.

ВЛИЯНИЕ ВОЗРАСТА ПЕРВОГО ОСЕМЕНЕНИЯ НА ПРОДУКТИВНОЕ ДОЛГОЛЕТИЕ КОРОВ ЧЕРНО-ПЕСТРОЙ И ХОЛМОГОРСКОЙ ПОРОДЫ

The influence of the age at the first fruitful insemination on the productive longevity of the blackand-white and Kholmogory cows in Udmurt republic was analysed. The study results are presented in the paper. The economic use period of the study cows did not have statistical differences and lasted 3,42–3,43 lactation periods. Black-and-white cows exceeded Kholmogory cows in the lifetime milk yield (by 3416,5 kg), fat content in milk (by 0,47 %) and milk amount in terms of basic standards (by 6317,7 kg) (P &gt; 0,999). The optimal age for the first insemination of black-and-white cows can be considered 16–17 months, since insemination at the specified age ensures highest longevity in cows (3,85 lactations) and the highest lifetime milk yield indices (21347,8 kg), also expressed in terms of basic standards (27065,6 kg). Too early insemination of the black-and-white cows (up to 15 months) is not recommended, as it results in the decreased lifetime milk yields (up to 15491,4 kg), fat and protein content and shortens the economic use period of the animals up to 3,33 lactation periods. The lowest longevity (3,07 lactation periods) was observed in the black-and-white cows inseminated at the age of more than 20 months. The Kholmogory cows demonstrated an increase in lifetime milk yields (1084,5 kg (P &gt; 0,95)) and the economic use period (1,05 lactation period (P &gt; 0,999)) when the age of the first insemination was increased. However, as the fat mass ratio in milk decreased (by 0,06 % (P &gt; 0,999)) and the protein mass ratio in milk fell (by 0,02 % (P &gt; 0,999)), the increase in lifetime milk yield in terms of basic standards resulted from the increase in the age of the first insemination has no significant differences.

Design of combined crosslinked enzyme aggregates (combi-CLEAs) of β-galactosidase and glucose isomerase for the one-pot production of fructose syrup from lactose

A new bi-enzymatic catalyst has been produced by precipitation and crosslinking (combi-CLEAs) of β-galactosidase and glucose isomerase for catalyzing the cascade reactions of lactose conversion into fructose, producing a lactose-fructose syrup (LFS). Glucose isomerase was chemically aminated to increase its reactive surface groups for favour the crosslinking step. The effect of β-galactosidase to glucose isomerase activity ratio and glutaraldehyde to protein mass ratio in combi-CLEAs production was evaluated. The selected combi-catalyst was successfully used in the production of fructose syrup from lactose in a single reaction vessel. The biocatalyst could be used at least in five sequential batches of LFS production, remaining fully stable after a total of 50 h of reaction, obtaining a product of constant quality. A robust bi-enzymatic catalyst was produced that can be repeatedly used in LFS production, an attractive mild sweetener for the dairy food industry.

A Robust, Resilient, and Multi-Functional Soy Protein-Based Hydrogel

Soy protein is one of the most abundant plant protein in nature. Despite numerous studies on soy protein-based materials, the applications of soy protein hydrogel are still extremely limited because of its cumbersome gelation process and poor mechanical properties. Herein, we present a facile method to prepare robust soy protein hydrogels by the introduction of oxidized dextran, a natural polysaccharide derivative, as a macromolecular cross-linking agent. The preparation conditions such as pH value of reaction system and the mass ratio of soy protein to oxidized dextran have been extensively investigated. The resultant soy protein hydrogels exhibit better mechanical properties than the previously reported soy protein-based hydrogels. The best formulated hydrogel shows the compressive modulus of 4.3 kPa and fracture stress of 401 kPa at 87% compression. Also, the hydrogels demonstrate an excellent flexibility to withstand high compression with minimal hysteresis. Owing to the protein and polysaccharides nature of soy protein and dextran, the soy protein hydrogels maintain a good biocompatibility along with excellent mechanical properties. Finally, we show the possibility to design such a soy protein hydrogel as a tolerant multifunctional platform for fluorescence imaging, photothermal therapy, drug carrier, and antibacterial agent. The developed soy protein-based hydrogel is natural, sustainable, robust, and biocompatible and hence has great potential as a multifunctional material for various applications.

Comparative experiments of fibril formation from whey protein concentrate with homogeneous and secondary nuclei

Two types of special structures, homogeneous and secondary nuclei, form during fibril formation. The structural and functional properties of amyloid fibrils in whey protein concentrate (WPC) with different ratios of added homogeneous nuclei to secondary nuclei were investigated. Thioflavin T fluorescence analysis and kinetic equations indicated that two types of nuclei could accelerate WPC fibrillation compared with WPC self-assembling into amyloid fibrils, thereby reducing the lag time and increasing the number of fibrils. However, there were considerable differences in the nucleation-inducing capability of WPC fibrillation between homogeneous and secondary nuclei. The number of fibrils formed by adding homogeneous nuclei was higher than that obtained with secondary nuclei, the increase in the Th T fluorescence intensity induced by homogeneous nuclei was 1.83-fold much than secondary nuclei. Meanwhile, secondary nuclei yielded a 2.71-fold faster aggregation rate of WPC than homogeneous nuclei, particularly during the first hour of thermal treatment (protein mass ratio of nuclei to WPC 1:1). The gelation time of WPC after secondary nuclei addition was shorter, from 10 h (WPC (2.0/6.5)) to 4 h (WPC + HN) to 2 h (WPC + SN); however, the gel microstructure of WPC after the addition of homogeneous nuclei was denser, yielding a preferred water holding capacity.