Effects of Spray Drying and Freeze Drying on the Properties of Protein Isolate from Rice Dreg Protein

Non-covalent interaction of rice protein and polyphenols: The effects on their emulsions

In this study, we investigated the non-covalent interaction mechanism between rice protein (RP) and three polyphenols with different concentrations (ferulic acid FA, gallic acid GA, and tannic acid TA) and their effects on the structure and emulsion stability of the proteins. Hydrophobic forces dominated the binding of RP to the polyphenols, and the reaction was heat-absorbing. The three polyphenols are bound to RP in the form of static quenching to form a non-covalent complex, and during the binding process, the RP provides one binding site. RP-polyphenol complexes, particularly RP-GA, enhanced ABTS scavenging and FRAP reduction. Polyphenols improved RP emulsion oxidative stability, inhibiting lipid oxidation and enhancing emulsion rheology and interfacial structure. RP-GA was most effective, maintaining low POV. These findings support the potential applications of RP-polyphenol noncovalent complexes in food processing.

Effects of Different Drying Methods on Physicochemical Properties and Nutritional Quality of Abalone Bioactive Peptides

This study conducted a systematic comparison of four drying methods (vacuum freeze-drying, spray drying, spray freeze-drying, and hot air drying) on abalone bioactive peptides, investigating their effects on physicochemical properties and nutritional composition. Scanning electron microscopy revealed distinct morphological characteristics: hot-air-dried samples showed compact structures with large particles, and vacuum-freeze-dried samples exhibited flaky morphology, while spray-freeze-dried and spray-dried samples demonstrated advantageous smaller particle sizes. Spray freeze-drying achieved superior emulsification capacity and fat absorption, significantly higher than hot air drying. The enhanced performance was attributed to increased exposure of hydrophobic amino acid residues and improved surface activity. Regarding nutritional composition, vacuum freeze-drying demonstrated optimal protein and total amino acid preservation, while spray freeze-drying showed the highest retention of Ca and Fe. Interestingly, hot air drying exhibited superior vitamin A retention, attributed to its fat-soluble nature and stability below 100 °C. The particle size reduction in spray-freeze-dried samples enhanced solvent-solute contact area, contributing to improved solubility and consequently superior foaming properties. These findings provide valuable insights into the relationship between drying methods and product characteristics, offering guidance for optimizing processing conditions in marine protein production.

Pickering emulsions stabilized by ultrasound-assisted phosphorylated cantaloupe seed protein isolate -chitosan: Preparation, characterization and stability

Cantaloupe seed protein isolate (CSPI) has attracted the attention of its low cost, easy digestion and balanced composition of essential amino acids. However, due to the low solubility of CSPI, its application in the food industry is limited. Therefore, the present study investigated the effect of ultrasound-assisted phosphorylation on the solubility of CSPI and the structural properties were characterized. The solubility of cantaloupe seed protein increased from 9.17 % to 63.27 % by ultrasound assisted phosphorylation, and resulting in an increase in the absolute value of CSPI potential, a decrease in particle size, and a stable structure, which could be used for the construction of the food emulsification system. The modified CSPI was combined with chitosan (CS) to prepare stabilized Pickering emulsion for subsequent stability study. The results showed that stable Pickering emulsions could be prepared with CSPI at pH 7, CS 0.5 % and oil phase fraction 55 %. Ultrasound-assisted phosphorylation enhanced electrostatic interaction between CS's -NH3 groups and CSPI's -COO-groups which improved the storability of stabilized Pickering emulsion. This will help to broaden the application range of CSPI and provide a theoretical basis for CPI stable Pickering emulsion.

Spray dried protein concentrates from white button and oyster mushrooms produced by ultrasound-assisted alkaline extraction and isoelectric precipitation

BACKGROUND

In the present study, the optimization of ultrasound-assisted alkaline extraction (UAAE) and isoelectric precipitation (IEP) was applied to white button (WBM) and oyster (OYM) mushroom flours to produce functional spray dried mushroom protein concentrates. Solid-to-liquid ratio (5-15% w/v), ultrasound power (0-900 W) and type of acid [HCl or acetic acid (AcOH)] were evaluated for their effect on the extraction and protein yields from mushroom flours submitted to UAAE-IEP protein extraction.

RESULTS

Prioritized conditions with maximized protein yield (5% w/v, 900 W, AcOH, for WBM; 5% w/v, 900 W, HCl for OYM) were used to produce spray dried protein concentrates from white button (WBM-PC) and oyster (OYM-PC) mushrooms with high solids recovery (62.3-65.8%). WBM-PC and OYM-PC had high protein content (5.19-5.81 g kg-1), in addition to remarkable foaming capacity (82.5-235.0%) and foam stability (7.0-162.5%), as well as antioxidant phenolics. Highly pH-dependent behavior was observed for solubility (> 90%, at pH 10) and emulsifying properties (emulsification activity index: > 50 m2 g-1, emulsion stability index: > 65%, at pH 10). UAAE-IEP followed by spray drying increased surface hydrophobicity and free sulfhydryl groups by up to 196.5% and 117.5%, respectively, which improved oil holding capacity (359.9-421.0%) and least gelation concentration (6.0-8.0%) of spray dried mushroom protein concentrates.

CONCLUSION

Overall, the present study showed that optimized UAAE-IEP coupled with spray drying is an efficient strategy to produce novel mushroom protein concentrates with enhanced functional attributes for multiple food applications. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Combined high voltage atmospheric cold plasma and ultraviolet-cold plasma inhibited Aspergillus flavus growth and improved physicochemical properties of protein in peanuts

To improve the application value of peanuts, the fungicidal effect and physicochemical properties of the protein in peanuts were investigated by combining high voltage atmospheric cold plasma (HVCP) and ultraviolet-cold plasma (UVCP) in this study. Compared to the single HVCP or UVCP treatment, the combined treatments exhibited a higher fungicidal efficiency of A. flavus spores in peanuts, decreasing by 0.79-2.97 log10 cfu/g after 8-min treatment. The A. flavus growth and aflatoxin production in peanuts during storage were also lower than the single plasma groups. Moreover, cold plasma treatments could modify the molecular structures of protein in peanuts by changing secondary and tertiary structures, decreasing particle size and increasing zeta potential, which contributed to improve the solubility and emulsification of protein. Overall, this research provides a unique strategy for the combined application of cold plasma in grain decontamination and protein modification.

Exploring the effect of natural deep eutectic solvents on zein: Structural and functional properties

This study evaluated the effects of chemical modification, including ethanol, acetic acid, and natural deep eutectic solvents (NADES), on the secondary and tertiary structures, hydrophobicity, free amine content, protein-protein interactions, and functional properties of zein. The NADES used included choline chloride: oxalic acid, choline chloride: urea, choline chloride: glycerol, and glucose: citric acid. The results reveal that the NADES system significantly altered zein's structures, as evidenced by Fourier transform infrared spectroscopy, fluorescence, and Ultraviolet-Visible Spectroscopy analysis. Circular dichroism spectroscopy analysis indicated significant conformational change in modified zein, with decreased α-helix and increased random coil content. Notably, the NADES system leads to greater disruption of hydrogen bonds and facilitates the exposure of hydrophobic regions compared to water, ethanol, and acetic acid systems. This resulted in enhanced solubility, surface hydrophobicity, and free amine content in zein, indicating a more significant change in protein structure. In contrast, water and acetic acid solvents maintained more stable disulfide bonds within zein, which correlates with lower solubility and less unfolding. The NADES system promoted interactions between zein and its solvent components, improving emulsifying properties. Water, ethanol, and acetic acid systems had higher solubility in urea, thiourea, and dithiothreitol than the NADES system, revealing disruption of both covalent and noncovalent bonds in zein modified by NADES. Overall, this study highlights the superior ability of the NADES system to modify zein's structure and functionality compared to conventional solvents, suggesting its potential for enhancing protein applications in the industrial production of foods.

Enzymatic hydrolysis of duck blood protein produces stable bioactive peptides: Pilot-scale production, identification, and stability during gastrointestinal and plasma digestion

This study addresses the valorization of duck blood, an underutilized protein-rich by-product from the poultry industry, into bioactive protein hydrolysates with antioxidant and ACE inhibitory properties. Raw and heat-treated duck blood were compared as substrates for enzymatic hydrolysis using Neutrase and Papain. Gel electrophoresis revealed that heat treatment reduced fibrinogen content, while FTIR analysis showed that heat treatment modified the protein structure, increasing β-sheet content from 21.13 % to 34.96 %. Heat-treated duck blood hydrolyzed by Neutrase exhibited superior hydrolysis (9.53 %) and protein recovery (60.28 %) compared to raw blood. Pilot-scale production (1000 L) enhanced hydrolysate yield and maintained bioactive properties. LC-MS/MS analysis identified five novel bioactive peptides derived from the hydrolysate's 4-h simulated gastrointestinal (GI) digestion, with WMHVR demonstrating the highest antioxidant and ACE inhibitory activities. Molecular docking simulations revealed that WMHVR competitively inhibits ACE by binding to the S1, S2, and S' pockets through van der Waals and hydrogen bonding interactions. The GI-hydrolysate and identified peptides maintained bioactivity during simulated GI and blood plasma digestion, with ACE inhibition increasing over time. This research transforms food industry waste into functional protein hydrolysates, offering applications in nutraceuticals and functional foods while promoting sustainable practices through waste protein valorization.

Toward Diverse Plant Proteins for Food Innovation

This review highlights the development of plant proteins from a wide variety of sources, as most of the research and development efforts to date have been limited to a few sources including soy, chickpea, wheat, and pea. The native structure of plant proteins during production and their impact on food colloids including emulsions, foams, and gels are considered in relation to their fundamental properties, while highlighting the recent developments in the production and processing technologies with regard to their impacts on the molecular properties and aggregation of the proteins. The ability to quantify structural, morphological, and rheological properties can provide a better understanding of the roles of plant proteins in food systems. The applications of plant proteins as dairy and meat alternatives are discussed from the perspective of food structure formation. Future directions on the processing of plant proteins and potential applications are outlined to encourage the generation of more diverse plant-based products.

The construction of Moringa oleifera seed protein emulsion: in vitro digestibility and delivery of β-carotene

BACKGROUND

β-Carotene (BC) is difficult to apply effectively in the food industry due to its low solubility and bioavailability. This work aimed to fabricate Moringa oleifera seed protein (MOSP) stabilized emulsions as delivery vehicles for BC and investigate the effect of aqueous phase conditions including pH and ionic strength on this system.

RESULTS

All MOSP samples were positively charged and the particle size of MOSP increased with the increase of pH. At pH 5.0 and 0.2 mol L-1 sodium chloride (NaCl), the MOSP emulsion demonstrated the highest stability coefficient and minimal creaming index, while exhibiting a lower release rate in vitro digestion. The rheological behavior of all MOSP emulsions within the frequency range of 0.1-10 Hz was dominated by viscoelasticity, forming an elastic network structure through dispersed droplets. Additionally, the MOSP emulsion loaded with BC prepared at pH 5.0 and 0.2 mol L-1 NaCl displayed enhanced ultraviolet light stability (52.31 ± 0.03% and 51.86 ± 0.05%) as well as thermal stability (72.39 ± 8.67% and 86.78 ± 10.69%). Furthermore, the BC in the emulsion at pH 7.0 exhibited favorable stability (65.14 ± 0.02%) and optimal bioaccessibility (40.30 ± 0.04%) in vitro digestion.

CONCLUSION

The results provided reference data for utilizing MOSP as a novel emulsifier and broadening the application of BC in the food industry. © 2024 Society of Chemical Industry.

The effect of rice protein-polyphenols covalent and non-covalent interactions on the structure, functionality and in vitro digestion properties of rice protein

The characteristics of the crosslinking between rice protein (RP) and ferulic acid (FA), gallic acid (GA), or tannin acid (TA) by covalent binding of Laccase and non-covalent binding were evaluated. The RP-polyphenol complexes greatly improved the functionality of RP. The covalent effect with higher polyphenol binding equivalence showed higher emulsion activity than the non-covalent effect. The solubility, and antioxidant activity of covalent binding were higher than that of non-covalent binding in the RP-FA group, but there was a contrasting behavior in the RP-GA group. The RP-FA was most soluble in conjugates, while the RP-GA had the highest solubility in mixtures. It was found that the covalent complexes were more stable in the intestinal tract. The content of polyphenols in the RP-TA group was rapidly increased at the later intestinal digestion, which indicated the high polyphenol-protective effect in this group. Meanwhile, the RP-TA group showed high reducing power but low digestibility.

Characterization and in vitro digestibility of soybean tofu: Influence of the different kinds of coagulant

This study explored the effect of diverse coagulants (glucono-δ-lactone (GDL), gypsum (GYP), microbial transglutaminase (MTGase), and white vinegar (WVG)) on microstructure, quality, and digestion properties of tofu. The four kinds of tofu were significantly different in their structure, composition, and digestibility. Tofu coagulated with MTGase had the highest springiness and cohesiveness while GDL tofu had the highest enthalpy (6.54 J/g). However, the WVG and GYP groups outperformed others in terms of thermodynamic, and digestion properties. The WVG group exhibited the highest nitrogen release (84.3%), water content, denaturation temperature, and the highest free-SH content but the lowest S-S content. Compared to WVG, the GYP group had the highest ash content, hardness, and chewiness. Results demonstrated that the tofu prepared by WVG and GYP show high digestibility. Meanwhile, the former has better thermal properties and the latter has better texture properties.

Green alternative for sodium metabisulfite substitution: Comparison of bacterial and fungal proteases effect in hard biscuit making

Sodium metabisulfite is one of the most employed reducing agents in hard biscuit making. The recent results about its adverse effects on human health have pushed us to look in new safer and greener directions. Two different proteases, from distinct strains (bacterial and fungal), were selected and their effects on the dough thermomechanical performances, texture, and structure of the hard biscuits were compared with those obtained from the sodium metabisulfite. Doughs treated with fungal protease showed higher stability during mixing and higher consistency throughout the heating stage. On the other hand, bacterial protease had the greatest weakening effect on protein with a marked reduction of starch gelatinization. Doughs processed with fungal enzymes reached similar values to those containing sodium metabisulfite. In terms of hardness, no significant (p < 0.05) differences were found between biscuits made with bacterial protease and sodium metabisulfite. Analysis of the volumetric characteristics highlighted that bacterial enzymes gave higher values of specific volume and surface area. Regarding the structure of the hard biscuits, sodium metabisulfite produced a more uniform structure with fewer and smaller pockets as compared with the samples treated with proteases.

Euglena gracilis Protein: Effects of Different Acidic and Alkaline Environments on Structural Characteristics and Functional Properties

Due to the growing demand for human-edible protein sources, microalgae are recognized as an economically viable alternative source of proteins. The investigation into the structural characteristics and functional properties of microalgin is highly significant for its potential application in the food industry as an alternative source of protein. In this research, we extracted protein from Euglena gracilis by using alkaline extraction and acid precipitation and investigated its structural characteristics and functional properties in different acidic and alkaline environments. The molecular weight distribution of Euglena gracilis protein (EGP), as revealed by the size exclusion chromatography results, ranges from 152 to 5.7 kDa. EGP was found to be rich in hydrophobic amino acids and essential amino acids. Fourier infrared analysis revealed that EGP exhibited higher α-helix structure content and lower β-sheet structure content in alkaline environments compared with acidic ones. EGP exhibited higher foaming properties, emulsifying activity index, solubility, free sulfhydryl, and total sulfhydryl in pH environments far from its isoelectric point, and lower fluorescence intensity (2325 A.U.), lower surface hydrophobicity, larger average particle size (25.13 µm), higher emulsifying stability index, and water-holding capacity in pH environments near its isoelectric point. In addition, X-ray diffraction (XRD) patterns indicated that different acidic and alkaline environments lead to reductions in the crystal size and crystallinity of EGP. EGP exhibited high denaturation temperature (Td; 99.32 °C) and high enthalpy (ΔH; 146.33 J/g) at pH 11.0, as shown by the differential scanning calorimetry (DSC) results. The findings from our studies on EGP in different acidic and alkaline environments provide a data basis for its potential commercial utilization as a food ingredient in products such as emulsions, gels, and foams.

Exploring the effect of high pressure in the denaturation of casein micelles by in-situ SERS

To investigate the structural changes of casein in response to the pressurization process under varying pressure levels, this study carried out both ex-situ and in-situ high-pressure experiments. In the in-situ experiments, the surface-enhanced Raman scattering (SERS) technique was combined with a diamond anvil cell (DAC). The high-pressure experiments indicated that significant dissociation of casein occurred at 200 MPa. Over the range of 0-302 MPa, casein exhibited both dissociation and aggregation behaviors. However, casein tended towards aggregation at pressures of 302-486 MPa, with a further increase observed beyond 486 MPa.

Relationship between the baking quality of wheat (Triticum aestivum L.) and the protein composition and structure after shading

Although wheat (Triticum aestivum L.) grain protein content is increased by shade stress, the relationship between the baking quality of wheat flour and protein composition and structure remains unclear. Here, we investigated the effects of shade stress on wheat flour protein composition and structure. The contents of the flour protein, α/β-gliadins and disulfide and hydrogen bonds were significantly increased by shade stress. Glutenins, UPP%, and β-sheet contents also increased, whereas that of α-helices decreased. Spearman correlations revealed that the flour protein content, Glu:Gli ratio, and disulfide, hydrogen, and ionic bonds can predict the specific volume and number of crumb cells in bread, whereas α/β-gliadins content can predict the crumb cell wall thickness and diameter of bread. Under shade stress, variations in protein composition and structure help increase the specific volume and crumb cells number and decrease crumb cell wall thickness and diameter of bread, ultimately leading to improved baking quality.

Unraveling the potential of non-thermal ultrasonic contact drying for enhanced functional and structural attributes of pea protein isolates: A comparative study with spray and freeze-drying methods

The challenge of preserving the quality of thermal-sensitive polymeric materials specifically proteins during a thermal drying process has been a subject of ongoing concern. To address this issue, we investigated the use of ultrasound contact drying (USD) under non-thermal conditions to produce functionalized pea protein powders. The study extensively examined functional and physicochemical properties of pea protein isolate (PPI) in powder forms obtained through three drying methods: USD (30 °C), spray drying (SD), and freeze drying (FD). Additionally, physical attributes such as powder flowability and color, along with morphological properties, were thoroughly studied. The results indicated that the innovative USD method produced powders of comparable quality to FD and significantly outperformed SD. Notably, the USD-PPI exhibited higher solubility across all pH levels compared to both FD-PPI and SD-PPI. Moreover, the USD-PPI samples demonstrated improved emulsifying and foaming properties, a higher percentage of random coil form (56.2 %), increased gel strength, and the highest bulk and tapped densities. Furthermore, the USD-PPI displayed a unique surface morphology with visible porosity and lumpiness. Overall, this study confirms the effectiveness of non-thermal ultrasound contact drying technology in producing superior functionalized plant protein powders, showing its potential in the fields of chemistry and sustainable materials processing.

Seaweed Proteins: A Step towards Sustainability?

This review delves into the burgeoning field of seaweed proteins as promising alternative sources of protein. With global demand escalating and concerns over traditional protein sources' sustainability and ethics, seaweed emerges as a viable solution, offering a high protein content and minimal environmental impacts. Exploring the nutritional composition, extraction methods, functional properties, and potential health benefits of seaweed proteins, this review provides a comprehensive understanding. Seaweed contains essential amino acids, vitamins, minerals, and antioxidants. Its protein content ranges from 11% to 32% of dry weight, making it valuable for diverse dietary preferences, including vegetarian and vegan diets. Furthermore, this review underscores the sustainability and environmental advantages of seaweed protein production compared to traditional sources. Seaweed cultivation requires minimal resources, mitigating environmental issues like ocean acidification. As the review delves into specific seaweed types, extraction methodologies, and functional properties, it highlights the versatility of seaweed proteins in various food products, including plant-based meats, dairy alternatives, and nutritional supplements. Additionally, it discusses the potential health benefits associated with seaweed proteins, such as their unique amino acid profile and bioactive compounds. Overall, this review aims to provide insights into seaweed proteins' potential applications and their role in addressing global protein needs sustainably.

Effect of a novel drying method based on supercritical carbon dioxide on the physicochemical properties of sorghum proteins

The aim of this research was to use supercritical carbon dioxide (SC-CO2) drying as a novel approach for generating sorghum protein concentrates/isolates with enhanced functional properties. Sorghum protein extracts were obtained from white whole-grain sorghum flour and were dried by two methods, namely, freeze-drying and SC-CO2 drying. The collected proteins were characterized for their morphology, color, crystallinity, surface hydrophobicity, emulsifying activity index (EAI), creaming index (CI), foaming capacity (FC), foaming stability (FS), protein solubility, chemical interactions, and viscosity. The SC-CO2-dried proteins exhibited higher porosity compared to the freeze-dried ones with smaller particle sizes (∼5.1 vs. 0.4 μm, respectively). The XRD patterns indicated that the SC-CO2-dried proteins had a lower crystallinity than the freeze-dried proteins. However, the surface hydrophobicities of the freeze-dried and SC-CO2-dried proteins were similar. The EAI results showed that the emulsifying activity of freeze-dried protein powder (40.6) was better than that of SC-CO2-dried protein powder (29.8). Nevertheless, the solubility of SC-CO2-dried proteins was higher than that of freeze-dried proteins in most of the pHs investigated. Overall, the proposed SC-CO2 drying method has the potential to generate porous protein powders with improved solubility that can be used in developing functional foods.

The physicochemical properties, functionality, and digestibility of hempseed protein isolate as impacted by spray drying and freeze drying

Hempseed protein has gained increasing attention for its sustainability and nourishment. This study aimed to investigate the effects of spray drying and freeze drying on the physicochemical properties, functionality, and digestibility of hempseed protein isolate (HPI). Compared to undried-HPI, both drying techniques altered physicochemical and structural properties. Particularly, protein denaturation temperature increased in freeze-dried HPI (FD-HPI) and spray-dried HPI (SD-HPI) samples (∼90 °C) than in undried-HPI (82.5 °C). Lysine content decreased from 38.26 mg/g in undried-HPI to 35.03 and 33.18 mg/g in FD-HPI and SD-HPI, respectively. Results revealed the loss of 26 and 17 kDa bands after drying. Notably, FD-HPI exhibited higher emulsifying stability and oil-holding capacity than SD-HPI. While both FD-HPI and SD-HPI had higher digestibility than undried-HPI, a 50% reduction in the liberation of free α-amino groups after digestion was found. This study provided information regarding changes in HPI after drying, offering insights for HPI production and application in the food industry.

Towards Sustainable Protein Sources: The Thermal and Rheological Properties of Alternative Proteins

Reducing meat consumption reduces carbon emissions and other environmental harms. Unfortunately, commercial plant-based meat substitutes have not seen widespread adoption. In order to enable more flexible processing methods, this paper analyzes the characteristics of commercially available spirulina, soy, pea, and brown rice protein isolates to provide data for nonmeat protein processing that can lead to cost reductions. The thermal and rheological properties, as well as viscosity, density, and particle size distribution, were analyzed for further study into alternative protein-based food processing. The differential scanning calorimetry analysis produced dry amorphous-shaped curves and paste curves with a more distinct endothermic peak. The extracted linear temperature ranges for processing within food production were 70-90 °C for spirulina, 87-116 °C for soy protein, 67-77 °C for pea protein, and 87-97 °C for brown rice protein. The viscosity analysis determined that each protein material was shear-thinning and that viscosity increased with decreased water concentration, with rice being an exception to the latter trend. The obtained viscosity range for spirulina was 15,100-78,000 cP, 3200-80,000 cP for soy protein, 1400-32,700 cP for pea protein, and 600-3500 cP for brown rice protein. The results indicate that extrusion is a viable method for the further processing of protein isolates, as this technique has a large temperature operating range and variable screw speed. The data provided here can be used to make single or multi-component protein substitutes.

Enhancing the solubility and emulsion properties of rice protein by deamidation of citric acid-based natural deep eutectic solvents

The characteristics of rice protein deamidated (DRP) by choline chloride-citric acid and glucose-citric acid natural deep eutectic solvents (C-C NADES, G-C NADES) at different dilutions were investigated. Compared with the effect of citric acid deamidation on the structural and functional properties of the protein, the DRP from the NADESs led to remarkable differences in the degree of hydrolysis (DH), SDS-PAGE, morphology, surface hydrophobicity, average particle size, intrinsic fluorescence, amino acid compositions, and emulsion activity. The results of SDS-PAGE, DH, and SEM showed the NADESs reduced the occurrence of uncontrolled hydrolysis of protein during acid deamidation. DRP from C-C and G-C NADESs was found to significantly improve solubility. DRP prepared by C-C NADES showed a more than 40 % solubility over a wide pH range associated with its higher emulsifying activity (37.62-44.19 m2/g) and emulsifying stability (73.76-86.9 min), as well as a better deamidation effect while lower DH. Thus, these findings showed that acid-based NADESs had great potential as a deamidation solvent to expand the application of protein.

Non-thermal ultrasonic contact drying of pea protein isolate suspensions: Effects on physicochemical and functional properties

Pea protein isolate (PPI) is a popular plant-based ingredient, typically produced through alkaline-isoelectric precipitation and thermal drying. However, high temperatures and long drying times encountered in thermal drying can denature PPI and cause loss of functionality. This study investigated the use of an innovative ultrasonic dryer (US-D) at 30 °C for drying PPI suspensions, compared to conventional hot air drying (HA-D) at 60 °C. US-D led to an increase in the drying rate and correspondingly reduced the drying time by 55 %, when compared to HA-D. The average effective moisture diffusivity in the US-D process was 325 % higher than that in the HA-D process. The resulting PPI exhibited higher solubility, emulsification, and foaming properties than HA-D PPI, with a unique surface morphology and higher surface area. This study demonstrated that drying with acoustic energy is a promising approach for producing dried plant protein ingredients with improved functional properties, reduced processing time, and increased production efficiency.

Influence of pH on Heat-Induced Changes in Skim Milk Containing Various Levels of Micellar Calcium Phosphate

The present study investigated the effect of micellar calcium phosphate (MCP) content and pH of skim milk on heat-induced changes in skim milk. Four MCP-adjusted samples, ranging from 67 to 113% of the original MCP content, were heated (90 °C for 10 min) at different pH values (6.3, 6.6, 6.9, and 7.2), followed by determining changes in particle size, turbidity, protein distribution, and structure. The results demonstrate a strong effect of MCP level and pH on heat-induced changes in milk, with the MCP67 samples revealing the greatest thermal stability. Specifically, decreasing MCP content by 33% (MCP67) led to a smaller increase in non-sedimentable κ-casein and a lower decrease in αs2-casein concentrations after heating compared to other samples. Lower MCP content resulted in a moderate rise in the average particle size and turbidity, along with lower loading of β-turn structural component after heating at low pH (pH 6.3). Notably, MCP113 exhibited instability upon heating, with increased particle size, turbidity, and a significant decrease in non-sedimentable αs2-casein concentration, along with a slight increase in non-sedimentable κ-casein concentration. The FTIR results also revealed higher loading of intermolecular β-sheet, β-turn, and random coil structures, as well as lower loading of α-helix and β-sheet structures in MCP-enhanced skim milk samples. This suggests significant changes in the secondary structure of milk protein and greater formation of larger aggregates.

L-lysine moderates thermal aggregation of coconut proteins induced by thermal treatment

This work attempts to investigate the inhibitory effect of L-lysine (Lys) on the thermal aggregation of coconut protein (CP). The results showed that under neutral conditions (pH = 7), temperature reduced the solubility and enhanced the thermally induced gel formation of CP. In addition, Lys reduced the fluorescence properties, particle size and increased the turbidity of CP, which had an inhibitory effect on heat induced gels. The results indicate that Lys plays an important role in inhibiting protein thermal aggregation by interacting with CP to create steric hindrance and increase protein electrostatic repulsion.

Effects of Food Factors and Processing on Protein Digestibility and Gut Microbiota

Protein is an essential macronutrient. The nutritional needs of dietary proteins are met by digestion and absorption in the small intestine. Indigestible proteins are further metabolized in the gut and produce metabolites via protein fermentation. Thus, protein indigestibility exerts a wide range of effects on gut microbiota composition and function. This review aims to discuss protein digestibility, the effects of food factors, such as protein sources, intake level, and amino acid composition, and making meat analogues. Besides, it provides an inventory of antinutritional factors and processing techniques that influence protein digestibility and, consequently, the diversity and composition of intestinal microbiota. Future studies are warranted to understand the implication of plant-based analogues on protein digestibility and gut microbiota and to elucidate the mechanisms concerning protein digestibility to host gut microbiota using various omics techniques.

Effects of spray drying and freeze drying on the structure and emulsifying properties of yam soluble protein: A study by experiment and molecular dynamics simulation

This study focused on the effects of freeze drying (FD) and sprays drying (SD) on the structure and emulsifying properties of yam soluble protein (YSP). The results showed that the surface hydrophobicity (Ho) value, free sulfhydryl group (SH) content, turns content, denaturation temperature and enthalpy value of spray-dried YSP (SD-YSP) were higher than freeze-dried YSP (FD-YSP), but the apparent hydrodynamic diameter (Dh) value of SD-YSP was smaller. The smaller Dh, higher Ho and free SH led to higher percentage of adsorbed proteins and stronger binding between protein and oil droplet in emulsions. Thus, the emulsifying properties of SD-YSP were better, and the SD-YSP-stabilized emulsion had better dynamical rheological properties. Molecular dynamics (MD) simulations suggested that some intramolecular disulfide bonds and hydrogen bonds of dioscorin were broken, and some helices transformed into turns during the SD process. These structural changes resulted in better thermal stability and emulsification properties of SD-YSP.

The effect of alkaline extraction and drying techniques on the physicochemical, structural properties and functionality of rice bran protein concentrates

Rice bran protein concentrates (RBPC) were extracted using mild alkaline solvents (pH: 8, 9, 10). The physicochemical, thermal, functional, and structural aspects of freeze-drying (FD) and spray-drying (SD) were compared. FD and SD of RBPC had porous and grooved surfaces, with FD having non-collapsed plates and SD being spherical. Alkaline extraction increases FD's protein concentration and browning, whereas SD inhibits browning. According to amino acid profiling, RBPC-FD9's extraction optimizes and preserves amino acids. A tremendous particle size difference was prominent in FD, thermally stable at a minimal maximum of 92 °C. Increased pH extraction gives FD greater exposal surface hydrophobicity and positively relates to denaturation enthalpy. Mild pH extraction and drying significantly impacted solubility, improved emulsion properties, and foaming properties of RBPC as observed in acidic, neutral, and alkaline environments. RBPC-FD9 and RBPC-SD10 extracts exhibit outstanding foaming and emulsion activity in all pH conditions, respectively. Appropriate drying selection, RBPC-FD or SD potentially employed as foaming/emulsifier agent or meat analog.

Salt Solubilization Coupled with Membrane Filtration-Impact on the Structure/Function of Chickpea Compared to Pea Protein

The demand for pulse proteins as alternatives to soy protein has been steeply increasing over the past decade. However, the relatively inferior functionality compared to soy protein is hindering the expanded use of pulse proteins, namely pea and chickpea protein, in various applications. Harsh extraction and processing conditions adversely impact the functional performance of pea and chickpea protein. Therefore, a mild protein extraction method involving salt extraction coupled with ultrafiltration (SE-UF) was evaluated for the production of chickpea protein isolate (ChPI). The produced ChPI was compared to pea protein isolate (PPI) produced following the same extraction method in terms of functionality and feasibility of scaling. Scaled-up (SU) ChPI and PPI were produced under industrially relevant settings and evaluated in comparison to commercial pea, soy, and chickpea protein ingredients. Controlled scaled-up production of the isolates resulted in mild changes in protein structural characteristics and comparable or improved functional properties. Partial denaturation, modest polymerization, and increased surface hydrophobicity were observed in SU ChPI and PPI compared to the benchtop counterparts. The unique structural characteristics of SU ChPI, including its ratio of surface hydrophobicity and charge, contributed to superior solubility at both a neutral and acidic pH compared to both commercial soy protein and pea protein isolates (cSPI and cPPI) and significantly outperformed cPPI in terms of gel strength. These findings demonstrated both the promising scalability of SE-UF and the potential of ChPI as a functional plant protein ingredient.

Fortification of Crude Protein Extract from Sung Yod and Hom Rajinee Rice Brans in the Development of Functional Jelly Products

Rice bran protein (RBP) has shown good nutritional and biological values. The present study aimed to determine the functional properties of rice bran crude protein (RBCP) and apply RBCP to a rice jelly recipe to improve the jelly quality and make it an acceptable product for consumers. The design used in the jelly formulation was a central composite design. The freeze-dried crude protein of Sung Yod (SY; 0.00–0.50%) and Hom Rajinee (HR; 0.00–0.50%) rice brans were applied to the rice jelly recipe. The crude protein extract significantly influenced the physicochemical, sensory, and angiotensin I converting enzyme (ACE)-inhibitory activity of the developed jellies (p < 0.05). The optimized jelly contained 0.11% SY and 0.50% HR crude protein extract. The rice jelly fortified with lyophilized RBCP presented a high content of bioactive compounds (phenolic and flavonoids) with antioxidant activity and ACE-inhibitory activity. Therefore, the crude protein extract of rice brans is a potential raw material that can be used in jelly products as a cheap material to improve the jelly’s nutritional quality without affecting consumer acceptability. The outcome of the present investigation confirms that rice bran extracts may have the potential to be further exploited as ingredients in foods.

Physicochemical, Structural Structural and Functional Properties of Non-Waxy and Waxy Proso Millet Protein

The physicochemical, structural and functional properties of proso millet protein from waxy and non-waxy proso millet were investigated. The secondary structures of proso millet proteins consisted mainly of a β-sheet and ɑ-helix. The two diffraction peaks of proso millet protein appeared at around 9° and 20°. The solubility of non-waxy proso millet protein was higher than that of waxy proso millet protein at different pH values. Non-waxy proso millet protein had a relatively better emulsion stability index (ESI), whereas waxy proso millet protein had a better emulsification activity index (EAI). Non-waxy proso millet protein showed a higher maximum denaturation temperature (T_d) and enthalpy change (ΔH) than its waxy counterpart, indicating a more ordered conformation. Waxy proso millet exhibited higher surface hydrophobicity and oil absorption capacity (OAC) than non-waxy proso millet, suggesting that the former may have potential applications as a functional ingredient in the food industry. There was no significant difference in the intrinsic fluorescence spectra of different waxy and non-waxy proso millet proteins at pH 7.0.

Production and functional characteristics of low-sodium high-potassium soy protein for the development of healthy soy-based foods

The plant-based products that are mainly produced by soy protein isolate (SPI) present significantly higher sodium (Na) content than the corresponding animal-based products. Accordingly, the production of low-sodium soy protein ingredients becomes a challenging task. For this purpose, alternative soy fractionation processes were investigated, and the use of KOH as the replacement for NaOH has been established to produce soy protein fractions (SPFs). The obtained MF-K contained 0.2 mg sodium and 24 mg potassium per 100 g of fraction, which was 3 % of the sodium content in the SPI, and the potassium content was over 10 times higher than SPI. Besides, using KOH increased the protein content of SPFs by almost 7 %, as well as their water holding capacity (WHC) and thermal stability; however, the yields of SPFs were dropped by around 4-8 % while the protein solubility of SPFs was reduced companied with the application of KOH. The fractionation processes mainly affected the protein composition, powder morphology, and viscosity of SPFs, while the sodium and potassium content showed limited impacts on the variations. Overall, the application of KOH during different fractionation procedures provided the possibility to produce low-sodium high‑potassium soy protein ingredients for the development of healthy soy-based foods.

Physicochemical and Structural Properties of Gluten-Konjac glucomannan Conjugates Prepared by Maillard Reaction

Gluten (Glu) is important to wheat products by forming a three-dimensional matrix. This study aimed to investigate the physicochemical and structural properties of gluten after conjugation with konjac glucomannan (KGM) through the Maillard reaction. The study revealed that the degree of graft increased with the prolonged reaction time. The Glu-KGM conjugates were possessed of increased β-sheet but decreased α-helix and β-turn, as well as unfolding and loose tertiary structures as the reaction proceeded. Among three different proportions, the Glu-KGM 1:1 conjugate was proved to have the most excellent foaming and emulsifying properties, and could form more rigid and firm gelation structures, which could be related to the decreased particle size and increased zeta potential of the conjugate. Overall, the physicochemical and structural properties of gluten were significantly related to the KGM ratios as well as the reaction period.

Drying methods affect physicochemical and functional characteristics of Clanis Bilineata Tingtauica Mell protein

Clanis Bilineata Tingtauica Mell Protein (CBTMP) was a kind of natural full-price protein which has a bright application prospect in the food industry. Since the functional properties of protein can be significantly affected by drying method, this study aims to explore the effect of different drying methods, namely freeze drying (FD), vacuum drying (VD),and hot-air drying (HD) on the structure and functional properties of CBTMP. The results showed that the degree of oxidation of CBTMP was found to be in the following order: HD &gt; VD &gt; FD. Functional characteristics revealed that the CBTMP prepared by VD had relatively high foaming ability (150.24 ± 5.34°C) among three drying methods. However, the stability of emulsion and rheological properties prepared by FD was superior to other samples. Differential scanning calorimeter (DSC) showed CBTMP made by HD had the relatively good thermal stability (Tp = 91.49 ± 0.19 °C), followed by VD and FD. Digestive properties reflected that heating treatment could significantly increase its degree of hydrolysis in vitro. To sum up, the research could provide experimental guidance and theoretical support for the preparation method and utilization of CBTMP.

Freeze-drying for the preservation of immunoengineering products

Immunoengineering technologies harness the power of immune system modulators such as monoclonal antibodies, cytokines, and vaccines to treat myriad diseases. Immunoengineering innovations have showed great promise in various practices including oncology, infectious disease, autoimmune diseases, and transplantation. Despite the countless successes, the majority of immunoengineering products contain active moieties that are prone to instability. The current review aims to feature freeze-drying as a robust and scalable solution to the inherent stability challenges in immunoengineering products by preventing the active moiety from degradation. Furthermore, this review describes the stability issues related to immunoengineering products and the utility of the lyophilization process to preserve the integrity and efficacy of immunoengineering tools ranging from biologics to nanoparticle-based vaccines. The concept of the freeze-drying process is described highlighting the quality by design (QbD) for robust process optimization. Case studies of lyophilized immunoengineering technologies and relevant clinical studies using immunoengineering products are discussed.

Physicochemical and functional properties of protein isolate recovered from Rana chensinensis ovum based on different drying techniques

This work was dedicated to evaluating the drying methods (freeze drying, spray drying, and vacuum drying) of food Rana chensinensis ovum protein isolate (RCOPI) based on comparison of the physicochemical and functional properties. The characterization and evaluation were conducted using scanning electron microscopy, surface hydrophobicity, SDS-PAGE, amino acid composition and nutritional parameters, Fourier transform infrared spectroscopy, and autofluorescence spectroscopy. The results showed the protein structure and conformation of RCOPI were greatly affected by drying techniques, leading to different physicochemical and functional properties. RCOPI possessed four main subunit bands distributed around 110, 90, 35 and 32 kDa. Seven essential amino acids were detected, accounting for 43.27-43.65% of total amino acids. Freeze drying RCOPI (FD-RCOPI) showed superior functional features, including solubility, water holding capacity, oil holding capacity, stabilization of Pickering emulsion and antioxidant capacity. FD-RCOPI exhibited applicability for the manufacture of viscous foods, bakery products and Pickering emulsions.

Effect of Homogenization Modified Rice Protein on the Pasting Properties of Rice Starch

Modification of plant-based protein for promoting wide applications is of interest to the food industry. Rice protein from rice residues was modified by homogenization, and its effect on pasting properties (including gelatinization and rheology) of rice starch was investigated. The results showed that homogenization could significantly decrease the particle size of rice protein and increase their water holding capacity without changing their band distribution in SDS-PAGE. With the addition of protein/homogenized proteins into rice starch decreased peak viscosity of paste. The homogenized proteins decreased breakdown and setback value when compared with that of original protein, indicating homogenized protein might have potential applications for increasing the stability and inhibiting short-term retrogradation of starch paste. The addition of protein/homogenized proteins resulted in a reduction in the viscoelasticity behavior of starch paste. These results indicate that homogenization would create a solution to alter the physicochemical properties of plant proteins, and the homogenized proteins may be a potential candidate for development of protein-rich starchy products.

Industrially Produced Rice Protein Ameliorates Dextran Sulfate Sodium-Induced Colitis via Protecting the Intestinal Barrier, Mitigating Oxidative Stress, and Regulating Gut Microbiota

Inflammatory bowel disease (IBD) poses a threat to health and compromises the immune system and gut microflora. The present study aimed to explore the effects of rice protein (RP) purified from rice dregs (RD) on acute colitis induced by dextran sulfate sodium (DSS) and the underlying mechanisms. Results showed that RP treatment could alleviate the loss of body weight, colon shortening and injury, and the level of disease activity index, repair colonic function (claudin-1, ZO-1 and occludin), regulate inflammatory factors, and restore oxidative balance (malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and total antioxidant capability (T-AOC)) in mice. Also, RP treatment could activate the Kelch-like ECH-associating protein 1 (Keap1)-nuclear factor E2-related factor 2 (Nrf2) signaling pathway, mediate the expression of downstream antioxidant protease (NQO-1, HO-1, and Gclc), regulate gut microbiota by enhancing the relative abundance of Akkermansia and increasing the value of F/B, and adjust short-chain fatty acid levels to alleviate DSS-induced colitis in mice. Thus, RP may be an effective therapeutic dietary resource for ulcerative colitis.