Functional Properties Of Proteins Research Articles

Sustainable approach from underutilized Leucaena leucocephala biomass by polyphenols composition and protein functional properties assessment

Sustainable approach from underutilized Leucaena leucocephala biomass by polyphenols composition and protein functional properties assessment

Effect of extraction methods on functional properties of plant proteins: A review

Effect of extraction methods on functional properties of plant proteins: A review

Characterization and emulsification of BSA/theaflavins complexes

Complex interactions occurring between proteins and polyphenols can impact the structural and functional properties of proteins, thereby enhancing their potential applications in food. We here used bovine serum albumin (BSA) as a prototypical protein for examining the structural and functional properties of the complex formed using theaflavins/BSA (BSA/TFs) in varying ratios. Additionally, the stability and rheological properties of the complex were analyzed as an emulsifier in high internal phase emulsions (HIPEs). According to the findings, the non-covalent bonding of TFs with BSA primarily involves hydrogen bonding, which changes BSA’s secondary structure, including a reduction in α-helix and an increase in β-sheet. Additionally, BSA/TFs exhibited low interfacial tension, thereby forming a highly efficient adsorbent layer on the oil–water interface and improving the stability of the emulsion film. HIPEs stabilized using BSA/TFs as an emulsifier have good storage stability and rheological properties. The particle size of d(4, 3) after 30 days of storage was 19 μm. Regarding rheological properties, the elastic modulus was larger than the viscous modulus, which indicated the gel characteristics of the complex. The structural recovery degree was greater than 1, which demonstrated the anti-thixotropy and superior emulsification effect. This study provides a theoretical foundation and experimental direction regarding the implementation of protein–polyphenol complexes for augmenting food quality and functionality.

Preparation and functional properties of rice bran globulin-chitooligosaccharide-quercetin-resveratrol covalent complex.

As the major protein (approximately 36%) in rice bran, globulin exhibits excellent foaming and emulsifying properties, endowing its useful application as a foaming and emulsifying agent in the food industry. However, the low water solubility restricts its commercial potential in industrial applications. The present study aimed to improve this protein's processing and functional properties. A novel covalent complex was fabricated by a combination of the Maillard reaction and alkaline oxidation using rice bran globulin (RBG), chitooligosaccharide (C), quercetin (Que) and resveratrol (Res). The Maillard reaction improved the solubility, emulsifying and foaming properties of RBG. The resultant glycosylated protein was covalently bonded with quercetin and resveratrol to form a (RBG-C)-Que-Res complex. (RBG-C)-Que-Res exhibited higher thermal stability and antioxidant ability than the native protein, binary globulin-chitooligosaccharide or ternary globulin-chitooligosaccharide-polyphenol (only containing quercetin or resveratrol) conjugates. (RBG-C)-Que-Res exerted better cytoprotection against the generation of malondialdehyde and reactive oxygen species in HepG2 cells, which was associated with increased activities of antioxidative enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) through upregulated genes SOD1, CAT, GPX1 (i.e. gene for glutathione peroxidase-1), GCLM (i.e. gene for glutamate cysteine ligase modifier subunit), SLC1A11 (i.e. gene for solute carrier family 7, member 11) and SRXN1 (i.e. gene for sulfiredoxin-1). The anti-apoptotic effect of (RBG-C)-Que-Res was confirmed by the downregulation of caspase-3 and p53 and the upregulation of B-cell lymphoma-2 gene expression. The present study highlights the potential of (RBG-C)-Que-Res conjugates as functional ingredients in healthy foods. © 2024 Society of Chemical Industry.

Effects of fibrillation combined with glycation by different chain length sugars on structural and functional properties of soybean protein

The key objective of this study was to investigate the effects of fibrillation combined with glycation of soybean protein isolate (SPI) on the protein structure and functional properties. SPI fibrils alone, glycated proteins and glycated fibrils with different chain lengths (glucose–G, maltose–M and dextran–D) were prepared and characterized by spectroscopy and microscopy methods. The results of the O-phthalaldehyde assay, ultraviolet–visible spectroscopy and fluorescent advanced glycation endproducts indicated the degree of glycation. The thioflavin T fluorescence assay, transmission electron microscopy (TEM) and Fourier-transform infrared (FTIR) spectroscopy results demonstrated that the fibril morphology improved, and more flexible and aggregated fibrils were produced after glycation, further improving the protein functional properties. With EAI and ESI values of 37.31 m2/g and 33.80%, respectively, the emulsifying properties of SPI fibrils glycated by dextran were higher than the others. Foam properties and antioxidant activity were highest for the fibrils glycated by glucose. These results are of scientific significance for in-depth understanding and reasonable regulation of protein functional properties for industrial production in a complex food system.

High Hydrostatic Pressure: Influences on Allergenicity, Bioactivities, and Structural and Functional Properties of Proteins from Diverse Food Sources.

High hydrostatic pressure (HHP) has gained prominence in the food processing industry over the last decade. In addition to the effectiveness of microbial and enzymatic inactivation, HHP directly impacts protein structures and properties. Accordingly, this review article aims to consolidate relevant research findings elucidating the effects of HHP on protein structure, allergenicity, bioactivities, and functional properties across diverse protein sources. They encompass cereals, legumes, nuts, meat, poultry products, milk, eggs, seafood, algae, insects, seeds, and vegetables. This review provides insights into the consistent trends of HHP effects on each protein source. In conclusion, HHP induces alterations in non-covalent bonds within protein structures, leading to the unfolding of their interior regions and consequential changes in their properties. Remarkably, the allergenicity of cereals, legumes, and nuts decreases while their bioactivities and digestibility escalate. The disruption of non-covalent bonds during HHP results in the exposure of the interior hydrophobic regions to the surface microenvironment, thereby enhancing the surface hydrophobicity of proteins, particularly those derived from seeds and vegetables. HHP weakens the allergenicity and elevates the foaming properties of proteins from dairy products, including improving the gelling properties and antioxidant activities of egg proteins. Texture profiles of meat and poultry, particularly hardness, are enhanced. Furthermore, HHP demonstrates the potential to diminish the allergenicity of seafood proteins and augment insect protein bioactivities. Lastly, HHP enhances the extraction of algal bioactive components, improving their nutritional quality.

Structural modeling and gene expression analysis of phosvitinless vitellogenin (vgc) in the Indian freshwater murrel, Channa punctatus (Bloch, 1793)

Vitellogenin (Vg) is a female-specific egg-yolk precursor protein, synthesized in the liver of fish in response to estrogens. In the present study, complete gene of phosvitinless vitellogenin (vgc) was sequenced, its 3D structure was predicted and validated by web-based softwares. The complete nucleotide sequence of vgc was 4126 bp which encodes for 1272 amino acids and showed the presence of three conserved domains viz. LPD_N, DUF1943 and DUF1944. The retrieved amino acid sequence of VgC protein was subjected to in silico analysis for understanding the structural and functional properties of protein. mRNA levels of multiple vg genes have also been quantified during annual reproductive cycle employing qPCR. A correlation has been observed between seasonal changes in gonadosomatic index with estradiol levels and hepatic expression of three types of vg genes (vga, vgb, vgc) during ovarian cycle of murrel. During preparatory phase, when photoperiod and temperature are low; low titre of E2 in blood induces expression of vgc gene. A rapid increase in the levels of E2 favours induction of vgb and vga genes in liver of murrel during early pre-spawning phase when photoperiod is long and temperature is high in nature. These results suggest that among three vitellogenin proteins, VgC is synthesized earlier than VgA and VgB during oogenesis.

Impact of defatting method on oat protein isolate structure-function characteristics

Oat (Avena sativa) is valued for its high protein content of 15–20% and potential health benefits. Oat also contains a notable lipid content, ranging from 6% to 10%, which can lead to rapid oxidation and rancidity, lowering product shelf life. Thus, defatting is imperative for the production of high-quality oat-based ingredients. This study focuses on evaluating the impact of various defatting techniques, including hexane-based defatting, supercritical carbon dioxide extraction, and supercritical carbon dioxide extraction with ethanol, on the structural and functional characteristics of oat protein isolate. Oat protein isolate was produced through alkaline extraction-isoelectric precipitation and assessed for its proximate composition, structural characteristics, encompassing protein profile, surface hydrophobicity, denaturation, and functional properties, including solubility, foaming capacity, and emulsification. Our results indicate that supercritical fluid methods are promising in their effectiveness in defatting oat flour although characteristics such as protein purity and solubility need improvement. Nevertheless, supercritical carbon dioxide defatting methods were found to yield oat protein with functional and structural properties closely comparable to the hexane-based method. In conclusion, given the environmental impacts associated with hexane, supercritical defatting methods can be further optimized and used as an eco-friendly alternative to conventional solvent-based fat extraction techniques.

Pulsed ultrasound assisted extraction of alternative plant protein from sugar maple leaves: Characterization of physical, structural, thermal, electrical, and techno-functional properties

Plant proteins are gaining in popularity and are increasingly being considered as an alternative to animal protein, thus a sustainable, yet comparable source of plant protein is highly recommended. To this end, the current study was conducted to investigate the structural, thermal, physical, and functional attributes, as well as the volatile profile of sugar maple leaves (SML) protein. To this end, SML protein was extracted by homogenization (10000 rpm, 5 min) pretreated ultrasound-assisted extraction (120000 J, 60% amplitude, 5:5 pulse, 25 °C, and 15 min) at varying pH (8−10) and compared with conventionally extracted SML protein. Among the different protein extracts, sonicated extract (pH9) provided a good protein yield (up to 7%) having higher protein content (210 mg Bovine serum albumin/g dry matter), thermal stability (onset of denaturation temperature:114 °C), and functional properties (solubility, emulsion capacity, water holding capacity, and antioxidant activity). On contrary, the characteristic green aroma, caused by 3-hexen-1-ol and nonanal, was found higher in sonicated protein extracts than that of macerated extracts. Having said that, this study showed the versatile properties of SML protein fractions that can be used as plant-based food ingredients.

Effects of the Roasting-Assisted Aqueous Ethanol Extraction of Peanut Oil on the Structure and Functional Properties of Dreg Proteins.

The effects of the roasting-assisted aqueous ethanol extraction of peanut oil on the structure and functional properties of dreg proteins were investigated to interpret the high free oil yield and provide a basis for the full utilization of peanut protein resources. The roasting-assisted aqueous ethanol extraction of peanut oil obtained a free oil yield of 97.74% and a protein retention rate of 75.80% in the dreg. The water-holding capacity of dreg proteins increased significantly, and the oil-holding capacity and surface hydrophobicity decreased significantly, reducing the binding ability with oil and thus facilitating the release of oil. Although the relative crystallinity and denaturation enthalpy of the dreg proteins decreased slightly, the denaturation temperatures remained unchanged. Infrared and Raman spectra identified decreases in the C-H stretching vibration, Fermi resonance and α-helix, and increases in random coil, β-sheet and β-turn, showing a slight decrease in the overall ordering of proteins. After the roasting treatment, 62.57-135.33% of the protein functional properties were still preserved. Therefore, the roasting-assisted aqueous ethanol extraction of peanut oil is beneficial for fully utilizing the oil and protein resources in peanuts.

Extraction of canola protein via natural deep eutectic solvents compared to alkaline treatments: Isolate characteristics and protein structural and functional properties

The capacity of four formulations of natural deep eutectic solvents (NDESs) for extraction of canola protein was compared to alkaline extractions at pH 12 and pH 9. NDESs were prepared with a 1:2:1 ratio of choline chloride/d-sorbitol, glycerol, d-glucose or urea/water. The urea formulation showed the lowest viscosity and density and highest polarity; and extracted a bright-yellow isolate with extraction efficiency of 52.89% and protein content of 84.03%. The rest of NDESs extracted light-green isolates with efficiencies of approximately 44%. Furthermore, All NDESs offered lower extraction efficiencies than pH 12 (68.34%, dark-green isolate) but higher than pH 9 (39.14%, yellow isolate). Molecular analysis via SE-HPLC and SDS-PAGE showed the presence of cruciferins and napins in all isolates, but higher napin contents for NDES isolates with cruciferin-to-napin ratios of around 60:40. NDESs also altered the secondary and tertiary structure of the protein to a lesser extent. The functionality analyses at pH range of 3–7 revealed better solubility for pH 9 (72.09%–39.35%) and glycerol formulation (68.61%–39.05%) isolates; and better foaming properties for all NDES isolates, possibly due to their higher napin contents. NDES isolates also showed better emulsifying properties at pH 5 and 7, while alkaline isolates produced more stable emulsions at pH 3, possibly due to the better solubility of their cruciferins at pH 3. Overall, NDES isolates offered higher extraction efficiencies and a close functionality compared to pH 9 isolate, better color and functionality than pH 12 isolate, and better preservation of native protein structure compared to both alkaline treatments.

Effect of extraction pH on amino acids, nutritional, in-vitro protein digestibility, intermolecular interactions, and functional properties of guar germ proteins

The chemical compositions, intermolecular interactions, and functional properties of guar germ proteins (GGP) were investigated at different extraction pH (7 to 11). The protein efficiency ratio, essential amino acid index (46.53), predicted biological value (39.02), nutritional index (42.67), and protein purity (91.69 %) were found to be highest at pH 9. The in-vitro protein digestibility of GGP sample was highest at pH 11. From SDS-PAGE, the band intensity (<10 kDa) became thinner with an increase in extraction pH from 7 to 9 and then thicker. Meanwhile, smallest particle size and weaker ionic and hydrogen bonds were found at pH 11. The β-sheet content was more dominating in GGP samples. Moreover, higher denaturation temperatures of GGP samples indicated that protein molecules had a compact tertiary structure. Furthermore, the GGP extracted at pH 7 showed better functional properties. The principal component analysis suggested that pH 9 was more suitable for isolating GGP.

Atmospheric-pressure cold plasma-assisted enzymatic extraction of high-temperature soybean meal proteins and effects on protein structural and functional properties

To increase the extraction rate of high-temperature soybean meal proteins and improve their functional properties, we used atmospheric-pressure cold plasma (ACP)-assisted enzymatic method to extract proteins from high-temperature soybean meal, and studied the effects of different ACP conditions on the structural and functional properties of the proteins. At the power of 300 w, time of 45 s, and air inlet volume of 120 mL/min, the extraction rate maximized to 83.26 ± 0.89%, which was about 1.2 times that of enzymatic hydrolysis alone (70.03%). After ACP treatment, the proteins' solubility, emulsifying activity and stability, foaming capacity and stability, hydrophobicity, and oil holding capacity were all improved. Fourier transform infrared spectroscopy, fluorescence spectroscopy, and scanning electron microscopy showed ACP changed the proteins' secondary, tertiary and microscopic structures. Thus, the ACP-assisted enzymatic method can improve the extraction rate of high-temperature soybean meal proteins, change the structures, and improve the functional properties of the proteins. This is a very potential method for the extraction of high-temperature soybean meal proteins.

Quantitative at-line monitoring of enzymatic hydrolysis using benchtop diffusion nuclear magnetic resonance spectroscopy.

Benchtop diffusion nuclear magnetic resonance (NMR) spectroscopy was used to perform quantitative monitoring of enzymatic hydrolysis. The study aimed to test the feasibility of the technology to characterize enzymatic hydrolysis processes in real time. Diffusion ordered spectroscopy (DOSY) was used to measure the signal intensity and apparent self-diffusion constant of solubilized protein in hydrolysate. The NMR technique was tested on an enzymatic hydrolysis reaction of red cod, a lean white fish, by the endopeptidase alcalase at 50°C. Hydrolysate samples were manually transferred from the reaction vessel to the NMR equipment. Measurement time was approximately 3 min per time point. The signal intensity from the DOSY experiment was used to measure protein concentration and the apparent self-diffusion constant was converted into an average molecular weight and an estimated degree of hydrolysis. These values were plotted as a function of time and both the rate of solubilization and the rate of protein breakdown could be calculated. In addition to being rapid and noninvasive, DOSY using benchtop NMR spectroscopy has an advantage compared with other enzymatic hydrolysis characterization methods as it gives a direct measure of average protein size; many functional properties of proteins are strongly influenced by protein size. Therefore, a method to give protein concentration and average size in real time will allow operators to more tightly control production from enzymatic hydrolysis. Although only one type of material was tested, it is anticipated that the method should be applicable to a broad variety of enzymatic hydrolysis feedstocks.

Promoting Soybean Protein Functional Properties By Enzymatic Hydrolysis: Characterization, Antioxidant Activity, Functional Properties And Application.

Promoting Soybean Protein Functional Properties By Enzymatic Hydrolysis: Characterization, Antioxidant Activity, Functional Properties And Application.

The effect of non-thermal hydrodynamic cavitation process on structural and function properties of casein protein

The effect of hydrodynamic cavitation (HC) on protein functionality is an emerging area of interest in the field of non-thermal processing. The effect of HC on Casein protein's physicochemical and functional properties. HC reduced the crystallization temperature from 230.9 °C in CP1 to 223.2 °C in CP2. The initial viscosity increased significantly to 39,080 Pa s from 26,590 Pa s. HC increased the concentration of amino acids following in-vitro digestion from 145.79 ± 5.7 μg/ml to 194.58 ± 6.3 μg/ml. Trypsin inhibitory reduced up to 44 ± 0.02 % in CP3. The solubility increased from 11.21 ± 0.50 μg/ml to 25.70 ± 1.44 μg/ml in CP2. The water holding capacity of the treated sample increased from 1.73 ± 0.19 g/g in CP1 to 2.52 ± 0.0036 g/g. The oil holding capacity of the treated sample decreased from 0.85 ± 0.02 g/g to 0.67 ± 0.03 g/g.

Protein from rapeseed for food applications: Extraction, sensory quality, functional and nutritional properties

The application of rapeseed protein in human foods is limited by residual antinutritive components and poor sensory quality. The effects of five extraction protocols on rapeseed protein yield, sensory, functional and nutritional properties were systematically evaluated in this study. In particular, the potential of weakly acidic salt (pH 6.5, 150 mmol·L−1 MgCl2) extraction as a mild method for recovering edible rapeseed protein was investigated compared with conventional alkali extraction. All salt-extracted proteins showed above 40 % extraction yield and low antinutritional factor contents. They also had ideal amino acid patterns and better in vitro gastroduodenal digestibility than alkaline-extracted proteins. Additionally, the lighter color and odor, as well as better solubility, emulsion activity, foaming property, and water/oil holding capacity were found in weakly acidic salt extraction-ultrafiltered proteins. These findings suggest that weakly acidic salt extraction-ultrafiltration could be used for obtaining edible rapeseed protein, while extraction yield should be improved for scale application.

Olive leaf protein: Extraction optimization, in vitro digestibility, structural and techno-functional properties

Olive leaf, as an important by-product of olive farming, is generated from the pruning and harvesting of olive trees and represents >10 % of the total olive weight. The present study was conducted to evaluate the composition, functional and structural characterizations, as well as the in vitro digestibility of olive leaf proteins isolated from ultrasonic-assisted extraction, comparing to classical and industrial techniques. The ultrasound-assisted extraction of olive leaf protein was optimized by the simultaneous maximization of the yield and purity of protein using a Box-Behnken design (BBD) of response surface methodology (RSM). The results indicated that the optimal extraction conditions were as follows: pH of 10.99, temperature of 40.48 °C, sonication time of 47.25 min, and solvent/solid ratio of 24.08 mL/g. Under these conditions, the extraction yield and protein content were 11.67 and 51.2 %, respectively, which were significantly higher than those obtained by the conventional techniques. Regarding the functionality of protein, extraction technique had significant impacts on the structural and functional properties of proteins. In general, ultrasound assisted extraction had higher solubility, and better foaming and thermal properties and in vitro digestibility but lower emulsifying stability and fluid binding capacity compared to conventional ones. Ultrasound-assisted alkaline extraction has great potential to produce edible olive leaf protein with modified functional properties that can be used for various aims in the food applications.

The effect of Hofmeister series anions on the critical overlap concentration of soybean isolate protein

The influence of different concentrations of Hofmeister series anions on the critical overlap concentration (c*) of soybean isolate protein (SPI) was investigated, along with its potential mechanisms. Techniques including SDS-PAGE electrophoresis, endogenous and exogenous fluorescence spectroscopy, circular dichroism spectrum, Fourier infrared spectroscopy, and solubility analyses were employed. Results demonstrated that higher concentrations of various anions within the solution had an impact on the protein's secondary structure, in line with the principles of the Hofmeister series. This led to a decline in the α-helix proportion and a concomitant increase in the ratio of β-sheets and random coils. Consequently, the protein's structural integrity was compromised, revealing more hydrophobic groups. This alteration in turn affected protein solubility, ultimately influencing the c* of SPI. Furthermore, analysis of scanning electron microscopy images indicated that the introduction of anions indeed influenced the degree of aggregation and the visual characteristics of SPI, with this aggregation trend closely mirroring that of the Hofmeister series anions. In conclusion, the Hofmeister series anions were found to modulate the c* of SPI by inducing changes in the protein's structural arrangement and functional properties.

Oligochitosan glycosylation of casein by TGase: Protective effect and mechanism on alcohol-induced intestinal injury in C57BL/6 mice

Glycosylated protein by transglutaminase-type could alter the structures and functional properties of proteins. However, the beneficial effects of glycosylated proteins against alcohol-induced intestinal injury remain unclear. Herein, the protective role and mechanism of glycosylated casein ameliorating alcohol-induced intestinal injury were assessed in vivo. The results showed that glycosylated casein and casein significantly relieved alcohol-induced oxidative stress and inflammatory responses in a concentration-dependent manner. The interventions of glycosylated casein and casein decreased serum parameters, improved the activities of antioxidant enzymes, reduced levels of inflammatory cytokines, and alleviated histopathological impairment in intestine tissues. Glycosylated casein and casein treatment downregulated protein expressions of TLR4, NF-κB p65, IKB-α, and MyD88 in mice, which activated the TLR4/NF-κB signaling pathway as a protective mechanism. More importantly, glycosylated caseinate showed a better effect against alcohol-induced intestinal injury than casein, suggesting that transglutaminase-mediated glycosylation of proteins is a useful technique to enforce protein biofunctions in the intestine.