Effects of electron beam irradiation (EBI) on structure characteristics and thermal properties of walnut protein flour

Effect of electron beam irradiation on raw goat milk: microbiological, physicochemical and protein structural analysis

BACKGROUND

Goat milk is considered a nutritionally superior resource, owing to its advantageous nutritional attributes. Nevertheless, it is susceptible to spoilage and the persistence of pathogens. Electron beam irradiation stands as a promising non-thermal processing technique capable of prolonging shelf life with minimal residue and a high degree of automation.

RESULTS

The effects of electron beam irradiation (2, 3, 5, and 7 kGy) on microorganisms, physicochemical properties, and protein structure of goat milk compared with conventional pasteurized goat milk (PGM) was evaluated. It was found that a 2 kGy electron beam irradiation reduces the total microbial count of goat milk by 6-logs, and the irradiated goat milk protein secondary structure showed a significant decrease in ɑ-helix content. Low irradiation doses led to microaggregation and crosslinking. In contrast, high doses (≥ 5 kGy) slightly disrupted the aggregates and decreased the particle size, disrupting the microscopic surface structure of goat milk, verified by scanning electron microscopy and confocal laser scanning microscopy.

CONCLUSION

The irradiation of goat milk with a 2 kGy electron beam may effectively inactivate harmful microorganisms in the milk and maintain/or improve the physicochemical quality and protein structure of goat milk compared to thermal pasteurization. © 2024 Society of Chemical Industry.

Electron beam irradiation induced aggregation, structural and functional changes of soybean 11S globulin

This study investigated the effects of different irradiation doses of an electron beam (e-beam) (0, 2, 4, 6, 8, and 10 kGy) on the structure, emulsification, foaming, and rheological and gel properties of soybean 11S globulin. The irradiation treatment at 4 and 6 kGy significantly increased the solubility, surface hydrophobicity, disulfide bonding, and ζ-potential of 11S globulin, decreased the particle size of the protein solution, and effectively improved the emulsifying activity and foaming stability of the protein solution. Moreover, irradiation induced moderate cross-linking and aggregation of the proteins, thereby increasing the apparent viscosity and shear stress of the protein solution. In addition, the low-field NMR and microstructure analysis results revealed that protein gels formed a dense and homogeneous three-dimensional mesh structure after irradiation (6 kGy), along with increased content of bound water (T2b) and water not readily flowable (T21) and a decrease content of free water (T22). Overall, our results confirmed that e-beam irradiation could significantly improve the physicochemical properties of soybean 11S globulin. Our study thus provides a new technical means for the application of electron beam irradiation technology toward protein modification and broadens the high-value utilization of soybean 11S globulin in the food processing industry.

Effect of electron beam irradiation on the structural characteristics and functional properties of goat's milk casein

The effects of electron beam irradiation (EBI) at different doses (0, 2, 4, 6, 8, and 10 kGy) were investigated on the structural and functional properties of casein, including their interrelationship. A gradual reduction in the α-helix content of the secondary structure (as a stable structure) indicates that casein under EBI treatment mainly undergoes fragmentation and aggregation from a structural perspective. Furthermore, the hydrophobic group and tryptophan in the tertiary structure were exposed, which opened up the internal structure of the protein. In addition, a continuously increasing irradiation dose led to casein aggregation, as confirmed by electron microscopy. The structural changes affected its functional properties, such as solubility, emulsification, foaming, and rheological properties, all of which increased first and subsequently decreased. Finally, at irradiation doses of 4-6 kGy, casein was modified to exhibit optimal functional properties, which enhanced its food processing value and performance.

Improvement of foaming properties of ovalbumin: Insights into the synergistic effect of preheating and high-intensity ultrasound on physicochemical properties and structure analysis

Ovalbumin (OVA), characterized by its high concentration in eggs, possesses remarkable foaming properties. Nevertheless, OVA is highly sensitive to thermal changes and acid-base conditions, substantially hampering its application potential for foaming purposes within the food industry. This experiment aimed to examine the effects of preheating and high-intensity ultrasound (HIU) treatment at different powers on OVA foaming properties and explore the underlying mechanisms. The results revealed that OVA exhibited the highest foaming capacity (31.5 %) and foaming stability (96.7 %) under the treatment condition of 200w + 60°C. Additionally, significant improvements were observed in the content of free sulfhydryl groups (37.27 μmg/g), solution viscosity (142.33 mPa·s), and surface hydrophobicity (37.27 μg BPB) under this condition. The absolute value of the zeta potential (-10.28 mV) was significantly increased in the 200w + 60°C treatment group. Moreover, the polymer dispersity index of OVA (0.6045) was significantly reduced, resulting in improved dispersion than the control group. The structural analysis revealed significant changes in the α-helix and β-sheet content of OVA after treatment at 200w + 60 °C. The X-ray diffraction pattern exhibited sharper peaks, indicating a crystal structure, and the fluorescence peak displayed a slight blue shift along with increased hydrophobicity. Moreover, the preheating and HIU treatment induced a continuous uneven and irregular pore structure in OVA, which ultimately enhanced its foaming properties. In conclusion, the preheating and HIU treatment offers a novel approach to enhance the foaming properties of OVA.

Electron Beam Irradiation Alters the Physicochemical Properties of Chickpea Proteins and the Peptidomic Profile of Its Digest

Irradiation can be used for the preservation of chickpea protein as it can destroy microorganisms, bacteria, virus, or insects that might be present. However, irradiation may provoke oxidative stress, and therefore modify the functionality and nutritional value of chickpea protein. In order to study the effects of irradiation on the physicochemical properties and digestion behaviour of chickpea protein, chickpea protein concentrate (CPC) was treated with electron beam irradiation (EBI) at doses of 5, 10, 15, and 20 kGy. After irradiation, protein solubility first increased at 10 kGy and 15 kGy, and then decreased at the higher dose of 20 kGy. This was supported by SDS-PAGE, where the intensity of major protein bands first increased and then decreased. Increased doses of EBI generally led to greater oxidative modification of proteins in CPC, indicated by reduced sulfhydryls and increased carbonyls. In addition, the protein structure was modified by EBI as shown by Fourier transform infrared spectroscopy analysis, where α-helix generally decreased, and β-sheet increased. Although the protein digestibility was not significantly affected by EBI, the peptidomic analysis of the digests revealed significant differences among CPC irradiated with varying doses. A total of 337 peptides were identified from CPC irradiated with 0 kGy, 10 kGy, and 20 kGy, with 18 overlapping peptides and 60, 29, and 40 peptides specific to the groups of 0, 10, and 20 kGy respectively. Theoretical calculation showed that the distribution of peptide length, hydrophobicity, net charge, and C-terminal residues were affected by irradiation. The 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity showed a marginal decrease with an increasing dose of irradiation. In conclusion, EBI led to oxidative modification and structural changes in chickpea protein, which subsequently affected the physicochemical properties of peptides obtained from in-vitro digestion of CPC, despite similar digestibility.

Yeast protein as a novel dietary protein source: Comparison with four common plant proteins in physicochemical properties

Currently, with the preference for a healthy diet and increased awareness of reducing the carbon footprint, the demand for protein is becoming more and more diversified. In this study, the physicochemical properties of yeast protein (YP) and four common plant proteins (soy protein isolate, pea protein isolate, wheat gluten, and peanut protein) were compared. The most prevalent secondary structure in YP is the β-sheet. Furthermore, YP is in an aggregated state, and it has a high surface hydrophobicity. The tryptophan residues are primarily exposed on the polar surface of YP. The results of in vitro digestibility indicated that YP (84.91 ± 0.52%) was a high-quality protein. Moreover, YP has a higher thermal stability and relatively stable low apparent viscosity, which provides ample possibility for its application in food processing and in foods for people with swallowing difficulties. This study provides theoretical basis in the potential of YP as an alternative protein source.

Walnut Protein: A Rising Source of High-Quality Protein and Its Updated Comprehensive Review

Recently, plant protein as a necessary nutrient source for human beings, a common ingredient of traditional processed food, and an important element of new functional food has gained prominence due to the increasing demand for healthy food. Walnut protein (WP) is obtained from walnut kernels and walnut oil-pressing waste and has better nutritional, functional, and essential amino acids in comparison with other vegetable and grain proteins. WP can be conveniently obtained by various extraction techniques, including alkali-soluble acid precipitation, salting-out, and ultrasonic-assisted extraction, among others. The functional properties of WP can be modified for desired purposes by using some novel methods, including free radical oxidation, enzymatic modification, high hydrostatic pressure, etc. Moreover, walnut peptides play an important biological role both in vitro and in vivo. The main activities of the walnut peptides are antihypertensive, antioxidant, learning improvement, and anticancer, among others. Furthermore, WP could be applied in the development of functional foods or dietary supplements, such as delivery systems and food additives, among others. This review summarizes recent knowledge on the nutritional, functional, and bioactive peptide aspects of WP and possible future products, providing a theoretical reference for the utilization and development of oil crop waste.

Effects of electron beam irradiation treatment on the structural and functional properties of okara insoluble dietary fiber

BACKGROUND

Insoluble dietary fiber (IDF) has beneficial physiological effects, such as the promoting of intestinal peristalsis, the improving of intestinal flora, and the absorbing of some harmful substances. Okara, a byproduct of soybean processing, is a potential source of IDF. But the larger particle size and poor water solubility of okara IDF have adverse effects on sensory properties and functional characteristics. Therefore, we used an emerging type of physical method is electron beam irradiation (EBI) to modify okara, and investigated that the effects of EBI doses on the structure and functional properties of okara IDF.

RESULTS

It was found that the electron beam treatment damaged the crystalline structure of IDF. Observation of the surface of EBI-treated IDF revealed a loose and porous morphology rather than the typical smooth structure. At a dose of 6 kGy, a smallest particle size and largest specific surface area of IDF was obtained, and these factors increased the apparent viscosity of an IDF dispersion. The water holding capacity, swelling capacity and the oil holding capacity upon irradiation at 6 kGy increased 74.13%, 84.76% and 41.62%, respectively. In addition, the capacity for adsorption of cholesterol, sodium cholate, glucose and nitrite ion were improved after electron beam treatment.

CONCLUSION

The modified okara IDF showed improved particle sizes and hydration properties, and these changes correlated with an improvement to the rough taste of IDF and improvements to the texture and storage period upon supplementation into food. © 2022 Society of Chemical Industry.

Recent advances on the impact of novel non-thermal technologies on structure and functionality of plant proteins: A comprehensive review

The recent trend in consumption of plant-based protein over animal protein opens up a new avenue for sustainable agriculture practice, less environmental impact and greenhouse gas emission. The modification of plant-based proteins by novel non-thermal technologies includes the structural transformation followed by the modulation of their functional properties that are exploited to develop a protein ingredient system for application in food formulation. This review explores the impact of non-thermal process technologies on structural modification of plant proteins followed by improvement in protein's function in food formulation. Novel concepts articulating the impact of non-thermal technologies on structural and functional modification of plant proteins affecting it's digestibility and bioavailability are addressed. Limitations and prospects of applying non-thermal technologies in developing an alternative plant-based protein food system are also summarized. Non-thermal processes are considered as the emerging technologies that results in conformational changes in secondary, tertiary and quaternary structure of plant proteins which helps in modification of functional properties without jeopardizing the organoleptic properties and bioactivity of the protein. However, extensive future study is needed to optimize the non-thermal process parameters along with the finding of new protein sources to achieve healthy and sustainable plant-based food system.

The Current Situation of Pea Protein and Its Application in the Food Industry

Pea (Pisum sativum) is an important source of nutritional components and is rich in protein, starch, and fiber. Pea protein is considered a high-quality protein and a functional ingredient in the global industry due to its low allergenicity, high protein content, availability, affordability, and deriving from a sustainable crop. Moreover, pea protein has excellent functional properties such as solubility, water, and oil holding capacity, emulsion ability, gelation, and viscosity. Therefore, these functional properties make pea protein a promising ingredient in the food industry. Furthermore, several extraction techniques are used to obtain pea protein isolate and concentrate, including dry fractionation, wet fractionation, salt extraction, and mild fractionation methods. Dry fractionation is chemical-free, has no loss of native functionality, no water use, and is cost-effective, but the protein purity is comparatively low compared to wet extraction. Pea protein can be used as a food emulsifier, encapsulating material, a biodegradable natural polymer, and also in cereals, bakery, dairy, and meat products. Therefore, in this review, we detail the key properties related to extraction techniques, chemistry, and structure, functional properties, and modification techniques, along with their suitable application and health attributes.

Effects of High-Intensity Ultrasound Pretreatment on Structure, Properties, and Enzymolysis of Walnut Protein Isolate

The purpose of this paper was to investigate the effect of high-intensity ultrasonication (HIU) pretreatment before enzymolysis on structural conformations of walnut protein isolate (WPI) and antioxidant activity of its hydrolysates. Aqueous WPI suspensions were subjected to ultrasonic processing at different power levels (600-2000 W) and times (5-30 min), and then changes in the particle size, zeta (ζ) potential, and structure of WPI were investigated, and antioxidant activity of its hydrolysates was determined. The particle size of the particles of aqueous WPI suspensions was decreased after ultrasound, indicating that sonication destroyed protein aggregates. The ζ-potential values of a protein solution significantly changed after sonication, demonstrating that the original dense structure of the protein was destroyed. Fourier transform infrared spectroscopy indicated a change in the secondary structure of WPI after sonication, with a decrease in β-turn and an increase in α-helix, β-sheet, and random coil content. Two absorption peaks of WPI were generated, and the fluorescence emission intensity of the proteins decreased after ultrasonic treatment, indicating that the changes in protein tertiary structure occurred. Moreover, the degree of hydrolysis and the antioxidant activity of the WPI hydrolysates increased after sonication. These results suggest that HIU pretreatment is a potential tool for improving the functional properties of walnut proteins.

Modifying the plant proteins techno-functionalities by novel physical processing technologies: a review

Plant proteins have recently gained market demand and momentum due to their environmentally friendly origins and health advantages over their animal-derived counterparts. However, their lower techno-functionalities, digestibility, bioactivities, and anti-nutritional compounds have limited their application in foods. Increased demand for physically modified proteins with better techno-functionalities resulted in the application of different thermal and non-thermal treatments to modify plant proteins. Novel physical processing technologies (NPPT) considered 'emerging high-potential treatments for tomorrow' are required to alter protein functionality, enhance bioactive peptide formations, reduce anti-nutritional, reduce loss of nutrients, prevention of damage to heat liable proteins and clean label. NPPT can be promising substitutes for the lower energy-efficient and aggressive thermal treatments in plant protein modification. These facts captivated the interest of the scientific community in designing novel functional food systems. However, these improvements are not verifiable for all the plant proteins and depend immensely on the protein type and concentration, other environmental parameters (pH, ionic strength, temperature, and co-solutes), and NPPT conditions. This review addresses the most promising approaches of NPPT for the modification of techno-functionalities of plant proteins. New insights elaborating the effect of NPPTs on proteins' structural and functional behavior in relation to other food components are discussed. The combined application of NPPTs in the field of plant-based bioactive functionalities is also explored.

The effect of gamma and electron beam irradiation on the structural and physicochemical properties of myofibrillar protein and myosin from grass carp

Myofibrillar protein (MPS) and myosin (MS) from grass carp was irradiated by γ-ray and electron beam (EB) irradiation with different dose (2, 4, 6, 8, and 10 kGy). The changes in the physicochemical properties (solubility, Ca2+ -ATPase activity, total and reactive sulfhydryl content, surface hydrophobicity [S0 -ANS]), and structure of MPS and MS were investigated in the present work. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that there were degradation and aggregation of MPS and MS caused by irradiation, and the disappearance of myosin heavy chains (MHC) irradiated by EB was earlier than that of irradiated by γ-ray. As compared with MPS, the extracted MS was more easily destroyed. With the increase of irradiation dose, the particle size, solubility, Ca2+ -ATPase activity, and SH content of MPS and MS decreased (p < .05), while the S0 -ANS first increased and then decreased. Two-way analysis of variance results suggested that the degree of protein denaturation depends on the irradiation mode and dose. Compared with γ-ray irradiation, the EB irradiation had a greater impact on the physicochemical properties of MPS and MS.

Characterization of structural, functional and antioxidant properties and amino acid composition of pepsin-derived glutelin-1 hydrolysate from walnut processing by-products

Glutelin-1 of defatted walnut meal protein (DWPG-1) was modified by pepsin enzymatic hydrolysis to improve its functional properties and antioxidant activities. The amino acid composition, structural characteristics, physicochemical and functional properties as well as antioxidant activities of the hydrolysate were compared with those of unmodified DWPG-1. The analysis of X-ray diffraction patterns, surface microstructure and particle size distribution indicated that enzymatic hydrolysis changed the structures of DWPG-1. Compared with the natural unhydrolyzed protein, the hydrolysate showed better physicochemical properties, such as surface hydrophobicity, solubility, emulsifying properties, foaming properties and water absorption capacity. In addition, the hydrolysate also exhibited significantly stronger antioxidant activities than DWPG-1. In conclusion, the results of this study prove that pepsin-mediated hydrolysis of walnut glutelin-1 can effectively modify the structure, function and antioxidant activity of DWPG-1, and could be used as an effective technology to produce bioactive multifunctional hydrolysates.

Pepsin-mediated hydrolysis can be used as an effective tool to improve the functional and antioxidant properties of walnut glutelin-1.

Proton Dynamics of Water Diffusion in Shrimp Hydrolysates Flour and Effects of Moisture Absorption on Its Properties

Moisture absorbed into shrimp hydrolysates (SHs) flour profoundly affected its properties. The unstored hydrolysate flour was called SHs-0h and SHs stored for 30 h at 25 °C and 75% relative humidity was named SHs-30. During the process of storage, the moisture dynamics in SHs flour were investigated by dynamic vapor sorption (DVS) and low-field nuclear magnetic resonance (LF-NMR). The effects of moisture absorption on the radicals scavenging rates of SHs flour were evaluated by electron paramagnetic resonance (EPR). The effects of moisture absorption on secondary structure were studied by mid-infrared (MIR) spectroscopy and infrared microimaging spectroscopy. The changes of volatile components were monitored by purge and trap coupled with gas chromatography-mass spectrometry (PT-GC-MS). DVS results showed that the moisture absorption rate of SHs flour could reach a maximum of 88.93%. Meanwhile, the water was transformed into more stable water with shorter relaxation times. The porous structure of the SHs-30 h flour disappeared and became smoother compared to SH-0 h flour. DPPH (31.09 ± 0.54%) and OH (26.62 ± 1.14%) radicals scavenging rates of SHs-30 h significantly reduced (p < 0.05) compared to that of SHs-0 h flour. The vibrations of the MIR absorbance peaks were changed. Finally, eight volatile components disappeared and six new volatile compounds were found. This study provided a theory basis for moisture dynamics in peptide flour during the storage process.

Food irradiation: a promising technology to produce hypoallergenic food with high quality

The increasing incidence of food allergy cases is a public health problem of global concern. Producing hypoallergenic foods with high quality, low cost, and eco-friendly is a new trend for the food industry in the coming decades. Food irradiation, a non-thermal food processing technology, is a powerful tool to reduce the allergenicity with the above advantages. This review presents a summary of recent studies about food irradiation to reduce the allergenicity of food, including shellfish, soy, peanut, milk, tree nut, egg, wheat and fish. Principles of food irradiation, including mechanisms of allergenicity-reduction, irradiation types and characteristics, are discussed. Specific effects of food irradiation are also evaluated, involving microbial decontamination, improvement or preservation of nutritional value, harmful substances reduction of food products. Furthermore, the advantages, disadvantages and limitations of food irradiation are analyzed. It is concluded that food irradiation is a safety tool to reduce the allergenicity of food effectively, with high nutritional value and long shelf-life, making it a competitive alternative technology to traditional techniques such as heating treatments. Of note, a combination of irradiation with additional processing may be a trend for food irradiation.

Effect of X-rays on structural, physicochemical and functional properties of gluten protein

Abstract The gluten protein was exposed to the X-ray radiations for different time range, comprising 1 and 3 seconds. The objective of this study was to determine the effect of x-ray radiations on the physicochemical properties of gluten protein. Different functional properties of proteins like water and oil holding capacities, protein solubility, emulsification activity, and stability index, foaming action and stability, water solubility, protein, and moisture content, along with SDS PAGE, FTIR, Xeta potential net charge was carried out to evaluate the effect of X-ray radiation on gluten protein. Results showed that the enhancement of water holding capacity up to 38.12%, as well as oil holding capacity up to 35% could be seen, whereas a significant decrease in emulsification activity and stability index, foaming capacity and stability, even protein content could be observed in treated samples. The net charge on protein in water solution was found to increase towards the positive side. The structure of the protein remained unchanged based on no change was observed in SDS PAGE electrograph, FTIR secondary structure region. Hence, X-ray treatment can be a possible way to alter the protein structure for “tailor-made applications” in food industries.

Effects of multiple freeze–thaw treatments on physicochemical and biological activities of egg phosvitin and its phosphopeptides

Multiple freeze–thaw treatments improved the emulsifying and biological activities of egg phosvitin.