Effects of ozone processing on chemical, structural and functional properties of whey protein isolate

Effect of enzymatic hydrolysis with Alcalase or Protamex on technological and antioxidant properties of whey protein hydrolysates

The aim of this study was to evaluate the effect of the enzymatic hydrolysis, performed using Alcalase and Protamex enzymes, on the technological functionalities and the antioxidant capacity of whey protein hydrolysates (WPHs) to identify the conditions allowing to obtain target functionality/ies. Samples were characterized for hydrolysis degree (DH), molecular weight distribution, structural properties, and food-related functionalities. Free sulfhydryl groups and surface hydrophobicity significantly decreased with the increase in DH, regardless of the used enzyme. The foaming and antioxidant properties of Alcalase WPHs were higher as compared to those of WPI, reaching the maximum value at DH = 18-20 %, while higher DH resulted in impaired functionality. Gelling properties were guaranteed when WPI was hydrolysed by Protamex at DH < 15 % while foaming and antioxidant abilities were fostered at 15 < DH < 21 %. These results were well correlated with MW distribution and were rationalized into a road map which represents a useful tool in the selection of proper hydrolysis conditions (time, DH, enzyme type) to obtain WPHs with tailored functionalities. Research outcomes highlighted the possibility to drive protein hydrolysis to optimize the desired functionality/ies.

Chemical and physical changes induced by cold plasma treatment of foods: A critical review

Cold plasma treatment is an innovative technology in the food processing and preservation sectors. It is primarily employed to deactivate microorganisms and enzymes without heat and chemical additives; hence, it is often termed a "clean and green" technology. However, food quality and safety challenges may arise during cold plasma processing due to potential chemical interactions between the plasma reactive species and food components. This review aims to consolidate and discuss data on the impact of cold plasma on the chemical constituents and physical and functional properties of major food products, including dairy, meat, nuts, fruits, vegetables, and grains. We emphasize how cold plasma induces chemical modification of key food components, such as water, proteins, lipids, carbohydrates, vitamins, polyphenols, and volatile organic compounds. Additionally, we discuss changes in color, pH, and organoleptic properties induced by cold plasma treatment and their correlation with chemical modification. Current studies demonstrate that reactive oxygen and nitrogen species in cold plasma oxidize proteins, lipids, and bioactive compounds upon direct contact with the food matrix. Reductions in nutrients and bioactive compounds, including polyunsaturated fatty acids, sugars, polyphenols, and vitamins, have been observed in dairy products, vegetables, fruits, and beverages following cold plasma treatment. Furthermore, structural alterations and the generation of volatile and non-volatile oxidation products were observed, impacting the color, flavor, and texture of food products. However, the effects on dry foods, such as seeds and nuts, are comparatively less pronounced. Overall, this review highlights the drawbacks, challenges, and opportunities associated with cold plasma treatment in food processing.

Short-time ozone treatment promotes protease-mediated destruction of B cell allergen epitopes by altering the structural characteristics of whey protein

A novel processing method combining short-time ozone pretreatment with hydrolysis has been developed to reduce whey protein allergenicity. The results showed that ozone treatment altered the whey protein spatial structure, initially increasing the surface hydrophobicity index, and then decreasing due to polymer formation as the time increased. Under the optimized conditions of alkaline protease-mediated hydrolysis, a 10-second pre-exposure to ozone significantly promoted the reduction in the IgE binding capacity of whey protein without compromising the hydrolysis efficiency. Compared with whey protein, the degranulation of KU812 cells stimulated by this hydrolysate decreased by 20.54%, 17.99%, and 22.80% for IL-6, β-hexosaminidase, and histamine, respectively. In vitro simulated gastrointestinal digestion confirmed increased digestibility and reduced allergenicity. Peptidomics identification revealed that short-time ozonation exposed allergen epitopes, allowing alkaline protease to target these epitopes more effectively, particularly those associated with α-lactalbumin. These findings suggest the promising application of this processing method in mitigating the allergenicity of whey protein.

Insights into Cold Plasma Treatment on the Cereal and Legume Proteins Modification: Principle, Mechanism, and Application

Cereal and legume proteins, pivotal for human health, significantly influence the quality and stability of processed foods. Despite their importance, the inherent limited functional properties of these natural proteins constrain their utility across various sectors, including the food, packaging, and pharmaceutical industries. Enhancing functional attributes of cereal and legume proteins through scientific and technological interventions is essential to broadening their application. Cold plasma (CP) technology, characterized by its non-toxic, non-thermal nature, presents numerous benefits such as low operational temperatures, lack of external chemical reagents, and cost-effectiveness. It holds the promise of improving proteins' functionality while maximally retaining their nutritional content. This review delves into the pros and cons of different cold plasma generation techniques, elucidates the underlying mechanisms of protein modification via CP, and thoroughly examines research on the application of cold plasma in augmenting the functional properties of proteins. The aim is to furnish theoretical foundations for leveraging CP technology in the modification of cereal and legume proteins, thereby enhancing their practical applicability in diverse industries.

Fabrication and characterisation of collagen/pullulan ultra-thin fibers by electrospinning

Collagen electrospun fibers are promising materials for food packaging and tissue engineering. The conventional electrospinning of collagen, however, is usually carried out by dissolving it in organic reagents, which are toxic. In this study, collagen/pullulan (COL/PUL) ultra-thin fibers were prepared by electrospinning using acetic acid as a solvent. Compared to the conventional preparation method, the proposed method is safe and does not produce toxic solvent residues. The introduction of PUL increased the degree of molecular entanglement in the solution, so the viscosity of the COL/PUL electrospun solution increased from 0.50 ± 0.01 Pa∙s to 4.40 ± 0.08 Pa∙s, and the electrical conductivity decreased from 1954.00 ± 1.00 mS/cm to 1372.33 ± 0.58 mS/cm. Scanning electron microscopy analysis confirmed that PUL improved the spinnability of COL, and smooth, defect-free COL/PUL ultra-thin fibers with diameters of 215.32 ± 40.56 nm and 240.97 ± 53.93 nm were successfully prepared at a viscosity of greater than 1.18 Pa∙s. As the proportion of PUL increased, intramolecular hydrogen bonds became the dominant interaction between COL and PUL. The intermolecular hydrogen bonding content decreased from 52.05 % to 36.45 %, and the intramolecular hydrogen bonding content increased from 46.11 % to 62.95 %. The COL was gradually unfolded, the content of α-helices decreased from 33.57 % to 25.91 % and the random coils increased from 34.22 % to 40.09 %. More than 36 % of the triple helix fraction of COL was retained by the COL/PUL ultra-thin fibers, whereas only 16 % of the triple helix fraction of COL was retained by the COL nanofibers prepared with 2.2.2-trifluoroethanol. These results could serve as a reference for the development of green food COL-based fibers.

The effect of subzero temperatures on the properties and structure of soy protein isolate emulsions

Different freezing temperatures (-5, -20, -40 and -80 ℃) could change soy protein isolate (SPI) structure and emulsion properties. After freezing at -5 ℃ and -20 ℃, the structure of the SPI loosened, the fluorescence intensity was red shifted, and the proportion of Phe, Tyr and Trp exposed increased. With decreasing temperature, the surface hydrophobicity (H0 × 100), the number of sulfhydryl groups and the number of disulfide bonds all rose, then fell (-40 ℃), and rose again (-80 ℃). The β-sheet content in the protein secondary structure increased from 32.71% (control) to 50.66% (-40 ℃) and then decreased to 37.05% (-80 ℃), while the β-turn and random coil contents showed the opposite pattern, which also confirmed aggregation. The emulsification performance of SPI after freezing treatment was decreased. The results of this study provide theoretical support for future production of frozen foods with added SPI.

Modifications to structural, techno-functional and rheological properties of sesame protein isolate by high pressure homogenization

In this study, we aimed to determine the effect of high pressure homogenization (HPH) at a pressure up to 150 MPa on microstructural, techno-functional and rheological properties of sesame protein isolate (SPI). HPH treatment caused a partial change in the secondary structure of SPI, however, the changes in surface hydrophobicity and free -SH groups, indicating HPH had significant effect on the tertiary structure. After the HPH treatment, the particles dispersed homogeneously with more rougher surface. Sesame proteins had the smallest particle size (0.79 μm) and highest zeta potential (38.83 mV) at 100 MPa pressure. The most developed water/oil holding capacity, emulsification and foaming properties were achieved at 100 MPa pressure. However, the maximum stable foam formation (83.33 %) was determined at 150 MPa pressure. When the shear rate is fixed as 50 1/s, an increase in the viscosity value of the samples treated with 100 and 150 MPa pressure was detected compared to the control sample, while the lowest viscosity was determined the ones treated at 50 MPa. In all samples except 50 MPa pressure-treated proteins, viscoelastic character became dominant with increasing frequency (G' > G″). Modification with HPH resulted in a decrease of about 15 °C in the gelation temperature of SPI.

Enhanced properties of non-starch polysaccharide and protein hydrocolloids through plasma treatment: A review

Hydrocolloids are important ingredients in food formulations and their modification can lead to novel ingredients with unique functionalities beyond their nutritional value. Cold plasma is a promising technology for the modification of food biopolymers due to its non-toxic and eco-friendly nature. This review discusses the recent published studies on the effects of cold plasma treatment on non-starch hydrocolloids and their derivatives. It covers the common phenomena that occur during plasma treatment, including ionization, etching effect, surface modification, and ashing effect, and how they contribute to various changes in food biopolymers. The effects of plasma treatment on important properties such as color, crystallinity, chemical structure, rheological behavior, and thermal properties of non-starch hydrocolloids and their derivatives are also discussed. In addition, this review highlights the potential of cold plasma treatment to enhance the functionality of food biopolymers and improve the quality of food products. The mechanisms underlying the effects of plasma treatment on food biopolymers, which can be useful for future research in this area, are also discussed. Overall, this review paper presents a comprehensive overview of the current knowledge in the field of cold plasma treatment of non-starch hydrocolloids and their derivatives and highlights the areas that require further investigation.

Impact of emerging food processing technologies on structural and functional modification of proteins in plant-based meat alternatives: An updated review

In the past decade, the plant-based meat alternative industry has grown rapidly due to consumers' demand for environmental-friendly, nutritious, sustainable and humane choices. Consumers are not only concerned about the positive relationship between food consumption and health, they are also keen on the environmental sustainability. With such increased consumers' demand for meat alternatives, there is an urgent need for identification and modification of protein sources to imitate the functionality, textural, organoleptic and nutritional characteristics of traditional meat products. However, the plant proteins are not readily digestible and require more functionalization and modification are required. Proteins has to be modified to achieve high quality attributes such as solubility, gelling, emulsifying and foaming properties to make them more palatable and digestible. The protein source from the plant source in order to achieve the claims which needs more high protein digestibility and amino acid bioavailability. In order to achieve these newer emerging non-thermal technologies which can operate under mild temperature conditions can reach a balance between feasibility and reduced environmental impact maintaining the nutritional attributes and functional attributes of the proteins. This review article has discussed the mechanism of protein modification and advancements in the application of non-thermal technologies such as high pressure processing and pulsed electric field and emerging oxidation technologies (ultrasound, cold plasma, and ozone) on the structural modification of plant-based meat alternatives to improve, the techno-functional properties and palatability for successful food product development applications.

Effect of atmospheric pin-to-plate cold plasma on oat protein: Structural, chemical, and foaming characteristics

The impact of novel pin-to-plate atmospheric cold plasma was investigated with input voltage (170 V, 230 V) and exposure time (15 & 30 min) on oat protein by studying structural (FTIR, circular dichroism (CD), UV-vis, Fluorescence), morphological (particle size analysis, SEM, turbidity), chemical (pH, redox potential (ORP), ζ potential, carbonyl, sulfhydryl, surface hydrophobicity), and foaming characteristics. The plasma treatment reduced the pH while increasing the ORP of the dispersions. These ionic environment changes affected the ζ potential and particle size leading to the formation of larger aggregates (170-15; 230-15) and distorted smaller ones (170-30; 230-30) as confirmed by SEM. The FTIR spectra showed reduced intensity at specific amide bands (1600-1700 cm^-1) and also an increase in carbonyl stretching (1743 cm^-1) representing oxidative carbonylation (increase in carbonyl content). Thus, the partial exposure of hydrophobic amino acids increases surface hydrophobicity. The altered secondary structure (rise in α-helix, decrement in β-sheets and turns), and tertiary structures were observed in circular dichroism (CD) and UV absorbance and fluorescence characteristics of proteins respectively. Furthermore, the increase in free sulfhydryl content and disulfide content was highly affected by the plasma treatments due to observed protein unfolding and aggregations. Besides, the increased solubility and reduced surface tension contributed to the improved foaming characteristics. Thus, plasma processing influences protein structure affecting their characteristics and other functionalities.

Structural and Functional Changes in Soybean Protein via Remote Plasma Treatments

To the best of our knowledge, few studies have utilized cold plasma to improve soybean protein extraction yield and the functional properties of soybean protein. In this study, we aimed to assess the benefits of remote plasma treatments on soybean with respect to the utilization of soybean protein. This study involved two different sample forms (whole and crushed beans), two different plasma chemistry modes (ozone and nitrogen oxides [NO_x = NO + NO₂]), and a novel pressure-swing reactor. Crushed soybeans were significantly affected by NO_x-mode plasma treatment. Crushed soybeans treated with NO_x-mode plasma had the best outcomes, wherein the protein extraction yield increased from 31.64% in the control to 37.90% after plasma treatment. The water binding capacity (205.50%) and oil absorption capacity (267.67%) of plasma-treated soybeans increased to 190.88% and 246.23 % of the control, respectively. The emulsifying activity and emulsion stability slightly increased compared to those of the control. The secondary structure and surface hydrophobicity were altered. The remote plasma treatment of crushed soybeans increased soybean protein extraction yield compared to plasma-treated whole beans as well as untreated beans and altered the structural and physicochemical properties of soybean proteins.

Structural Characterization, Technofunctional and Rheological Properties of Sesame Proteins Treated by High-Intensity Ultrasound

Plant-derived proteins, such as those from sesame seeds, have the potential to be used as versatile food ingredients. End-use functionality can be further improved by high-intensity ultrasound treatments. The effects of high-intensity ultrasound on the properties of sesame protein isolates from cold-pressed sesame cake were evaluated. The SDS-PAGE demonstrated no significant changes in the molecular weight of proteins. Ultrasound treatments resulted in decreased particle size with a more uniform distribution, resulting in the exposure of hydrophobicity and free -SH groups and increased zeta potential. Although FTIR spectra of proteins were similar after ultrasonication, a partial increase in the intensity of the amide A band was observed. The ultrasound significantly (p < 0.05) affected the secondary structure of proteins. While optical micrographics revealed a dispersed structure with smaller particles after treatments, microstructural observations indicated more rough and irregular surfaces. Water solubility was improved to 80.73% in the sample subjected to 6 min of ultrasonication. Sesame protein solutions treated for 4 and 6 min exhibited viscoelastic structure (storage modulus (G') > loss modulus (G'')). In addition, the gelation temperature of proteins decreased to about 60-65 °C with increasing treatment time. Overall, ultrasound is a useful technique for the modification of sesame protein isolates.

Non-thermal plasma modulation of the interaction between whey protein isolate and ginsenoside Rg1 to improve the rheological and oxidative properties of emulsion

Molecular interaction forces regulate the interfacial properties of oil-in-water emulsion and play a key role in the rheology and stability of the emulsion in the food industry. In this study, the effects of non-thermal plasma (NTP) treatment on the structural and functional properties of whey protein isolate (WPI) and its binding interaction with ginsenoside Rg₁ (GR₁) were investigated. The results based on surface hydrophobicity, infrared spectroscopy and fluorescence spectroscopy test showed that the NTP treatment induced the unfolding of the structure of WPI and promoted the binding affinity between WPI and GR₁. By comparing with untreated WPI (an α-helix content of 19.63 % and a β-sheet content of 31.66 %), there was a greater decrease in α-helix content and an increase in β-sheet content of WPI in N₂₀-WPI (α-helix = 9.63 %, β-sheet = 39.63 %) and N₂₀-WPI-GR₁ (α-helix = 4.98 %, β-sheet = 48.66 %) groups. Importantly, the NTP treatment increased the interfacial adsorption and antioxidant capacity of the WPI-GR1 complexes, which contributed to the improvement of the rheological properties and oxidation stability of the emulsion. As a result, the NTP treatment could markedly improve the rheological and antioxidative properties of the WPI-GR₁ complexes and the NTP-treated WPI-GR₁ emulsions was more stable than that untreated. The present research indicated that NTP-treated formation of protein-saponin complexes could enhance the functional properties of the proteins, thus expanding their application as functional ingradients in nutritionally fortified food.

The Use of Ozone Technology: An Eco-Friendly Method for the Sanitization of the Dairy Supply Chain

The dairy field has considerable economic relevance in the agri-food system, but also has the need to develop new 'green' supply chain actions to ensure that sustainable products are in line with consumer requirements. In recent years, the dairy farming industry has generally improved in terms of equipment and product performance, but innovation must be linked to traditional product specifications. During cheese ripening, the storage areas and the direct contact of the cheese with the wood must be carefully managed because the proliferation of contaminating microorganisms, parasites, and insects increases significantly and product quality quickly declines, notably from a sensory level. The use of ozone (as gas or as ozonated water) can be effective for sanitizing air, water, and surfaces in contact with food, and its use can also be extended to the treatment of waste and process water. Ozone is easily generated and is eco-sustainable as it tends to disappear in a short time, leaving no residues of ozone. However, its oxidation potential can lead to the peroxidation of cheese polyunsaturated fatty acids. In this review we intend to investigate the use of ozone in the dairy sector, selecting the studies that have been most relevant over the last years.

Potential implications of oxidative modification on dietary protein nutritional value: A review

During food processing and storage, proteins are sensitive to oxidative modification, changing the structural characteristics and functional properties. Recently, the impact of dietary protein oxidation on body health has drawn increasing attention. However, few reviews summarized and highlighted the impact of oxidative modification on the nutritional value of dietary proteins and related mechanisms. Therefore, this review seeks to give an updated discussion of the effects of oxidative modification on the structural characteristics and nutritional value of dietary proteins, and elucidate the interaction with gut microbiota, intestinal tissues, and organs. Additionally, the specific mechanisms related to pathological conditions are also characterized. Dietary protein oxidation during food processing and storage change protein structure, which further influences the in vitro digestion properties of proteins. In vivo research demonstrates that oxidized dietary proteins threaten body health via complicated pathways and affect the intestinal microenvironment via gut microbiota, metabolites, and intestinal morphology. This review highlights the influence of oxidative modification on the nutritional value of dietary proteins based on organs and the intestinal tract, and illustrates the necessity of appropriate experimental design for comprehensively exploring the health consequences of oxidized dietary proteins.

Improved Stability and In Vitro Anti-Arthritis Bioactivity of Curcumin-Casein Nanoparticles by Ultrasound-Driven Encapsulation

Curcumin possesses beneficial biological functions, namely anti-inflammation and anti-diabetic functions. However, due to its low solubility and crystallinity, its applications are limited. In this work, curcumin was encapsulated in casein micelles in order to form curcumin-casein nanoparticles by ultrasound treatment (5 min). The ultrasound treatment induced the entry of the hydrophobic groups to the inner micelles and the polar sulfydryl groups to the surface of the micelles in order to form compact curcumin-casein nanoparticles of an appropriate size (100-120 nm) for cellular endocytosis. The product exhibited excellent stability during 8 months of cold storage, 6 days at room temperature, and 2 days at body temperature. Advanced in vitro experiments demonstrated that curcumin-casein nanoparticles displayed significantly greater inhibitory activity against the proliferation and proinflammatory cytokines of human fibroblast-like synoviocyte-osteo arthritis (HFLS-OA) cells and HFLS-rheumatoid (RA) cells than native curcumin due to better cellular uptake as a result of the low crystallinity and the appropriate nano-size of the nano-form. The results provide a reference for the use of ultrasound treatment to encapsulate other drug molecules and curcumin-casein nanoparticles as potential treatment for arthritis.

Degradation of malathion and carbosulfan by ozone water and analysis of their by-products

BACKGROUND

Treatment by ozone water is an emerging technology for the degradation of pesticide residues in vegetables. The ozone dissolved in water generates hydroxyl radicals (^· OH), which are highly effective in decomposing organic substances, such as malathion and carbosulfan.

RESULTS

We found that washing pak choi with 2.0 mg L^-1 ozone water for 30 min resulted in 58.3% and 38.2% degradation of the malathion and carbosulfan contents respectively, and the degradation rates of these pure pesticides were 83.0% and 66.3% respectively. In addition, the 'first + first'-order reaction kinetic model was found to predict the trend in the pesticide content during ozone water treatment. Based on investigations by gas chromatography-mass spectrometry combined with the structures of the pesticides, the by-products generated were identified. More specifically, the ozonation-based degradation of carbosulfan generated carbofuran and benzofuranol, whereas malathion produced succinic acid and phosphoric acid. Although some new harmful compounds were formed during degradation of the parent pesticides, these were only present in trace quantities and were transient intermediates that eventually disappeared during the reaction.

CONCLUSION

Our results, therefore, indicate that ozone water treatment technology for pesticide residue degradation is worthy of popularization and application. © 2022 Society of Chemical Industry.

Effects of ethanol pre-treated whey protein isolates on the physical stability and protein-lipid co-oxidation in oil-in-water emulsions

The changes of physical stability and protein-lipid co-oxidation of oil-in-water (O/W) emulsions which stabilized by whey protein isolates (WPI) and ethanol pre-treated WPI (EWPI) under different homogenization methods were investigated. Compared with WPI, EWPI could obviously enhance the O/W emulsion's stability due to smaller particle size and higher level of adsorbed proteins. Moreover, protein-lipid co-oxidation was observed in both WPI and EWPI stabilized O/W emulsions and controlled by the characteristics of the adsorbed proteins. EWPI protect themselves from attacked of lipid oxidation products more effectively than WPI, showing lower N'-formyl-l-kynurenine or carbonyl contents and degree of aggregation, as well as higher fluorescence intensity. Furthermore, high-pressure homogenization induced higher levels of adsorbed proteins in O/W emulsions than ultrasound homogenization, resulting in a higher degree of protein oxidation and lower degree of lipid oxidation. Therefore, EWPI can be applied as an efficient emulsifier in emulsion foods with higher physical and oxidative stabilities.

Effect of atmospheric nonthermal plasma on physicochemical, morphology and functional properties of sunn pest ( Eurygaster integriceps )‐damaged wheat flour

To improve the quality of sunn pests (Eurygaster integriceps)‐damaged wheat flour, the effects of nonthermal plasma on physicochemical, rheological, functional, and microstructural properties were investigated. Gas type (air and oxygen), voltage (22 and 25 volts), and time (0, 2, 4, 6, 8, and 10 min) were the variables of the experiments conducted using a completely randomized design with three replications. The results show that with increasing voltage and time of plasma treatment, the pH decreased significantly (p ≥ .05), and brightness parameter, yellow–blue parameter, water‐solubility, water absorption, oil absorption, and swelling power increased significantly (p ≥ .05). The duration of plasma treatment, voltage, and change in input gas from air to oxygen did not significantly change the gluten index, particle size, and negative electric charge of flour particles, and the amount of zeta potential of samples. Differential calorimetric analysis showed the first and second peaks of the thermogram in the range 55–99°C and also 114–99°C. Infrared spectroscopy (FT‐IR) showed hydroxyl group, CH bonds, C=O bonds, as well as the presence of types I and II amide bonds in the structure. Microstructural results indicated that plasma treatment reduced the particle size and increased particle sorting. By Increasing voltage and the duration of plasma treatment, peak viscosity, final viscosity, breakdown viscosity, pasting time and temperature significantly increased and setback viscosity decreased (p ≥ .05), which reduced retrogradation which improved the dough stability during the cooling process.

Atmospheric cold plasma: a new approach to modify protein and lipid properties of myofibrillar protein isolate from hairtail (Trichiurus lepturus) fish

BACKGROUND

Quite recently, considerable attention has been paid to atmospheric cold plasma (ACP) as an eco-friendly and highly efficient technology to modify the functional properties of foods. This study focuses on the effect of ACP on the myofibril protein and lipid quality of hairtail (Trichiurus lepturus) fish. In achieving this, the samples were treated with ACP at 50 kV for different times (30, 60, 120, 180, 240, 300 s).

RESULTS

The findings indicated slight changes in peroxide value and thiobarbituric acid reactive substances in the samples treated with ACP. A significant increase (P < 0.05) in the surface hydrophobicity (from 131.71 ± 0.81 μg to 146. 34 ± 0.81 μg), turbidity (from 0.13 ± 0.001 to 0.27 ± 0.01), and water-holding capacity (from 61.63% ± 5.7% to 64.86% ± 1.5%) were detected with treated samples.

CONCLUSIONS

We conclude that ACP treatment induces marked changes in the protein and lipid properties of myofibril protein isolated from hairtail fish, which strengthen the gel formation of hairtail fish. © 2021 Society of Chemical Industry.

Modification methods and applications of egg protein gel properties: A review

Egg protein (EP) has a variety of functional properties, such as gelling, foaming, and emulsifying. The gel characteristics provide a foundation for applications in the food industry and research on EP. The proteins denature and aggregate to form a dense three-dimensional gel network structure, with a process influenced by protein concentration, pH, ion type, and strength. In addition, the gelation properties of EP can be altered to varying degrees by applying different treatment conditions to EP. Currently, modification methods for proteins include physical modification (heat-induced denaturation, freeze-thaw modification, high-pressure modification, and ultrasonic modification), chemical modification (glycosylation modification, phosphorylation modification, acylation modification, ethanol modification, polyphenol modification), and biological modification (enzyme modification). Pidan, salted eggs, egg tofu, and other egg products have unique sensory properties, due to the gel properties of EP. In accessions, EP has also been used as a new ingredient in food packaging and biopharmaceuticals due to its gel properties. This review will further promote EP gel research and provide guidance for its full application in many fields.

Impact of plasma reactive species on the structure and functionality of pea protein isolate

The impact of plasma-produced reactive oxygen and nitrogen species, in particular O₃, N_xO_y, H₂O₂ and OH, on the structure and functionality of pea protein isolate (PPI) was evaluated. Reactive species were produced through a combination of controlled measurements and plasma treatments. Pronounced structural and functional effects were observed upon treatment with reactive species at pH 2. All reactive species induced protein denaturation and the formation of disulfide-linked soluble aggregates. A significant increase in surface hydrophobicity and β-sheet content was only induced by treatment with O₃ and OH. These specific changes resulted in significant enhancement in gelation and emulsification. While H₂O₂ enhanced PPI color by increasing whiteness, it had the least impact on protein structure and functionality. Results of this work can be used to optimize cold atmospheric plasma treatment of PPI to induce specific structural changes and a directed enhancement in functionality.

Fabrication of a New, Low-Cost, and Environment-Friendly Laccase-Based Biosensor by Electrospray Immobilization with Unprecedented Reuse and Storage Performances

The fabrication of enzyme-based biosensors has received much attention for their selectivity and sensitivity. In particular, laccase-based biosensors have attracted a lot of interest for their capacity to detect highly toxic molecules in the environment, becoming essential tools in the fields of white biotechnology and green chemistry. The manufacturing of a new, metal-free, laccase-based biosensor with unprecedented reuse and storage capabilities has been achieved in this work through the application of the electrospray deposition (ESD) methodology as the enzyme immobilization technique. Electrospray ionization (ESI) has been used for ambient soft-landing of laccase enzymes on a carbon substrate, employing sustainable chemistry. This study shows how the ESD technique can be successfully exploited for the fabrication of a new promising environment-friendly electrochemical amperometric laccase-based biosensor, with storage capability up to two months without any particular care and reuse performance up to 63 measurements on the same electrode just prepared and 20 measurements on the one-year-old electrode subjected to redeposition. The laccase-based biosensor has been tested for catechol detection in the linear range 2-100 μM, with a limit of detection of 1.7 μM, without interference from chrome, cadmium, arsenic, and zinc and without any memory effects.

Structural changes and exposed amino acids of ethanol-modified whey proteins isolates promote its antioxidant potential

Whey protein isolates (WPI) were treated with different ethanol level (20, 40, 60, and 80%, v/v) to promote structural unfolding and subsequent aggregation. In general, protein aggregation gradually increased with increasing ethanol level in a dose-dependent manner, which was implied by notably increased turbidity and gradually decreased solubility. The formation of aggregates, which were confirmed by the results of circular dichroism spectrum and total sulfhydryl content, were promoted mainly through disulfide bonds and intra-molecular hydrogen bonds. Moreover, ethanol treated WPI (E-WPI) had significantly enhanced antioxidant activities over native WPI, which was mainly attribute to the higher contents of specific amino acids (such as hydrophobic amino acids, aromatic amino acids, and sulfur-containing amino acids), and E-WPI prepared with moderate ethanol concentration (40% in our present study) exhibited the highest antioxidant activities. These results reveal that antioxidant activities of WPI can be increased by ethanol treatment and are possibly achieved through molecular unfolding of native WPI.

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Ethanol treatment caused unfolding and aggregation of whey protein isolate (WPI).

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Aggregation enhanced with increasing ethanol concentration (EC).

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Medium EC (40%, v/v) rendered the highest antioxidant activities of WPI.

Cold Plasma Processing on Fruits and Fruit Juices: A Review on the Effects of Plasma on Nutritional Quality

This review aims to present the effects of cold plasma technology on the nutritional quality of fruits and fruit juices. This review focuses on the chemical changes induced by plasma on several bioactive compounds, such as sugars, starch, lipids, vitamins, phenolic compounds, carotenoids, and anthocyanins. The main plasma-reacting species that reacts with fruit compounds are presented and discussed. The review presents the mechanisms that lead to the improvement and degradation of the main compounds, showing both the advantages and disadvantages of cold plasma technology.

Study on preparation of acylated soy protein and stability of emulsion

BACKGROUND

Protein can be used as an emulsifier to improve emulsion stability at the interface of water-in-oil emulsion. However, natural soybean protein isolate (SPI) does not meet the high demands as an emulsifier in the food industry. The effect of acylation modification by ethylenediaminetetraacetic dianhydride (EDTAD; 0-300 g kg-1 ) on the physicochemical properties of SPI was studied.

RESULTS

The results of the Fourier transform infrared spectra analyses showed that carboxyl groups were introduced into the SPI structure by the EDTAD treatment. The carboxyl concentration of SPI was increased by 30-74.07% with an increase in EDTAD addition from 50 to 300 g kg-1 . When 150 g kg-1 EDTAD was added, the surface hydrophobicity, the emulsifying activity, and the absolute value of the zeta potential were increased by 213%, 120%, and 68% respectively, and the particle size decreased to 247 nm. The droplet size of emulsion decreased to 10 μm when pH was 6. At the same concentration of SPI and pH, the absolute value of zeta potential of the emulsion was biggest. A comparison of the emulsions during storage showed the improvement of emulsion stability was related to the increase in the zeta potential and the decrease in the average particle size. The experimental group showed no destabilization on day 21, and no obvious aggregation phenomenon was observed.

CONCLUSION

Acylation modification by EDTAD changed the emulsifying properties of SPI and enhanced the stability of the SPI emulsion. © 2021 Society of Chemical Industry.

Effect of ultrasound pretreatment on structural, physicochemical, rheological and gelation properties of transglutaminase cross-linked whey protein soluble aggregates

A solution (10%, w/v) of whey protein soluble aggregates (WPISA) was pretreated with high-intensity ultrasound (HUS, 20 kHz) for different durations (10-40 min) before incubation with transglutaminase (TGase) to investigate the effect of HUS on the structural, physicochemical, rheological, and gelation properties of TGase cross-linked WPISA. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that HUS increased the amounts of high-molecular-weight polymers/aggregates in WPISA after incubation with TGase. HUS significantly increased (P < 0.05) the degree of TGase-mediated cross-linking in WPISA, as demonstrated by a reduction in free amino group contents. HUS significantly increased (P < 0.05) the particle size, intrinsic fluorescence intensity, and surface hydrophobicity of TGase cross-linked WPISA, but had no significant impact (P > 0.05) on the zeta-potential or total free sulfhydryl group content of TGase cross-linked WPISA. The apparent viscosity and the consistency index of TGase cross-linked WPISA were significantly increased by HUS (P < 0.05), which indicated that HUS facilitated the formation of more high-molecular-weight polymers. HUS significantly increased (P < 0.05) the water holding capacity and gel strength of glucono-δ-lactone (GDL)-induced TGase cross-linked WPISA gels. The results indicated that HUS could be an efficient tool for modifying WPISA to improve its degree of TGase-mediated cross-linking, which would lead to improved rheological and gelation properties.

Impact of ozone-induced oxidation on the textural, moisture, micro-rheology and structural properties of egg yolk gels

The impact of ozone-induced oxidation on the gel properties of egg yolk was investigated for the first time in this research. The textural properties, water-holding capacity, cooking loss rate and color of the chicken egg yolk gel (CEYG) were significantly improved after ozonation. The maximum hardness value (976.04 g) was reached at 20 min of ozonation and it was 134.92 g higher than that of the natural group. Additionally, the ozone-treated yolk showed an increase of 58.47% in carbonyl content and a decrease of 44.33% in free sulfhydryl groups. The results of low-field nuclear magnetic resonance indicated that ozone promoted the conversion of free water to non-flowing water in the CEYG. Scanning electron microscopy represented that the moderate ozone treatment resulted in a more regular, continuous and smooth network structure of the CEYG. These results provided a theoretical basis for the application of ozone to improve the performance of heat-induced CEYG.

Comparative Study of Oxidative Structural Modifications of Unadsorbed and Adsorbed Proteins in Whey Protein Isolate-Stabilized Oil-in-Water Emulsions under the Stress of Primary and Secondary Lipid Oxidation Products

The impact of typical primary or secondary lipid oxidation (LPO) products, selected as linoleic acid 13-hydroperoxide (13-HPODE) and malondialdehyde (MDA), on the structural modification of unadsorbed or adsorbed proteins in whey protein isolate (WPI)-stabilized oil-in-water (O/W) emulsions during storage up to 48 h at 37 °C in the dark was investigated. The results showed that either 13-HPODE and MDA could lead to structural modifications of unadsorbed or adsorbed proteins with a concentration-dependent manner and time relationship, respectively. Moreover, higher levels of MDA rendered a higher degree of oxidative modifications of WPI than 13-HPODE, indicated by the higher protein carbonyl contents and N'-formyl-L-kynurenine (NFK) and lower fluorescence intensity. Additionally, adsorbed proteins were more easily oxidized by LPO products than unadsorbed proteins. Overall, our results indicated that the formation of secondary LPO products and the protein position were crucial factors to increase the degree of oxidative modifications of WPI in O/W emulsion systems.

Ultrasonic treatment increased functional properties and in vitro digestion of actomyosin complex during meat storage

We investigated the effects of ultrasonic treatment (400 W, 20 kHz, 45.52 W/L) and storage time (0 d, 3 d, 7 d and 10 d) on functional properties, structural changes and in vitro digestion of actomyosin complex isolated from vacuum-packed pork. As storage time increased, turbidity, surface hydrophobicity, active sulfhydryl and total sulfhydryl of actomyosin complex increased, while protein solubility decreased. Ultrasonic treatment increased surface hydrophobicity, protein solubility and active sulfhydryl content but decreased turbidity and total sulfhydryl content compared with the control. Ultrasonic treatment caused a reduction in α-helix content on 0 day and the fluorescence intensity of tryptophan and tyrosine residues. It increased pancreatin digestibility of actomyosin complex and the number of peptides of smaller than 1 kDa. However, it decreased the number of peptides. The findings provide a new insight into the application of appropriate ultrasonic treatment to promote meat digestibility.

Animal and Plant Protein Oxidation: Chemical and Functional Property Significance

Protein oxidation, a phenomenon that was not well recognized previously but now better understood, is a complex chemical process occurring ubiquitously in food systems and can be induced by processing treatments as well. While early research concentrated on muscle protein oxidation, later investigations included plant, milk, and egg proteins. The process of protein oxidation involves both radicals and nonradicals, and amino acid side chain groups are usually the site of initial oxidant attack which generates protein carbonyls, disulfide, dityrosine, and protein radicals. The ensuing alteration of protein conformational structures and formation of protein polymers and aggregates can result in significant changes in solubility and functionality, such as gelation, emulsification, foaming, and water-holding. Oxidant dose-dependent effects have been widely reported, i.e., mild-to-moderate oxidation may enhance the functionality while strong oxidation leads to insolubilization and functionality losses. Therefore, controlling the extent of protein oxidation in both animal and plant protein foods through oxidative and antioxidative strategies has been of wide interest in model system as well in in situ studies. This review presents a historical perspective of food protein oxidation research and provides an inclusive discussion of the impact of chemical and enzymatic oxidation on functional properties of meat, legume, cereal, dairy, and egg proteins based on the literature reports published in recent decades.

Atmospheric cold plasma treatment of soybean protein isolate: insights into the structural, physicochemical, and allergenic characteristics

Currently, there has been a surge of interest in revealing the interactions between plasma and food matrices. In this study, we investigated the impacts of atmospheric cold plasma (ACP) treatment on the structural, physicochemical and allergenic characteristics of soybean protein isolate (SPI). SPI dispersions were subjected to ACP treatments at different frequencies (80 to 100 Hz) and durations (1 to 10 min) to investigate the effects of exposing conditions. Results showed that ACP induced reactive oxygen species-mediated oxidation of soy proteins, resulting in modifications in the secondary and ternary structures of SPI. As a consequence, functional properties of SPI, such as emulsifying (56 to 168%, compared with control) and foaming properties (60 to 194%) were influenced by varying degrees. In addition, under certain circumstance (120 Hz, 5 min), the IgE-binding level of SPI was decreased by up to 75%, when compared to the control. Moderate treatment yielded products with improved functionality and reduced allergenicity, while extensive exposure induced a loss of vendibility due to protein aggregation. PRACTICAL APPLICATION: In this study, we demonstrated for the first time, that plasma species reacted with soybean proteins, resulting in spatial structural changes which are closely related with protein functionality and allergenicity. ACP interacts with macromolecules in aqueous systems and thus can be an alternative and promising nonthermal approach in modifying soybean proteins, whereas the exact role of different processing parameters needs to be well-elaborated.

Gaseous ozone treatment of chickpea grains, part I: Effect on protein, amino acid, fatty acid, mineral content, and microstructure

The effect of gaseous ozone (500-1000 ppm) treatment on the protein, amino acid, and fatty acid profiles, mineral content, and the microstructure of the chickpea grains were evaluated. Though protein content was not altered significantly, SDS PAGE profiling exhibited minor modifications in the protein bands of the treated chickpea. The essential amino acids (EAA) and total amino acids (TAA) slightly decreased, ratio of EAA to TAA increased, while the calculated protein efficiency ratio decreased. Significant decrease in the SH content and non-significant increase in SS content was observed at higher doses of ozone. The overall saturated and unsaturated fatty acids (%) were in the range of 13.05-13.49 and 86.51-87.61, respectively. The minerals were stable and the HCl extractability decreased in the ozonated samples. There was some minor degradation of intracellular cell wall and distribution of starch and protein bodies in the ozonated sample.