Recent approaches in physical modification of protein functionality

Improving myofibrillar proteins solubility and thermostability in low-ionic strength solution: A review

The development of myofibrillar proteins drinks (MPDs) can provide meat protein nutrition to specific groups of people. However, one major challenge is that myofibrillar proteins (MPs) are insoluble in solutions with a low ionic strength. Another functional constraint is the susceptibility of MPs to heat-induced aggregation. Currently, the primary approach used to improve the water solubility of MPs is to inhibit the assembly of myofilaments. Increasing the thermostability of MPs primarily inhibits the aggregation of myosin or oxidizes myosin to soluble substances. This review focuses on the description of several chemical and physical strategies, with an emphasis on the advantages, disadvantages, and recent progress. Under the myosin filament assembly process and the cross-linking aggregation mechanism, this summary helps improve our understanding of the solution and thermostability of MPs in low-ionic-strength solutions, thus providing new ideas to the development of MPDs.

Proteins from pseudocereal seeds: solubility, extraction, and modifications of the physicochemical and techno-functional properties

Pseudocereals (amaranth, buckwheat and quinoa) are emerging as popular gluten-free crops. This may be attributed to their wide-ranging health benefits, including antioxidant, hypoglycemic and serum-cholesterol reducing properties. Proteins of these crops have a high nutritional quality as a result of the presence of essential amino acids. Additionally, amaranth, buckwheat and quinoa proteins (AP, BP and QP, respectively) have physicochemical properties that are useful for the manufacture of different types of food. However, native pseudocereal proteins demonstrate a low solubility in water, mainly because of their composition. The major components of these proteins are albumins (water-soluble) and globulins (salt-soluble), although some proportions of glutelin (alkali-soluble) and prolamins (alcohol-soluble) are also found. The most commonly used method for extracting pseudocereal proteins is the alkaline extraction method, which may contribute to the low solubility of pseudocereal protein. Fortunately, different methods for modifying physicochemical (or techno-functional) properties have been proposed to extend their industrial application. For example, high-intensity ultrasound (HIUS) proved useful for improving the solubility of API and QP. Heating can allow for the formation of soluble aggregates of QP. The combination of heating and HIUS can improve the digestibility, solubility and foam properties of AP. Conjugation through the Maillard reaction can improve BPI and QP interfacial properties. Thus, present study provides a review of the solubility, extraction and modification of the techno-functional properties of AP, BP and QP. © 2022 Society of Chemical Industry.

Application of emerging technologies to obtain legume protein isolates with improved techno-functional properties and health effects

Current demand of consumers for healthy and sustainable food products has led the industry to search for different sources of plant protein isolates and concentrates. Legumes represent an excellent nonanimal protein source with high-protein content. Legume species are distributed in a wide range of ecological conditions, including regions with drought conditions, making them a sustainable crop in a context of global warming. However, their use as human food is limited by the presence of antinutritional factors, such as protease inhibitors, lectins, phytates, and alkaloids, which have adverse nutritional effects. Antitechnological factors, such as fiber, tannins, and lipids, can affect the purity and protein extraction yield. Although most are removed or reduced during alkaline solubilization and isoelectric precipitation processes, some remain in the resulting protein isolates. Selection of appropriate legume genotypes and different emerging and sustainable facilitating technologies, such as high-power ultrasound, pulsed electric fields, high hydrostatic pressure, microwave, and supercritical fluids, can be applied to increase the removal of unwanted compounds. Some technologies can be used to increase protein yield. The technologies can also modify protein structure to improve digestibility, reduce allergenicity, and tune technological properties. This review summarizes recent findings regarding the use of emerging technologies to obtain high-purity protein isolates and the effects on techno-functional properties and health.

Pea protein composition, functionality, modification, and food applications: A review

The demand for proteins continues to increase due to their nutritional benefits, the growing world population, and rising protein deficiency. Plant-based proteins represent a sustainable source to supplement costly animal proteins. Pea (Pisum sativum L.) is one of the most produced plant legume crops in the world and contributes to 26% of the total pulse production. The average protein content of pea is about 20%-25%. The commercial utilization of pea proteins is limited, partially due to its less desirable functionalities and beany off-flavor. Protein modification may change these properties and broaden the application of pea proteins in the food industry. Functional properties such as protein solubility, water and oil holding capacity, emulsifying/foaming capacity and stability, and gelation can be altered and improved by enzymatic, chemical, and physical modifications. These modifications work by affecting protein chemical structures, hydrophobicity/hydrophilicity balance, and interactions with other food constituents. Modifiers, reaction conditions, and degree of modifications are critical variables for protein modifications and can be controlled to achieve desirable functional attributes that may meet applications in meat analogs, baking products, dressings, beverages, dairy mimics, encapsulation, and emulsions. Understanding pea protein characteristics will allow us to design better functional ingredients for food applications.

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.

Functional modification of grain proteins by dual approaches: Current progress, challenges, and future perspectives

Protein modification is a practical strategy to enhance the functional characteristics of proteins and broaden their commercial applications. Various chemical (e.g., pH-shifting, deamidation, succinylation), physical (e.g., sonication, high-speed shearing), or biological (e.g., microbial transglutaminase cross-linking, enzymatic hydrolysis) modification methods have frequently been employed to improve the functionality of native grain proteins. However, progress in intensification has led to the emergence of advanced methodologies, which involve the combination of modification techniques, generally known as "Dual Modification". This paper aims to comprehensively review the most recent researches focusing on the effects of dual modification on the functionality of grain proteins. Particular emphasis is given to elucidate the impact of this technique on physicochemical and structural properties. Furthermore, existing challenges and limitations associated with the utilization of this approach are highlighted, and prospects are proposed.

Influence of Emerging Technologies on the Utilization of Plant Proteins

Protein from plant sources is claimed alternatives to animal sources in the human diet. Suitable protein sources need high protein digestibility and amino acid bioavailability. In terms of protein functionality and food applications, they also need high-quality attributes, such as solubility, gelling, water- and oil-holding capacities, emulsifying, and foaming. Thermal processing can improve the nutritional quality of plants with some disadvantages, like reducing the assimilation of micronutrients (vitamins and minerals). Emerging technologies-such as ultrasound, high-pressure, ohmic heating, microwave, pulsed electric field, cold plasma, and enzymatic processes-can overcome those disadvantages. Recent studies demonstrate their enormous potential to improve protein techno-functional properties, protein quality, and decrease protein allergenicity. However, the literature lacks a broader evaluation, including protein digestibility, industrial-scale optimization, and exploring applications to these alternative protein sources.

Effect of Dietary Protein and Processing on Gut Microbiota-A Systematic Review

The effect of diet on the composition of gut microbiota and the consequent impact on disease risk have been of expanding interest. The present review focuses on current insights of changes associated with dietary protein-induced gut microbial populations and examines their potential roles in the metabolism, health, and disease of animals. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol was used, and 29 highly relevant articles were obtained, which included 6 mouse studies, 7 pig studies, 15 rat studies, and 1 in vitro study. Analysis of these studies indicated that several factors, such as protein source, protein content, dietary composition (such as carbohydrate content), glycation of protein, processing factors, and protein oxidation, affect the digestibility and bioavailability of dietary proteins. These factors can influence protein fermentation, absorption, and functional properties in the gut and, consequently, impact the composition of gut microbiota and affect human health. While gut microbiota can release metabolites that can affect host physiology either positively or negatively, the selection of quality of protein and suitable food processing conditions are important to have a positive effect of dietary protein on gut microbiota and human health.

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.

Starch granule size: Does it matter?

Nature has developed starch granules varying in size from less than 1 μm to more than 100 μm. The granule size is an important factor affecting the functional properties and the applicability of starch for food and non-food applications. Within the same botanical species, the range of starch granule size can be up to sevenfold. This review critically evaluated the biological and environmental factors affecting the size of starch granules, the methods for the separation of starch granules and the measurement of size distribution. Further, the structure at different length scales and properties of starch-based on the granule size is elucidated by specifying the typical applications of granules with varying sizes. An amylopectin cluster model showing the arrangement of amylopectin from inside toward the granule surface is proposed with the hypothesis that the steric hindrance for the growth of lamellar structure may limit the size of starch granules.

Two Statistical Tools for Assessing Functionality and Protein Characteristics of Different Fava Bean (Vicia faba L.) Ingredients

Fava bean (Vicia faba L.) is a promising source of proteins that can be potentially used as nutritional and/or functional agents for industrial food applications. Fava ingredients are industrially produced, modified, and utilized for food applications. Their processing conditions influence physico-chemical protein properties that further impact ingredient functionality. To design a functionally suitable ingredient, an understanding of the interrelationships between different properties is essential. Hence, this work aimed to assess two statistical analytical tools, Pearson’s correlation and Principal Component Analysis (PCA), for investigating the role of the process conditions of fava ingredients on their functional and protein properties. Fava concentrates were processed by pH (2, 4, 6.4 and 11), temperature (55, 75 and 95 °C) and treatment duration (30 and 360 min) into different modified ingredients. These were utilized under two application conditions (pH 4 and 7), and their foam and emulsion properties as well as their ingredient characteristics (charge, solubility, and intrinsic fluorescence) were measured. The results show that foam and emulsion properties are not correlated to each other. They are associated with different protein and non-protein attributes as fava concentrate is a multi-component matrix. Importantly, it is found that the results from the two statistical tools are not fully comparable but do complement each other. This highlights that both statistical analytical tools are equally important for a comprehensive understanding of the impact of process conditions on different properties and the interrelationships between them. Therefore, it is recommended to use Pearson’s correlation and principal component analysis in future investigations of new plant-based proteins.

A comprehensive review on impact of non-thermal processing on the structural changes of food components

Non-thermal food processing is a viable alternative to traditional thermal processing to meet customer needs for high-quality, convenient and minimally processed foods. They are designed to eliminate elevated temperatures during processing and avoid the adverse effects of heat on food products. Numerous thermal and novel non-thermal technologies influence food structure at the micro and macroscopic levels. They affect several properties such as rheology, flavour, process stability, texture, and appearance at microscopic and macroscopic levels. This review presents existing knowledge and advances on the impact of non-thermal technologies, for instance, cold plasma treatment, irradiation, high-pressure processing, ultrasonication, pulsed light technology, high voltage electric field and pulsed electric field treatment on the structural changes of food components. An extensive review of the literature indicates that different non-thermal processing technologies can affect the food components, which significantly affects the structure of food. Applications of novel non-thermal technologies have shown considerable impact on food structure by altering protein structures via free radicals or larger or smaller molecules. Lipid oxidation is another process responsible for undesirable effects in food when treated with non-thermal techniques. Non-thermal technologies may also affect starch properties, reduce molecular weight, and change the starch granule's surface. Such modification of food structure could create novel food textures, enhance sensory properties, improve digestibility, improve water-binding ability and improve mediation of gelation processes. However, it is challenging to determine these technologies' influence on food components due to differences in their primary operation and equipment design mechanisms and different operating conditions. Hence, to get the most value from non-thermal technologies, more in-depth research about their effect on various food components is required.

The non-covalent interaction between two polyphenols and caseinate as affected by two types of enzymatic protein crosslinking

Caseinate was crosslinked by horseradish peroxidase (HRP) or microbial transglutaminase (TGase) and mixed with kaempferol and quercetin at 293-313 K (i.e. 20-40 °C), respectively. Generally, these two polyphenols dose-dependently induced fluorescent quenching in caseinate or its crosslinked products via a static mechanism, while enzymatic crosslinking endowed caseinate with higher affinity for the polyphenols with increased apparent binding constants [(9.94-168.77) × 10⁵versus (4.92-6.53) × 10⁵ L/mol], unchanged binding site number and slightly shortened binding distance. To form protein-polyphenol complexes, hydrophobic force was the main driving force for the HRP-crosslinked caseinate and unreacted caseinate, while hydrogen-bonds and van der Waals force were the main driving forces for the TGase-crosslinked caseinate. Overall, quercetin was more potent than kaempferol to bind to the proteins, while TGase-mediated caseinate crosslinking induced the highest affinity to the polyphenols with the largest ΔG decrease. Thus, two types of crosslinking impacted the driving forces, apparent binding constant and thermodynamic indices of caseinate-polyphenol interaction.

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.

Recent advances in the application of ultrasound in dairy products: Effect on functional, physical, chemical, microbiological and sensory properties

Alternative methods for improving traditional food processing have increased in the last decades. Additionally, the development of novel dairy products is gaining importance due to an increased consumer demand for palatable, healthy, and minimally processed products. Ultrasonic processing or sonication is a promising alternative technology in the food industry as it has potential to improve the technological and functional properties of milk and dairy products. This review presents a detailed summary of the latest research on the impact of high-intensity ultrasound techniques in dairy processing. It explores the ways in which ultrasound has been employed to enhance milk properties and processes of interest to the dairy industry, such as homogenization, emulsification, yogurt and fermented beverages production, and food safety. Special emphasis has been given to ultrasonic effects on milk components; fermentation and spoilage by microorganisms; and the technological, functional, and sensory properties of dairy foods. Several current and potential applications of ultrasound as a processing technique in milk applications are also discussed in this review.

A review on protein extracts from sunflower cake: techno-functional properties and promising modification methods

De-oiled sunflower cake is a sustainable and promising protein source with high phenolic and fiber contents. The cake, which is an industrial by-product has been the subject of many studies investigating various aspects such as protein extraction, functional properties, interaction with other ingredients, and its performance in a wide range of food products. Innovative and conventional techniques of protein extraction from sunflower cake have been investigated to increase extraction yield and improve desired functional characteristics. Modulation of structure of plant-based proteins helps to control their techno-functional properties and widen their applications. Structure modification of proteins by physical methods including ultrasound treatment and gamma irradiation as well as enzymatic and chemical methods has been used to improve the functional properties of sunflower protein. This review collects and critically discusses the available information on techno-functional properties of protein extracts from sunflower cake and how its techno-functional properties can be tailored using various structure modification methods.

Optimization of High Hydrostatic Pressure Treatments on Soybean Protein Isolate to Improve Its Functionality and Evaluation of Its Application in Yogurt

This work aimed to improve the functional properties of soybean protein isolate (SPI) by high hydrostatic pressure (HHP) and develop SPI incorporated yogurt. Response surface methodology (RSM) was used to optimize the HHP treatment parameters, including pressure, holding time, and the ratio of SPI/water. Water holding capacity, emulsifying activity index, solubility, and hardness of SPI gels were evaluated as response variables. The optimized HPP treatment conditions were 281 MPa of pressure, 18.92 min of holding time, and 1:8.33 of SPI/water ratio. Water and oil holding capacity, emulsifying activity, and stability of SPI at different pH were improved. Additionally, relative lipoxygenase (LOX) activity of HHP treated SPI (HHP-SPI) was decreased 67.55 ± 5.73%, but sulphydryl group content of HHP-SPI was increased 12.77%, respectively. When incorporating 8% of SPI and HHP-SPI into yogurt, the water holding capacity and rheological properties of yogurt were improved in comparison with yogurt made of milk powders. Moreover, HHP-SPI incorporated yogurt appeared better color and flavor.

The improvement of gel and physicochemical properties of porcine myosin under low salt concentrations by pulsed ultrasound treatment and its mechanism

The effects of pulsed ultrasound treatment (250 W, 0-12 min) on gel and physicochemical properties of porcine myosin at low-salt group (0.3 mol/L) and control groups (0.6 and 0.9 mol/L) were investigated. The texture and water holding capacity (WHC) of low-salt group gel were remarkably lower than in medium-salt (0.6 mol/L) and high-salt group (0.9 mol/L). However, 6-min ultrasound treatment could obviously improve the texture and WHC of low-salt group gel. After ultrasound treatment, the protein solubility was increased, as the degree of protein aggregation was reduced. Simultaneously, ultrasound treatment led to unfolding of protein structure and increasing surface hydrophobicity. The three-dimensional network of myosin gel gradually became uniform by 6-min ultrasound treatment. Under 12-min ultrasound treatment, the protein aggregated excessively during the gelation, which led to the deterioration of gel quality. These results suggested that moderate ultrasound treatment is promising to be used to enhance the quality of salt-reduced meat products.

Glycation of Plant Proteins Via Maillard Reaction: Reaction Chemistry, Technofunctional Properties, and Potential Food Application

Plant proteins are being considered to become the most important protein source of the future, and to do so, they must be able to replace the animal-derived proteins currently in use as techno-functional food ingredients. This poses challenges because plant proteins are oftentimes storage proteins with a high molecular weight and low water solubility. One promising approach to overcome these limitations is the glycation of plant proteins. The covalent bonding between the proteins and different carbohydrates created via the initial stage of the Maillard reaction can improve the techno-functional characteristics of these proteins without the involvement of potentially toxic chemicals. However, compared to studies with animal-derived proteins, glycation studies on plant proteins are currently still underrepresented in literature. This review provides an overview of the existing studies on the glycation of the major groups of plant proteins with different carbohydrates using different preparation methods. Emphasis is put on the reaction conditions used for glycation as well as the modifications to physicochemical properties and techno-functionality. Different applications of these glycated plant proteins in emulsions, foams, films, and encapsulation systems are introduced. Another focus lies on the reaction chemistry of the Maillard reaction and ways to harness it for controlled glycation and to limit the formation of undesired advanced glycation products. Finally, challenges related to the controlled glycation of plant proteins to improve their properties are discussed.

Exploring the Effect of Pulsed Electric Fields on the Technological Properties of Chicken Meat

Pulsed electric field (PEF) is a non-thermal technology which is increasingly drawing the interest of the meat industry. This study aimed at evaluating the effect of PEF on the main technological properties of chicken meat, by investigating the role of the most relevant process parameters such as the number of pulses (150 vs. 300 and 450 vs. 600) and the electric field strength (0.60 vs. 1.20 kV/cm). Results indicated that PEF does not exert any effect on meat pH and just slightly affects lightness and yellowness. Low-intensity PEF treatments improved the water holding capacity of chicken meat by significantly (p < 0.001) reducing drip loss up to 28.5% during 4 days of refrigerated storage, without damaging proteins' integrity and functionality. Moreover, from the analysis of the process parameters, it has been possible to highlight that increasing the number of pulses is more effective in reducing meat drip loss rather than doubling the electric field strengths. From an industrial point of view, the results of this explorative study suggested the potential of PEF to reduce the undesired liquid inside the package, thus improving consumer acceptance.

Methods for the Modification and Evaluation of Cereal Proteins for the Substitution of Wheat Gluten in Dough Systems

The substitution of wheat gluten in the food industry is a relevant research area because the only known treatment for celiac disease is abstinence from this protein complex. The use of gluten-free cereals in dough systems has demonstrated that the viscoelastic properties of gluten cannot be achieved without the modification of the protein fraction. The quality of the final product is determined by the ability of the modification to form a matrix similar to that of gluten and to reach this, different methods have been proposed and tested. These procedures can be classified into four main types: chemical, enzymatic, physical, and genetic. This article provides a comprehensive review of the most recent research done in protein modification of cereal and pseudocereals for gluten substitution. The reported effects and methodologies for studying the changes made with each type of modification are described; also, some opportunity areas for future works regarding the study of the effect of protein modifications on gluten-free products are presented.

Fava bean (Vicia faba L.) for food applications: From seed to ingredient processing and its effect on functional properties, antinutritional factors, flavor, and color

The food industry, along with the consumers, is interested in plant-based diet because of its health benefits and environmental sustainability. Vicia faba L. (V. faba) is a promising source of pulse proteins for the human diet and can yield potential nutritional and functional ingredients, namely, flours, concentrates, and isolates, which are relevant for industrial food applications. Different processes produce and functionalize V. faba ingredients relevant for industrial food applications, along with various alternatives within each unit operation used in their production. Processing modifies functional properties of the ingredients, which can occur by (i) changing in overall nutritional composition after processing steps and/or (ii) modifying the structure and conformation of protein and of other components present in the ingredients. Furthermore, V. faba limitations due to off-flavor, color, and antinutritional factors are influenced by ingredient production and processing that play a significant role in their consumer acceptability in foods. This review attempts to elucidate the influence of different ways of processing on the functional, sensory, and safety aspects of V. faba L. ingredients, highlighting the need for further research to better understand how the food industry could improve their utilization in the market.