Food protein functionality: A comprehensive approach

Role of amino groups in the structural assembly of β-lactoglobulin nanofibers

In recent years, protein fibrillation has attracted extensive attention because of self-assembly mechanism. The structure of β-lactoglobulin (β-Lg) nanofibers, with all residues visible in the fibril core, remains elusive, and the mechanisms of side-chain interactions are poorly understood, complicating our understanding of their formation. Here, we identified 31 core building blocks of the full-length structure of β-Lg nanofibers via enzymatic hydrolysis combined with proteomic methods. Notably, all core building blocks included essential nonsecondary structural residues were crucial for maintaining cross-β structure. Amino groups were the main groups that stabilized the interstrand and intersheet stacking in the cross-β structure, and their absence resulted in nanofibers exhibiting a preference for lateral growth and a looser cross-β structure with increased interstrand and intersheet distances. Meanwhile, the number of nanofibers decreased by approximately 20.39 %, the kinetic self-assembly rate decreased, and the thermodynamic assembly energy-barrier increased, particularly during the lag phase of fibrillation. The position and quantity of amino groups affected the core building blocks of β-Lg nanofibers: 27 core building blocks were changed, and 9 core building blocks were lost in the absence of amino groups, severely inhibiting the conversion of α-helices to β-strands during β-Lg fibrillation. These results may provide new approaches and important information for revealing the assembly mechanism of nanofibers at the molecular level.

Effects of heat treatment on the binding between the key aroma-active compounds in Zanthoxylum bungeanum oil and pork myofibrillar proteins (MPs)

The mechanism underlying effective binding between the aroma compounds in Zanthoxylum bungeanum oil and pork, especially during heating, remains unclear, restricting accurate regulation of numbing flavor in meat dishes. Therefore, this study investigated the effects of heating on the binding between pork myofibrillar proteins (MPs) and four key aroma-active compounds in Zanthoxylum bungeanum oil and the related mechanism. Results showed that higher temperatures within 70-90 °C induced larger particle sizes and zeta potential values of MPs while reducing endogenous fluorescence. The surface hydrophobicity and secondary structure increased when heating to 80 °C and subsequently declined. Besides aroma compounds, these structural changes of MPs also affected their affinity for aromatic compounds. Higher binding percentages were observed in 2,3-butanediol (36 %-90 %) and linalyl acetate (12 %-55 %), while heating at 80 °C increased their binding amounts. Further correlation analysis and molecular docking revealed that these aroma compounds primarily bound with MPs via hydrogen bonding and various hydrophobic interactions.

Enhancing emulsification properties of pea protein isolate: Impact of heat treatment and soy hull polysaccharides on conformational modification and stability

In order to investigate the effect of conformational change in pea protein isolate (PPI) on its emulsification properties, soy hull polysaccharides (SHP) were added to modify the conformation following heat treatment at 70-100 °C to improve emulsification. The results of UV and fluorescence spectroscopy indicated that the heat treatment exposed the amino acid residues to a more hydrophobic environment. The mean volume diameter (d4,3) of PPI was reduced from 67.25 ± 3.31 to 45.50 ± 0.62 μm, and secondary structure of protein became more ordered. The addition of SHP enhanced the adsorption of protein at the oil-water interface and reduced the interfacial tension. Interestingly, SHP decreased the short-term (12h) thermal stability index (TSI) from 3.5 to 2.8 in PPI/SHP emulsion treated at 100 °C. These findings validated that heat treatment combined with SHP modification can improve the emulsification of PPI, which positively impacts the development of pea-based products for high temperatures applications.

A Review of Processing Techniques and Rheological Properties of Yogurts

The rheology of yogurt, a critical factor influencing its texture, stability, and sensory appeal from production to consumption is explored in this review. Yogurt undergoes a transformation from a Newtonian liquid to a non-Newtonian thixotropic gel during fermentation, a process shaped by factors such as milk source, starter culture, and fat content. Recent advances in non-thermal treatments, such as ultrasound, microfiltration, high-pressure processing (HPP), and ultraviolet C (UV-C) light treatment, promise to enhance nutritional and sensory qualities of yogurt. Additionally, incorporating herbs and fruits into yogurt not only diversifies consumer options but also affects its texture, viscosity, and overall mouthfeel. The review examines how different yogurt styles-set, stirred, Greek, and drinkable-develop unique textures through varied production processes. Advances in rheological techniques and microstructural analysis have deepened our understanding of the interactions between proteins and fat globules, providing insights into the complex gel network of yogurt. Despite significant progress, further research is needed in areas such as non-destructive rheological testing during production, the impact of extended storage, and the development of plant-based yogurt alternatives. The insights are valuable for the dairy industry to support innovation and meet growing consumer demands.

Enhanced solubility, stability, bioaccessibility, and antioxidant activity of curcumin with hydrolyzed pea protein-based nano-micelles: pH-driven method vs ethanol-induced method

Pea protein nano-micelles gained with partial hydrolysis by a proteolytic enzyme (Protamex) were employed as nanocarriers to encapsulate and stabilize liable and hydrophobic curcumin (CUR) with two various methods (pH-driven method (PDM) and ethanol-induced method (EIM)). Both CUR-loaded pea protein hydrolysates (PPHs) nano-micelles by PDM and EIM exhibited spherical shapes, and uniform particle size distributions. Highest CUR loading amount (3.21 %) was gained with PPHs by PDM. The interaction between PPHs nano-micelles and curcumin was comprehensively examined with optical spectroscopy. These outcomes obviously demonstrated the water solubility, storage stability against UV light and heating, bioaccessibility and in vitro antioxidant activity of CUR can be pronouncedly enhanced with PPHs-based nanocarriers. Interestingly, PPHs-CUR nano-micelles fabricated with PDM have higher loading amount, light stability, and better bioaccessibility as well as antioxidant activity than those by EIM. These results clearly show that PDM may be a better method than EIM and provide useful information in nutraceuticals encapsulation with vegetable proteins-based delivery systems.

Stabilization and extraction of alfalfa (Medicago sativa) protein following multiple postharvest processing techniques coupled with protease inactivation

There is an ever-increasing demand for novel plant proteins that are non-allergenic, nutritionally complete, adequately functional, and can be sustainably sourced. RuBisCo is a protein that fulfills these requirements and can be sourced from alfalfa (Medicago sativa). Therefore, this study investigated several techniques to adequately extract alfalfa protein. Protein extraction from commercial sun-dried alfalfa was largely unsuccessful (≤ 5 % protein yield) due to endogenous proteolytic activity. Flash freezing of freshly harvested alfalfa followed by juicing and freeze drying (FF/J/FD) effectively preserved protein integrity with 12 % degree of hydrolysis (%DH) compared to 20 % DH in the oven dried (OD) sample. However, the FF/J/FD sample had significantly higher protease activity than the OD sample (26 vs. 11 Units/g protein). A combined acid (pH 3.0) and thermal (95 °C) treatment reduced protease activity to a negligible level in both FF/J/FD and FF/J/spray dried (FF/J/SD) samples. Protein extraction utilizing FF/J/FD sample subjected to acid/thermal protease inactivation was relatively successful with 32 % protein yield and 74 % protein purity. Protein polymerization due to thermal treatment contributed to reduced protein yield. This work provided not only foundational basis to determine the best post-harvest management practices to control proteolysis in alfalfa, but also essential information that will guide future attempts at protein extraction from green biomass to produce valuable protein ingredients for various food applications.

Elucidating the role of compositional and processing variables in tailoring the technological functionalities of plant protein ingredients

Although various plant protein (PP) ingredients are available on the market, their application in foods is not trivial, and food companies are struggling to identify PP ingredients fitting the intended use. To fill this gap, abundant literature has appeared but data are hardly comparable due to the absence of a recognized classification of PP ingredients accounting not only for protein purity but also for the process history, and of standardised protocols for technological functionality assessment. In this review, a comprehensive analysis of comparable literature data was thus carried out to elucidate the effect of composition and processing variables on PP technological functionalities. The review presents four sections describing: (i) the approach followed for the construction of a database of PP ingredient functionalities; (ii) the composition and processing factors relevant to PP ingredients; (iii) PP ingredient functional properties and methods used for their determination; (iv) the effect of composition and processing factors on PP ingredient functionalities. This analysis showed legume proteins to present the highest solubility and interfacial properties while pseudocereal ones the highest water-holding capacity. Although pure ingredients show higher functionalities, non-protein components could contribute to interfacial properties. Alkaline extraction, isoelectric precipitation and freeze-drying is the process mostly used in academic research to obtain PP ingredients. However, other extraction, purification, and drying methods can be properly combined, resulting in specific PP ingredient functionalities. Overall, this review highlights that, besides protein purity and source, knowledge of the processing history is required to select PP ingredients with desired functionalities.

Modification approaches of walnut proteins to improve their structural and functional properties: A review

Walnut protein has a high gluten content and compact structure, which limits its water solubility and affects its applications. Therefore, improving the sustainability of walnut proteins is an urgent issue that must be addressed. Physical modification can directly alter the structure of walnut proteins, leading to enhanced functional properties. Chemical modifications typically involve the introduction of exogenous substances that react with walnut proteins to obtain novel products with improved processing attributes. As a highly specific modification technique, biomodification uses enzymes or microorganisms to break down walnut proteins into small peptide molecules or cross-link them to form soluble polymers, thereby enhancing their functional properties and bioactivity. This review presents various methods for modifying walnut proteins and their effects on the structure and functional properties of walnut proteins. The challenges associated with the application and development of these unique technologies are also discussed.

Emulsifying properties of quinoa protein fibrillar aggregates and their influence on quinoa protein emulsion gel formation

Fibrillization is a potential approach to improving functionality of seed storage proteins. Herein, the solubility, morphology, wettability, interfacial adsorption and emulsifying properties of quinoa protein fibrillar aggregates were compared with those of quinoa protein isolate (QPI). Effect of fibrillar aggregates on the formation of heat-induced QPI emulsion gels was investigated in the presence 0 or 100 mM NaCl. The results showed that fibrillization enhanced the relative solubility of QPI by ∼10 %, and reduced the contact angle from 130.5° to 83.4°. Both QPI and fibrillar aggregates exhibited outstanding emulsifying capacity and emulsion stability, preventing flocculation/coalescence. The interfacial protein concentration of fibrillar aggregate-stabilized emulsions was higher than that of QPI-stabilized emulsions, ranging from 16.3 to 33.4 vs. 12.4 to 29.2 mg/m2 at emulsifier concentrations of 0.5-3 % w/w. The self-standing emulsion gels were formed by heating 10 % w/w QPI emulsions with a storage modulus of 1886 Pa and a fracture stress of 582 Pa. Fibrillar aggregates acted as active fillers in QPI emulsions gels (8 % w/w QPI + 2 % w/w fibrillar aggregates) with a storage modulus of 2566 Pa and a fracture stress of 741 Pa. However, the addition of 100 mM NaCl destructed the gel network, leading to a reduction of gel strength.

Impact of genotypic variation and cultivation conditions on the techno-functional characteristics and chemical composition of 25 new Canadian quinoa cultivars

The utilization of quinoa in food production requires comprehensive information on its processing characteristics. Twenty-five new quinoa cultivars developed by the Northern Quinoa Breeding Program, grown in three Canadian locations over two seasons, were characterized for their proximate composition, pasting properties, thermal properties, water absorption index, water solubility index, foaming capacity, foaming stability, oil holding capacity, and emulsion activity crucial for potential food applications. Results showed significant variations in the proximate composition among the cultivars, which was also influenced by the growing location and harvest year. Significant differences (p < 0.05) were also observed in the pasting properties, thermal stability, hydration properties, foaming properties, oil holding capacity, and emulsion activity. The hierarchical cluster and principal component analyses were associated with five distinct clusters of quinoa cultivars, each with unique techno-functional attributes, suggesting their potential for different food applications. These findings emphasize the need for further research to explore the performance of quinoa flours in specific food products and their impact on end-product quality.

Changes of structural characteristics, functional properties and volatile compounds of Tenebrio molitor larvae protein after sustainable defatting process: Influence of the different volume ratios of n-hexane to ethanol

This work aimed to study the effect of defatting via the mixture of n-hexane and ethanol under different volume ratio on the changes of structural characteristics, functional properties and volatile compounds of Tenebrio molitor larvae protein (TMLP). The results showed that 1:0.6 vol ratio of n-hexane to ethanol rendered the highest defatting rate (P < 0.05), as well as led to the highest EAA/AA contents, sulfhydryl contents, surface hydrophobicity, solubility, water/oil holding capacities and emulsifying properties of TMLP (P < 0.05). However, higher volume ratio of n-hexane to ethanol led to negative impacts on functionalities of TMLP. Moreover, the contents of aldehydes and hydrocarbons which rendered off-flavour to TMLP significantly decreased with the increasing volume ratio of n-hexane to ethanol (P < 0.05), while the contents of pleasure flavour (hydrocarbons and ester compounds) were obviously enhanced. This study provides an eco-friendly defatting method on the processing of TMLP with superior quality attributes.

The composition, extraction, functional property, quality, and health benefits of coconut protein: A review

Coconut is widely appreciated for its distinctive flavor and is commonly utilized in the production of a variety of goods. Coconut protein, a by-product derived from coconut oil and coconut milk cake, is frequently underutilized or discarded. This study provides a comprehensive overview of the distribution and composition of coconut protein. Analyses reveal that coconut protein, specifically 11S globulin and 7S globulin, is predominantly found in coconut flesh. Furthermore, various extraction techniques for coconut protein, such as chemical, enzymatic, and physical methods, are discussed. The alkali dissolution and acid precipitation methods are widely utilized for extracting coconut protein, with the potential for enhancement through the incorporation of physical methods such as ultrasound. The evaluation of functional properties, quality, and health benefits of coconut protein is essential, given the limitations imposed by its solubility. Modification may be necessary to optimize its functional properties. Coconut presents a promising source of food protein, characterized by balanced amino acid composition, high digestibility, and low allergenic potential. In conclusion, this study provides a comprehensive overview of the extraction methods, functional properties, quality, and nutritional benefits of coconut protein, offering insights for potential future research directions in the field. Additionally, the information presented may serve as a valuable reference for incorporating coconut protein into plant-based food products.

Optimization and Preparation of Ultrasound-Treated Whey Protein Isolate Pickering Emulsions

This study aimed to create Pickering emulsions with varying oil fractions and assess the impact of ultrasonic treatment on the properties of Whey Protein Isolates (WPIs). At 640 W for 30 min, ultrasound reduced WPI aggregate size, raised zeta potential, and improved foaming, emulsifying, and water-holding capacities. FTIR analysis showed structural changes, while fluorescence and hydrophobicity increased, indicating tertiary structure alterations. This suggests that sonication efficiently modifies WPI functionality. Under ideal conditions, φ = 80 emulsions were most stable, with no foaming or phase separation. Laser scanning revealed well-organized emulsions at φ = 80. This study provides a reference for modifying and utilizing WPI.

Blue food proteins: Novel extraction technologies, properties, bioactivities and applications in foods

With the growing demand for healthy and sustainable food, blue food proteins have emerged as an important way to address resource-intensive production and environmental concerns. This paper systematically reviewed the extraction technologies, properties and bioactivities of blue food proteins and explored their wide range of applications. The novel extraction technologies not only improve the extraction efficiency of the proteins, shorten the production time and have environmental advantages, but also enhance the protein properties and facilitate subsequent applications. The amino acid composition of the blue food proteins is close to the FAO recommended standard and better than most of the livestock proteins, with excellent solubility and water holding capacity. Some of the proteins also have significant bioactivity and show great potential for improving health. Applications include emulsions, protein films, microcapsules, food colorants, dietary supplements, 3D printing materials, and cultured meat. This paper provides theoretical support for further research and application of blue food proteins and promotes their wider application in future food products.

Legumes as an alternative protein source in plant-based foods: Applications, challenges, and strategies

Since animal proteins may pose a threat to the global environment and human health, the development of alternative proteins has become an inevitable trend in the future. Legumes are considered to be one of the most promising sources of sustainable alternative animal proteins. Legume proteins are considered to exhibit excellent processing properties, including emulsification, gelation, and foaming, which have led to their widespread use in the food industry. Moreover, legume proteins are not only taken as substitutes for meat proteins, they also play an essential role in novel plant-based foods (meat, dairy, fermented food, and fat). However, there are few comprehensive overview studies on the application of legume proteins in plant-based foods. Therefore, this review provides a general overview of the main sources, functional properties, and applications in plant-based foods of legume proteins. In addition, challenges to the application of legume proteins in plant-based foods and specific strategies to address these challenges are presented. The review may provide some references for the further application of legume proteins in novel plant-based foods.

Toward Diverse Plant Proteins for Food Innovation

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

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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

Composite hydrogels assembled from food-grade biopolymers: Fabrication, properties, and applications

Biopolymer hydrogels have a broad range of applications as soft materials in a variety of commercial products, including foods, cosmetics, agrochemicals, personal care products, pharmaceuticals, and biomedical products. They consist of a network of entangled or crosslinked biopolymer molecules that traps relatively large quantities of water and provides semi-solid properties, like viscoelasticity or plasticity. Composite biopolymer hydrogels contain inclusions (fillers) to enhance their functional properties, including solid particles, liquid droplets, gas bubbles, nanofibers, or biological cells. These fillers vary in their composition, size, shape, rheology, and surface properties, which influences their impact on the rheological properties of the biopolymer hydrogels. In this article, the various types of biopolymers used to fabricate composite hydrogels are reviewed, with an emphasis on edible proteins and polysaccharides from sustainable sources, such as plants, algae, or microbial fermentation. The different kinds of gelling mechanism exhibited by these biopolymers are then discussed, including heat-, cold-, ion-, pH-, enzyme-, and pressure-set mechanisms. The different ways that biopolymer molecules can organize themselves in single and mixed biopolymer hydrogels are then highlighted, including polymeric, particulate, interpenetrating, phase-separated, and co-gelling systems. The impacts of incorporating fillers on the rheological properties of composite biopolymer hydrogels are then discussed, including mathematical models that have been developed to describe these effects. Finally, potential applications of composite biopolymer hydrogels are presented, including as delivery systems, packaging materials, artificial tissues, wound healing materials, meat analogs, filters, and adsorbents. The information provided in this article is intended to stimulate further research into the development and application of composite biopolymer hydrogels.

Pulsed Electric Fields Effects on Proteins: Extraction, Structural Modification, and Enhancing Enzymatic Activity

Pulsed electric field (PEF) is an innovative physical method for food processing characterized by low energy consumption and short processing time. This technology represents a sustainable procedure to extend food shelf-life, enhance mass transfer, or modify food structure. The main mechanism of action of PEF for food processing is the increment of the permeability of the cell membranes by electroporation. However, it has also been shown that PEF may modify the technological and functional properties of proteins. Generating a high-intensity electric field necessitates the flow of an electric current that may have side effects such as electrochemical reactions and temperature increments due to the Joule effect that may affect food components such as proteins. This article presents a critical review of the knowledge on the extraction of proteins assisted by PEF and the impact of these treatments on protein composition, structure, and functionality. The required research for understanding what happens to a protein when it is under the action of a high-intensity electric field and to know if the mechanism of action of PEF on proteins is different from thermal or electrochemical effects is underlying.

Food Proteins as Functional Ingredients in the Management of Chronic Diseases: A Concise Review

Chronic diseases have emerged as a formidable global health concern, with their prevalence steadily rising over the years. Several approaches to addressing these concerns include the use of medications, which are often expensive, contain synthetic chemical substances, and have reported adverse effects. The use of foods, especially proteins, as an alternative approach to addressing chronic health concerns by treating and managing chronic diseases is increasing. This review evaluates the intriguing role of food proteins in mitigating chronic diseases and improving our understanding of the therapeutic potential of different protein types, including those derived from legumes, nuts, and seeds, dairy, fish, and numerous other sources. They have been reported to offer promising avenues for managing chronic diseases, including cardiovascular diseases, diabetes, chronic inflammation, weight management, bone health, glycemic control, muscle preservation, and many other health benefits. Although the exact mechanisms for these actions are still not properly elucidated, it is, however, understood that food proteins exert these health-beneficial effects by their unique nutritional and bioactive profiles, especially their bioactive peptides and amino acids. Practical applications are also discussed, including dietary interventions that are tailored towards incorporating protein-rich foods and the development of functional foods for disease prevention and management. Food proteins are a promising approach to combating chronic diseases that can turn around public health practices.

Compatibility of pulse protein in the formulation of plant based yogurt: a review of nutri-functional properties and processing impact

With the increased environmental concerns and health awareness among consumers, there has been a notable interest in plant-based dairy alternatives. The plant-based yogurt market has experienced rapid expansion in recent years. Due to challenges related to cultivation, higher cost of production and lower protein content researchers have explored the viability of pulse-based yogurt which has arisen as an economically and nutritionally abundant solution. This review aims to examine the feasibility of utilizing pulse protein for yogurt production. The nutritional, antinutritional, and functional characteristics of various pulses were discussed in detail, alongside the modifications in these properties during the various stages of yogurt manufacturing. The review also sheds light on pivotal findings from existing literature and outlines challenges associated with the production of pulse-based yogurt. Pulses have emerged as promising base materials for yogurt manufacturing due to their favorable nutritional and functional characteristics. Further, the fermentation process can effectively reduce antinutritional components and enhance digestibility. Nonetheless, variations in sensorial and rheological properties were noted when different types of pulses were employed. This issue can be addressed by employing suitable combinations to achieve the desired properties in pulse-based yogurt.

Development and Characterization of Hybrid Meat Analogs from Whey Protein-Mushroom Composite Hydrogels

There is a need to reduce the proportion of animal-derived food products in the human diet for sustainability and environmental reasons. However, it is also important that a transition away from animal-derived foods does not lead to any adverse nutritional effects. In this study, the potential of blending whey protein isolate (WPI) with either shiitake mushroom (SM) or oyster mushroom (OM) to create hybrid foods with enhanced nutritional and physicochemical properties was investigated. The impact of OM or SM addition on the formation, microstructure, and physicochemical attributes of heat-set whey protein gels was therefore examined. The mushroom powders were used because they have relatively high levels of vitamins, minerals, phytochemicals, and dietary fibers, which may provide nutritional benefits, whereas the WPI was used to provide protein and good thermal gelation properties. A variety of analytical methods were used to characterize the structural and physicochemical properties of the WPI-mushroom hybrids, including confocal microscopy, particle electrophoresis, light scattering, proximate analysis, differential scanning calorimetry, thermogravimetric analysis, dynamic shear rheology, textural profile analysis, and colorimetry. The charge on whey proteins and mushroom particles went from positive to negative when the pH was raised from 3 to 9, but whey protein had a higher isoelectric point and charge magnitude. OM slightly increased the thermal stability of WPI, but SM had little effect. Both mushroom types decreased the lightness and increased the brownness of the whey protein gels. The addition of the mushroom powders also decreased the hardness and Young's modulus of the whey protein gels, which may be because the mushroom particles acted as soft fillers. This study provides valuable insights into the formation of hybrid whey protein-mushroom products that have desirable physiochemical and nutritional attributes.

Innovation in precision fermentation for food ingredients

A transformation in our food production system is being enabled by the convergence of advances in genome-based technologies and traditional fermentation. Science at the intersection of synthetic biology, fermentation, downstream processing for product recovery, and food science is needed to support technology development for the production of fermentation-derived food ingredients. The business and markets for fermentation-derived ingredients, including policy and regulations are discussed. A patent landscape of fermentation for the production of alternative proteins, lipids and carbohydrates for the food industry is provided. The science relating to strain engineering, fermentation, downstream processing, and food ingredient functionality that underpins developments in precision fermentation for the production of proteins, fats and oligosaccharides is examined. The production of sustainably-produced precision fermentation-derived ingredients and their introduction into the market require a transdisciplinary approach with multistakeholder engagement. Successful innovation in fermentation-derived ingredients will help feed the world more sustainably.

Protein, lipid, and chitin fractions from insects: Method of extraction, functional properties, and potential applications

Edible insects are accepted as food and feed ingredients in many parts of the world. Insects account for more than 80% of animal kingdom providing rich biodiversity of protein and lipid profiles compared to conventional livestock. Insect biomasses contain an average of 35-62% protein, 3-57% lipid, and 3-12% chitin, and their nutritional values are widely recognized due to their presence, including minerals, and vitamins. While whole insects are consumed as eggs, larvae, pupae, or adults, there has been a recent uptick in interest to use fractions, e.g., protein, lipid, and chitin, as food and feed ingredients. To utilize these fractions in various food and feed preparations, a deeper understanding of the physicochemical as well as functional properties of the ingredients is required, which are generally impacted by extraction and preparation processes. Thus, the methods of extraction/purification are important to preserve the quality and functional properties of these ingredients. This paper discusses the extraction methods for insect protein, lipid, and chitin, their functional properties, and potential applications in food and feed applications.

Heat-Induced Gelation of Chickpea and Faba Bean Flour Ingredients

This study aimed to investigate the gelling behavior of faba bean (FB) and chickpea (CP) flour between 10 and 20% (w/w) concentration at pH 3.0, 5.0, and 7.0. Both sources formed at pH 3.0 and 5.0 self-standing gels with 12% (w/w) of flour, while 16% (w/w) of flour was required to obtain a gel at pH 7.0. During gelling between 40 and 70 °C, a sharp increase of the elastic modulus G' was observed in both flours, mainly due to water absorption and swelling of the starch, one of the major constituents in the ingredients. Increasing the temperature at 95 °C, G' increased due to the denaturation of globulins and therefore the exposure of their internal part, which allowed more hydrophobic interactions and the formation of the gel. After cooling, both FB and CP gels displayed a solid-like behavior (tan δ ranging between 0.11 and 0.18) with G' values at pH 3.0 and 5.0 significantly (p < 0.05) higher than those at pH 7.0, due to the lower electrostatic repulsions at pHs far from the isoelectric point. The rheological properties were supported by the water binding capacity values, confirming the better gels' strength described by rheological analysis. These results will enhance our understanding of the role of legume flours in formulating innovative and sustainable food products as alternatives to animal ones.

Different source of commercial soy protein isolates: Structural, compositional, and physicochemical characteristics in relation to protein functionalities

This study aimed to illustrate the relationship among physicochemical properties, subunit composition and protein functionalities in a broad collection of commercial soy protein isolates (SPIs) from China and the EU. The results indicated that SPIs had large variations in glycinin/β-conglycinin composition, protein denaturation, and water- and oil-binding capacity (WBC and OBC) and solubility. These SPIs could be roughly divided into pre-denatured SPI, partially hydrolyzed SPI, and less modified SPI. The pre-denatured SPI with high surface hydrophobicity and large particle sizes showed reduced WBC and OBC due to increased protein aggregation, and partially hydrolyzed SPI showed high protein solubility owing to the exposure of hydrophilic regions and reduction in molecular size. The processing-induced physicochemical changes played a pivotal role in determining protein functionalities, whereas subunit composition affected protein functionality less. Overall, this study highlighted the obvious difference in raw material quality of commercial SPI, and provided promising methods for SPI categorization.

Recent advance in modification strategies and applications of soy protein gel properties

Soy protein gel can be developed into a variety of products, ranging from traditional food (e.g., tofu) to newly developed food (e.g., soy yogurt and meat analog). So far, efforts are still needed to be made on modifying the gel properties of soy protein for improving its sensory properties as animal protein-based food substitutes. Furthermore, there is always a need to regulate its gel properties for designing novel and tailored products of soy protein gels due to the fast-growing plant protein-based product market. This review gave an emphasis on the latest modification strategies and applications of gel properties of soy protein. The modifying methods of soy protein gel properties were reviewed from an aspect of composition or processing. Compositional modification included changing protein composition and gelling conditions and using additives, whereas processing strategies can be achieved through physical, chemical, and enzymatic treatments. Several compositional modification and processing strategies have been both proven to alter the gel properties of soy protein effectively. So far, soy protein gel has been applied in the field of food and biomedicine. In the future, more mechanistic studies on the modification methods are still needed to facilitate the full application of soy protein gel.

Formation of amyloid fibrils from ovalbumin under Ohmic heating

Ohmic heating (OH) is an alternative sustainable heating technology that has demonstrated its potential to modify protein structures and aggregates. Furthermore, certain protein aggregates, namely amyloid fibrils (AF), are associated with an enhanced protein functionality, such as gelation. This study evaluates how Ohmic heating (OH) influences the formation of AF structures from ovalbumin source under two electric field strength levels, 8.5 to 10.5 and 24.0-31.0 V/cm, respectively. Hence, AF aggregate formation was assessed over holding times ranging from 30 to 1200 sunder various environmental conditions (3.45 and 67.95 mM NaCl, 80, 85 and 90 °C, pH = 7). AF were formed under all conditions. SDS-PAGE revealed that OH had a higher tendency to preserve native ovalbumin molecules. Furthermore, Congo Red and Thioflavin T stainings indicated that OH reduces the amount of AF structures. This finding was supported by FTIR measurements, which showed OH samples to contain lower amounts of beta-sheets. Field flow fractioning revealed smaller-sized aggregates or aggregate clusters occurred after OH treatment. In contrast, prolonged holding time or higher treatment temperatures increased ThT fluorescence, beta-sheet structures and aggregate as well as cluster sizes. Ionic strength was found to dominate the effects of electric field strength under different environmental conditions.

Design of Plant-Based Food: Influences of Macronutrients and Amino Acid Composition on the Techno-Functional Properties of Legume Proteins

Imitating animal-based products using vegetable proteins is a technological challenge that can be mastered based on their techno-functional properties. These properties of legume proteins can be influenced by multiple factors, among which the macronutrients and amino acid contents play an important role. Therefore, the question arises as to what extent the techno-functional properties are related to these factors. The water- and oil-holding capacities and the emulsion and foaming properties of commercially available legume protein powders were analyzed. Correlations between macronutrient, amino acid content, steric structure, and techno-functional properties were conducted. However, the protein concentration is the focus of techno-functional properties, as well as the type of protein and the interaction with the non-protein ingredients. The type of protein is not always quantified by the quantity of amino acids or by their spatial arrangement. In this study, the effects of the three-dimensional structure were observed by the used purification method, which overshadow the influencing factors of the macronutrients and amino acid content. In summary, both the macronutrient and amino acid contents of legume proteins provide a rough indication but not a comprehensive statement about their techno-functional properties and classification in an adequate product context.

Monodisperse Plant Protein Nanoparticles Prepared by Cation-Exchange Resins for Stabilization of Pickering Emulsions

Our understanding of the microstructure of many plant proteins is based on the ancient and conventional methods of alkali extraction and acid precipitation, which generate considerable amounts of NaCl causing salting-out effects and aggregation of their molecules. In this study, monodisperse rice protein (RP) nanoparticles were prepared using cation-exchange resins that release H+ and absorb Na+, thus avoiding the generation of NaCl during neutralization of the alkali extracts. The generated RP nanoparticles of small diameter (20 nm) and excellent uniformity (0.17 polydispersity) quickly diffuse to and stabilize the oil-water interface, producing oil-in-water Pickering emulsions. The emulsifying ability and emulsion stability afforded with these nanoparticles were 17 and 3.5 times higher than those of nanoparticles prepared by conventional alkali extraction and acid precipitation methods, respectively. Furthermore, increased RP nanoparticle concentration created more stable emulsions with smaller droplets and reduced flocculation index vital for practical applications. This study provides a convincing example of how to prepare monodisperse protein nanoparticles that adsorb at a fluid interface, which may find numerous applications in food and cosmetic formulations.

Nrf2-mediated protective effect of protein hydrolysates from Protaetia brevitarsis larvae against oxidative stress-induced hepatotoxicity

In this study, we hypothesized that Protaetia brevitarsis larvae (PBL) protein hydrolysates, which have been previously reported to exhibit strong antioxidant activity, might protect liver cells against oxidative stress-induced injury. Thus, the cytoprotective effects and related mechanisms of PBL hydrolysates were investigated in AML12 liver cells. Among PBL hydrolysates prepared by three different proteases, the PBL flavouryzme hydrolysate showed significantly higher protective effect against H2O2-induced cytotoxicity than other hydrolysates in AML12 cells. Further mechanistic studies showed that pretreatment with PFH reduces cellular level of reactive oxygen species through induction of Nrf2-mediated antioxidant enzymes such as catalase and heme oxygenase-1. In addition, the free amino acid analysis revealed that PFH was rich in branched-chain amino acids, aromatic amino acids, and hydrophobic amino acids as compared to other hydrolysates, which could contribute to its hepatoprotective effect. These findings suggest that PFH represents a potential source of nutraceuticals that supports liver functions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01279-0.

Alternative Processing Options for Improving the Proteins Functionality by Maillard Conjugation

Conjugation of the proteins with carbohydrates, occurring in the early stages of the Maillard reactions, received increased attention because of the high potential to ensure the improvement of the biological activity and functional properties of the proteins of different origins. The Maillard conjugates are conventionally formed through wet or dry heating, but the use of alternative technologies involving ultrasound, microwave, pulsed electric fields, high-pressure, or electrodynamic treatments appears to be efficient in accelerating the reaction steps and limiting the formation of toxic compounds. An overview of the mechanisms of these processing technologies, the main parameters influencing the Maillard conjugate formation, as well as their advantages and disadvantages, is provided in this paper. Different strategies employing these alternative technologies are reported in the literature: as pretreatment of the proteins, either alone or in admixture with the carbohydrates, followed by conventional heating, as a single alternative treatment step, or as a combination of heating and alternative processing. The desired functional properties of the proteins can be achieved by selecting the appropriate processing strategy and optimizing the reaction parameters. Moreover, alternative technologies can be exploited to obtain Maillard conjugates with remarkable biological activity in terms of antioxidant, antimicrobial, antihypertensive, anti-inflammatory, antimutagenic, or bifidogenic properties.

Application of small angle scattering (SAS) in structural characterisation of casein and casein-based products during digestion

In recent years, small and ultra-small angle scattering techniques, collectively known as small angle scattering (SAS) have been used to study various food structures during the digestion process. These techniques play an important role in structural characterisation due to the non-destructive nature (especially when using neutrons), various in situ capabilities and a large length scale (of 1 nm to ∼20 μm) they cover. The application of these techniques in the structural characterisation of dairy products has expanded significantly in recent years. Casein, a major dairy protein, forms the basis of a wide range of gel structures at different length scales. These gel structures have been extensively researched utilising scattering techniques to obtain structural information at the nano and micron scale that complements electron and confocal microscopy. Especially, neutrons have provided opportunity to study these gels in their natural environment by using various in situ options. One such example is understanding changes in casein gel structures during digestion in the gastrointestinal tract, which is essential for designing personalised food structures for a wide range of food-related diseases and improve health outcomes. In this review, we present an overview of casein gels investigated using small angle and ultra-small angle scattering techniques. We also reviewed their digestion using newly built setups recently employed in various research. To gain a greater understanding of micro and nano-scale structural changes during digestion, such as the effect of digestive juices and mechanical breakdown on structure, new setups for semi-solid food materials are needed to be optimised.

Impact of Stabilization Technology on the Extraction Yield and Functionality of Macroconstituents from Biomass: A Systematic Review

Biomass contains different macroconstituents (polysaccharides, lipids, and proteins) with nutritional and functional properties. However, after harvest or processing, stabilization of biomass is necessary to preserve the macroconstituents from degradation by microbial growth and enzymatic reactions. Because these stabilization methods affect the structure of the biomass, extraction of valuable macroconstituents can be impacted. Literature, in general, focuses on either stabilization or extraction, but systematic information on the interlinkage between these processes has rarely been reported. This review summarizes recent research on physical, biological, and chemical stabilization methods on macroconstituent extraction yields and functionalities. Often, freeze drying as a stabilization method resulted in a good extraction yield and functionality, independent of the macroconstituent. Less documented treatments, such as microwave drying, infrared drying, and ultrasound stabilization, result in better yields compared to conventional physical treatments. Biological and chemical treatments were rarely performed but could be promising as stabilization methods before performing an extraction step.

Ultrasound-assisted alkaline extraction of protein from Tenebrio molitor larvae: Extraction kinetics, physiochemical, and functional traits

Currently, as a promising alternative protein source, the interest of edible insect protein has been continuously increased. However, the extraction processing had distinct effects on the physicochemical properties and functionalities of this novel and sustainable protein. In this study, Tenebrio molitor larvae protein (TMLP) was extracted via ultrasound (US)-assisted alkaline extraction. The changes of extraction kinetics, physicochemical characteristics, and functional properties of TMLP as a function of US time (10, 20, 30, 40, 50 min) were investigated. The results showed that 30 min US treatment rendered the maximum protein yield (60.04 %) (P < 0.05). Meanwhile, Peleg's model was considered a suitable model to represent the extraction kinetics of TMLP, with a correlation coefficient of 0.9942. Moreover, the protein secondary structure, particle size, and amino acid profiles of TMLP were changed under the US-assisted alkaline extraction process. Additionally, a significant improvement of the functional properties of TMLP extracted with this method was observed compared to traditional alkaline extraction. In conclusion, the present work suggests that US-assisted alkaline extraction could be considered as a potential method to improve the protein yield, quality profiles, and functional properties of TMLP.

Effects of glycation methods on the interfacial behavior and emulsifying performance of soy protein isolate-gum Arabic conjugates

Glycated conjugation of plant protein such as soy protein isolate (SPI) with saccharides is one popular strategy to modify the physicochemical characteristics of these plant protein resources, which may be affected by the glycation methods including dry-heating and wet-heating. In this study, the impact of these two glycation methods on the rheological and emulsifying properties of a binary system made by SPI-gum Arabic (GA) was studied. The results indicated that dry-heating conjugates had higher viscosity and more elastic characteristics than those wet-heating conjugates. The emulsifying properties of SPI-GA conjugates by different preparation routes were evaluated by various oil phases including eugenol, cinnamaldehyde and soybean oil. Overall, emulsions stabilized by dry-heating conjugates showed lower zeta-potential value than those with wet heating conjugates. The interfacial properties of these conjugates were compared using soybean oil emulsion as a model. Higher emulsifying ability and stability were obtained by emulsions with dry-heating conjugates, which was attributed to their more compact structures, higher protein adsorption capacity and thicker viscoelastic films formed at the interface, and therefore enhanced electrostatic repulsion between droplets. The findings in this study are useful for fabrication and utilization of protein-polysaccharide glycation conjugates as emulsifiers in functional foods.

Effect of protein-starch interactions on starch retrogradation and implications for food product quality

Starch retrogradation is a consequential part of food processing that greatly impacts the texture and acceptability of products containing both starch and proteins, but the effect of proteins on starch retrogradation has only recently been explored. With the increased popularity of plant-based proteins in recent years, incorporation of proteins into starch-based products is more commonplace. These formulation changes may have unforeseen effects on ingredient functionality and sensory outcomes of starch-containing products during storage, which makes the investigation of protein-starch interactions and subsequent impact on starch retrogradation and product quality essential. Protein can inhibit or promote starch retrogradation based on its exposed residues. Charged residues promote charge-dipole interactions between starch-bound phosphate and protein, hydrophobic groups restrict amylose release and reassociation, while hydrophilic groups impact water/molecular mobility. Covalent bonds (disulfide linkages) formed between proteins may enhance starch retrogradation, while glycosidic bonds formed between starch and protein during high-temperature processing may limit starch retrogradation. With these protein-starch interactions in mind, products can be formulated with proteins that enhance or delay textural changes in starch-containing products. Future work to understand the impact of starch-protein interactions on retrogradation should focus on integrating the fields of proteomics and carbohydrate chemistry. This interdisciplinary approach should result in better methods to characterize mechanisms of interaction between starch and proteins to optimize their food applications. This review provides useful interpretations of current literature characterizing the mechanistic effect of protein on starch retrogradation.

Current Status and Nutritional Value of Green Leaf Protein

Green leaf biomass is one of the largest underutilized sources of nutrients worldwide. Whether it is purposely cultivated (forage crops, duckweed) or upcycled as a waste stream from the mass-produced agricultural crops (discarded leaves, offcuts, tops, peels, or pulp), the green biomass can be established as a viable alternative source of plant proteins in food and feed processing formulations. Rubisco is a major component of all green leaves, comprising up to 50% of soluble leaf protein, and offers many advantageous functional features in terms of essential amino acid profile, reduced allergenicity, enhanced gelation, foaming, emulsification, and textural properties. Nutrient profiles of green leaf biomass differ considerably from those of plant seeds in protein quality, vitamin and mineral concentration, and omega 6/3 fatty acid profiles. Emerging technological improvements in processing fractions, protein quality, and organoleptic profiles will enhance the nutritional quality of green leaf proteins as well as address scaling and sustainability challenges associated with the growing global demand for high quality nutrition.

Correlating process parameters and print accuracy of 3D-printable heat acid coagulated milk semisolids and polyol matrix: implications for testing methods

The primary additive manufacturing (AM) technique for all high-viscosity food composites is extrusion-based. Therefore, understanding the impact of process parameters involved is crucial in fulfilling the demand characteristics of the printed constructs. In this regard, a correlation between print accuracy and critical 3D printing (3DP) process variables as a strategy for expediting the selection of 3D printable food inks has the most potential for success. This paper studies the effectiveness of using heat-acid coagulated milk semisolids and polyol matrix as 3D printable food ink for high-quality prints. The study focused on the critical material properties and conducted rheological characterization and particle size distribution analysis. The study obtained the effective range of printing parameters for various process variables using a mathematical model that employed finite element analysis (FEA) to define the flow field characteristics. The dimensional accuracy of the printed constructs under different process variables was determined by utilizing image processing methods. A multi-objective optimization was carried out using the desirability function method to obtain the key correlations between the process parameters for the best-printed construct.

Insights into Ultrasonication Treatment on the Characteristics of Cereal Proteins: Functionality, Conformational and Physicochemical Characteristics

BACKGROUND

It would be impossible to imagine a country where cereals and their byproducts were not at the peak of foodstuff systems as a source of food, fertilizer, or for fiber and fuel production. Moreover, the production of cereal proteins (CPs) has recently attracted the scientific community's interest due to the increasing demands for physical wellbeing and animal health. However, the nutritional and technological enhancements of CPs are needed to ameliorate their functional and structural properties. Ultrasonic technology is an emerging nonthermal method to change the functionality and conformational characteristics of CPs. Scope and approach: This article briefly discusses the effects of ultrasonication on the characteristics of CPs. The effects of ultrasonication on the solubility, emulsibility, foamability, surface-hydrophobicity, particle-size, conformational-structure, microstructural, enzymatic-hydrolysis, and digestive properties are summarized.

CONCLUSIONS

The results demonstrate that ultrasonication could be used to enhance the characteristics of CPs. Proper ultrasonic treatment could improve functionalities such as solubility, emulsibility, and foamability, and is a good method for altering protein structures (including surface hydrophobicity, sulfhydryl and disulfide bonds, particle size, secondary and tertiary structures, and microstructure). In addition, ultrasonic treatment could effectively promote the enzymolytic efficiency of CPs. Furthermore, the in vitro digestibility was enhanced after suitable sonication treatment. Therefore, ultrasonication technology is a useful method to modify cereal protein functionality and structure for the food industry.

Relevance of the air-water interfacial and foaming properties of (modified) wheat proteins for food systems

A shift from animal protein- to plant protein-based foods is crucial in transitioning toward a more sustainable global food system. Among food products typically stabilized by animal proteins, food foams represent a major category. Wheat proteins are ubiquitous and structurally diverse, which offers opportunities for exploiting them for food foam and air-water interface stabilization. Notably, they are often classified into those that are soluble in aqueous systems (albumins and globulins) and those that are not (gliadins and glutenins). However, gliadins are at least to an extent water extractable and thus surface active. We here provide a comprehensive overview of studies investigating the air-water interfacial and foaming properties of the different wheat protein fractions. Characteristics in model systems are related to the functional role that wheat proteins play in gas cell stabilization in existing wheat-based foods (bread dough, cake batter, and beer foam). Still, to further extend the applicability of wheat proteins, and particularly the poorly soluble glutenins, to other food foams, their modification is required. Different physical, (bio)chemical, and other modification strategies that have been utilized to alter the solubility and therefore the air-water interfacial and foaming properties of the gluten protein fraction are critically reviewed. Such approaches may open up new opportunities for the application of (modified) gluten proteins in other food products, such as plant-based meringues, whippable drinks, or ice cream. In each section, important knowledge gaps are highlighted and perspectives for research efforts that could lead to the rational design of wheat protein systems with enhanced functionality and overall an increased applicability in food industry are proposed.

Investigating the Effect of Supercritical Carbon Dioxide Treatment on the Rheological, Thermal, and Functional Properties of Plum (Prunus domestica L.) Kernel Protein Isolates

Plum kernels are a promising source of dietary proteins that are irretrievably lost during processing. The recovery of these underexploited proteins could be eminently vital for human nutrition. Plum kernel protein isolate (PKPI) was prepared and exposed to a targeted supercritical carbon dioxide (SC-CO₂) treatment to diversify its effectiveness in industrial applications. The impacts of SC-CO₂ treatment at different processing temperatures (30-70 °C) on dynamic rheology, microstructure, thermal, and techno-functional characteristics of PKPI were investigated. The results revealed that the dynamic viscoelastic characteristics of SC-CO₂-treated PKPIs showed higher storage modulus, loss modulus, and lower tan δ value than native PKPI, indicating greater strength and elasticity of the gels. Microstructural analysis showed that the proteins experienced denaturation at elevated temperatures and resulted in the formation of soluble aggregates, which increased the heat requirement for thermal denaturation of SC-CO₂-treated samples. SC-CO₂-treated PKPIs demonstrated a decline of 20.74% and 30.5% in crystallite size and crystallinity. PKPIs treated at 60 °C showed the highest dispersibility, which was 1.15-fold higher than the native PKPI sample. SC-CO₂ treatment offers a novel path to improve the techno-functional properties of PKPIs and extend its use in food and non-food applications.

Impacts of sonication and high hydrostatic pressure on the structural and physicochemical properties of quinoa protein isolate dispersions at acidic, neutral and alkaline pHs

Herein, 1 wt% quinoa protein isolate (QPI) was exposed to sonication using a 20 kHz ultrasonicator equipped with a 6 mm horn (14.4 W, 10 mL, up to 15 min) or high hydrostatic pressure (HHP, up to 600 MPa, 15 min) treatments at pH 5, pH 7, and pH 9. The changes to physicochemical properties were probed by SDS-PAGE, FTIR, free sulfhydryl group (SH), surface hydrophobicity (H0), particle size and solubility. As revealed by SDS-PAGE, substantial amounts of 11S globulin participated in the formations of aggregates via SS bond under HHP, particularly at pH 7 and pH 9. However, protein profiles of QPI were not significantly affected by the sonication. Free SH groups and surface hydrophobicity were increased after the sonication treatment indicating protein unfolding and exposure of the embedded SH and/or hydrophobic groups. An opposite trend was observed in HHP treated samples, implying aggregation and reassociation of structures under HHP. HHP and sonication treatments induced a decrease in ordered secondary structures (random coil and β-turn) accompanied with an increase in disordered secondary structures (α-helix and β-sheet) as probed by FTIR. Finally, the sonication treatment induced a significant improvement in the solubility (up to ∼3 folds at pH 7 and ∼2.6 folds at pH 9) and a reduction in particle sizes (up to ∼3 folds at pH 7 and ∼4.4 folds at pH 9). However, HHP treatment (600 MPa) only slightly increased the solubility (∼1.6 folds at pH 7 and ∼1.2 folds at pH 9) and decreased the particle size (∼1.3 folds at pH 7 and ∼1.2 folds at pH 9). This study provides a direct comparison of the impacts of sonication and HHP treatment on QPI, which will enable to choose the appropriate processing methods to achieve tailored properties of QPI.

Structure-Function Guided Extraction and Scale-Up of Pea Protein Isolate Production

The lack of adequate guidance and control of the extraction conditions as well as the gap between bench- and industrial-scale production, contributes to the poor functionality of commercial pea protein isolate (cPPI). Therefore, pea protein extraction conditions were evaluated and scaled up to maximize protein purity and yield, while maintaining structural integrity, following mild alkaline solubilization with isoelectric precipitation and salt solubilization coupled with membrane filtration. Both extraction methods resulted in high protein yield (>64%) and purity (>87%). Structure-function characterization illustrated the preserved structural integrity of PPI samples and their superior solubility, gelation, and emulsification properties compared to cPPI. Results confirmed, for the first time, that double solubilization at mild pH (7.5) can replace single solubilization at high alkalinity and achieve a similar yield while preserving structural integrity. Additionally, this study demonstrated, the scalability of the benchtop salt extraction coupled with ultrafiltration/diafiltration. Scaling up the production eliminated some structural and functional differences between the salt-extracted PPI and pH-extracted PPI. Scaling-up under mild and controlled conditions resulted in partial denaturation and a low degree of polymerization, coupled with the superior functionality of the produced isolates compared to cPPI. Results of this work can be used as a benchmark to guide the industrial production of functional pea protein ingredients.

Nutritional Quality, Techno-Functional Characteristics, and Safety of Biomass Powder and Protein Isolate Produced from Penicillium maximae

This study investigated the suitability of Penicillium maximae biomass powder and protein isolate as a food product or food ingredient. The biomass powder is rich in proteins (34.8%) and insoluble fiber (36.2%) but poor in lipids (3.1%). Strong water hydration (8.3 g/g, 8.5 g/g) and oil holding (6.9 g/g, 16.3 g/g) capacity were observed in the biomass powder and protein isolate, respectively, besides 100% emulsion stability, indicating multiple applications in the food industry. No locomotor impairment was induced in Drosophila melanogaster flies after consuming extracts of P. maximae biomass powder. Furthermore, decreased production of reactive oxygen species and preservation of survival, viability, and fertility parameters were observed in the nematode Caenorhabditis elegans, which reinforces the potential of P. maximae biomass for human and animal consumption. Together, the results show the vast food applicability of P. maximae biomass and protein isolate as protein substitutes with several health and environmental benefits.

Effect of high hydrostatic pressure processing on the structure, functionality, and nutritional properties of food proteins: A review

Proteins are important food ingredients that possess both functional and nutritional properties. High hydrostatic pressure (HHP) is an emerging nonthermal food processing technology that has been subject to great advancements in the last two decades. It is well established that pressure can induce changes in protein folding and oligomerization, and consequently, HHP has the potential to modify the desired protein properties. In this review article, the research progress over the last 15 years regarding the effect of HHP on protein structures, as well as the applications of HHP in modifying protein functionalities (i.e., solubility, water/oil holding capacity, emulsification, foaming and gelation) and nutritional properties (i.e., digestibility and bioactivity) are systematically discussed. Protein unfolding generally occurs during HHP treatment, which can result in increased conformational flexibility and the exposure of interior residues. Through the optimization of HHP and environmental conditions, a balance in protein hydrophobicity and hydrophilicity may be obtained, and therefore, the desired protein functionality can be improved. Moreover, after HHP treatment, there might be greater accessibility of the interior residues to digestive enzymes or the altered conformation of specific active sites, which may lead to modified nutritional properties. However, the practical applications of HHP in developing functional protein ingredients are underutilized and require more research concerning the impact of other food components or additives during HHP treatment. Furthermore, possible negative impacts on nutritional properties of proteins and other compounds must be also considered.