Impact of pH Modification on Protein Polymerization and Structure⁻Function Relationships in Potato Protein and Wheat Gluten Composites

On the modification of plant proteins: Traditional methods and the Hofmeister effect

With increasing consumer health awareness and demand from some vegans, plant proteins have received a lot of attention. Plant proteins have many advantages over animal proteins. However, the application of plant proteins is limited by a number of factors and there is a need to improve their functional properties to enable a wider range of applications. This paper describes the advantages and disadvantages of traditional methods of modifying plant proteins and the appropriate timing for their use, and collates and describes a method with fewer applications in the food industry: the Hofmeister effect. It is extremely simple but efficient in some respects compared to traditional methods. The paper provides theoretical guidance for the further development of plant protein-based food products and a reference value basis for improving the functional properties of proteins to enhance their applications in the food industry, pharmaceuticals and other fields.

Plant protein-based edible films and the effect of phenolic additives

The use of protein-based films in food preservation has been investigated as an alternative to synthetic plastics in recent years. Being biodegradable, edible, natural, and upcycling from food waste/by-products are the benefits of protein-based edible films. Their use ensures food safety as an alternative to synthetic plastics, and their film-forming properties can be improved with the addition of bioactive compounds. This review summarizes the studies on the changes in certain quality parameters of plant protein-based films, including mechanical, physicochemical, or morphological properties with the use of different forms of phenolic additives (pure phenolics, phenolic extracts, essential oils) and their application in foods during storage. Phenolics affect protein film matrix formation by acting as plasticizers or cross-linking agents and confer additional health benefits by providing bioactive properties to protein films. On the other hand, the effects were more pronounced with the use of their oxidized forms or higher concentrations. Consequently, phenolic additives have great potential to improve protein films, but further studies are still required to investigate the effects and mechanisms of phenolic addition to the protein-based films.

Thermomechanical Stress Analysis of Hydrated Vital Gluten with Large Amplitude Oscillatory Shear Rheology

Vital gluten is increasingly researched as a non-food product for biodegradable materials. During processing, the protein network is confronted with increased thermal and mechanical stress, altering the network characteristics. With the prospect of using the protein for materials beyond food, it is important to understand the mechanical properties at various processing temperatures. To achieve this, the study investigates hydrated vital gluten under thermomechanical stress based on large amplitude oscillatory shear (LAOS) rheology. LAOS rheology was conducted at increasing shear strains (0.01-100%), various frequencies (5-20 rad/s) and temperatures of 25, 45, 55, 65, 70 and 85 °C. With elevating temperatures up to 55 °C, the linear viscoelastic moduli decrease, indicating material softening. Then, protein polymerization and the formation of new cross-links due to thermal denaturation cause more network connectivity, resulting in significantly higher elastic moduli. Beyond the linear viscoelastic regime, the strain-stiffening ratio rises disproportionately. This effect becomes even more evident at higher temperatures. Lacking a viscous contribution, the highly elastic but also stiff network shows less mechanical resilience. Additionally, at these elevated temperatures, structural changes during the protein's denaturation and network shrinkage due to water evaporation could be visualized with confocal laser scanning microscopy (CLSM).

Green Chemistry to Modify Functional Properties of Crambe Protein Isolate-Based Thermally Formed Films

Proteins are promising precursors to be used in production of sustainable materials with properties resembling plastics, although protein modification or functionalization is often required to obtain suitable product characteristics. Here, effects of protein modification were evaluated by crosslinking behavior using high-performance liquid chromatography (HPLC), secondary structure using infrared spectroscopy (IR), liquid imbibition and uptake, and tensile properties of six crambe protein isolates modified in solution before thermal pressing. The results showed that a basic pH (10), especially when combined with the commonly used, although moderately toxic, crosslinking agent glutaraldehyde (GA), resulted in a decrease in crosslinking in unpressed samples, as compared to acidic pH (4) samples. After pressing, a more crosslinked protein matrix with an increase in β-sheets was obtained in basic samples compared to acidic samples, mainly due to the formation of disulfide bonds, which led to an increase in tensile strength, and liquid uptake with less material resolved. A treatment of pH 10 + GA, combined either with a heat or citric acid treatment, did not increase crosslinking or improve the properties in pressed samples, as compared to pH 4 samples. Fenton treatment at pH 7.5 resulted in a similar amount of crosslinking as the pH 10 + GA treatment, although with a higher degree of peptide/irreversible bonds. The strong bond formation resulted in lack of opportunities to disintegrate the protein network by all extraction solutions tested (even for 6 M urea + 1% sodium dodecyl sulfate + 1% dithiothreitol). Thus, the highest crosslinking and best properties of the material produced from crambe protein isolates were obtained by pH 10 + GA and pH 7.5 + Fenton, where Fenton is a greener and more sustainable solution than GA. Therefore, chemical modification of crambe protein isolates is effecting both sustainability and crosslinking behavior, which might have an effect on product suitability.

Plant Protein-Based Delivery Systems: An Emerging Approach for Increasing the Efficacy of Lipophilic Bioactive Compounds

The development of plant protein-based delivery systems to protect and control lipophilic bioactive compound delivery (such as vitamins, polyphenols, carotenoids, polyunsaturated fatty acids) has increased interest in food, nutraceutical, and pharmaceutical fields. The quite significant ascension of plant proteins from legumes, oil/edible seeds, nuts, tuber, and cereals is motivated by their eco-friendly, sustainable, and healthy profile compared with other sources. However, many challenges need to be overcome before their widespread use as raw material for carriers. Thus, modification approaches have been used to improve their techno-functionality and address their limitations, aiming to produce a new generation of plant-based carriers (hydrogels, emulsions, self-assembled structures, films). This paper addresses the advantages and challenges of using plant proteins and the effects of modification methods on their nutritional quality, bioactivity, and techno-functionalities. Furthermore, we review the recent progress in designing plant protein-based delivery systems, their main applications as carriers for lipophilic bioactive compounds, and the contribution of protein-bioactive compound interactions to the dynamics and structure of delivery systems. Expressive advances have been made in the plant protein area; however, new extraction/purification technologies and protein sources need to be found Their functional properties must also be deeply studied for the rational development of effective delivery platforms.

Plant Proteins for Future Foods: A Roadmap

Protein calories consumed by people all over the world approximate 15-20% of their energy intake. This makes protein a major nutritional imperative. Today, we are facing an unprecedented challenge to produce and distribute adequate protein to feed over nine billion people by 2050, in an environmentally sustainable and affordable way. Plant-based proteins present a promising solution to our nutritional needs due to their long history of crop use and cultivation, lower cost of production, and easy access in many parts of the world. However, plant proteins have comparatively poor functionality, defined as poor solubility, foaming, emulsifying, and gelling properties, limiting their use in food products. Relative to animal proteins, including dairy products, plant protein technology is still in its infancy. To bridge this gap, advances in plant protein ingredient development and the knowledge to construct plant-based foods are sorely needed. This review focuses on some salient features in the science and technology of plant proteins, providing the current state of the art and highlighting new research directions. It focuses on how manipulating plant protein structures during protein extraction, fractionation, and modification can considerably enhance protein functionality. To create novel plant-based foods, important considerations such as protein-polysaccharide interactions, the inclusion of plant protein-generated flavors, and some novel techniques to structure plant proteins are discussed. Finally, the attention to nutrition as a compass to navigate the plant protein roadmap is also considered.

Acylation of agricultural protein biomass yields biodegradable superabsorbent plastics

Superabsorbent polymers (SAP) are a central component of hygiene and medical products requiring high liquid swelling, but these SAP are commonly derived from petroleum resources. Here, we show that sustainable and biodegradable SAP can be produced by acylation of the agricultural potato protein side-stream (PPC) with a non-toxic dianhydride (EDTAD). Treatment of the PPC yields a material with a water swelling capacity of ca. 2400%, which is ten times greater than the untreated PPC. Acylation was also performed on waste potato fruit juice (PFJ), i.e. before the industrial treatment to precipitate the PPC. The use of PFJ for the acylation implies a saving of 320 000 tons as CO₂ in greenhouse gas emissions per year by avoiding the industrial drying of the PFJ to obtain the PPC. The acylated PPC shows biodegradation and resistance to mould growth. The possibilities to produce a biodegradable SAP from the PPC allows for future fabrication of environment-friendly and disposable daily-care products, e.g. diapers and sanitary pads.

Protein based packaging of plant origin: Fabrication, properties, recent advances and future perspectives

Huge plastic waste is receiving worldwide attention nowadays due to its resistance to degradation and toxicity on environmental components including humans. Improper disposal of plastics affect the food chain and compromise various activities of aquatic life. Each facet of the plastic waste problem requires a significant attention and compels its elimination from the environment due to its ecologically deleterious threats. Therefore, this problem of plastic pollution and issues related thereof merits an attention regarding the alternatives wherein biopolymer based packaging has a potential role to play. This line of research has received a renewed focus where biodegradable films are being developed from proteins which are obtained from animals (include fish myofibrillar protein, collagen, gelatine, etc), and plants especially graminacea (rice, wheat, maize, barley etc), leguminaceae (soya beans, pea, etc.), asteraceae (sunflower) but little attention has been paid towards the potential of aquatic plants for development of packaging material. The present review provides a comprehensive account of biodegradable films developed from plant proteins viz. soy protein, wheat gluten, corn zein and sunflower protein as emerging supplement to plastics. Moreover, this article also tip-offs the potential of macrophytes for fabrication of protein based packaging films incorporated with bioactive materials extracted from macrophytes.

Preparation and quality evaluation of potato steamed bread with wheat gluten

The present study aimed to study the preparation and quality evaluation of potato steamed bread by using potato flour, wheat flour, and gluten at the presence of yeast and inorganic additives. As the rheological properties of the potato-wheat formulated flour negatively related to the potato flour, the potato-wheat formulated flour with 35% potato flour was set as the basic flour (100%). The effects of wheat gluten on the rheological properties of the dough were also evaluated, and gluten addition amount was set at 6.5%. The effects of yeast, sodium bicarbonate, citric acid, and monocalcium phosphate addition on steamed bread properties have been studied and optimized by orthogonal test. The obtained potato steamed bread formula was 100% basic flour (potato/wheat mass ratio of 35:65), 6.5% wheat gluten, 1.1% yeast, 1.4% NaHCO3, 0.75% citric acid, and 0.50% Ca(H2PO4)2. The prepared potato steamed bread has good sensory and texture properties, with natural potato flavor.

Modeling to Understand Plant Protein Structure-Function Relationships-Implications for Seed Storage Proteins

Proteins are among the most important molecules on Earth. Their structure and aggregation behavior are key to their functionality in living organisms and in protein-rich products. Innovations, such as increased computer size and power, together with novel simulation tools have improved our understanding of protein structure-function relationships. This review focuses on various proteins present in plants and modeling tools that can be applied to better understand protein structures and their relationship to functionality, with particular emphasis on plant storage proteins. Modeling of plant proteins is increasing, but less than 9% of deposits in the Research Collaboratory for Structural Bioinformatics Protein Data Bank come from plant proteins. Although, similar tools are applied as in other proteins, modeling of plant proteins is lagging behind and innovative methods are rarely used. Molecular dynamics and molecular docking are commonly used to evaluate differences in forms or mutants, and the impact on functionality. Modeling tools have also been used to describe the photosynthetic machinery and its electron transfer reactions. Storage proteins, especially in large and intrinsically disordered prolamins and glutelins, have been significantly less well-described using modeling. These proteins aggregate during processing and form large polymers that correlate with functionality. The resulting structure-function relationships are important for processed storage proteins, so modeling and simulation studies, using up-to-date models, algorithms, and computer tools are essential for obtaining a better understanding of these relationships.

Extrusion of Porous Protein-Based Polymers and Their Liquid Absorption Characteristics

The production of porous wheat gluten (WG) absorbent materials by means of extrusion processing is presented for the future development of sustainable superabsorbent polymers (SAPs). Different temperatures, formulations, and WG compositions were used to determine a useful protocol that provides the best combination of porosity and water swelling properties. The most optimal formulation was based on 50 wt.% WG in water that was processed at 80 °C as a mixture, which provided a porous core structure with a denser outer shell. As a green foaming agent, food-grade sodium bicarbonate was added during the processing, which allowed the formation of a more open porous material. This extruded WG material was able to swell 280% in water and, due to the open-cell structure, 28% with non-polar limonene. The results are paving the way towards production of porous bio macromolecular structures with high polar/non-polar liquid uptake, using extrusion as a solvent free and energy efficient production technique without toxic reagents.

Carboxylated Wheat Gluten Proteins: A Green Solution for Production of Sustainable Superabsorbent Materials

Functionalized wheat gluten (WG) protein particles with the ability to absorb fluids within the superabsorbent range are presented. Ethyleneditetraacetic dianhydride (EDTAD), a nontoxic acylation agent, was used for the functionalization of the WG protein at higher protein content than previously reported and no additional chemical cross-linking. The 150-550 μm protein particles had 50-150 nm nanopores induced by drying. The EDTAD treated WG were able to absorb 22, 5, and 3 times of, respectively, water, saline and blood, per gram of dry material (g/g), corresponding to 1000, 150 and 100% higher values than for the as-received WG powder. The liquid retention capacity after centrifugation revealed that almost 50% of the saline liquid was retained within the protein network, which is similar to that for petroleum-based superabsorbent polymers (SAPs). An advantageous feature of these biobased particulate materials is that the maximum swelling is obtained within the first 10 min of exposure, that is, in contrast to many commercial SAP alternatives. The large swelling in a denaturation agent (6 M urea) solution (about 32 g/g) suggests that the secondary entangled/folded structure of the protein restricts protein network expansion and when disrupted allows the absorption of even higher amounts of liquid. The increased liquid uptake, utilization of inexpensive protein coproducts, easy scalable protocols, and absence of any toxic chemicals make these new WG-based SAP particles an interesting alternative to petroleum-based SAP in, for example, absorbent disposable hygiene products.

Synthesis and Applications of Biopolymer Composites

In recent years, there has been a growing demand for a clean and pollution-free environment and an evident target to minimizing fossil fuel [...].