Effects of microwave-vacuum pre-treatment with different power levels on the structural and emulsifying properties of lotus seed protein isolates

A new method and mechanism for the rapid detoxification of the herb Pinelliae Rhizoma from the Araceae family, based on the dual destruction of raphides and lectin proteins

Pinelliae Rhizoma (PR), a traditional herbal medicine and dietary supplement, is valued for its cough relief and anti-inflammatory effects. However, it can cause significant throat irritation. And unfortunately, current processing techniques can lead to a considerable loss of active constituents in PR. This study employed microwave irradiation to process PR and elucidated the mechanisms underlying its attenuation of PR's irritation. The results demonstrated that microwave irradiation significantly enhanced the processing efficiency, reducing the traditional processing cycle from 5 to 15 days to just 10 min, while preserving active ingredients and mitigating irritation. Subsequent analysis of the irritant components found that microwave treatment significantly reduced the raphides content, altering their morphology. Concurrently, the secondary structure of lectin proteins underwent significant changes, including an increase in β-sheets, a decrease in β-turns and random coils content, and the formation of insoluble aggregates. In conclusion, microwave irradiation is an effective method for reducing the irritation of PR, with the mechanism attributed to the physical destruction of raphides and alterations in the hydrophobicity of lectin proteins. This study provides a novel approach and method for the processing and development of Araceae herbs, as well as food products such as yam, konjac, and pineapple.

Protein extraction from lupin (Lupinus angustifolius L.) using combined ultrasound and microwave techniques: Impact on protein recovery, structure, and functional properties

This study presents the first application of combined ultrasound (US) and microwave (MW) techniques for the efficient extraction of lupin protein isolates (LPI) from Irish-grown narrow-leaved lupin grain, variety 'PRIMADONNA'. This variety was chosen due to its suitability for growth in the Irish temperate climate, which may influence protein extraction characteristics. By employing these emerging techniques, this research demonstrates a potential approach for improving protein recovery rates as well as enhancing the structural and functional properties of LPI. US and MW treatments significantly outperformed conventional extraction (CE), with combined US and MW treatments showing synergistic effects that significantly enhanced extraction yield and protein recovery rates of LPI (P < 0.05) within a shorter processing time (10 min) compared to 1 h CE. SDS-PAGE analyses revealed that US and MW treatment preserved the primary structure of LPI, while Fourier transform infrared spectrometer (FTIR) analyses showed that high-power MW induced significant changes in the secondary structure, transferring protein structures from highly ordered (β-sheet and α-helix) to disordered forms (random coil and β-turn). Lower power combinations (US50 + MW25) effectively improved protein solubility and reduced particle size, whereas higher power combinations (US50 + MW50, US100 + MW50) decreased solubility and increased particle size and viscosity significantly (p < 0.05). These findings underscore the potential of US and MW combinations for efficient lupin protein extraction, providing a new approach to sustainable plant extraction.

Exploration of Pea Protein Isolate-Sodium Alginate Complexes as a Novel Strategy to Substitute Sugar in Plant Cream: Synergistic Interactions Between the Two at the Interface

This study aims to explore the feasibility of using pea protein isolate (PPI)/sodium alginate (SA) complex as a sugar substitute to develop low sugar plant fat cream. Firstly, this study analyzed the influence of SA on the structure and physicochemical properties of PPI and evaluated the types of interaction forces between PPI and SA. The addition of SA effectively induces the unfolding and structural rearrangement of PPI, causing structural changes and subunit dissociation of PPI, resulting in the exposure of internal-SH groups. In addition, the addition of SA increased the content of β-folding in PPI, making the structure of PPI more flexible and reducing interfacial tension. The ITC results indicate that the binding between PPI and SA exhibits characteristics of rapid binding and slow dissociation, which is spontaneous and accompanied by heat release. Next, the effect of PPI/SA ratio on the whipping performance and quality of low sugar plant fat creams was studied by using PPI/SA complex instead of 20% sugar in the cream. When using a PPI/SA complex with a mass ratio of 1:0.3 instead of sugar, the stirring performance, texture, and stability of plant fat cream reach their optimum. Finally, the relevant analysis results indicate that the flexibility and interface characteristics of PPI are key factors affecting the quality of cream. This study can provide theoretical support for finding suitable sugar substitute products and developing low sugar plant fat cream.

Unveiling the potential of bean proteins: Extraction methods, functional and structural properties, modification techniques, physiological benefits, and diverse food applications

Bean proteins, known for their sustainability, versatility, and high nutritional value, represent a valuable yet underutilized resource, receiving less industrial attention compared to soy and pea proteins. This review examines the structural and molecular characteristics, functional properties, amino acid composition, nutritional value, antinutritional factors, and digestibility of bean proteins. Their applications in various food systems, including baked goods, juice and milk substitutes, meat alternatives, edible coatings, and 3D printing inks, are discussed. The physiological benefits of bean proteins, such as antidiabetic, cardioprotective, antioxidant, and neuroprotective effects, are also presented, highlighting their potential for promoting well-being. Our review emphasizes the diversity of bean proteins and highlights ultrasound as the most effective extraction method among available techniques. Beyond their physiological benefits, bean proteins significantly enhance the structural, technological, and nutritional properties of food systems. The functionality can be further improved through various modification techniques, thereby expanding their applicability in the food industry. While studies have explored the impact of bean protein structure on their nutritional and functional properties, further research is needed to investigate advanced modification techniques and the structure-function relationship. This will enhance the utilization of bean proteins in innovative and sustainable food applications.

Effect of microwave treatment and water-bath heating treatment on the performance of glutenin from Tiger nut seed meal: Insights into changes in structural characteristics, functional properties, and in vitro gastrointestinal digestibility

In this study, the structural characteristics, functional properties, and in vitro gastrointestinal digestibility of glutenin from Tiger nut seed meal (TNSMG) treated by microwave (140-700 W, 20-60 s) and water-bath heating (40-100 °C, 10-30 min) were investigated. Analysis of the surface hydrophobicity, intrinsic fluorescence spectroscopy and Fourier transform infrared spectroscopy indicated that both microwave and water-bath heating treatments caused structure changes of TNSMG. The results showed an increase in the exposure of sulfhydryl groups and the content of β-sheet, coupled with a decrease in the content of α-helix and β-turn. These structural changes contributed to the improved solubility, foamability, emulsification properties, and digestibility of TNSMG under proper thermal treatment conditions. TNSMG exhibited the best solubility (68.48%) and foamability (85.56%) after water-bath heating treatment for 20 min at 80 °C. Furthermore, TNSMG showed the best emulsification property (9.61 m2/g) and digestibility (78.58%) when treated by microwave treatment at 560 W for 40 s.

Structure, functional and physicochemical properties of lotus seed protein under different pH environments

BACKGROUND

The present study investigated the structure, functional and physicochemical properties of lotus seed protein (LSP) under different pH environments. The structures of LSP were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy (FTIR), zeta potential, particle size distributions, free sulfhydryl and rheological properties. The functional and physicochemical properties of LSP were characterized by color, foaming property, emulsification property, solubility, oil holding capacity, water holding capacity, differential scanning calorimetry analysis and surface hydrophobicity.

RESULTS

LSP was mainly composed of eight subunits (18, 25, 31, 47, 51, 56, 65 and 151 kDa), in which the richest band was 25 kDa. FTIR results showed that LSP had high total contents of α-helix and β-sheet (44.81-46.85%) in acidic environments. Meanwhile, there was more β-structure and random structure in neutral and alkaline environments (pH 7.0 and 9.0). At pH 5.0, LSP had large particle size (1576.98 nm), high emulsion stability index (91.43 min), foaming stability (75.69%) and water holding capacity (2.21 g g-1), but low solubility (35.98%), free sulfhydryl content (1.95 μmol g-1) and surface hydrophobicity (780). DSC analysis showed the denaturation temperatures (82.23 °C) of LSP at pH 5.0 was higher than those (80.10, 80.52 and 71.82 °C) at pH 3.0, 7.0 and 9.0. The analysis of rheological properties showed that LSP gel had high stability and great strength in an alkaline environment.

CONCLUSION

The findings of the present study are anticipated to serve as a valuable reference for the implementation of LSP in the food industry. © 2024 Society of Chemical Industry.

Application of soy protein isolate-naringenin complexes as fat replacers in low-fat cream: Based on protein conformational changes, aggregation states and interfacial adsorption behavior

In this study, changes in the structural and functional properties of soybean protein isolate (SPI)-naringenin (NG) complexes under different amounts of naringenin treatments were explored, elucidating the effect of the complexes as fat replacers at the 15 % substitution level on the properties of low-fat cream. Finally, the correlation between the structure and function of the complex and the properties of low-fat cream was further analyzed. The addition of NG promotes the increase of SPI aggregation and particle size, and reduces the interfacial tension of the complex. Meanwhile, at the mass ratio of 48:3, NG and SPI formed a dendritic network structure suitable for stabilizing cream. The fat properties of cream indicate that low-fat creams stabilized by appropriate proportions of SPI-NG complexes displayed small and dense fat crystal network structures. In addition, low-fat cream stabilized by the SPI-NG complexes have improved whipping time, overrun, firmness, storage stability and rheological properties compared to natural SPI. It is worth noting that the overall quality of the cream stabilized by the SPI-NG complex with a mass ratio of 48:3 was almost close to that of full-fat cream. Therefore, this study promotes the potential applications of protein-polyphenol complexes as fat replacers in the food industry.

Protein extraction from chlorella pyrenoidosa microalgae: Green methodologies, functional assessment, and waste stream valorization for bioenergy production

C. pyrenoidosa, a species of microalgae, has been recognized as a viable protein source for human consumption. The primary challenges in this context are the development of an efficient extraction process and the valorization of the resultant waste streams. This study, situated within the paradigm of circular economy, presents an innovative extraction approach that achieved a protein extraction efficiency of 62 %. The extracted protein exhibited remarkable oil-water emulsifying performances, such as uniform morphology with high creaming stability, suggesting a sustainable alternative to conventional emulsifiers. Additionally, hydrothermal liquefaction technique was employed for converting the residual biomass and waste solution from the extraction process into biocrude. A biocrude yield exceeding 40 wt%, characterized by a carbon content of 73 % and a higher heating value of 36 MJ/kg, were obtained. These findings demonstrate the promising potential of microalgae biorefinery, which is significant for paving toward circular economy and zero-waste society.

A comparative study of the impacts of preparation techniques on the rheological and textural characteristics of emulsion gels (emulgels)

A subtype of soft solid-like substances are emulsion gels (emulgels; EGs). These composite material's structures either consist of a network of aggregated emulsion droplets or a polymeric gel matrix that contains emulsion droplets. The product's rheological signature can be used to determine how effective it is for a specific application. The interactions between these structured system's separate components and production process, however, have a substantial impact on their rheological imprint. Therefore, rational comprehension of interdependent elements, their structural configurations, and the resulting characteristics of a system are essential for accelerating our progress techniques as well as for fine-tuning the technological and functional characteristics of the finished product. This article presents a comprehensive overview of the mechanisms and procedures of producing EGs (i.e., cold-set and heat-set) in order to determine the ensuing rheological features for various commercial applications, such as food systems. It also describes the influence of these methods on the rheological and textural characteristics of the EGs. Diverse preparation methods are the cause of the rheological-property correlations between different EGs. In many ways, EGs can be produced using various matrix polymers, processing techniques, and purposes. This may lead to various EG matrix structures and interactions between them, which in turn may affect the composition of EGs and ultimately their textural and rheological characteristics.

Effects of microwave on the structural and emulsifying properties and interfacial properties of oxidized soybean protein aggregates

This research explored microwave treatment impact on the structuro-functional aspects of oxidized soy protein aggregates (OSPI). Data showed that oxidative treatment promoted the formation of high molecular weight aggregates through hydrophobic interactions, thereby disrupting the structure of natural soy protein isolates (SPI). Microwave treatment for an appropriate time (≤30 s) caused the molecular structure of OSPI to open up and reduction in molecular weight and disulfide bond content, while absolute zeta potential increased. These modifications increased emulsifying capacity of OSPI, as well as the interfacial adsorption of protein. Longer microwave treatment times (>30 s) caused OSPI to exhibit a tendency to aggregate in TEM and CLSM images. It indicated the appropriate microwave electromagnetic field effect and microwave heating effect could coordinatively regulate soy protein functional properties by modifying their aggregation behavior. The results provided new ideas for reducing resource waste, and further expanding soy protein application in the food industry.

Effects of Pulsed Electric Field on the Physicochemical and Structural Properties of Micellar Casein

Pulsed electric field (PEF) as a green processing technology is drawing greater attention due to its eco-friendliness and potential to promote sustainable development goals. In this study, the effects of different electric field strengths (EFS, 0-30 kV/cm) on the structure and physicochemical features of casein micelles (CSMs) were investigated. It was found that the particle sizes of CSMs increased at low EFS (10 kV/cm) but decreased at high EFS (30 kV/cm). The absolute ζ-potential at 30 kV/cm increased from -26.6 (native CSMs) to -29.5 mV. Moreover, it was noticed that PEF treatment leads to changes in the surface hydrophobicity; it slightly increased at low EFS (10 kV/cm) but decreased at EFS > 10 kV/cm. PEF enhanced the protein solubility from 84.9 (native CSMs) to 87.1% (at 10 kV/cm). PEF at low EFS (10 kV/cm) intensified the emission fluorescence spectrum of CSMs, while higher EFS reduced the fluorescence intensity compared to native CSMs. Moreover, the analysis of the Amide Ι region showed that PEF-treated CSMs reduced the α-helix and increased the β-sheet content. Raman spectra confirmed that PEF treatment > 10 kV/cm buried tyrosine (Tyr) residues in a hydrophobic environment. It was also found that PEF treatment mainly induced changes in the disulfide linkages. In conclusion, PEF technology can be employed as an eco-friendly technology to change the structure and physiochemical properties of CSMs; this could improve their techno-functional properties.

Effects of high-pressure homogenization on the physicochemical, foaming, and emulsifying properties of chickpea protein

In order to expand the utilization of chickpeas in various food products, this study investigated the effects of different homogenization pressures (0-150 MPa) and cycles (1-3) on the physicochemical, and functional properties of chickpea protein. After high-pressure homogenization (HPH) treatment, hydrophobic groups and sulfhydryl groups of chickpea protein was exposed which increased its surface hydrophobicity and decreased its total sulfhydryl content. SDS-PAGE analysis showed that the molecular weight of modified chickpea protein remained unchanged. The particle size and turbidity of chickpea protein significantly decreased with an increase in homogenization pressure and cycles. Furthermore, the solubility, foaming, and emulsifying properties of chickpea protein were all enhanced by HPH treatment. In addition, the emulsions prepared by modified chickpea protein showed better stability capacity due to its smaller particle size and higher zeta potential. Therefore, HPH might be an effective technique to improve the functional properties of chickpea protein.

Molecular mechanisms affecting the stability of high internal phase emulsions of zein-soy isoflavone complexes fabricated with ultrasound-assisted dynamic high-pressure microfluidization

In this study, zein-soy isoflavone complex (ZSI) emulsifiers were fabricated using ultrasound-assisted dynamic high-pressure micro fluidization to stabilise highinternal phase pickering emulsions. Ultrasound-assisted dynamic high-pressure micro-fluidization enhanced surface hydrophobicity, zeta potential, and soy isoflavone binding capacity, while it decreased particle size, especially during ultrasound and subsequent microfluidization. The treated ZSI could produce small droplet clusters and gel-like structures, with excellent viscoelasticity, thixotropy and creaming stability owing to their neutral contact angles. Ultrasound and subsequent micro fluidization treatment of the ZSI complexes were highly effective in preventing droplet flocculation and coalescence after long-term storage or centrifugation due to their higher surface load, thicker multi-layer interfacial structure, and stronger electronic repulsion between the oil droplets. This study provides insights and extends our current knowledge of how non-thermal technology affects the interfacial distribution of plant based particles and the physical stability of emulsions.

Protein-Stabilized Emulsion Gels with Improved Emulsifying and Gelling Properties for the Delivery of Bioactive Ingredients: A Review

In today's food industry, the potential of bioactive compounds in preventing many chronic diseases has garnered significant attention. Many delivery systems have been developed to encapsulate these unstable bioactive compounds. Emulsion gels, as colloidal soft-solid materials, with their unique three-dimensional network structure and strong mechanical properties, are believed to provide excellent protection for bioactive substances. In the context of constructing carriers for bioactive materials, proteins are frequently employed as emulsifiers or gelling agents in emulsions or protein gels. However, in emulsion gels, when protein is used as an emulsifier to stabilize the oil/water interface, the gelling properties of proteins can also have a great influence on the functionality of the emulsion gels. Therefore, this paper aims to focus on the role of proteins' emulsifying and gelling properties in emulsion gels, providing a comprehensive review of the formation and modification of protein-based emulsion gels to build high-quality emulsion gel systems, thereby improving the stability and bioavailability of embedded bioactive substances.

Insight into the incredible effects of microwave heating: Driving changes in the structure, properties and functions of macromolecular nutrients in novel food

Microwave heating technology performs the characteristics of fast heating, high efficiency, green energy saving and easy control, which makes it deeply penetrate into the food industry and home cooking. It has the potential to alter the appearance and flavor of food, enhance nutrient absorption, and speed up the transformation of active components, which provides an opportunity for the development of innovation foods. However, the change of food driven by microwave heating are very complex, which often occurs beyond people's cognition and blocks the development of new food. It is thus necessary to explore the transformation mechanism and influence factors from the perspectives of microwave technology and food nutrient diversity. This manuscript focuses on the nutritional macromolecules in food, such as starch, lipid and protein, and systematically analyzes the change rule of structure, properties and function under microwave heating. Then, the flavor, health benefits, potential safety risks and bidirectional allergenicity associated with microwave heating are fully discussed. In addition, the development of new functional foods for health needs and future market based on microwave technology is also prospected. It aims to break the scientific fog of microwave technology and provide theoretical support for food science to understand the change law, control the change process and use the change results.

Structural, Thermal and Pasting Properties of Heat-Treated Lotus Seed Starch–Protein Mixtures

The interactions between starch and protein, the essential components of lotus seed, strongly influence the quality of lotus seed processing by-products. This study investigated the effects of lotus seed starch–protein (LS-LP) interactions on the structural, thermal and gelatinization properties of LS-LP mixtures, using LS/LP ratios of 6:1, 6:2, 6:3, 6:4, 6:5, or 1:1, after heat treatment (95 °C, 30 min). Fourier transform infrared peaks at 1540 cm⁻¹ and 3000–3600 cm⁻¹ revealed the major interactions (electrostatic and hydrogen bonding) between LS and LP. The UV–visible absorption intensities (200–240 nm) of LS-LP mixtures increased with increased protein content. X-ray diffraction and electron microscopy revealed that LS-LP consists of crystalline starch granules encapsulated by protein aggregates. Increasing the addition of protein to the mixtures restricted the swelling of the starch granules, based on their solubility, swelling properties and thermal properties. Viscometric analysis indicated that the formation of LS-LP mixtures improved structural and storage stability. These findings provide a practicable way to control the thermal and gelatinization properties of lotus seed starch–protein mixtures, by changing the proportions of the two components, and provide a theoretical basis for developing novel and functional lotus-seed-based foods.

Gel Property of Soy Protein Emulsion Gel: Impact of Combined Microwave Pretreatment and Covalent Binding of Polyphenols by Alkaline Method

This study investigated the effects of microwave modification, alkali polyphenol (ferulic acid) covalently combined modification, and microwave-alkali polyphenol covalently combined modification on the gel properties of soy protein emulsions. The results showed that the properties of soy protein emulsions were improved significantly by the three modification methods. After three kinds of modification, the viscoelasticity of soy protein emulsion gel increased, and a gel system with stronger elasticity was formed. The texture, water-holding, and hydration properties of the emulsion gel increased significantly. The SEM and ClSM results showed that the modified soy protein emulsion gel had a more compact and uniform porous structure, and the oil droplets could be better embedded in the network structure of the gel. Among the three modification methods, the microwave-alkali method polyphenol covalently combining the compound modification effect was best, and the microwave modification effect was least effective compared to the other two methods. Our obtained results suggested that for gel property modification of soy protein emulsion gels, microwave pretreatment combined with the covalent binding of polyphenols by an alkaline method is an effective method.

Pulsed Electric Field: Fundamentals and Effects on the Structural and Techno-Functional Properties of Dairy and Plant Proteins

Dairy and plant-based proteins are widely utilized in various food applications. Several techniques have been employed to improve the techno-functional properties of these proteins. Among them, pulsed electric field (PEF) technology has recently attracted considerable attention as a green technology to enhance the functional properties of food proteins. In this review, we briefly explain the fundamentals of PEF devices, their components, and pulse generation and discuss the impacts of PEF treatment on the structure of dairy and plant proteins. In addition, we cover the PEF-induced changes in the techno-functional properties of proteins (including solubility, gelling, emulsifying, and foaming properties). In this work, we also discuss the main challenges and the possible future trends of PEF applications in the food proteins industry. PEF treatments at high strengths could change the structure of proteins. The PEF treatment conditions markedly affect the treatment results with respect to proteins' structure and techno-functional properties. Moreover, increasing the electric field strength could enhance the emulsifying properties of proteins and protein-polysaccharide complexes. However, more research and academia-industry collaboration are recommended to build highly effective PEF devices with controlled processing conditions.

Changes in Myosin from Silver Carp (Hypophthalmichthys molitrix) under Microwave-Assisted Water Bath Heating on a Multiscale

To further prove the advantages of microwave-assisted water bath heating (MWH) in low-value fish processing, the effects of different heating methods (two heating stage method, high temperature section respectively using MWH1, MWH2, MWH3, WH—water heating, MH—microwave heating) on secondary and tertiary myosin structures, SDS-PAGE, surface morphology, scanning electron microscopy (SEM), and particle size distribution were compared and analyzed. The findings revealed that MH and MWH aided in the production of gel formations by promoting myosin aggregation. Myosin from silver carps demonstrated enhanced sulfhydryl group and surface hydrophobicity after MWH treatment, as well as a dense network structure. The distribution of micropores becomes more uniform when the microwave time is increased. Actually, the total effect of microwave time on myosin is not substantially different. The correlation between particle size distribution and protein aggregation was also studied, in terms of time savings, the MWH of short microwave action is preferable since it not only promotes myosin aggregation but also avoids the drawbacks of a rapid warming rate. These discoveries give a theoretical foundation for understanding silver carp myosin under microwave modification, which is critical in the food industry.

Synthesis and characterization of lotus seed protein-based curcumin microcapsules with enhanced solubility, stability, and sustained release

BACKGROUND

Lotus seed protein (LSP) was extracted from lotus seed and used to encapsulate curcumin with or without complexing with pectin. The physicochemical properties of LSP-based microcapsules, including solubility, stability, and in vitro sustained release, were determined. The mechanism of interaction between curcumin, LSP, and pectin was revealed.

RESULTS

The encapsulation efficiency of curcumin was found to depend on LSP concentration and was highest (86.32%, w/w) at 50 mg mL^-1 . The curcumin in curcumin-LSP and curcumin-LSP-pectin powder particles achieved a solubility of 75.15% and 81.39%, respectively, which was a remarkable enhancement. The microencapsulation with LSP and LSP-pectin matrix showed a significant improvement in the antioxidant activity, photostability, thermostability, and storage stability of free curcumin. The microencapsulated curcumin showed sustained control release at the gastric stage and burst-type release in the subsequent intestinal stage, presenting cumulative release rates of 64.3% and 72.4% from curcumin-LSP and curcumin-LSP-pectin particles after gastrointestinal digestion. The LSP-pectin complex produced microcapsules with higher solubility, smaller particle size, enhanced physicochemical stability, and increased bioaccessibility. Fourier transform infrared, circular dichroism spectra, and differential scanning calorimetry data indicated that the encapsulated curcumin interacted with LSP and pectin mainly through hydrogen bonding, hydrophobic, and electrostatic interactions.

CONCLUSION

This work shows that LSP can be an alternative encapsulant for the delivery of hydrophobic nutraceuticals with enhanced solubility, stability, and sustained release. The results may contribute to the design of novel food-grade delivery systems based on LSP vehicles, thereby broadening the applications of LSP in the fields of functional food. © 2021 Society of Chemical Industry.

Influence of non-thermal microwaveradiationon emulsifying properties of sunflower protein

Sunflower protein isolate obtained from industrially de-oiled press cake was treated with non-thermal microwave, aiming to investigate how structure and emulsifying properties were affected. Our results indicated that the content of polar amino acids was decreased and solubility and surface hydrophobicity were altered upon exposure to non-thermal microwave. Higher solubility and surface hydrophobicity of the samples treated with defrost mode and also 350 W were accompanied by a smaller size and lower uniformity of the oil droplets compared to the control and other samples. Non-thermal microwave treatment improved the emulsion stability by 1.43 times and defrost mode treated sample had the lowest stability index after 120 min. Interfacial dilatational rheology measurements revealed that 70 and 350 W treated samples created higher elastic, less stretchable solid-like layer at the O/W interface in comparison with defrost mode treated and control samples. Consequently, non-thermal microwave treatment could be considered as a promising simple, fast, and "green" protein modification technique.

Molecular structure modification of ovalbumin through controlled glycosylation with dextran for its emulsibility improvement

Ovalbumin (OVA) is a high nutritious protein, but the poor emulsibility limited its application. The present study glycosylated OVA with dextran (Dex) by controlled wetheating (60-90 °C for 3 h). Temperature was an inductive factor for glycosylation degree (DG and browning intensity), and higher temperature could accelerate the reaction. Variations in molecular structure of OVA were analyzed by SDS-PAGE, FTIR, fluorescence spectroscopy and UV spectroscopy, which verified successes in the generation of glycoconjugate with more flexible structure. Emulsifying activity index (EAI) and emulsion stability index (ESI) for the emulsion of OVA-Dex glycoconjugates were significantly enhanced with the increasing of glycosylation temperature. Moreover, confocal laser scanning results revealed that the emulsion exhibited smaller size and more uniform distribution, and slower transmission profiles were checked by LUMiSizer centrifugal analysis as well, confirming the emulsibility improvement of OVA. Thus, controlled glycosylation reaction is an available method to improve the emulsifying properties of OVA.

Recent Developments in the Formulation and Use of Polymers and Particles of Plant-based Origin for Emulsion Stabilizations

The main scope of this Review was the recent progress in the use of plant-based polymers and particles for the stabilization of Pickering and non-Pickering emulsion systems. Due to their availability and promising performance, it was discussed how the source, modification, and formulation of cellulose, starch, protein, and lignin-based polymers and particles would impact their emulsion stabilization. Special attention was given toward the material synthesis in two forms of polymeric surfactants and particles and the corresponding formulated emulsions. Also, the effects of particle size, degree of aggregation, wettability, degree of substitution, and electrical charge in stabilizing oil/water systems and micro- and macro-structures of oil droplets were discussed. The wide range of applications using such plant-based stabilizers in different technologies as well as their challenge and future perspectives were described.

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.

Microwave technology: a novel approach to the transformation of natural metabolites

Microwave technology is used throughout the world to generate heat using energy from the microwave range of the electromagnetic spectrum. It is characterized by uniform energy transfer, low energy consumption, and rapid heating which preserves much of the nutritional value in food products. Microwave technology is widely used to process food such as drying, because food and medicinal plants are the same organisms. Microwave technology is also used to process and extract parts of plants for medicinal purposes; however, the special principle of microwave radiation provide energy to reaction for transforming chemical components, creating a variety of compounds through oxidation, hydrolysis, rearrangement, esterification, condensation and other reactions that transform original components into new ones. In this paper, the principles, influencing factors of microwave technology, and the transformation of natural metabolites using microwave technology are reviewed, with an aim to provide a theoretical basis for the further study of microwave technology in the processing of medicinal materials.

Comparison of the characteristics of prolamins among foxtail millet varieties with different palatability: Structural, morphological, and physicochemical properties

Recently, there are considerable interests in the influence of prolamins on eating quality of grains. To inquire the potential effect of prolamins on the palatability of foxtail millet, prolamin characteristics under its raw (PR) and post-cooked (PC) state among three typical varieties with high (Zhonggu, ZG), medium (Zhaonong, ZN), and low (Hongmiao, HM) palatability were compared. The distinctive differences in amino acid composition, molecular structure, physicochemical properties were found in PRs and PCs, especially for HM variety. HM-PR recorded the lowest hydrophobic amino acids and surface hydrophobicity while having the superior hydration properties. The lowest denaturation temperature was found in HM-PR, which also had the highest denaturation enthalpy (ΔH). Nevertheless, HM-PR exhibited irregularly spherical protein body with the largest mean diameter. Evidenced by the highest random coil and lower α-helix and β-sheet content, a less stable secondary structure of HM-PR was found, corresponding to the most intensified disulfide cross-linking and protein aggregations in HM upon cooking. Overall, HM-PR was presumed to greatly affect the hydro-thermal utilization efficiency of starch granules during cooking, given the steric-hindrance effect of prolamins on granules in endosperm. The Present study provided new insights into the role of prolamins on foxtail millet palatability.

Interfacial and Emulsion Characteristics of Oil-Water Systems in the Presence of Polymeric Lignin Surfactant

It is hypothesized that polymeric lignin surfactants have different affinities for stabilizing oil-water emulsions and that the emulsifying performance of these surfactants is highly affected by their adsorption performance at the oil-water interface. To validate this hypothesis, the adsorption performance of sulfethylated lignin (SEKL) surfactant at different oil-water interfaces was examined by assessing the contact angle, dynamic interfacial tension, and surface loading (Γ). Moreover, the interfacial adsorption kinetics of SEKL was comprehensively assessed in different oil-water systems to reveal the mechanisms of the SEKL adsorption at the interface. Also, the impacts of SEKL concentration and ionic strength on the performance of SEKL as an effective emulsifier for the emulsions were assessed. Furthermore, the droplet size and instability index of the emulsions were systematically correlated with the adsorption performance of SEKL at the interface of oil and water. For the first time, by implementing a modified Ward Toradai diffusion model, two distinct early stages of the adsorption of SEKL at the oil interface were identified. Interestingly, the second stage was the determining stage of adsorption with the diffusion-controlled mechanism when polymers reconfigured at the oil-water interface. Salt screening facilitated the clustering of SEKL upon charge repulsion elimination, which removed the energy barrier in the first stage of adsorption (ΔE_p→0 = 0), but it introduced a steric barrier upon the reconfiguration of polymers at the oil interfaces in the second stage of adsorption. In addition to the kinetics of adsorption, satisfactory correlations were observed between surface pressure (Δγ = γ_∞ - γ₀), surface loading (Γ) of polymers, and contact angle at oil interfaces on one hand and the oil droplet size and emulsion stability on the other hand.

Comprehensive analysis of AGPase genes uncovers their potential roles in starch biosynthesis in lotus seed

BACKGROUND

Starch in the lotus seed contains a high proportion of amylose, which endows lotus seed a promising property in the development of hypoglycemic and low-glycemic index functional food. Currently, improving starch content is one of the major goals for seed-lotus breeding. ADP-glucose pyrophosphorylase (AGPase) plays an essential role in regulating starch biosynthesis in plants, but little is known about its characterization in lotus.

RESULTS

We describe the nutritional compositions of lotus seed among 30 varieties with starch as a major component. Comparative transcriptome analysis showed that AGPase genes were differentially expressed in two varieties (CA and JX) with significant different starch content. Seven putative AGPase genes were identified in the lotus genome (Nelumbo nucifera Gaertn.), which could be grouped into two subfamilies. Selective pressure analysis indicated that purifying selection acted as a vital force in the evolution of AGPase genes. Expression analysis revealed that lotus AGPase genes have varying expression patterns, with NnAGPL2a and NnAGPS1a as the most predominantly expressed, especially in seed and rhizome. NnAGPL2a and NnAGPS1a were co-expressed with a number of starch and sucrose metabolism pathway related genes, and their expressions were accompanied by increased AGPase activity and starch content in lotus seed.

CONCLUSIONS

Seven AGPase genes were characterized in lotus, with NnAGPL2a and NnAGPS1a, as the key genes involved in starch biosynthesis in lotus seed. These results considerably extend our understanding on lotus AGPase genes and provide theoretical basis for breeding new lotus varieties with high-starch content.