Formation and Functional Attributes of Canola Protein Isolate—Gum Arabic Electrostatic Complexes

Classification of surfactants and admixtures for producing stable aqueous foam

Surfactants and foam have captured the interest of researchers worldwide due to their unique behavior of surface activity, the dynamic nature of foam formation, and simultaneous destruction. The present review focuses on the surfactants' classification, surfactant-solvent interaction, foam formation, characteristics, and a range of admixtures to enhance the foam performance. Although surfactants have been researched and developed for decades, recently, their sustainability has been given special attention. One such aspect is the development of green foaming agents from natural and renewable sources and assessing their suitability for different applications. Further, widely researched parameters are the type of surfactant, surfactant concentration, surfactant-solvent interaction, and foam production method on the foamability of a surfactant solution and related foam characteristics, including stability and texture. However, still, there is no rule to predict the best foam. Another vital concern is the non-standardization of foam assessment methods across industries and regions. Recently, research has progressed in identifying suitable admixtures for foam performance enhancement and utilizing them to produce stable foams for application in enhanced oil recovery, drug delivery, and manufacturing of aerated food products and foamed concrete. Although foam stabilization using various admixtures has been recognized well in the literature, the underlying mechanism requires further research. The interaction of surfactant and admixtures in solution is complicated and requires more research.

Simple and complex coacervation in systems involving plant proteins

Plant-based foods are gaining popularity as alternatives to meat and dairy products due to sustainability and health concerns. As a consequence, there is a renewed interest in the phase behaviour of plant proteins and of mixtures of plant proteins and polysaccharides, in particular in the cases where coacervation is found to occur, i.e., liquid-liquid phase separation (LLPS) into two phases, one of which is rich in biopolymers and one of which is poor in biopolymer. Here we review recent research into both simple and complex coacervation in systems involving plant proteins, and their applications in food- as well as other technologies, such as microencapsulation, microgel production, adhesives, biopolymer films, and more.

Impact of soybean protein isolate concentration on chitosan-cellulose nanofiber edible films: Focus on structure and properties

Chitosan and cellulose nanofiber films are frequently employed as biodegradable materials for food packaging. However, many exhibit suboptimal hydrophobicity and antioxidant properties. To address these shortcomings, we enhanced the performance by adding different concentrations of soybean protein isolate (SPI) to chitosan-cellulose nanofiber (CS-CNF) films. As SPI concentration varied, the turbidity, particle size, and ζ-potential of the film-forming solutions initially decreased and subsequently increased. This suggests that 1 % SPI augments the electrostatic attraction and compatibility. Rheological analysis confirmed a pronounced apparent viscosity at this concentration. Analyses using Fourier transform infrared spectra, Raman spectra, X-ray diffraction, and Scanning electron microscope revealed the presence of hydrogen bonds and electrostatic interactions between SPI and CS-CNF, indicative of superior compatibility. When SPI concentration was set at 1 %, notable enhancements in film attributes were observed: improvements in tensile strength and elongation at break, a reduction in water vapor permeability by 8.23 %, and an elevation in the contact angle by 18.85 %. Furthermore, at this concentration, the ABTS+ and DPPH scavenging capacities of the film surged by 61.53 % and 46.18 %, respectively. Meanwhile, the films we prepare are not toxic. This research offers valuable insights for the advancement and application of protein-polysaccharide-based films.

Impact of Electric Arcs and Pulsed Electric Fields on the Functional Properties of Beta-Lactoglobulin

Beta-lactoglobulin (β-lg) is a major whey protein with various techno-functional properties that can be improved by several treatments. Therefore, the objective of this study was to explore the impact of green high-voltage electrical treatments (HVETs)—namely, pulsed electric fields and electric arcs—on the functional properties of β-lg. Both emulsifying and foaming stability and capacity, as well as the hygroscopicity of non-treated and pretreated β-lg, were explored. The results demonstrated that the emulsifying capacity and stability of pretreated samples increased by 43% and 22% when compared to native β-lg, respectively. Likewise, the pretreated β-lg displayed better foaming stability compared to native β-lg. In addition, the HVETs significantly decreased the hygroscopicity of β-lg (by 48% on average), making it a good ingredient with reduced hygroscopicity for the food industry.

Complex coacervate formation between hemp protein isolate and gum Arabic: Formulation and characterization

In this study, intermolecular interactions and structure formation between hemp protein isolate (HPI) and gum Arabic (GA) were investigated to unravel their complexation mechanisms. For this purpose, structural transition as a function of pH (2.0-7.0) and protein to polysaccharide ratio (HPI:GA, R = 0.5:1-13:1 w/w) was evaluated via turbidimetric analysis, ζ-potentiometry, state diagram construction and coacervate yield. It was proved that critical phase transition pH shifted to higher values with R increase, until reaching a plateau at ratio 10:1, with complexes to be formed even at pH region where both biopolymers were negatively charged. The shift of pH value, where maximum turbidity was noticed (pH_opt), was well in accordance with net charge neutrality of HPI-GA mixtures found by electrophoretic mobility measurements. Maximum coacervation, occurred at ratio R = 2:1 and pH_opt = 3.5, was depicted by the highest yield (92%), while morphological characteristics of liquid as well as freeze-dried HPI-GA coacervates, obtained through optical and scanning electron microscope measurements, gave a further perception of the associative processes during complex coacervation. Additionally, the molecular interactions between HPI and GA were confirmed by Fourier transform infrared spectroscopy (FTIR) revealing primarily electrostatic interactions with secondary stabilization of hydrogen bonds. Therefore, these findings could provide useful information for the development of HPI - GA coacervates as a potential bioactive encapsulation means.

Canola/rapeseed protein - nutritional value, functionality and food application: a review

Plant-based diet and plant proteins specifically are predestined to meet nutritional requirements of growing population of humans and simultaneously reduce negative effects of food production on the environment. While searching for new sources of proteins, special emphasis should be placed on oilseeds of Brassica family comprising varieties of rapeseed and canola as they contain nutritionally valuable proteins, which have potential to be used in food, but are now rarely or not used as food components. The purpose of the present work is to provide a comprehensive review of main canola/rapeseed proteins: cruciferin and napin, with the focus on their nutritional and functional features, putting special emphasis on their possible applications in food. Technological challenges to obtain rapeseed protein products that are free from anti-nutritional factors are also addressed. As molecular structure of cruciferin and napin differs, they exhibit distinct features, such as solubility, emulsifying, foaming or gelling properties. Potential allergenic effect of 2S napin has to be taken under consideration. Overall, rapeseed proteins demonstrate beneficial nutritional value and functional properties and are deemed to play important roles both in food, as well as, non-food and non-feed applications.

Effect of pH and mixing ratio on interpolymer complexation of scallop (Patinopecten yessoensis) male gonad hydrolysates and κ-carrageenan

The electrostatic complex coacervation between scallop Patinopecten. yessoensis male gonad hydrolysates (SMGHs) and κ-carrageenan (κ-C) were monitored by using turbidimetry at various pH (1-12) and biopolymer mixing ratio (9:1-1:9). The pH_c exhibited ratio-independent behavior, and pH_φ1, pH_max exhibited ratio-dependent behavior, respectively. The decreasing ratio enhanced the gel strength of SMGHs/κ-C at higher pH while inversely at lower pH, ascribing to more SMGHs aggregates and stronger neutralization between positively charged patches in SMGHs and κ-C at lower pH and higher ratio. Moreover, SMGHs/κ-C gel at acid condition exhibited lower relaxation times (T₂₁ and T₂₃). Furthermore, the rheological and relaxation time T₂ data were well associated with microscopy images which indicated that SMGHs/κ-C gel showed a well-distributed network structure at more acidic domains, supporting stronger gel rigidity and water-holding capacity.

Ionic strength and hydrogen bonding effects on whey protein isolate-flaxseed gum coacervate rheology

Whey protein isolate (WPI) was mixed with anionic flaxseed (Linum usitatissimum L.) gum (FG), and phase transition during coacervate formation was monitored. Effects of ionic strength and hydrogen bonding on coacervation of WPI-FG system and corresponding rheological properties were investigated. During coacervate formation, structural transitions were confirmed by both turbidimetry and confocal laser scanning microscopy. Increasing ionic strength with sodium chloride (50 mM) decreased optical density (600 nm) at pHmax. Correspondingly, pHc and pHϕ1 decreased from pH 5.4 to 4.8 and from 5.0 to 4.6, respectively, while pHϕ2 increased from pH 1.8 to 2.4. Sodium chloride suppressed biopolymer electrostatic interactions and reduced coacervate formation. Adding urea (100 mM) shifted pHϕ1, pHmax, and pHϕ2 from 4.8, 3.8, and 1.8 to 5.0, 4.0, and 2.2, respectively, while pHc was unaffected. Optical density (600 nm) at pHmax (0.536) was lower than that of control in the absence of urea (0.617). This confirmed the role of hydrogen bonding during coacervate formation in the biopolymer system composed of WPI and FG. Dynamic shear behavior and viscoelasticity of collected coacervates were measured, and both shear-thinning behavior and gel-like properties were observed. Addition of sodium chloride and urea reduced ionic strength and hydrogen bonding, resulting in decreased WPI-FG coacervate dynamic viscosity and viscoelasticity. The disturbed charge balance contributed to a loosely packed structure of coacervates which were less affected by altered hydrogen bonding. Findings obtained here will help to predict flaxseed gum behavior in protein-based foods.

Rheological and Microstructural Characteristics of Canola Protein Isolate-Chitosan Complex Coacervates

Wastage of byproducts such as canola meal is a pressing environmental concern, and canola protein isolate (CPI)-chitosan (Ch) coacervates have a good potential to utilize and convert the wastes into a high value added product. Yet so far, there is very limited rheological and microstructural information to assist in proper utilization of CPI -Ch complex coacervates. The rheological and microstructural properties of the complex coacervates formed from CPI and chitosan Ch at various CPI-to-Ch mixing ratios (1:1, 16:1, 20:1, and 30:1) and pH values (5.0, 6.0, and 7.0) were therefore investigated. These CPI-Ch complex coacervate phases were found to exhibit elastic behavior as evidenced by significantly higher elastic modulus (G') compared to viscous modulus (G″) in all the tested ratios and pH ranges. They also exhibited shear-thinning behavior during viscous flow. The complex coacervates formed at the optimum CPI-to-Ch ratio of 16:1 and pH of 6.0 demonstrated the highest G', G″, and shear viscosity, which correlated well with the high strength of electrostatic interaction and thick-walled, sponge-like, less-porous microstructure at this condition. The higher shear viscosity of the coacervate at pH 6.0 was most likely induced by stronger attractive electrostatic interactions between CPI and Ch molecules, due to the formation of a rather densely packed complex coacervate structure. Hence, it can be concluded that the microstructural observations of denser structure correlated well with the rheological findings of stronger intermolecular bonds at the optimum CPI-to-Ch ratio of 16:1 and pH of 6.0. The complex coacervate phase formed at a CPI-to-Ch ratio of 16:1 and pH of 6.0 also showed glassy consistency at low temperatures and rubbery consistency above its glass-transition temperature. This study identified the potential for the newly developed CPI-Ch complex coacervate to be used as an encapsulating material due to its favorable strength. This would drastically reduce the wastage of byproducts, provide a solution to tackle the pressing global issue of wastage of byproducts, and bring about a more environmentally friendly paradigm.

Review on plant protein-polysaccharide complex coacervation, and the functionality and applicability of formed complexes

Controlling the interactions between plant proteins and polysaccharides can lead to the development of novel electrostatic complexed structures that can give unique functionality. This in turn can broaden the diversity of applications that they may be suitable for. Overwhelmingly in the literature, work and reviews relating to coacervation have involved the use of animal proteins. However, with the increasing demand for plant-based protein alternatives by industry and consumers, a greater understanding of how they interact with polysaccharides is essential to control structure, functionality and applicability. This review discusses the factors governing the nature of protein-polysaccharide interactions, their functional attributes and industrial applications, with special attention given to plant proteins. © 2018 Society of Chemical Industry.