Effect of alkaline extraction pH on structure properties, solubility, and beany flavor of yellow pea protein isolate

Isolation and characterization of nettle (Urtica dioica L.) seed proteins: Conversion of underutilized by-products of the edible oil industry into food emulsifiers

This study aimed to upcycle a byproduct of the edible oil industry, cold-pressed nettle seed meal (CPNSM), into a plant-based emulsifier, thereby increasing the sustainability of the food system. The protein content of the nettle seed protein (NSP) powder was 48.3% with glutamic acid (16.6%), asparagine (10.7%), and arginine (9.7%) being the major amino acids. NSPs had a denaturation temperature of 66.6 °C and an isoelectric point of pH 4.3. They could be used as emulsifiers to form highly viscous coarse corn oil-in-water emulsions (10% oil, 4% NSP). Nevertheless, 10-fold diluted emulsions exhibited rapid creaming under different pH (2-9), salt (0-500 mM NaCl) and temperature (>40 °C) conditions, but they were relatively stable to aggregation. Our findings suggest that NSPs could be used as emulsifiers in highly viscous or gelled foods, like dressings, sauces, egg, cheese, or meat analogs.

Unveiling differential impact of heat and microwave extraction treatments on the structure, functionality, and digestibility of jack bean proteins extracted under varying extraction pH

The poor extractability and digestibility of jack beans restrict their application in food systems. Thermal treatment could be a processing tool to disrupt the compact conformation of the plant matrix and inactivate inherent antinutrients. Therefore, this research investigated the impact of conventional heat-aided (HA-) and microwave-aided (MA-) extraction treatments on the structure, functional properties, and digestibility of jack bean protein concentrate (JBPC) under varying extraction pH. The novelty brought by the present study is establishing the thermal treatment/extraction pH combinations for improving techno-functionalities and digestibility of JBPC. Heat (50 °C for 1 h) and sequential microwave power (400 W, 600 W, and 800 W for 5 min) at three extraction pH (9.0, 10.0, and 11.0) were studied. Upon increasing extraction pH, a significant decrease in the protein content, and β-Sheet structure was observed, in the order of pH 11.0 > 10.0 > 9.0. JBPC extracted using HA treatments displayed the highest contents of surface hydrophobicity (90.02) and sulfhydryl groups. In functional properties, MA-extracted JBPC under 400 W showed significantly improved solubility (93.45 %), emulsifying activity index (45.23 m2/g), and foaming capacity (141.70 %) when compared to other thermal treatments. The degree of hydrolysis result revealed that MA treatment improved the JBPC in vitro digestibility at a low power level of 400 W. These findings suggest that MA extraction treatment can improve the functional and nutritional properties of JBPC regardless of the extraction pH, and thus, expand the potential application in food systems.

Characterization of structural and functional properties of soybean 11S globulin during renaturation after denaturation induced by changes in pH

BACKGROUND

This study explored the denaturation of 11S globulin, a protein known for its diverse functional properties in soy protein applications, at pH 3.0 and pH 10.0, followed by a gradual return to pH 7.0 to facilitate renaturation. It investigated the structural and functional changes during renaturation induced by a change in pH, revealing the stabilization mechanism of 11S globulin.

RESULTS

The findings revealed that during pH adjustment to neutral, the denatured soybean 11S globulin - resulting from alkaline (pH 10.0) or acidic (pH 3.0) treatments - experienced a refolding of its extended tertiary structure to varying extents. The particle size and the proportions of α-helix and β-sheet in the secondary structure aligned progressively with those of the natural-state protein. However, for the alkali-denatured 11S, the β-sheet content decreased upon adjustment to neutral, whereas an increase was observed for the acid-denatured 11S. In terms of functional properties, after alkaline denaturation, the foaming capacity (FC) and emulsifying activity index (EAI) of 11S increased by 1.4 and 1.2 times, respectively, in comparison with its native state. The solubility, foamability, and emulsifiability of the alkali-denatured 11S gradually diminished during renaturation but remained superior to those of the native state. Conversely, these properties showed an initial decline, followed by an increase during renaturation triggered by pH neutralization.

CONCLUSIONS

This research contributes to the enhancement of protein functionality, offering a theoretical foundation for the development of functional soy protein products and expanding their potential applications. © 2024 Society of Chemical Industry.

A comprehensive review on the recent trends in extractions, pretreatments and modifications of plant-based proteins

Plant-based proteins offer sustainable and nutritious alternatives to animal proteins with their techno-functional attributes influencing product quality and designer food development. Due to the inherent complexities of plant proteins, proper extraction and modifications are vital for their effective utilization. This review highlights the emerging sources of plant-based proteins, and the recent statistics of the techniques employed for pretreatment, extraction, and modifications. The pretreatment, extraction and modification approach to modify plant proteins have been classified, addressed, and the recent applications of such methodologies are duly indicated. Furthermore, this study furnishes novel perspectives regarding the potential impacts of emerging technologies on the intricate dynamics of plant proteins. A thorough review of 100 articles (2018-2024) shows the researchers' keen interest in investigating novel plant proteins and how they can be used; seeds being the main source for protein extraction, followed by legumes. Use of by-products as a protein source is increasing rapidly, which is noteworthy. Protein studies still lack knowledge on protein fraction, antinutrients, and pretreatments. The use of physical methods and their combination with other techniques are increasing for effective and environmentally friendly extraction and modification of plant proteins. Several studies explore the effect of protein changes on their function and nutrition, especially with a goal of replacing ingredients with plant proteins that have improved or enhanced qualities. However, the next step is to investigate the sophisticated modification methods for deeper insights into food safety and toxicity.

Reduction of Beany Flavor and Improvement of Nutritional Quality in Fermented Pea Milk: Based on Novel Bifidobacterium animalis subsp. lactis 80

Peas (Pisum sativum L.) serve as a significant source of plant-based protein, garnering consumer attention due to their high nutritional value and non-GMO modified nature; however, the beany flavor limits its applicability. In this study, the effects of Bifidobacterium animalis subsp. Lactis 80 (Bla80) fermentation on the physicochemical characteristics, particle size distribution, rheological properties, and volatile flavor compounds of pea milk was investigated. After fermentation by Bla80, the pH of pea milk decreased from 6.64 ± 0.01 to 5.14 ± 0.01, and the (D4,3) distribution decreased from 142.4 ± 0.47 μm to 122.7 ± 0.55 μm. In addition, Lactic acid bacteria (LAB) fermentation significantly reduced the particle size distribution of pea milk, which was conducive to improving the taste of pea milk and also indicated that Bla80 had the probiotic potential of utilizing pea milk as a fermentation substrate. According to GC-MS analysis, 64 volatile compounds were identified in fermented pea milk and included aldehydes, alcohols, esters, ketones, acids, and furans. Specifically, aldehydes in treated samples decreased by 27.36% compared to untreated samples, while esters, ketones, and alcohols increased by 11.07%, 10.96%, and 5.19%, respectively. These results demonstrated that Bla80 fermentation can significantly decrease the unpleasant beany flavor, such as aldehydes and furans, and increase fruity or floral aromas in treated pea milk. Therefore, Bla80 fermentation provides a new method to improve physicochemical properties and consumer acceptance of fermented pea milk, eliminating undesirable aromas for the application of pea lactic acid bacteria beverage.

Effect of extraction pH on amino acids, nutritional, in-vitro protein digestibility, intermolecular interactions, and functional properties of guar germ proteins

The chemical compositions, intermolecular interactions, and functional properties of guar germ proteins (GGP) were investigated at different extraction pH (7 to 11). The protein efficiency ratio, essential amino acid index (46.53), predicted biological value (39.02), nutritional index (42.67), and protein purity (91.69 %) were found to be highest at pH 9. The in-vitro protein digestibility of GGP sample was highest at pH 11. From SDS-PAGE, the band intensity (<10 kDa) became thinner with an increase in extraction pH from 7 to 9 and then thicker. Meanwhile, smallest particle size and weaker ionic and hydrogen bonds were found at pH 11. The β-sheet content was more dominating in GGP samples. Moreover, higher denaturation temperatures of GGP samples indicated that protein molecules had a compact tertiary structure. Furthermore, the GGP extracted at pH 7 showed better functional properties. The principal component analysis suggested that pH 9 was more suitable for isolating GGP.

Fortification of Pea and Potato Protein Isolates in Oat-Based Milk Alternatives; Effects on the Sensory and Volatile Profile

Oat-based milk alternatives (OMAs) are an important alternative to bovine milk, with prevalence of lactose intolerance, as well as soy and nut allergies limiting consumers options. However, OMAs are typically lower in protein content than both bovine milk and soy-based alternatives, with protein quality limited by low lysine levels, which can reduce protein digestibility. Addition of alternative plant proteins may increase the quantity of protein, as well as balancing the amino acid profile. However, plant-based proteins have additional sensory qualities and off-flavours, which may lead to undesirable characteristics when introduced to OMAs. This study aimed to assess the effect of pea and potato protein addition on the sensory profile, volatile profile, colour, and particle size in an OMA control product. Results demonstrated that pea protein contributed to a bitter and metallic taste, astringent aftertaste, and a significantly increased overall aroma correlated with higher levels of key volatiles. Whilst potato protein resulted in less flavour changes, it did lead to increased powdery mouthfeel and mouthcoating supported by a substantially increased particle size. Both protein fortifications led to detectable colour changes and a staler flavour. Fortification of OMA product with the pea protein led to significant sensory, volatile and physical changes, whilst the potato protein led to predominantly physical changes. Further investigation into alternative plant-based proteins is necessary to optimise sensory qualities whilst increasing protein content and the amino acid profile.

Colloidal and interfacial properties of spray dried pulse protein-blueberry polyphenol particles in model dispersion systems

The phytochemical composition and physicochemical attributes of polyphenol-enriched protein particle ingredients produced with pulse proteins (e.g. chickpea protein, pea protein, and a chickpea-pea protein blend) and polyphenols recovered from wild blueberry pomace were investigated for colloidal and interfacial properties. Anthocyanins were the major polyphenol fraction (27.74-36.47 mg C3G/g) of these polyphenol-rich particles (44.95-62.08 mg GAE/g). Dispersions of pea protein-polyphenol particles showed a superior phase stability before and after heat treatment compared to the chickpea pea protein-polyphenol system. This observation was independent of the added amount of NaCl in the dispersion. In general, at quasi equilibrium state, pulse protein-polyphenol particles and parental pulse protein ingredients showed similar oil-water interfacial tension. However, pea protein-polyphenol particles demonstrated a reduced diffusion-driven oil-water interfacial adsorption rate constant compared to the parental pea protein ingredient. Overall, the obtained results suggest application potential of pea protein-polyphenol particles as a functional food/beverage ingredient.

Effect of partial mutton meat substitution with Bambara groundnut (Vigna subterranea (L.) Verdc.) flour on physicochemical properties, lipid oxidation, and sensory acceptability of low-fat patties

Health concerns regarding fat consumption, as well as shifts in customer preference, have prompted substantial studies into low-fat products. This study examined the nutritional, color, functional, and antioxidant properties of Bambara groundnut (BGN) flour varieties (cream, brown, and red-coated) grains as well as their influence on the physicochemical properties, lipid oxidation, and sensory acceptability of low-fat mutton patties. The patties were formulated with 2.5%, 5%, 7.5%, and 10% of BGN flour for each variety, and 100% mutton patties were used as a control. The BGN flours showed significant (p < .05) differences in their nutritional composition (except for ash content), color, functional (excluding emulsion stability), and antioxidant properties. The increase in the percentage of substitution of BGN flours significantly increased the fiber (0.00% to 0.79%), ash (1.16% to 1.99%), and carbohydrates (2.14% to 1.99%) contents of the formulated mutton patties. However, moisture and protein contents decreased. The cooking yield of the formulated patties significantly increased with the increase in the percentage substitution of BGN flours (2.5%-10%), with values ranging from 76.39% to 86.80%, but the diameter reduction was limited. The increase in the inclusion of BGN flours significantly increased the lightness, hue angle, color difference, and whiteness of patties. Nevertheless, the redness, yellowness, chroma, and yellowness index of the patties decreased. The hardness and resilience of formulated patties significantly increased, with values varying from 16.41 to 17.66 N, and from 0.35 to 0.48 J/J, respectively, whereas the springiness, cohesiveness, and chewiness decreased. The lipid oxidation of formulated mutton patties significantly increased from Days 7 to 21, but was still less than that of the control sample within storage days. The sensory properties of formulated patties were not significantly different from the control sample and were above the acceptable score of five. All BGN varieties had positive effects on the mutton patties, more especially red, followed by brown, and cream, respectively. The inclusion of a 10% red BGN flour variety is highly recommended due to its significant impact on mutton patties. Nevertheless, different types of BGN varieties can each be used as additives in mutton patties without having detrimental effects on the quality parameters of the patties.

Potential inhibitory effect of highland barley protein hydrolysates on the formation of advanced glycation end-products (AGEs): A mechanism study

Advanced glycation end products (AGEs) can be caused during a glycoxidation reaction. This reaction is associated with complications of diabetes and the consequences of health problems. Therefore, we are exploring the prohibitory effect of highland barley protein hydrolysates (HBPHs) on AGE formation. Herein, first extracted the protein from highland barley with various pH conditions and then hydrolyzed using four different proteolytic enzymes (flavourzyme, trypsin, papain, pepsin) under different degrees of hydrolysis. We assessed three degrees of hydrolysates (lowest, middle, highest) of enzymes used to characterize the antioxidant activity and physicochemical properties. Among all the hydrolysates, flavourzyme-treated hydrolysates F-1, F-2, and F-3 indicated the high ability to scavenge DPPH (IC50 values of 0.97 %, 0.63 %, and 0.90 %), structural and functional properties. Finally, the inhibitory effect of the most active hydrolysates F-1, F-2, and F-3 against the AGEs formation was evaluated in multiple glucose-glycated bovine serum albumin (BSA) systems. Additionally, in a BSA system, F-3 exhibited the strong antiglycation activity, effectively suppressed the non-fluorescent AGE (CML), and the fructosamine level. Moreover, it decreased carbonyl compounds while also preventing the loss of thiol groups. Our results would be beneficial in the application of the food industry as a potential antiglycation agent for several chronic diseases.

Viscoelastic behavior, gelation properties and structural characterization of Deccan hemp seed (Hibiscus cannabinus) protein: Influence of protein and ionic concentrations, pH, and temperature

This study investigates the viscoelastic behavior, gelling properties, and structural characteristics of Deccan hemp seed protein (DHSP) to overcome limitations in its application in food formulations. Small amplitude oscillatory shear measurements were employed to investigate the impact of protein concentration, pH, ionic concentration, and temperature on DHSP's rheological features. The study revealed that the 20 % protein dispersion had the highest storage modulus (G') and yield stress at 63.96 ± 0.23 Pa and 0.61 Pa, respectively. DHSP dispersion exhibited pseudo-plastic behavior across various conditions. The gelling performance was higher at pH 4 and 8 and at ionic concentration in the range of 0.1 M - 0.5 M. Gelation time and temperature were observed from the temperature ramp test. Structural characterizations, including fluorescence spectroscopy, circular dichroism spectra, FTIR spectra, SEM, AFM images, zeta potential analysis, and DSC, provided insights into DHSP's tertiary and secondary conformation, surface characteristics, and thermal properties. Notably, the study highlighted DHSP's exceptional rheological properties, making it a promising gelling material for the food and nutraceutical industries. The findings also offer new insights into DHSP's structural characteristics, suggesting potential applications in food packaging and product development within 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.

Effect of heat treatment on the release of off-flavor compounds in soy protein isolate

The effects of different heat treatment conditions (65℃ for 30 min, 75℃ for 15 min, and 95℃ for 2, 15 and 30 min) on the evolution of off-flavor compounds in soy protein isolate (SPI) were investigated in terms of lipid oxidation, Maillard reaction and protein structural characteristics. Higher off-flavor concentrations were observed in control and 65℃ treated SPI due to lipoxygenase-mediated enzymatic lipid oxidation. Protein structure played an important role in the release of off-flavors above 65℃. When heated from 75℃ to 95℃ for 2 min, Maillard reaction occurred, glycinin was completely denatured, the particle size increased and the small molecular weight soluble aggregates were formed, resulting in an increase in the content of partial off-flavors. The off-flavor content decreased with time at 95℃, accompanied by the formation of larger molecular weight soluble aggregates. This finding provides practical implications for the beany removal through the SPI structural regulation.

Isolation of detoxified cassava (Manihot esculenta L.) leaf protein by alkaline extraction-isoelectric precipitation: Optimization and its characterization

The cassava leaves protein isolate extraction and optimization were investigated using response surface methodology, where the maximum protein content (21.83 ± 0.41 g/100 g dm), extraction yield (18.31 ± 0.53%), and protein recovery yield (69 ± 1.31%) were obtained at optimal conditions: 114 min extraction time, 46 °C extraction temperature, 23.5 mL/g solvent/solute ratio and pH 11.0 value. The presence of toxicant (Cyanide) and anti-nutrient (tannin) in cassava leaves reduced the bio-accessibility of its protein isolate, strictly prohibiting its consumption. Therefore, detoxification was applied to diminish cyanide and tannin to 85% and 69% in leaves, respectively, where the protein content was reduced to 9.7%. However, detoxified cassava leaf protein isolate exhibited changes in the compositional, structural, morphological, molecular, and thermal characteristics compared to the controlled one. Moreover, the functional properties in protein isolate improved after detoxification at different pH conditions, which can be used as an active ingredient in various foods.

Plant protein solubility: A challenge or insurmountable obstacle

Currently, there is an increasing focus on comprehending the solubility of plant-based proteins, driven by the rising demand for animal-free food formulations. The solubility of proteins plays a crucial role in impacting other functional properties of proteins and food processing. Consequently, understanding protein solubility in a deeper sense may allow a better usage of plant proteins. Herein, we discussed the definition of protein solubility from both thermodynamic and colloidal perspectives. A range of factors affecting solubility of plant proteins are generalized, including intrinsic factors (amino acids composition, hydrophobicity), and extrinsic factors (pH, ionic strength, extraction and drying methods). Current methods to enhance solubility are outlined, including microwave, high intensity ultrasound, hydrostatic pressure, glycation, pH-shifting, enzymatic hydrolysis, enzymatic cross-linking, complexation and modulation of amino acids. We base the discussion on diverse modified methods of nitrogen solubility index available to determine and analyze protein solubility followed by addressing how other indigenous components affect the solubility of plant proteins. Some nonproteinaceous constituents in proteins such as carbohydrates and polyphenols may exert positive or negative impact on protein solubility. Appropriate protein extraction and modification methods that meet consumer and manufacturers requirements concerning nutritious and eco-friendly foods with lower cost should be investigated and further explored.

The effect of different pre-treatments on unformulated pulse-based milk analogs: physicochemical properties and consumer acceptance

This is the first part of a study on developing pulse-based milk analogs using chickpea, faba bean, and cowpea as raw materials. The objectives of the present study were to determine the processing conditions for pulse-based milk analog production at laboratory-scale and to investigate the effects of some pre-treatments such as dry milling (control), soaking and wet milling, blanching, blanching and dehulling, vacuum, and germination on lipoxygenase (LOX) activity of the raw material and some physicochemical and sensory properties of the final products. Dry milling provided the lowest LOX activity and the highest yield while soaking and wet milling resulted in a substantial increase in LOX activity, lower product yield, and a final product with lower whiteness value, regardless of the pulse type. Germination caused a significant decrease in LOX activity in all pulse types, while milk analogs produced from germinated pulses received the lowest acceptability scores from consumers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05836-7.

Physicochemical properties of Pickering emulsion fabricated with polysaccharides/pea protein isolate complex and its application in plant-based patty

Incorporation of structured liquid oil within plant-based patties can be achieved through the utilization of food-grade Pickering emulsion (PE). Therefore, the aim of this study was to evaluate the quality characteristics of PE and its application in plant-based patty. The PEs were formulated using sunflower oil (SO), polysaccharides and protein, and the specific ratios employed were as following: methylcellulose (MC) 2 % only (MP0); MC 1.5 % + pea protein isolate (PPI) 0.5 % (MP1); MC 1 % + PPI 1 % (MP2); xanthan gum (XG) 2 % only (XP0); XG 1.5 % + PPI 0.5 % (XP1); XG 1 % + PPI 1 % (XP2). MP0 and MP1 were unstable as PEs, whereas MP2 and XP groups (XP0, XP1, and XP2) exhibited stability as a PE. In addition, MP2 and all XP groups showed increased oil binding capacity, hydrophobic interaction, thermal stability, crystallization, rheological properties, and oxidative stability, compared to MP0 and MP1. In PE-applied plant-based patties, MP2 and all XP groups had significantly lower cooking loss and higher emulsion stability than SO. Particularly, MP2-employed plant-based patties exhibited significantly improved textural and sensory properties. Therefore, our data suggest that PEs with methylcellulose and pea protein isolate could be an effective replacement of plant oil in plant-based meat analogs.

From Fundamental Amyloid Protein Self-Assembly to Development of Bioplastics

Proteins can self-assemble into a range of nanostructures as a result of molecular interactions. Amyloid nanofibrils, as one of them, were first discovered with regard to the relevance of neurodegenerative diseases but now have been exploited as building blocks to generate multiscale materials with designed functions for versatile applications. This review interconnects the mechanism of amyloid fibrillation, the current approaches to synthesizing amyloid protein-based materials, and the application in bioplastic development. We focus on the fundamental structures of self-assembled amyloid fibrils and how external factors can affect protein aggregation to optimize the process. Protein self-assembly is essentially the autonomous congregation of smaller protein units into larger, organized structures. Since the properties of the self-assembly can be manipulated by changing intrinsic factors and external conditions, protein self-assembly serves as an excellent building block for bioplastic development. Building on these principles, general processing methods and pathways from raw protein sources to mature state materials are proposed, providing a guide for the development of large-scale production. Additionally, this review discusses the diverse properties of protein-based amyloid nanofibrils and how they can be utilized as bioplastics. The economic feasibility of the protein bioplastics is also compared to conventional plastics in large-scale production scenarios, supporting their potential as sustainable bioplastics for future applications.

Outcomes of structure, function and flavor of pea protein isolate treated by AC, DC and pulsed electric fields

Based on the standpoint of low carbon footprint processing and less denaturation of plant protein ingredient, the effects of pulsed electric field (PEF), direct current electric field (DCEF), and alternating current electric field (ACEF) treatments on the structure, functional properties and volatile compounds of pea protein isolate were investigated. The results showed that the electric fields (EFs) caused both blueshifts (max. ∼8 cm-1) and redshifts (max. ∼7 cm-1) in the IR spectra and blueshifts (max. ∼5 nm) in the UV spectra. PEF caused an increase of emulsifying activity index and a decrease of emulsion stability index to DCEF and ACEF. A total of 27 volatile compounds were identified and the EFs could cause emerging of new volatiles and disappearing of inherent volatiles potentially to modify the flavor of products. Alterations were significantly observed among the types of EF, but seldomly among the operating parameter levels in the same EF.

A comprehensive review on hempseed protein: Production, functional and nutritional properties, novel modification methods, applications, and limitations

With the global population on the rise, challenges in meeting protein demands are amplified by recent crises, prompting a swift shift to alternative protein sources due to disruptions in the supply chain. Plant-based proteins are gaining momentum due to economic, cultural, and environmental considerations, aligning with the preference for sustainable diets and resulting in more affordable plant-based products. The distinction between drug and industrial hemp fuels demand for its nutritional value, digestibility, low allergenicity, and bioactive properties. Industrial hempseed, featuring minimal Δ9-Tetrahydrocannabinol (THC) content (<0.2 %), emerges as a promising crop, offering high-quality protein and oil. The de-oiled hempseed cake stands as an eco-friendly and promising protein source enriched with phenolic compounds and fiber. Ongoing research seeks to enhance techno-functional properties of hempseed protein, surmounting initial limitations for integration into various foods. A range of techniques, both conventional and innovative, optimize protein characteristics, while modifying plant-based protein structures augments their application potential. Modification approaches like ultrasound, high-pressure homogenization, conjugation, complexation, fibrillization, and enzymatic methods enhance hempseed protein functionality. The review critically evaluates the techno-functional attributes of hempseed protein and explores strategies for customization through structural modifications. Lastly, the review assesses its composition, potential as a plant-based source, addresses challenges, and discusses strategies for enhanced functionality.

Transglutaminase-Induced Polymerization of Pea and Chickpea Protein to Enhance Functionality

Pulse proteins, such as pea and chickpea proteins, have inferior functionality, specifically gelation, compared to soy protein, hindering their applications in different food products, such as meat analogs. To close the functionality gap, protein polymerization via targeted modification can be pursued. Accordingly, transglutaminase-induced polymerization was evaluated in pea protein isolate (PPI) and chickpea protein isolate (ChPI) to improve their functionality. The PPI and ChPI were produced following a scaled-up salt extraction coupled with ultrafiltration (SE-UF) process. Transglutaminase (TGase)-modified PPI and ChPI were evaluated in comparison to unmodified counterparts and to commercial protein ingredients. Protein denaturation and polymerization were observed in the TG PPI and TG ChPI. In addition, the TGase modification led to the formation of intermolecular β-sheet and β-turn structures that contributed to an increase in high-molecular-weight polymers, which, in turn, significantly improved the gel strength. The TG ChPI had a significantly higher gel strength but a lower emulsification capacity than the TG PPI. These results demonstrated the impact of the inherent differences in the protein fractions on the functional behavior among species. For the first time, the functional behavior of the PPI and ChPI, produced on a pilot scale under mild processing conditions, was comprehensively evaluated as impacted by the TGase-induced structural changes.

Water-soluble fraction of pea protein isolate is critical for the functionality of protein-glucose conjugates obtained via wet-heating Maillard reaction

Wet-heating Maillard reaction (MR) has been applied to improve the function of proteins by conjugating with soluble carbohydrates. However, the impact of soluble solutes particularly in plant protein on the degree of MR and the properties of the corresponding conjugates has yet to be discussed. In this study, high-intensity ultrasound (HIUS) was utilized to pretreat commercial pea protein isolate in order to improve its solubility. Two different fractions including soluble fraction (SUPPI) and whole solution (UPPI) of HIUS treated PPI were conjugated with glucose (G) to prepare SUPPI-G and UPPI-G, respectively, over a course of 24 h wet-heating at 80 °C. Conjugation was confirmed by the degree of glycation, SDS-PAGE, FTIR, and intrinsic fluorescence analysis. Color change and glucose content analysis showed that the degree of MR was greater when using SUPPI rather than UPPI. The solubility of SUPPI-G was further improved by 24 h of MR while it remained unchanged for UPPI-G. The emulsifying activity index and foaming capability of SUPPI-G were similar to those of UPPI-G. Interfacial properties determined by dynamic adsorption and dilatational rheology at both oil-water and air-water interface suggested that insoluble fraction of UPPI is essential to make stable emulsions and foams. In conclusion, the proportion of soluble protein in PPI is critical to its wet-heating MR based conjugation with glucose and the solubility of the conjugates.

Cricket Protein Isolate Extraction: Effect of Ammonium Sulfate on Physicochemical and Functional Properties of Proteins

Crickets are known to be a promising alternative protein source. However, a negative consumer bias and an off-flavor have become obstacles to the use of these insects in the food industry. In this study, we extracted the protein from commercial cricket powder by employing alkaline extraction-acid precipitation and including ammonium sulfate. The physicochemical and functional properties of the proteins were determined. It was found that, upon including 60% ammonium sulfate, the cricket protein isolate (CPI) had the highest protein content (~94%, w/w). The circular dichroism results indicated that a higher amount of ammonium sulfate drastically changed the secondary structure of the CPI by decreasing its α-helix content and enhancing its surface hydrophobicity. The lowest solubility of CPI was observed at pH 5. The CPI also showed better foaming properties and oil-holding capacity (OHC) compared with the cricket powder. In conclusion, adding ammonium sulfate affected the physicochemical and functional properties of the CPI, allowing it to be used as an alternative protein in protein-enriched foods and beverages.

Functionality of pea protein isolate solutions is affected by reconstitution conditions

Pea protein isolate (PPI), a high-concentration protein ingredient derived from peas, is increasingly utilized in food applications, including beverages, meat or dairy alternatives, and baked goods. The protein extraction process typically used to manufacture PPI renders the protein highly denatured, which can have a negative impact on its functionality. Therefore, it is critical to understand how to prepare and utilize PPI to maximize its functionality. The current study evaluates the effect of select reconstitution conditions on the structure and functionality of PPI, across a range of protein concentrations (4%-10%) relevant to a variety of food applications. Temperature during reconstitution with water and hydration time impacted both protein hydration and its functionality. Increasing reconstitution temperature from 20 to 60°C and increasing hydration time from 10 to 40 min decreased PPI particle size in solution and increased PPI solubility. Viscosity of PPI solutions also increased with mild heating and longer hydration time, whereas their flow behavior was highly dependent on protein concentration. Experimental data demonstrates that reconstitution conditions have a significant impact on PPI functionality. These findings can help food formulators develop high-quality food products that utilize PPI as a functional ingredient. PRACTICAL APPLICATION: Protein in commercially available pea protein isolates (PPIs) is usually highly denatured, and thus, it is important to find ways to maximize its functionality in practical applications. The findings of this study inform food scientists how to leverage PPI at various protein concentrations with optimal reconstitution conditions to develop high-quality products. Generally, mild heating and longer hydration times improve PPI functional performance.

Partial characterization of canola (Brassica napus L.) protein isolates as affected by extraction and purification methods

Canola (Brassica napus L.) meal represents a prominent alternative plant-based source for protein isolation. This work aimed to investigate the combined effect of extraction and purification methods for the production of canola protein isolates (CPIs). CPIs were characterized in terms of process yield, protein recovery, basic composition, amino acid profile, in vitro protein digestibility, techno-functional properties, structural properties, and molecular features. The results showed that the Alk-Uf method enhanced yield (16.23 %) and protein recovery (34.88 %). Meanwhile, the Et-Alk-Uf method exhibited the highest crude protein (89.71 %) and free amino nitrogen (4.34 mg g protein-1) contents. Furthermore, protein digestibility (95.5 %) and protein digestibility corrected amino acid score (1.0) were improved using the Et-Alk-Ac method. Conversely, the amino acid composition, secondary structure, and electrophoretic profiles were generally similar for all CPIs. The Alk-Uf and Et-Alk-Uf methods produced isolates with the highest water solubility (∼39.18 %), water absorption capacity (∼3.86 g water g protein-1), oil absorption capacity (∼2.77 g oil g protein-1), and foaming capacity (∼505.26 %). Finally, the foaming stability (93.75 %) and foaming density (34.38 %) were increased when employing the Alk-Ac method. These findings suggest that, in general, the Alk-Uf and Et-Alk-Uf methods can be used to obtain CPIs with high added value for use in food formulations.

Yellow Field Pea Protein (Pisum sativum L.): Extraction Technologies, Functionalities, and Applications

Yellow field peas (Pisum sativum L.) hold significant value for producers, researchers, and ingredient manufacturers due to their wealthy composition of protein, starch, and micronutrients. The protein quality in peas is influenced by both intrinsic factors like amino acid composition and spatial conformations and extrinsic factors including growth and processing conditions. The existing literature substantiates that the structural modulation and optimization of functional, organoleptic, and nutritional attributes of pea proteins can be obtained through a combination of chemical, physical, and enzymatic approaches, resulting in superior protein ingredients. This review underscores recent methodologies in pea protein extraction aimed at enhancing yield and functionality for diverse food systems and also delineates existing research gaps related to mitigating off-flavor issues in pea proteins. A comprehensive examination of conventional dry and wet methods is provided, in conjunction with environmentally friendly approaches like ultrafiltration and enzyme-assisted techniques. Additionally, the innovative application of hydrodynamic cavitation technology in protein extraction is explored, focusing on its prospective role in flavor amelioration. This overview offers a nuanced understanding of the advancements in pea protein extraction methods, catering to the interests of varied stakeholders in the field.

Quantifying the effects of pre-roasting on structural and functional properties of yellow pea proteins

Roasting could modify the protein structure/conformation, contributing to changes in functional properties. Here we investigated the effects of pre-roasting on the extraction efficiency, structural and functional properties of pea protein concentrates and isolates (PPC and PPI) produced from yellow split peas. The shorter roasting times (150 °C, 10 and 20 min) had little effect on protein yields and could increase the solubility of PPC or PPI by ∼ 12% at pH 7 and enhance the solubility of PPI by ∼ 12% (10-min roasting) and ∼ 24% (20-min roasting) at pH 3. However, a longer duration of pre-roasting (150 °C, 30 min) significantly reduced the extraction efficiency of PPC and PPI by ∼ 30% and ∼ 61%, respectively. Meanwhile, pre-roasting had minor effects on SDS-PAGE profiles and the secondary structures of pea proteins but significantly altered tertiary structures by reducing free sulfhydryl groups, increasing disulfide bonds and surface hydrophobicity. As for the emulsifying properties, pre-roasting improved the emulsion ability index (EAI) of PPC and PPI but decreased the emulsion stability index (ESI) of PPC and had no significant effect on PPI. Moreover, PPC and PPI with shorter pre-roasting duration (10 and 20 min) had endothermic peaks and showed a slight decrease in the denaturation temperature (Td) and the onset temperature (To), respectively. Overall, the study demonstrated that controlled pre-roasting at 150 °C for 10 min and 20 min altered protein structures (mainly tertiary structures), improving the solubility and EAI of pea proteins at pH 7, while retaining their thermal properties in comparison to unroasted samples.

Performance of rice protein hydrolysates as a stabilizing agent on oil-in-water emulsions

Rice protein isolate (RPI) has been receiving increasing attention from the food industry due to its performance as an emulsifier. However, it is possible to enlarge its field of applications through enzymatic hydrolysis. Therefore, this work aimed to investigate the effects of the controlled enzymatic hydrolysis (degree of hydrolysis DH as 2, 6, and 10%) using Flavourzyme on the physicochemical properties of rice protein and to identify the minimum concentration of these hydrolysates (0.5, 1.0, and 1.5%) to form and stabilize oil/water emulsion. The physicochemical, interfacial tension (IT), and surface characteristics of RPI and their hydrolysates (RPH) were determined. Even at a lower protein concentration (1.0%), protein hydrolysate presented lower IT when compared with RPI at a higher protein concentration (1.5%). The interfacial tension decreased from 17.6 mN/m to 9.9 mN/m when RPI was hydrolyzed. Moreover, enzymatic hydrolysis (DH 6 and 10%) enhanced the protein solubility by almost 20% over a pH range of 3-11. The improved amphiphilic property of RPH, supported by the results of IT and solubility, was confirmed by the higher emulsion stability indicated by the Turbiscan and emulsion stability indexes. Emulsions stabilized by RPH (DH 6% and 10%) at lower protein concentrations (1%) exhibited better physical stability than RPI at higher protein concentrations (1.5%). In this work, we verified the minimum concentration of rice protein hydrolysate required to form and stabilize oil-in-water (O/W) emulsions.

The Nutritional and Functional Properties of Protein Isolates from Defatted Chia Flour Using Different Extraction pH

This study aims to determine the effects of various alkaline pHs on the nutritional and functional properties of protein isolated from defatted chia flour (DCF). The DCF isolated using alkali extraction method at pH 8.5, 10.0, and 12.0 were coded as CPI-8.5, CPI-10.0, and CPI-12.0, respectively. The highest extraction yield and protein recovery yield was demonstrated by CPI-12.0 (19.10 and 59.63%, respectively), with a total protein content of 74.53%, and glutelin showed the highest portion (79.95%). The CPI-12.0 also demonstrated the most elevated essential (36.87%), hydrophobic (33.81%), and aromatic (15.54%) amino acid content among other samples. The DCF exhibited the highest water (23.90 gg-1) and oil (8.23 gg-1) absorption capacity, whereas the CPI-8.5 showed the highest protein solubility (72.31%) at pH 11. DCF demonstrated the highest emulsifying capacity at pH 11 (82.13%), but the highest stability was shown at pH 5 (82.05%). Furthermore, CPI-12.0 at pH 11 shows the highest foaming capacity (83.16%) and stability (83.10%). Despite that, the CPI-10.0 manifested the highest antioxidant capacity (DPPH: 42.48%; ABTS: 66.23%; FRAP: 0.19), as well as ACE-I (35.67%). Overall, the extraction pH had significant effects in producing chia protein isolates (CPI) with improved nutritional and functional qualities.

Structural Properties of Quinoa Protein Isolate: Impact of Neutral to High Alkaline Extraction pH

In this work, we extracted proteins from white quinoa cultivated in the northeast of Qinghai-Tibet plateau using the method of alkaline solubilization and acid precipitation, aiming to decipher how extraction pH (7-11) influenced extractability, purity and recovery rate, composition, multi-length scale structure, and gelling properties of quinoa protein isolate (QPI). The results showed that protein extractability increased from 39 to 58% with the increment of pH from 7 to 11 whereas protein purity decreased from 89 to 82%. At pH 7-11, extraction suspensions and QPI showed the similar major bands in SDS-PAGE with more minor ones (e.g., protein fractions at > 55 or 25-37 kDa) in suspensions. Extraction pH had limited effect on the secondary structure of QPI. In contrast, the higher-order structures of QPI were significantly affected, e.g., (1) emission maximum wavelength of intrinsic fluorescence increased with extraction pH; (2) surface hydrophobicity and the absolute value of zeta-potential increased with increasing extraction pH from 7 to 9, and then markedly decreased; (3) the particle size decreased to the lowest value at pH 9 and then increased to the highest value at pH 11; and (4) denaturation temperature of QPI had a large decrease with increasing extraction pH from 7/8 to 9/10. Besides, heat-set QPI gels were formed by loosely-connected protein aggregates, which were strengthened with increasing extraction pH. This study would provide fundamental data for industrial production of quinoa protein with desired quality.

Combined effects of isolation temperature and pH on functionality and beany flavor of pea protein isolates for meat analogue applications

The combined effects of isolation temperature (20, 30 and 40 °C) and pH (2.0-12.0) on yield, techno-functional properties, and beany flavor of pea protein isolates were investigated. Increasing pH from 2.0 to 9.5 and 11.0 increased yields from 37 % to 75 % and 79 %, respectively, at 20 °C. At a constant pH, increasing temperature from 20 to 40 °C did not increase protein recovery; rather, negatively affected the techno-functional properties such as protein solubility, foaming and gelation. Protein isolated at pH 11.0 (20 °C) provided a higher fat absorption, gelation capacity, gel hardness, cohesiveness, chewiness, and gumminess than at pH 9.5, due to higher protein denaturation as supported by their higher surface hydrophobicity. Volatile beany flavor marker hexanal was predominant in all isolates than the starting material, irrespective of isolation temperature, probably due to lipid oxidation. The results provide a basis for tuning the isolation process for producing pea protein isolates with desired techno-functional properties for meat analogue applications.

Comparative study on molecular and higher-order structures of legume seed protein isolates: Lentil, mungbean and yellow pea

Lentils and mungbean proteins are under-researched compared to pea and soybean. Lentils (green, red and black-lentils), mungbean and yellow pea protein isolates were obtained by alkaline extraction (pH 9)-isoelectric precipitation (pH 4.5) and investigated for molecular and higher-order structures using complementary and novel approaches. These extracted isolates showed comparable protein content but significantly greater nitrogen solubility index (NSI > 85 %) than commercial pea and soy protein isolates (NSI < 60 %). Based on molecular weight estimations from sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, the soluble proteins of lentils and yellow pea were identified as legumin-like and vicilin-like, while mungbean was dominated by vicilin-like proteins. The soluble extracts were confirmed to be in native structural condition by size exclusion chromatography and nano-differential scanning calorimetry, unlike commercial extracts. Further differences in secondary structure were evident on circular dichroism spectra of the soluble extracts and deconvolution of the Amide I region (1700-1600 cm-1) from Fourier Transform Infrared of the total protein.

The effect of alkaline extraction and drying techniques on the physicochemical, structural properties and functionality of rice bran protein concentrates

Rice bran protein concentrates (RBPC) were extracted using mild alkaline solvents (pH: 8, 9, 10). The physicochemical, thermal, functional, and structural aspects of freeze-drying (FD) and spray-drying (SD) were compared. FD and SD of RBPC had porous and grooved surfaces, with FD having non-collapsed plates and SD being spherical. Alkaline extraction increases FD's protein concentration and browning, whereas SD inhibits browning. According to amino acid profiling, RBPC-FD9's extraction optimizes and preserves amino acids. A tremendous particle size difference was prominent in FD, thermally stable at a minimal maximum of 92 °C. Increased pH extraction gives FD greater exposal surface hydrophobicity and positively relates to denaturation enthalpy. Mild pH extraction and drying significantly impacted solubility, improved emulsion properties, and foaming properties of RBPC as observed in acidic, neutral, and alkaline environments. RBPC-FD9 and RBPC-SD10 extracts exhibit outstanding foaming and emulsion activity in all pH conditions, respectively. Appropriate drying selection, RBPC-FD or SD potentially employed as foaming/emulsifier agent or meat analog.

Ultrasound-assisted alkali removal of proteins from wastewater generated during oil bodies extraction

In this study, an ultrasonic-assisted alkaline method was used to remove proteins from wastewater generated during oil-body extraction, and the effects of different ultrasonic power settings (0, 150, 300, and 450 W) on protein recovery were investigated. The recoveries of the ultrasonically treated samples were higher than those of the samples without ultrasonic treatment, and the protein recoveries increased with increasing power, with a protein recovery of 50.10 % ± 0.19 % when the ultrasonic power was 450 W. Amino acid analysis showed that the amino acids comprising the recovered samples were consistent, regardless of the ultrasonic power used, but significant differences in the contents of amino acids were observed. No significant changes were observed in the protein electrophoretic profile using dodecyl polyacrylamide gel, indicating that sonication did not change the primary structures of the recovered samples. Fourier transform infrared and fluorescence spectroscopy revealed that the molecular structures of the samples changed after sonication, and the fluorescence intensity increased gradually with increasing sonication power. The contents of α-helices and random coils obtained at an ultrasonic power of 450 W decreased to 13.44 % and 14.31 %, respectively, whereas the β-sheet content generally increased. The denaturation temperatures of the proteins were determined using differential scanning calorimetry, and ultrasound treatment reduced the denaturation temperatures of the samples, which was associated with the structural and conformational changes caused by their chemical bonding. The solubility of the recovered protein increased with increasing ultrasound power, and a high solubility was essential in good emulsification. The emulsification of the samples was improved well. In conclusion, ultrasound treatment changed the structure and thus improved the functional properties of the protein.

Salt Solubilization Coupled with Membrane Filtration-Impact on the Structure/Function of Chickpea Compared to Pea Protein

The demand for pulse proteins as alternatives to soy protein has been steeply increasing over the past decade. However, the relatively inferior functionality compared to soy protein is hindering the expanded use of pulse proteins, namely pea and chickpea protein, in various applications. Harsh extraction and processing conditions adversely impact the functional performance of pea and chickpea protein. Therefore, a mild protein extraction method involving salt extraction coupled with ultrafiltration (SE-UF) was evaluated for the production of chickpea protein isolate (ChPI). The produced ChPI was compared to pea protein isolate (PPI) produced following the same extraction method in terms of functionality and feasibility of scaling. Scaled-up (SU) ChPI and PPI were produced under industrially relevant settings and evaluated in comparison to commercial pea, soy, and chickpea protein ingredients. Controlled scaled-up production of the isolates resulted in mild changes in protein structural characteristics and comparable or improved functional properties. Partial denaturation, modest polymerization, and increased surface hydrophobicity were observed in SU ChPI and PPI compared to the benchtop counterparts. The unique structural characteristics of SU ChPI, including its ratio of surface hydrophobicity and charge, contributed to superior solubility at both a neutral and acidic pH compared to both commercial soy protein and pea protein isolates (cSPI and cPPI) and significantly outperformed cPPI in terms of gel strength. These findings demonstrated both the promising scalability of SE-UF and the potential of ChPI as a functional plant protein ingredient.

Physico-Chemical Properties and Texturization of Pea, Wheat and Soy Proteins Using Extrusion and Their Application in Plant-Based Meat

Four commercial pea protein isolates were analyzed for their physico-chemical properties including water absorption capacity (WAC), least gelation concentration (LGC), rapid visco analyzer (RVA) pasting, differential scanning calorimetry (DSC)-based heat-induced denaturation and phase transition (PTA) flow temperature. The proteins were also extruded using pilot-scale twin-screw extrusion with relatively low process moisture to create texturized plant-based meat analog products. Wheat-gluten- and soy-protein-based formulations were similarly analyzed, with the intent to study difference between protein types (pea, wheat and soy). Proteins with a high WAC also had cold-swelling properties, high LGC, low PTA flow temperature and were most soluble in non-reducing SDS-PAGE. These proteins had the highest cross-linking potential, required the least specific mechanical energy during extrusion and led to a porous and less layered texturized internal structure. The formulation containing soy protein isolate and most pea proteins were in this category, although there were notable differences within the latter depending on the commercial source. On the other hand, soy-protein-concentrate- and wheat-gluten-based formulations had almost contrary functional properties and extrusion characteristics, with a dense, layered extrudate structure due to their heat-swelling and/or low cold-swelling characteristics. The textural properties (hardness, chewiness and springiness) of the hydrated ground product and patties also varied depending on protein functionality. With a plethora of plant protein options for texturization, understanding and relating the differences in raw material properties to the corresponding extruded product quality can help tailor formulations and accelerate the development and design of plant-based meat with the desired textural qualities.

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.

The Impact of High-Intensity Ultrasound-Assisted Extraction on the Structural and Functional Properties of Hempseed Protein Isolate (HPI)

Hempseed protein has become a promising candidate as a future alternative protein source due to its high nutritional value. In the current study, hempseed protein isolate (HPI) was obtained using ultrasonic-assisted extraction with the aim to improve the functionality of HPI via protein structure modification. The solubility of HPI could be improved twofold under 20 kHz ultrasound processing compared to conventional alkaline extraction-isoelectric point precipitation. The protein solubility was gradually enhanced as the ultrasonic power improved, whereas excessive ultrasound intensity would cause a decline in protein solubility. Ultrasonic processing was found to have beneficial effects on the other functionalities of the extracted HPI, such as emulsifying and foaming properties. This improvement can be ascribed to the physical effects of acoustic cavitation that changed the secondary and tertiary structures of the protein to enhance surface hydrophobicity and decrease the particle size of the extracted protein aggregates. In addition, more available thiols were observed in US-treated samples, which could be another reason for improved functionality. However, the results of this study also revealed that prolonged high-power ultrasound exposure may eventually have a detrimental impact on HPI functional properties due to protein aggregation. Overall, this study suggests that high intensity ultrasound can enhance the functionality of HPI, which may ultimately improve its value in HPI-based food products.

A systematic study of the impact of the isoelectric precipitation process on the physical properties and protein composition of soy protein isolates

The functional properties of soy protein isolates (SPIs), which are crucial for their successful use in food applications, depend on their protein physical properties and composition. Although the production process of SPIs is well-known and established industrial practice, fundamental knowledge on how the different isolation steps and varying isolation conditions influence these properties is lacking. Here, these characteristics were systematically investigated by assessing the impacts of the various steps of a conventional isoelectric precipitation based SPI production protocol. Protein denaturation and colloidal state were evaluated with differential scanning calorimetry and dynamic light scattering combined with (ultra)centrifugation, respectively. The protein composition (on protein subunit level) was assessed via size-exclusion chromatography. Hexane defatting was found not to cause protein denaturation. Alkaline extraction at pH values between 7.0 and 9.0 resulted in no differences in protein physical properties or composition. Subsequent acid precipitation at pH 5.5 resulted in SPIs with a lower 7S/11S ratio and higher protein solubility at neutral pH than when produced at pH 4.5 and 3.5. SPIs obtained at all evaluated precipitation pH values contained a considerable amount of aggregated protein structures. Spray-drying of SPI did not result in a higher degree of protein denaturation or in a loss of protein solubility compared to freeze-drying, but a smaller amount of soluble aggregates was observed in spray-dried SPIs. Hence, alterations in the isolation procedure can result in SPIs with moderately different physical properties and protein composition, which might lead to different functional properties and thus applicabilities in certain food systems.

Elucidating the Role of Santalol as a Potent Inhibitor of Tyrosinase: In Vitro and In Silico Approaches

This research work focuses on the potential application of an organic compound, santalol, obtained from santalum album, in the inhibition of the enzyme tyrosinase, which is actively involved in the biosynthesis of melanin pigment. Over-production of melanin causes undesirable pigmentation in humans as well as other organisms and significantly downgrades their aesthetic value. The study is designed to explain the purification of tyrosinase from the mushroom Agaricus bisporus, followed by activity assays and enzyme kinetics to give insight into the santalol-modulated tyrosinase inhibition in a dose-dependent manner. The multi-spectroscopic techniques such as UV-vis, fluorescence, and isothermal calorimetry are employed to deduce the efficiency of santalol as a potential candidate against tyrosinase enzyme activity. Experimental results are further verified by molecular docking. Santalol, derived from the essential oils of santalum album, has been widely used as a remedy for skin disorders and a potion for a fair complexion since ancient times. Based on enzyme kinetics and biophysical characterization, this is the first scientific evidence where santalol inhibits tyrosinase, and santalol may be employed in the agriculture, food, and cosmetic industries to prevent excess melanin formation or browning.

Ultrasound-Assisted Extraction of Protein from Pumpkin Seed Press Cake: Impact on Protein Yield and Techno-Functionality

Conventional solvent-based methods widely used for isolating plant proteins may deliver an unsatisfactory protein yield and/or result in protein degradation. The present study started with the optimization of pumpkin seed protein from press cake by alkaline extraction and subsequent isoelectric precipitation. Subsequently, extraction was supported by ultrasound under three conditions: ultrasonic treatment followed by alkaline extraction (US+AE), concomitant ultrasonic treatment and alkaline extraction (UAE), and alkaline extraction followed by ultrasonic treatment (AE+US). Compared to the control group, an increase in protein yield was achieved after ultrasonic treatment, while the highest protein yield was obtained with AE+US (57.8 ± 2.0%). Isolates with a protein content of 94.04 ± 0.77 g/100 g and a yield of 43.6 ± 0.97% were obtained under optimized conditions. Following ultrasonic treatment applied during extraction, solubility, foaming capacity, foam stability, and denaturation enthalpy of the isolated protein increased, and water binding capacity decreased as compared to non-sonicated samples. The d₉₀ particle size percentile of the extracted suspensions was 376.68 ± 38.32 µm for the control experiments, and particle size was significantly reduced in ultrasound-assisted treatments down to d₉₀ = 179.93 ± 13.24 µm for the AE+US treatment). Generally, ultrasonication resulted in a significant increase in protein yield and improved techno-functional properties of the isolates.

Sensory characterization of yellow pea and ground chicken hybrid meat burgers using static and dynamic methodologies

To reduce animal protein consumption, new food products need to be created. Furthermore, there is a growing number of consumers who consciously act to reduce their meat consumption. Hybrid meat products (HMP) are food items that combine both plant and animal proteins. The objective of this study was to create a hybrid meat burger (HMB) using yellow pea and chicken and to evaluate the sensory properties of the new product using static (check-all-that-apply [CATA]) and dynamic (temporal check-all-that-apply [TCATA]) methods. Yellow pea flour was added to a chicken burger at 0% (control), 10%, 20%, 30%, and 40%. A sensory trial asked participants (n = 69) to evaluate the HMBs using hedonic scales and CATA. A second sensory trial asked experienced panelists (n = 14) to evaluate the items using TCATA. The addition of the yellow pea flour decreased the liking of the burgers, except for the 10% formulation. The burgers made with higher amounts of yellow pea were associated with off-flavors (beany and nutty; significantly different from the control) during both CATA and TCATA tasks and detracted from consumers' liking. Juicy, moist, meaty, salty, and soft attributes increased the consumers' liking. The study identified that the addition of yellow pea to chicken burgers is only acceptable to consumers in small quantities (10%). In addition, the yellow peas contributed off-flavors and a dry texture that was disliked by the consumers. PRACTICAL APPLICATION: The environmental impacts of livestock production have created a need to incorporate more plant-based proteins into consumers' diets to increase sustainability. The market for meat alternatives, including hybrid meat products, is expanding; however, current products do not always meet consumers' expectations. Chicken is the fastest-growing meat sector in North America, and therefore this study's objective was to determine the sensory properties of a burger made from chicken and pulses (yellow pea). It was found that if 10% of chicken in a burger was substituted with yellow pea, then the sensory properties and consumer liking were not significantly affected.

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.

Extraction Optimization, Functional and Thermal Properties of Protein from Cherimoya Seed as an Unexploited By-Product

Plant-based proteins are gaining in attraction compared with animal-based proteins due to their superior ethical profiles, growing concerns on the part of various organizations about animal health and welfare, and increased global greenhouse-gas emissions in meat production. In this study, the response surface methodology (RSM) using a Box-Behnken design (BBD) was applied to optimize the ultrasound-assisted alkaline extraction of cherimoya-seed proteins as valuable by-products. The effects of three pH, temperature, and time factors on the protein-extraction yield and protein content were investigated. The pH at 10.5 and temperature of 41.8 °C for 26.1 min were considered the optimal ultrasound-assisted alkaline-extraction conditions since they provided the maximum extraction yield (17.3%) and protein content (65.6%). An established extraction technique was employed to enhance the cherimoya-seed protein yield, purity, and functional properties. A thermogravimetric analysis (TGA) of the samples showed that the ultrasound-assisted alkaline extraction improved the thermal stability of the protein concentrate.

Structural, and functional properties of phosphorylated pea protein isolate by simplified co-spray drying process

In this work, to improve the functionality of pea protein isolate (PPI), sodium hexametaphosphate (SHMP) was added during last step of protein extraction and co-spray dried. The influence of PPI to SHMP mixing ratios (95:5 and 90:10) and reaction pH conditions (pH 6, 7, 8, and 9) on reaction efficiency, structural and functional properties of phosphorylated PPI were evaluated. Results showed that both mixing ratios had a similar degree of phosphorylation, suggesting the high efficiency of a 95:5 mixing ratio. The mixing ratio affected powder yield and proximate composition whereas hydrophobicity and denaturation temperature were regulated by pH conditions. For functionality, both mixing ratios showed significantly increased solubility at pH 6. Moreover, an increase in foaming capacity was observed in all phosphorylated PPI. The result from the current study may work as a basis for PPI phosphorylation in the food industry using the simplified method.