Protein-rich Fraction Research Articles

Influence of pH and salt conditions on extraction efficiency and functional properties of Macrotermes nigeriensis protein concentrate for food applications

The search for alternative proteins from non-conventional sources for food processing has become important due to the shortage of conventional protein sources. Protein extractability from Macrotermes nigeriensis and its functional properties were investigated under various conditions of pH (2–10) and salt concentration (0.1–1.0 M). Extracted proteins were precipitated through pH adjustment and micellization, respectively. Results showed that maximum protein extractability was 68% and 62.1% at 0.5 M salt concentration and pH10.0, respectively. Salt-extracted protein-rich fraction (SP) had the highest protein composition (68.68 ± 0.41 g/100 g), seconded by alkaline-extracted protein-rich fraction (AP) (62.91 ± 0.53 g/100 g), compared with the raw and defatted fraction (34.36 ± 0.44 and 42.12 ± 0.15 g/100 g), respectively. The highest emulsion capacity (49%) and emulsion stability (35%) were recorded in alkaline pH 10.0. In comparison, the highest foaming capacity (24%) and foaming stability (16%) were recorded in the salt-extracted fraction at 6%. This information could be useful for further studies on the food application potential of proteins isolated from edible M. nigeriensis.Graphical

Mechanistic insights into the foaming properties of potato proteins based on protein composition, colloidal state, and air-water interfacial properties

Potato proteins have been shown to be suitable alternatives for animal proteins in food foam formulations but their ability to form and stabilize foam is mechanistically ill-understood. The present study aimed to better understand the foaming properties of a protein fraction isolated from potato trimmings, a by-product from the potato industry. This was achieved by comparing the properties of these in-house isolated proteins to those of commercial and highly purified potato proteins. Protein isolates (53.8 ± 4.7 g/100 g dry weight) were produced from trimmings by alkaline solubilization (pH 9.0) and isoelectric precipitation (pH 4.0). The foaming properties of the in-house isolate at pH 3.0 and 7.0 were better than those of a blend of commercial potato proteins with similar relative amounts of patatin and protease inhibitors as the in-house isolate. Notably, this was the case despite the fact that more proteins were insoluble in the in-house isolate than in the commercial potato protein suspensions. Patatin and protease inhibitors were further shown to both contribute considerably to the formation and stabilization of foams. Interestingly, a beneficial effect on foam stability was found when patatin and protease inhibitors of various colloidal sizes were present. Additionally, impurities in the in-house isolates likely contributed to their superior foaming properties. In conclusion, a protein-rich fraction with good foaming properties can be recovered from potato trimmings. Mechanistic insights were gained into the foaming properties of potato protein (mixtures). This research also highlighted the importance of assessing protein colloidal state when investigating plant protein structure-function relationships.

Evaluation of Cytotoxicity and Acute Oral Toxicity of Saline Extract and Protein-Rich Fraction from Moringa oleifera Lam. Leaves.

Moringa oleifera Lam. (horseradish tree) leaves demonstrate high nutritional value, are rich in proteins, and are widely used in folk medicine and food. This study investigated the presence of secondary metabolites and antinutritional proteins in leaf extract (LE) and the protein-rich fraction (PRF) derived from M. oleifera leaves, as well as the cytotoxicity to human cells, hemolytic activity, and in vivo acute toxicity and genotoxicity in mice. The flavonoids rutin and vitexin as well as trypsin inhibitors and lectins were detected in LE and PRF. Neither sample demonstrated toxicity against human peripheral blood mononuclear cells and both showed low hemolytic action. In vivo, LE and PRF did not show antinutritional effects and caused no death. The hematological parameters of the animals in the treated group were similar to those of the control. A significant increase in the serum levels of alanine aminotransferase and a discrete leukocyte infiltration with cytoplasmic vacuolization of the hepatocytes in the liver were detected in LE-treated animals. The preparations were not genotoxic or mutagenic. This study shows that LE and PRF are not antinutritional agents and presented low acute toxicity and no genotoxicity or mutagenicity. The present study contributes to the determination of the safety of using M. oleifera leaf proteins.

Decoding the Duality of Antinutrients: Assessing the Impact of Protein Extraction Methods on Plant-Based Protein Sources.

This review aims to provide an updated overview of the effects of protein extraction/recovery on antinutritional factors (ANFs) in plant protein ingredients, such as protein-rich fractions, protein concentrates, and isolates. ANFs mainly include lectins, trypsin inhibitors, phytic acid, phenolic compounds, oxalates, saponins, tannins, and cyanogenic glycosides. The current technologies used to recover proteins (e.g., wet extraction, dry fractionation) and novel technologies (e.g., membrane processing) are included in this review. The mechanisms involved during protein extraction/recovery that may enhance or decrease the ANF content in plant protein ingredients are discussed. However, studies on the effects of protein extraction/recovery on specific ANFs are still scarce, especially for novel technologies such as ultrasound- and microwave-assisted extraction and membrane processing. Although the negative effects of ANFs on protein digestibility and the overall absorption of plant proteins and other nutrients are a health concern, it is also important to highlight the potential positive effects of ANFs. This is particularly relevant given the rise of novel protein ingredients in the market and the potential presence or absence of these factors and their effects on consumers' health.

Comparing green extraction methods for the recovery of protein-rich fraction from peach seeds (Prunus persica)

Peach processing generates significant volume of coproducts, such as the underutilized peach seeds, which are rich in fatty acids and protein. The recovery of protein-rich fractions from peach seeds is highly relevant because of the increasing demand for alternative non-animal protein sources. This study aimed to investigate different extraction techniques for protein recovery from the underestimated peach seeds, and evaluate the functionalities of the protein fraction. The peach seeds were defatted using the supercritical fluid extraction (SFE-CO2), with oily recovery up to 29.53% ± 0.45. Then, the protein fraction was recovered using the following methods: heat-stirred extraction (HSE) as a conventional method, and, as alternative procedures, microwave-assisted extraction (MAE), pressure liquid extraction (PLE), and ultrasound-assisted extraction (UAE) using NaOH solution as solvent. The PLE provided the highest protein content (95.10 % ± 0.98), followed by the HSE technique (55.09% ± 0.35). Furthermore, the PLE showed the best performance in techno-functional properties of the protein fraction: emulsion activity, foaming, turbidity, free sulfhydryl content, hydrophobicity, and color, compared to the classical HSE technique. Therefore, it is suggested that PLE (10 min) method recovered an isolated protein with better functional properties, providing promising result for protein purification. Therefore, PLE can be considered an alternative method to add value to underestimated peach seeds, conferring the upcycling concept.

Sensory profile of pulse-based high moisture meat analogs: A study on the complex effect of germination and extrusion processing.

Germination and extrusion are two processes that could affect beany flavors in pulse-based high-moisture meat analogs (HMMAs). This research studied the sensory profile of HMMAs made by protein-rich flours from germinated/ungerminated pea and lentil. Air-classified pulse protein-rich fractions were processed into HMMAs with twin screw extrusion cooking, optimized at 140°C (zone 5 temperature) and 800rpm screw speed. Overall, 30 volatile compounds were identified by Gas Chromatography-Mass Spectrometry/Olfactory. Chemometric analysis exhibited that the extrusion markedly (p<0.05) reduced beany flavor. A synergistic effect of germination and extrusion process was observed, decreasing some beany flavors such as 1-octen-3-ol and 2,4-decadienal, and the overall beany taste. Pea-based HMMAs are suitable for lighter, softer poultry meat, while lentil-based HMMAs are suited for darker, harder livestock meat. Those findings offer novel insights into the regulation of beany flavors, odor notes, color, and taste to improve the sensory quality of HMMAs.

In vitro digestion properties and use of automatic image analysis to assess the quality of wheat bread enriched with whole faba bean (Vicia faba L.) flour and its protein-rich fraction

The trend of incorporating faba bean (Vicia faba L.) in breadmaking has been increasing, but its application is still facing technological difficulties. The objective of this study was to understand the influence of substituting the wheat flour (WF) with 10, 20, 30 and 40 % mass of whole bean flour (FBF) or 10 and 20 % mass of faba bean protein-rich fraction (FBPI) on the quality (volume, specific volume, density, colour, and texture), nutritional composition (total starch, free glucose, and protein contents), and kinetics of in vitro starch and protein digestibility (IVSD and IVPD, respectively) of the breads. Automated image analysis algorithm was developed to quantitatively estimate the changes in the crumb (i.e., air pockets) and crust (i.e., thickness) due to the use of FBF or FBPI as part of the partial substitution of wheat flour. Higher levels of both FBF and FBPI substitution were associated with breads having significant (p < 0.05) lower (specific) volume (at least 25 % reduction) and higher density (up to 35 %), increased brownness (up to 49 % and 78 % for crust and crumb respectively), and up to 2.3-fold increase in hardness. Result from the image analysis has provided useful insights on how FBF and FBPI affecting bread characteristics during baking such as loss of crumb expansion, decrease in air pocket expansion and increase in crust thickness. Overall, incorporation of FBF or FBPI in wheat bread were favourable in reducing the starch content and improving the protein content and IVPD of wheat bread. Since bread remains as a staple food due to its convenience, versatility and affordability for individuals and families on a budget, wheat bread enriched with faba bean could be a perfect food matrix to increase daily protein intake.

Influence of extraction method on inherent properties and techno‐functional behavior of quinoa protein ingredients

AbstractThis study investigated the structural modification and functional properties of quinoa protein ingredients using dry and wet fractionation techniques. Alkali extraction at pH 9.0 produced a quinoa protein isolate (QPI) with 76.2% wt/wt protein (dry basis) and a concentrate (QPC) with 55.9% protein. However, the protein separation efficiencies (PSE) were 32.1% and 58.5%, respectively. In contrast, dry fractionation produced a quinoa protein rich fraction (QPRF) containing 24.7% wt/wt protein, but higher PSE at 69.9%. Despite varying final protein concentrations, SDS‐PAGE showed similar relative abundance of 11S, 7S, and 2S proteins among the ingredients and quinoa whole meal. Mass spectrometry revealed different levels of oxidative modifications to proteins, with QPI showing more pronounced oxidation. In starch pasting experiments, QPRF exhibited significantly higher viscosity than QPI and QPC, attributed to low starch content and the formation of protein–starch and protein–lipid complexes in QPI and QPC. Solubility over pH 2.0–9.0 followed a U‐shaped trend for all ingredients, with QPC showing lower solubility at pH &gt;7.0. Furthermore, foaming capacity and stability of foams converged at high ingredients concentration (3% wt/vol), while increasing protein refinement gave high foam stability at lower concentration (0.5–1% wt/vol). Similarly, emulsion activity index was favored at high purity (QPI), while emulsion stability was promoted at low protein purity (QPRF). This study demonstrated that dry fractionation enabled the retention of techno‐functional properties of the protein while enhancing quinoa bioresource recovery.

Dry fractionation process operations in the production of protein concentrates: A review.

The market for plant proteins is expanding rapidly as the negative impacts of animal agriculture on the environment and resources become more evident. Plant proteins offer competitive advantages in production costs, energy requirements, and sustainability. Conventional plant-protein extraction is water and chemical-intensive, posing environmental concerns. Dry fractionation is an energy-efficient and environmentally friendly process for protein separation, preserving protein's native functionality. Cereals and pulses are excellent sources of plant proteins as they are widely grown worldwide. This paper provides a comprehensive review of the dry fractionation process utilized for different seeds to obtain protein-rich fractions with high purity and functionality. Pretreatments, such as dehulling and defatting, are known to enhance the protein separation efficiency. Factors, such as milling speed, mill classifier speed, feed rate, seed type, and hardness, were crucial for obtaining parent flour of desired particle size distribution during milling. The air classification or electrostatic separation settings are crucial in determining the quality of the separated protein. The cut point in air classification is targeted based on the starch granule size of the seed material. Optimization of these operations, applied to different pulses and seeds, led to higher yields of proteins with higher purity. Dual techniques, such as air classification and electrostatic separation, enhance protein purity. The yield of the protein concentrates can be increased by recycling the coarse fractions. Further research is necessary to improve the quality, purity, and yield of protein concentrates to enable more efficient use of plant proteins to meet global protein demands.

Influence of germination and pulse type on texture of high moisture meat analogs

Enhancing the texture profile of high moisture meat analogs (HMMAs) presents a notable challenge, one that can potentially be addressed by diversifying the ingredients used. This research examines how the type of pulse - specifically peas and lentils - and the germination process can impact the functional properties and structural transformation of proteins within these ingredients. A twin-screw extrusion cooking process was used to produce HMMAs with an optimized screw speed of 800 rpm and a final zone temperature of 140 °C. The quality of the HMMAs was evaluated through an analysis of their textural properties and Scanning Electron Microscopy (SEM). Generally, germination and variations in pulse types were seen to create significant (p < 0.05) changes to the protein profile. These changes resulted in reduced subunit molecular weight, altered melting temperatures (120–127 °C), and increased quantities of disulfide bonds. In turn, these shifts elicited corresponding adjustments in the HMMAs when subjected to identical extrusion conditions. Notably, the protein-rich fraction derived from lentils was markedly different (p < 0.05) from that of peas, contributing to lower levels of cohesiveness, chewiness, and gumminess in HMMAs. SEM images taken at 250 × -1000 × magnification demonstrated filaments in HMMAs, illustrating the transformation of proteins from a globular to a fibrous form. Guided by the influence of melting temperature and shear force on pulse protein, the “Thermo-shear Protein Structuring Principle” was proposed. Overall, our findings offer critical insights into how germination and pulse selection can affect protein behavior during the production of HMMAs.

Protein-rich fraction of Protaetia brevitarsis seulensis larvae induce maturation of dendritic cells and Th1-polarization: A promising adjuvant for anticancer therapy

The objective of this study was to investigate the potential anticancer immunostimulatory properties of a protein-rich fraction obtained from larvae of Protaetia brevitarsis seulensis (PBLP), a highly nutritious edible insect, in CT-26 colon carcinoma-bearing mice. The most abundant essential amino acids (EAA) in PBLP were Val, Ile, and Leu, while the most abundant non-EAA were Pro, Glu, and Gly. PBLP increased the production of Th1-polarized cytokines and the phenotypic maturation of bone marrow-derived dendritic cells (BMDCs). PBLP-treated BMDCs stimulated naïve CD4+ and CD8+ T cells to produce IFN-γ and IL-2 but not IL-5. Significantly, dietary PBLP restored CD86 and MHC-I expression in splenic DCs, and also increased TNF-α+IL-2+IFN-γ+CD107+ polyfunctional CD4+ and CD8+ T cells in the spleen, thereby inhibiting tumor growth in CT-26 tumor-bearing mice. Collectively, PBLP synchronizes DCs and T cells for anticancer immunity, suggesting that it could serve as a potential adjuvant or supplement for cancer treatment.

Ingredient fractionation for monogastric animal nutrition: the worth of sum of parts versus the whole

Basic agricultural commodities such as cereal grains, pulses and oilseeds can be fractionated into separate products that can be targeted to high value markets within or outside the feed industry. Resulting nutrient-dense fractions that are enriched in starch, protein, fat, or fibre can then be targeted to animals with different nutritional demands. These value-added nutrient fractions might be targeted at the start of fractionating the commodities or result from human food or biofuel production. Fractions enriched in fibre might be targeted to the feed, paper, or wood industries. Two categories of processes can fractionate cereals, pulses, or oilseeds: (1) an up-front process that produces solely or mostly high value ingredient fractions, or (2) a process that separates one fraction for a high-value market. Examples of category 1 include air classification and sieving. Examples of category 2 include bioethanol production from cereal grains and oil extraction from soybean and canola seed. The resulting non-human edible co-products can be fed to livestock. Dry separation is useful to produce protein-rich fractions from pulse grains. Advantages of dry over wet fractionation are continuous flow rather than batch fractionation, absence of effluents and no drying cost. However, wet fractionation creates more concentrated fractions (isolates) of the nutrient of interest, e.g., protein. Category 1 and 2 processes can occur in tandem. For example, oil can be first extracted from soybeans, resulting in soy oil and soybean meal. Subsequently, soybean meal can be fractionated into protein concentrates or isolates with greater protein content than soybean meal. Fractionation usually has at least one main fraction with a target market in food or industry processes yielding products for human use. This approach is logical, because the feed industry is focussed mostly on small margins and large volumes, whereas higher margins per unit of product can be achieved in markets for food, petfood and feed for fish or animals with high nutritional demands. Animal agriculture remains an ideal approach to convert by-products from ingredient fractionation into high value animal protein. The economic implications of value-added processing are thus important, and sustainable animal agriculture plays a key role turning waste streams into a success story. Although ingredients can be fractionated successfully for animal nutrition, especially for higher margin markets such as aquaculture, petfood or animals with high nutritional demands, most ingredients are fractionated for the human food supply or industrial processes. Using the latter approach with at least one high value fraction targeted to human food or industry and then using non-human edible fractions for feed applications, will ensure that the sum of the parts can be worth more than the whole.

Optimizing protein recovery from plant substrate using ultrafiltration: A case study on wheatgrass

Providing the world's population with valuable food and proteins is considered as one of the greatest challenges of the upcoming decade. In this study, a process to recover nitrogen/protein concentrates from wheatgrass using a cascaded ultrafiltration was investigated. First, washing of wheatgrass during a mechanical extraction was examined with a ratio up to 1:2 (press cake/washing fluid, w/w). This was followed by a statistical investigation (full factorial experimental design) on the influences of substrate storage conditions (SSC), pre-shredding (PS) and washing conditions (WC) on the protein content of the resulting fraction, expressed by a nitrogen recovery rate (NRR). Washing of wheatgrass during the mechanical extraction was found to increase NRR by up to 29%–67.8% at a 1:2 ratio (1:0–46.0%, 1:0.5–53.0%, 1:1–58.0%). Significant effects (p-value <0.05) were found in the resulting crude juice for the variation of SSC between fresh and frozen/thawed wheatgrass (NRR 80.5%/62.8%) and for washing/non-washing during the mechanical extraction (NRR 76.1%/67.2%). These significant influences were detected in almost all subsequent fractions, whereas no significant effect was found for the influence of pre-shredding (p-value >0.05). An optimal process consisting of processing freshly harvested wheatgrass and a washing ratio of 1:2 during mechanical extraction led to a protein-rich fraction by ultrafiltration with a NRR of 34.4%. This NRR is comparable to recovery rates achieved with established substrates and processes. The protein-rich fraction can meet the daily requirements of protein quantities and macro minerals such as potassium, magnesium and phosphorous, providing more than 100% of the recommended intake. It was noted that 41.6% of the nitrogen in wheatgrass fell to by-product streams that need to be utilized to increase economic potential (biorefinery).

Composition, ζ Potential, and Molar Mass Distribution of 20 Must and Wine Colloids from Five Different Cultivars Obtained during Four Consecutive Vintages.

Colloids are responsible for undesirable haze formation in wine. Here, we characterized 20 colloid batches after isolation by ultrafiltration of musts and wines from five cultivars obtained from four consecutive vintages. Polysaccharide and protein concentrations of the colloids ranged from 0.10 to 0.65 and 0.03 to 0.40 mg/L, respectively. Protein profiling in must and wine colloids by fast protein liquid chromatography (FPLC) and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS) analyses indicated a lower number of proteins in wine than in must colloids. Molar mass distribution analyses revealed all colloids to consist of two carbohydrate- (424-33,390 and 48-462 kg/mol) and one protein-rich (14-121 kg/mol) fractions. The observed barely negative ζ potentials (-3.1 to -1.1 mV) in unstable wines unraveled that colloid instability might be partly related to their poor electrostatic repulsion in the wine matrix. ζ potentials of the colloids from pH 1 to 10 are also presented. Our data support future developments to eliminate haze-forming colloids from wine.

Extractability of defatted wheat germ protein and their functionalities in a deep eutectic solvent (DES)-Microwave extraction approach compared to conventional processing

Defatted wheat germ is a viable source of plant-based proteins and this could be attributed to its high protein content. In this study, protein-rich DWG fractions were precipitated from extracts obtained via conventional alkaline and novel DES-microwave extraction techniques. Protein yield, SDS-PAGE protein profile, gelation property, water/oil holding capacities, foaming capacity, emulsifying activity, emulsion stability, as well as protein solubility and digestibility were all succinctly investigated from the protein isolates. The comparative study showed 33.0 ± 0.2% and 12.5 ± 0.01% of protein recovery from DES-microwave and conventional extractions, respectively. Moreover, from the SDS-PAGE results, the DES-microwave-assisted extraction approach was just as effective as the conventional extraction method, with no evidence of protein hydrolysis or degradation. Additionally, the protein fraction extracted through the DES-microwave method exhibited higher water solubility with the formation of firmer gel structure; higher EA (50%); excellent WHC/OHC (3.892 mg H2O/mg sample; 6.410 mg oil/mg sample); good FC (75.9%), and higher D (85.03%). In comparison, the protein fraction from conventional alkaline extraction exhibited a water-holding capacity of 3.496 mg H2O/mg sample, oil holding 6.154 mg oil/mg sample, FC = 25.8%, EC = 25%, D = 78.69%). The enhanced functionalities of the DWG protein revealed DES-microwave-assisted approach as a promising technique for obtaining pure protein concentrate. This is the first study to provide insight into the functionalities of wheat germ protein using novel deep eutectic solvents (DES) via an electromagnetic-based microwaved medium.

Effects of fermentation and enzymatic treatment on phenolic compounds and soluble proteins in oil press cakes of canola (Brassica napus)

To develop novel processes for valorizing agro-industry side-streams, canola (Brassica napus) oil press cakes (CPC) were treated with lactic acid bacteria, carbohydrase, and protease. Altogether 29 protein-rich liquid fractions were obtained, of which the composition was analyzed using chromatographic and mass spectrometric methods. A clear association was revealed between the treatments and phenolic profile. Applying certain lactic acid bacteria enhanced the release of sinapic acid, sinapine, glycosylated kaempferols, and other phenolic compounds from CPC. Co-treatment using protease and Lactiplantibacillus plantarum was effective in degrading these compounds. The fraction obtained after 16 h of hydrolysis (with Protamex® of 2% dosage) and 48 h of fermentation (using L. plantarum) contained the lowest phenolic content (0.2 g/100 g DM) and a medium level of soluble proteins (78 g/100 g) among all samples studied. The fractions rich in soluble proteins and low in phenolics are potential food ingredients with improved bioavailability and sensory properties.

Shrimp head autolysis and use of protein-rich fraction for salted snacks enrichment

In order to contribute to the fight against malnutrition and to limit environmental pol-lution, shrimp head autolysis was performed. Resulting fractions were characterised to identify the protein-richest one which was used to improve the nutritional quality of wheat flour-based snacks. Supernatant fraction from shrimp head autolysis (SSHA) was found to have the highest protein content (73.56 ± 0.42%). In addition to 5% and 10% flour substitutions with powder SSHA, the direct use of liquid SSHA was performed against a control. As expected, the protein contents increased after the enrichments. They were similar (P&gt;0.05) for the 5% flour substitution (10.41±0.17%) and the use of liquid SSHA (10.08±0.21%). The proportion was 13.08±0.07% for the 10% flour substi-tution. The fat content increased significantly when the snacks were fortified. SSHA and snacks were of good microbiological quality despite the presence of moulds up to 1.0x102 CFU in the snacks. The use of SSHA in the snacks increased their appreciation. The snacks enriched with liquid SSHA were the most appreciated with a likeness score of 7.34. Liquid SSHA is thus a very interesting form of enrichment from a sensory point of view.

Lipid nanoparticles with erythrocyte cell-membrane proteins

When the separated erythrocyte membranes (known as ghosts) are ultrasonicated, a significant part of the membrane proteins are released in the aqueous solvent, instead of being incorporated into the membranes of the formed nanoerythrosomes. In contrast to their membrane-bound counterparts, where helices and β-strands dominate, the released proteins show perturbed secondary structures with an increased ratio of helices, presumably participating in molten globules, as it has been revealed by circular dichroism (CD) and infra-red spectroscopy (IR). The shape and size of these proteins is diverse, and even their aggregates appear. When excess lipid (palmitoyl-lysophosphatidylcholine, LPC) is added to different ghost-derivatives (the full nanoerythrosome system, and its ultracentrifugation pellet and supernatant) in 2 × and 5 × lipid-to-protein mass ratio, various lipid nanoparticles are produced. The core–shell and nanodisc structural models obtained by small-angle X-ray scattering (SAXS) indicate that the choice of the precursor system has a more prominent effect on the resulting shape than the amount of lipid added: when starting from the protein-rich supernatant fraction, small (approx. 5 nm high and 7 nm wide) nanodisks are created. When lipid membranes are already present (in the pellet and the full nanoerythrosome fraction), similar LPC addition results in prolate ellipsoidal particles, with an aspect ratio between 3 and 5, and decreasing overall size when the amount of added lipid is increased. The ellipsoids formed from the total nanoerythrosome fraction are smaller than those from the ultracentrifugation pellet (longest axis around 15 vs 26 nm), whereas for higher LPC-to-protein ratio, the size in both cases reduce to nearly the same (13–14 nm) in both cases.

Potential of air-currents assisted particle separation (ACAPS) technology for hybrid fractionation of clean-label faba bean (Vicia faba L.) protein

Air-currents assisted particle separation (ACAPS) of faba beans prior to wet separation was evaluated for its impact on chemical composition, yield and recovery of protein, starch and dietary fibre, and protein secondary structural changes. The protein and dietary fibre contents of faba bean cultivars Snowbird and Athena were positively correlated (r = 0.9, P < 0.0001) with the increasing particle size, which was offset by starch contents. ACAPS treatment of faba bean dehulled bean flours resulted in both protein- and dietary fibre-rich coarse fractions (75–500 μm). Subjecting the ACAPS-treated protein-rich (Snowbird: 38.96 ± 0.33% and Athena: 37.54 ± 0.20%) coarse fractions (250–500 μm) to micellization resulted in protein isolates (Snowbird: 97.74 ± 0.18% and Athena: 94.30 ± 0.29%). This method also resulted in starch isolates (Snowbird: 94.05 ± 1.67% and Athena: 94.33 ± 0.53%) and dietary fibre concentrates (Snowbird: 54.41 ± 1.87% and Athena: 44.89 ± 1.40%) as co-products, which were “clean label” ingredients. FTIR data confirmed that hybrid fractionation had minimal impact on protein secondary structures with β-sheets as the major structures.

Separation behavior of sieved endosperm-enriched oat fractions via tribo-electrostatic approach

Endosperm-enriched oat fraction passed through 106-μm aperture size sieving of oat groats was further processed by dry and chemical-free tribo-electrostatic separation approach for protein enrichment. The sieved oat flour consisting of both bran and endosperm particles was fluidized in dry air to be tribo-charged in a polytetrafluoroethylene (PTFE) tube before being separated under an external electric field into protein-rich and protein-depleted fractions. The effects of airflow rate and electric field strength were assessed by conducting fifteen tribo-electrostatic separations at five different plate voltages of ±1, ±3, ±7, ±12, and ± 15 kV, as well as three different airflow rates of 7, 10, and 14 l per minute (LPM), providing laminar, transient, and turbulent conditions in the tribo-charger tube, respectively. All fractions attracted to the negatively charged plate (i.e., NCP fraction) were enriched in protein. However, the fractions absorbed on the positively charged plate (PCP fraction) or collected by gravity at the bottom of the separation chamber (i.e., CB fraction) were all depleted of proteins. Higher protein enrichments were observed for NCP fractions at laminar airflow rate, where the lowest yields and protein separation efficiencies were obtained. Increasing plate voltages slightly reduced the NCP fractions' protein content but significantly improved their yields and protein separation efficiencies. Therefore, a laminar airflow rate of 7 LPM and a high plate voltage of ±12 kV was selected as the best separation conditions for sieved oat flour. The SEM images of the NCP fraction obtained at 7 LPM and ± 12 kV showed the presence of bran and endosperm particles, while the PCP and CB fractions were depleted of bran particles. The full compositional analysis of the fractions produced at 7 LPM and ± 12 kV conditions showed the highest percentage of dietary fiber content in the PCP fraction. A negative correlation was observed between the protein content and mean particle size (D50) of the electrostatically separated fractions at the laminar and transient airflow rates. However, the protein-rich NCP fractions had the largest particle sizes at the turbulent airflow rate due to particle agglomeration and intense particle-particle interactions. An indirect offline approach was adapted to assess the charging behavior of all electrostatically separated fractions as functions of their protein content and particle sizes. All NCP fractions acquired higher charge density values than other fractions, which could be attributed to their higher protein contents. An online tribo-charge analysis method should be developed to assess the particle-particle interactions in the tribo-charger tube during electrostatic separation.