Commercial Pea Protein Research Articles

Characterization and comparison of structure, thermal and functional characteristics of various commercial pea proteins

Pea protein (PP) presents an attractive raw material for its excellent nutritional value and functional properties. Nevertheless, data of nutritional composition, structure and functional properties of various commercial PPs remain scarce. The purpose of this work is to comprehensively analyze and compare the composition, structural, thermal and functional characteristics of eight commercially available PPs from multiple batches and sources. Specifically, the contents of total, soluble and non-denatured protein of eight PP samples were in the range of 76%–85%, 57%–61% and 0.8%–7.0%, respectively. Additionally, the total contents of amino acids and hydrophilic amino acids of PP-Ⅳ sample were significantly higher than that of PP-Ⅰ, PP-Ⅴ, PP-Ⅵ and PP-Ⅶ (P < 0.05). Fourier transform infrared spectroscopy showed that PP-Ⅴ exhibited higher β-sheet content and better gelation properties than other PPs. Differential scanning calorimeter analysis suggested that denaturing temperature of PP-Ⅳ was 85.81 °C, which was higher than that of other PPs. Furthermore, the solubility and emulsion stability of PP-Ⅲ and PP-Ⅳ were significantly higher than other six PPs (P < 0.05). PP-Ⅳ also had higher significant foaming capacity and foaming stability than other seven samples (P < 0.05). Moreover, principal component analysis indicated that the total score of PP-Ⅳ was the highest among the eight PPs. This study is helpful to comprehensively evaluate the quality characteristics of PPs and provide theoretical reference for the industrial production of PP products with multifunctional characteristics.

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.

Pea protein isolates affected by ultrasound and NaCl used for dysphagia's texture-modified food: Rheological, gel, and structural properties

Providing texture-modified food for dysphagia patients has been one of the most effective treatment methods. The current study aimed to evaluate a specially designed commercial pea protein isolate (PPIc) -based texture-modified food by ultrasonic treatment (US, 390 W; 20 min) at different NaCl concentrations by adjusting its texture and structure. The results showed that US can improve the texture properties of PPIc within a certain range of NaCl concentration (0.03–0.6 M). The prepared PPIc samples exhibited good mastication and swallowing characteristics with proper viscosity (33.31–704.2 mPa·s), softness (gel strength <30 g), wetness (good solubility and water holding capacity), etc. While with ultrasonic condition at the low NaCl concentration (0.1 M), the PPIc could achieve an overall superior textural attribute than those with other salt concentrations. Further research showed that US-NaCl combination could facilitate PPIc gel to maintain a more proper dysphagia texture, not only by reducing the number of pores and unfolding structures during processing, but also by enhancing the surface area of protein particles and cross-linking interaction of proteins through more exposure of sulfhydryl groups. It was also found that the β-turns of untreated-PPIc transformed to β-sheets at high salt concentration, whereas inverted transformation was observed at low NaCl concentration (0.03 M). We further unveiled US significantly enhanced the solubility, water holding capacity, and gelling ability of the PPIc. Overall, US-NaCl would be a promising method for the preparation of modified textural PPIc, which provides a new approach to formulate low-salt, high-nutrition, and customizable food for special populations such as the elderly and dysphagia.

Quantitative structure-property relationships of thermoset pea protein gels with ethanol, shear, and sub-zero temperature pretreatments

Pea protein is often processed to alter the protein's native structure, enhancing desirable textures in meat and dairy analog products. Cold denaturation is a universal phenomenon in protein that exposes hydrophobic amino acids, though little information exists about this in food science research. In this work, ethanol, shear forces, and low temperatures were used to modify the structure of commercial pea protein isolate, and impacts on gelation are characterized. Treatment at −10 °C in ethanol with applied shear forces led to gels with the lowest tan δ values during temperature ramps and frequency sweeps. A quantitative structure-property relationship (QSPR) method found that hydrogen bonding can be derived from secondary structure (R 2 = 0.960), and hydrogen bonding correlated with the temperature dependence of G′ during cooling in treatments. This work suggests cold denaturation forms hydrophobically bound gels that may aid in replacing fatty textures, and a QSPR framework aids in interpreting rheological data. • Ethanol, shear forces, and low-temperature treatment increase pea protein gel strength. • The number of hydrogen bonds can be estimated from protein secondary structure resulting from FTIR. • Hydrogen bonding correlates to the degree of stiffening during gelation. • Hydrogen bonding correlates to the number of crosslinks estimated using rubber elasticity theory. • Cold denaturation facilitates the design of new cold processing methods to enhance functionality of proteins.

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.

Structure, texture, and sensory properties of plant-meat hybrids produced by high-moisture extrusion

Hybrid products, in which a portion of meat is replaced with plant proteins, could be an effective solution to reduce meat consumption and its environmental impact, and provide well-balanced nutritious food. This study focused on exploring the potential of creating hybrid meat products by high-moisture extrusion from a mixture of minced beef (with 7 or 17% fat) and two different commercial pea protein ingredients. Hybrid extrudates were successfully produced from a 1:1 mixture of beef and either pea protein isolate (PI) or milled texturised pea protein concentrate (TPC). Differences in the appearance, texture and sensory properties of the hybrid extrudates depended both on ingredient properties and extrusion processing parameters (especially temperature). Extrudates with beef and PI were softer and layered, while extrudates with beef and TPC were harder and had smaller fibres. The fat content of the beef did not significantly affect the textural properties of the extrudates. The extrudates with beef and TPC had a meat-like odour and umami taste, while extrudates with beef and PI had a dominant pea-like taste and odour.

Emulsification of Rosemary and Oregano Aqueous Extracts and Their In Vitro Bioavailability.

Due to their richness in phenolic compounds, Mediterranean plants such as rosemary and oregano are increasingly recommended for consumption for their numerous health benefits. The pH shift and the presence of digestive enzymes significantly reduce the bioavailability of these biochemicals as they pass through the gastrointestinal tract. To prevent this degradation of phenolic compounds, methods such as emulsification of plant aqueous extracts are used. The aim of this study was to investigate the effects of emulsification conditions on the chemical properties (total polyphenolic content and antioxidant activity) of emulsified rosemary and oregano extracts. Response surface methodology was applied to optimize sunflower oil concentration, rotational speed, and emulsifier concentration (commercial pea protein). The emulsions prepared under optimal conditions were then used in bioavailability studies (in vitro digestion). The antioxidant activity of the emulsified rosemary/oregano extracts, measured by the DPPH method, remained largely stable when simulating in vitro digestion. Analysis of antioxidant activity after in vitro simulation of the gastrointestinal system revealed a higher degree of maintenance (up to 76%) for emulsified plant extracts compared to aqueous plant extracts. This article contributes to our understanding of how plant extracts are prepared to preserve their biological activity and their application in the food industry.

Pea protein isolates: emulsification properties as affected by preliminary pretreatments

The surface and emulsifying properties of a commercial pea protein isolate in oil-in-water model emulsions and the role of insoluble residues in emulsion stability were investigated. Droplet size distribution, flocculation index, microstructure, and protein coverage of the emulsions were evaluated. The insoluble fraction positively contributed to the pea proteins’ emulsifying properties, allowing the formation of emulsions with higher dispersion degree, especially at low isolate concentration, with an enhancement of the physical stability.

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.

Structure analysis of multi-component pastes – The effect of water distribution on the rheological properties

Techno-functional properties of multi-component blends and ingredients are determined by the contribution of each ingredient and the water distribution between those ingredients in the blends. However, ingredients can consist of multiple components, which should be considered to better understand the properties of ingredients and blends thereof. Recently, empirical models were used to describe the viscosity of mildly refined ingredient blends. While many compositions were described well by the empirical models, blends with high fiber contents were not predicted sufficiently well. Therefore, in this research, the multi-component blends of commercial pea protein, pea starch, and pea fiber isolates were investigated on their rheological properties as a function of dry matter content. The same properties were then measured for blends of two of these isolates mixed in different ratios. From the rheological experiments, estimations of the water distribution were made with the polymer blending law. The results were compared with CLSM images. A quantitative analysis of the CLSM images mostly confirmed the model outcomes. The isolate ratio could describe the isolate blends sufficiently well, meaning that it was not necessary to know the exact compositions of the ingredients. It was concluded that changes in meso-structure of the blends, for example a phase transition at high fiber contents, caused the lower predictability by the recently published empirical viscosity models. This study demonstrates that the water distribution in multi-component blends plays a crucial role for their viscoelastic properties and the contribution of the individual isolates and components. Moreover, these polymer blending laws that include water distribution provide extra mechanical insights into the fraction behavior in multi-component blends.

Unraveling the mechanism by which high intensity ultrasound improves the solubility of commercial pea protein isolates

Although plant-based proteins potentially provide merits for long-term global food security, their poor functionality particularly solubility has hampered the utilization as functional biopolymers in the industry. High intensity ultrasound (HIUS, 20 kHz) has been researched extensively for its possible application in modifications of protein functionality. Here, we show that the solubility of commercial pea protein isolate (PPI) is drastically improved from 7.2 to 58.4 mg/mL at an intermediate power (150 W) after a sequential HIUS treatment with an elevated power (100, 150, 200, 300, and 400 W). The dynamic changes of protein structure and confirmation over the course of sequential HIUS treatment are comprehensively investigated. This allows us to address the knowledge gap among the extensively studied power of HIUS and the structure changes of pea protein. Quantifying nonproteinaceous constituents (dietary fiber and β-glucan) and observing the morphological changes of the resultant pea protein solution have served as a critical step toward understanding the mechanism of action of HIUS in improving protein solubility. These successive investigation unravels that the formation of soluble aggregates between pea proteins and soluble complex between pea protein and indigenous dietary fiber is the underlying reason that HIUS improves the solubility of poorly soluble pea protein. Our findings offer unprecedented insights into the fundamental role of HIUS on structure modification of plant protein, thus paving the way for their industrial applications as green technique in fabricating plant proteins with improved solubility. • High-intensity ultrasound (HIUS) increases solubility of pea protein isolate (PPI). • Different fractions of PPI are dissolved under elevated powders of sequential HIUS. • Both soluble aggregates and complex are observed in the soluble fractions of PPI. • Indigenous carbohydrate forms soluble complex with pea protein upon HIUS.

Variation of in vitro digestibility of pea protein powder dispersions from commercially available sources

With raising consumer demand for plant-derived proteins, there has been an increased interest in the utilization of pea ingredients in food formulations. It was hypothesized that differences in processing history and composition affect their colloidal properties and their breakdown during in vitro simulated gastrointestinal digestion. The gastrointestinal fate of three different commercial pea protein ingredients, two protein isolates and one less refined concentrate was compared. The concentrate dispersion showed greater solubility, different protein composition and smaller particle size than the reconstituted pea protein isolates. When heat-treated, the release of free amino groups decreased for the isolates, but increased for the concentrate dispersions. LC-TQMS of free amino acids in the intestinal digestates indicated a significantly higher release of methionine (limiting amino acid in pea protein) in the concentrates than in the isolates. This work highlights the influence of processing and composition on techno-functional and digestion properties of pea ingredients.

High-pressure homogenization: A potential technique for transforming insoluble pea protein isolates into soluble aggregates

High-pressure homogenization (HPH) is a technique that impacts the aggregation of globular proteins. In this study, the effect of HPH (at a pressure of 30/50 MPa for three cycles) was investigated on the aggregation states and functional properties of insoluble commercial pea protein isolates (CPPI). Results showed that HPH significantly improved the solubility, foaming and emulsifying capacity of CPPI. Samples treated at 50 MPa demonstrated better foaming and emulsifying capacity than that at 30 MPa. Surface hydrophobicity, intrinsic fluorescence, SDS-PAGE and FTIR analysis revealed that insoluble precipitates/aggregates (most legumins included) of CPPI were broken down and converted into soluble aggregates. Low-pressure HPH (30 MPa) can break non-covalent bonds (hydrophobic interactions), whereas higher pressure (50 MPa) can further break covalent bonds (SS). The study sheds light on the mechanism of disruption of insoluble CPPI under HPH and proposes a method to enhance their techno-functional properties for application in food formulations.

Characterization of soluble and insoluble fractions obtained from a commercial pea protein isolate

In this study, the characteristics of pea protein isolates after aqueous fractionization into water-soluble and water-insoluble fractions by centrifugation, decantation, and lyophilization were studied. Chemical composition and physicochemical properties upon pH changes were determined. The overall protein compositions of both soluble and insoluble pea protein fractions were similar containing albumins, globulins, and lipoxygenases, but amino acid compositions slightly varied. Distinct differences were observed in their charge properties, particle sizes, and voluminosities. The soluble pea protein fraction was free of measurable particles at pH 7, whereas the insoluble proteins contained particles with sizes of > 80 µm. Close to their respective isoelectric points, the soluble (pI = 3.9) and insoluble pea proteins (pI = 4.9) had very similar sizes of 40–50 µm. At pH 3, the particle sizes of soluble proteins did not change, however, the insoluble pea proteins had again sizes of > 80 µm. Voluminosity of the insoluble fraction was pH-dependent and had its highest voluminosity at pH 3 and 7, indicating changes in water binding as a function of pH. In contrast, the voluminosity of the soluble pea protein fraction did not change with pH. Taken together, this study showed that water-soluble and insoluble pea protein fractions of a commercial isolate may differ substantially with respect to their physicochemical properties. Observed inconsistencies in technofunctionality of various commercial preparations could thus be promoted by varying ratios between the two fractions.

In vitro gastro-small intestinal digestion of conventional and mildly processed pea protein ingredients

We report on the effect of processing, particularly heating, on the digestion dynamics of pea proteins using the standardised semi-dynamic in vitro digestion method. Fractions with native proteins were obtained by mild aqueous fractionation of pea flour. A commercial pea protein isolate was chosen as a benchmark. Heating dispersions of pea flour and mild protein fractions reduced the trypsin inhibitory activity to levels similar to that of the protein isolate. Protein-rich and non-soluble protein fractions were up to 18% better hydrolysed after being thermally denatured, particularly for proteins emptied later in the gastric phase. The degree of hydrolysis throughout the digestion was similar for these heated fractions and the conventional isolate. Further heating of the protein isolate reduced its digestibility as much as 9%. Protein solubility enhances the digestibility of native proteins, while heating aggregates the proteins, which ultimately reduces the achieved extent of hydrolysis from gastro-small intestinal enzymes.

Physicochemical properties of different pea proteins in relation to their gelation ability to form lactic acid bacteria induced yogurt gel

Three commercial pea proteins and a laboratory sample (PL) were assessed for their physicochemical properties (subunit composition, secondary structure, surface hydrophobicity, solubility) and gelation properties (rheology, texture, intermolecular forces) in fermentation induced yogurt gel. The results showed that the dissociation of legumin was occurred in all three commercial pea proteins, accompanied by the formation of large protein aggregates. The contents of α-helix and β-sheet were significantly lower in the commercial pea proteins than PL (p < 0.05). However, commercial pea protein prepared by sour liquid processing method (PS) showed relatively higher solubility and β-sheet content than both of the two commercial samples prepared by alkali extraction isoelectric precipitation methods (PA). In addition, rheological properties results revealed that the gelation abilities of the three commercial pea proteins declined compared with the PL. Among all commercial pea protein-based yogurt gels, PS-based yogurt gel presented a higher hardness than PA-based yogurt gels. According to this study, the decreased gelation ability of commercial pea proteins could attribute to the dissociation of legumin and decrease in β-sheet structure, which weaken the hydrophobic force to form yogurt gels induced by lactic acid bacteria.

Flavor formation and regulation of peas (Pisum sativum L.) seed milk via enzyme activity inhibition and off-flavor compounds control release

Ascorbic acid, quercetin, epigallocatechin-3-gallate and reduced glutathione as well as high hydrostatic pressure were used to regulate the flavor of milk prepared from pea seeds. Activities of lipoxygenase (LOX) pathway enzymes and fatty acid contents of pea milk were determined. The hexanal content was positively correlated with the activity of LOX-2, but was negatively correlated with the contents of linoleic acid and α-linolenic acid. The intensity of the sensory attribute “fatty” was reduced when epigallocatechin-3-gallate or high hydrostatic pressure were combined with quercetin. Decreases in hexanal, pentanol, and 2-pentylfuran contents may have caused the change in sensory properties of pea milk. Pea protein, sodium sulfate and/or propylene glycol were used to regulate interactions between pea protein and flavor compounds. The hexanal content was reduced by commercial pea protein. Sodium sulfate and propylene glycol individually reduced the hexanal content and together reduced the hexanol content.

Comparison of physicochemical and emulsifying properties of commercial pea protein powders

There is an increasing trend in the food industry to utilize plant-based proteins. Pea protein (PP) is one such protein that is a promising alternative emulsifier. However, there is a significant functionality gap between laboratory and commercially produced PP that limits its usage. The physicochemical and emulsification properties of five commercial PP powders were characterized to better understand the functionality gap. Four of the five commercial powders displayed low solubility, high surface hydrophobicity, and an abundance of large insoluble aggregates. High-pressure homogenization was able to break up the aggregates, reduce surface hydrophobicity, and increase solubility. There was a significant correlation between the homogenized solubility and the emulsification properties of the commercial PPs. There was not a significant correlation between the emulsification properties and the other physicochemical properties (unhomogenized solubility, zeta potential, surface hydrophobicity, and interfacial tension). The conformational changes caused by the commercial isolation process may disrupt the correlations between the physicochemical and emulsification properties of PP. Solubility is a key physicochemical property to enable good emulsification properties for PP. Homogenization is an effective step to improve the solubility of commercial PP and therefore promote its functional properties before industrial usage. © 2021 Society of Chemical Industry.

Validation of Bioinformatic Modeling for the Zeta Potential of Vicilin, Legumin, and Commercial Pea Protein Isolate

Validation of Bioinformatic Modeling for the Zeta Potential of Vicilin, Legumin, and Commercial Pea Protein Isolate