Research Outputs

Transglutaminase-Induced Polymerization of Pea and Chickpea Protein to Enhance Functionality
Brigitta P. Yaputri, Samira Feyzi and Baraem P. Ismail
Gels 2024, 10, 11.
Abstract: 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. (Published: December 22, 2023)

Pea protein globulins: Does their relative ratio matter?

Holly Husband, Sungil Ferreira, Fan Bu, Samira Feyzi, Baraem P. Ismail
Food Hydrocolloids 148 (2024) 109429
The relatively low abundance of 11S legumin in pea protein, coupled with the wide diversity in 7S vicilin to 11S legumin ratio among pea protein ingredients, are assumed contributors to inferior and inconsistent properties relative to soy protein. To improve the performance of pea protein ingredients in food applications, optimum protein profile must be identified. Therefore, this work followed a holistic approach to determine the impact of 7S/11S ratio on pea protein structure, functionality, and nutritional quality. Vicilin- and legumin-rich fractions were isolated and combined in different proportions to produce samples of varying 7S/11S ratios. For the first time, pea protein isolate was also enriched with 11S legumin to evaluate the impact of 11S abundance on
functionality within an unfractionated protein matrix. The low abundance of 11S in pea protein did not seem to be the cause of inferior properties. In fact, 7S vicilin had 6-fold higher gel strength and 5-fold higher emulsification capacity, but significantly lower nutritional quality, than 11S legumin. Despite having significantly higher sulfur-containing amino acids, high protein polymerization in 11S legumin contributed to relatively low functionality. Further, fractionation induced unique changes to amino acid composition, resulting in significantly lower amino acid scores for isolated 7S vicilin and 11S legumin relative to pea protein isolate. Accordingly, 11S legumin enrichment of pea protein isolate did not improve functionality or nutritional quality. Nevertheless, this work contributed foundational knowledge that will provide direction for future studies aiming at devising strategies to improve the quality and consistency of pea protein ingredients. (Published October 19, 2023)

Impact of extraction conditions and seed variety on the characteristics of pennycress (Thlaspi arvense) protein: a structure and function approach
Rachel Mitacek, M. David Marks, Nicole Kerr, Daniel Gallaher, Baraem P. Ismail

Journal of the American Oil Chemists' Society, 2023, 1-20
Abstract: As the consumer demand for plant proteins continues to grow, the food industry is seeking novel and sustainable protein sources to incorporate in various food products. Pennycress (Thlaspi arvense), a sustainable cover crop, produces oilseeds high in protein, warranting investigation. Accordingly, protein extraction from pennycress was evaluated under various extraction conditions, using alkaline extraction and salt solubilization coupled with ultrafiltration. Given the superior color and functionality of the salt extracted pennycress protein isolate (PcPI), its production was scaled-up about two hundred folds in a pilot plant. Furthermore, a new pennycress accession bred to have zero erucic acid (0EA) was evaluated to determine the impact of seed variety on protein characteristics. Structural and functional characterization was performed on PcPI and compared to native (nSPI) and commercial (cSPI) soy protein isolates. Salt extracted PcPI had comparable gel strength to cSPI, three times higher solubility under acidic conditions, and 1.5 times better emulsification capacity. PcPI extracted from 0EA was mildly different in structure and functionality from that extracted from wildtype pennycress, with the slight variation attributed to genetic variance. Finally, the protein digestibility-corrected amino acid score (PDCAAS) of the salt extracted PcPI, calculated in vivo (0.72) and in vitro (0.87), was superior or comparable to other plant protein sources. This research provided, for the first time, a comprehensive evaluation of different protein extraction protocols to produce a functional PcPI that can compete with soy protein for various food applications, such as acidic beverages, meat and dairy products, and emulsified systems. (Published: July 24, 2023)

Enhancement of pea protein solubility and thermal stability for acidic beverage applications via endogenous Maillard-induced glycation and chromatography purification
Alissa A. Schneider , Fan Bu , Baraem P. Ismail

Current Research in Food Science, 2023, 6, 100452.
Abstract: A clean-label process to endogenously glycate and purify pea protein was investigated. The production of maltodextrin from pea starch with a specific dextrose equivalent (DE) was optimized. The produced maltodextrin (14.6 DE) was used to initiate a limited and controlled Maillard-induced glycation of pea protein. The partially glycated pea protein (PG-PP) was subjected to hydrophobic interaction chromatography to remove unreacted carbohydrate, followed by characterization of the purified product. The extent of Maillard-induced glycation was monitored by assessing changes in color, free amino groups, and protein/glycoprotein profiles. The purified PGPP was evaluated for thermal denaturation, surface properties, protein secondary structure, protein solubility, thermal stability, and digestibility. Maillard-induced glycation was limited to initial stages and resulted in a moderate blockage of amine groups (~30%). The purified PG-PP had a relatively low surface hydrophobicity, a markedly enhanced protein solubility (~90%) at pH 3.4, and a nonimpacted protein in vitro digestibility (~100%). This work provided the impetus needed for future scale-up and process optimization for the production of value-added pea protein ingredient intended for high protein beverage applications. (Published: February 8, 2023)

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

Brigitta P. Yaputri, Fan Bu and Baraem P. Ismail

Foods, 2023, 12, 1694.
Abstract: 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. (Published: April 19, 2023)

Investigation of novel cold atmospheric plasma sources and their impact on the structural and functional characteristics of pea protein
Fan Bu, Samira Feyzi, Gaurav Nayak, Qingqing Mao, V.S. Santosh K. Kondeti, Peter Bruggeman, Chi Chen, Baraem P. Ismail

Innovative Food Science and Emerging Technologies, 2023, 83, 103248.
Abstract: The impact of three cold atmospheric plasma (CAP) sources, atmospheric pressure plasma jet (APPJ), two-dimension dielectric barrier discharge (2D-DBD), and nanosecond pulsed discharge (ns-pulsed) on the structure, functionality, and amino acid composition of pea protein was evaluated. Different plasma sources and associated reactive species resulted in protein denaturation, increased surface hydrophobicity, formation of soluble aggregates mostly by disulfide linkages, and changes in secondary structures. Enhancement in surface properties, presence of soluble aggregates, and increase in β-sheet contributed to significant improvement in gelation and emulsification. Enhanced emulsion stability was attributed to relatively small droplet sizes and high surface charge. Differences among CAP-treated samples were attributed to differences in fluence and composition of plasma-produced reactive species. While all three plasma treatments could be appreciable functionalization approaches, 2D-DBD (Ar + O2) treatment for 30 min had insignificant effect on the amino acid composition. (Published: December 21, 2022)

Structure‑Function Guided Extraction and Scale‑Up of Pea Protein Isolate Production
Lucy Hansen, Fan Bu, Baraem P. Ismail

Foods, 2022, 11, 3773.
Abstract: 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. (Published: November 23, 2022)

Monitoring the Aroma Profile during the Production of a Pea Protein Isolate by Salt Solubilization Coupled with Membrane Filtration
Yara L. Benavides-Paz, Baraem P. Ismail, Gary A. Reineccius

ACS Food Science and Technology, 2022, 2, 280.
Abstract: The volatile profile was monitored during an optimized salt extraction process (salt solubilization coupled with membrane filtration) to produce a pea protein isolate (PPI). Aroma compounds from samples collected at different steps of the manufacturing process were isolated using solvent-assisted flavor evaporation (SAFE) and analyzed by gas chromatography−mass spectrometry−olfactometry (GC−MS−O) and GC−time-of-flight mass spectrometry (GC−TOF-MS). A sensory evaluation of pea flour (PF) and PPI aqueous solutions was also conducted. Twelve aroma compounds were perceived with a “moderate” odor intensity by panelists from the sniffing port of GC−MS−O. From the sensory evaluation, the aroma descriptors used to describe the PF and PPI testing solutions were also used to describe individual compounds eluting from the sniffing port. This observation
supports the hypothesis that the 12 compounds identified in this study by GC−MS−O are likely to be the main contributors to the aroma profile of the samples analyzed. (Published: February 8, 2022)

Monitoring the Aroma Profile During the Production of a Pea Protein Isolate by Alkaline Solubilization Coupled with Isoelectric Precipitation
Yara L. Benavides-Paz, Baraem P. Ismail, Gary A. Reineccius

ACS Food Science and Technology, 2022, 2, 321.
Abstract: The aroma profile was monitored during an optimized pH-extraction method (alkaline solubilization coupled with isoelectric precipitation) to produce pea protein isolates (PPIs). Samples were taken at different steps throughout the protein extraction. The aroma compounds were isolated from these samples using solvent-assistant flavor evaporation (SAFE) and were identified by gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and gas chromatography-time-of-flight-mass spectrometry (GC-TOF-MS). A sensory evaluation of pea flour (PF) and PPI aqueous solutions was also conducted. From the instrumental analysis, 13 compounds were found to be likely the main contributors to the aroma profile of the samples examined. This hypothesis was also supported by the sensory data, which showed that the PF and PPI aqueous solutions were described with some of the odor descriptors used during the instrumental analysis. No new aroma compounds appear to be produced via the optimized pH-extraction and no existing compounds were completely removed from making a sensory contribution as determined by the olfactory analysis. (Published: January 24, 2022)

Impact of plasma reactive species on the structure and functionality of pea protein isolate
Fan Bu, Gaurav Nayak, Peter Bruggeman, George Annor, Baraem P. Ismail

Food Chemistry, 2022, 371, 131135.
Abstract: The impact of plasma-produced reactive oxygen and nitrogen species, in particular O3, NxOy, H2O2 and OH, on the structure and functionality of pea protein isolate (PPI) was evaluated. Reactive species were produced through a combination of controlled measurements and plasma treatments. Pronounced structural and functional effects were observed upon treatment with reactive species at pH 2. All reactive species induced protein denaturation and the formation of disulfide-linked soluble aggregates. A significant increase in surface hydrophobicity and β-sheet content was only induced by treatment with O3 and OH. These specific changes resulted in significant enhancement in gelation and emulsification. While H2O2 enhanced PPI color by increasing whiteness, it had the least impact on protein structure and functionality. Results of this work can be used to optimize cold atmospheric plasma treatment of PPI to induce specific structural changes and a directed enhancement in functionality. (Published: September 15, 2021)

Method for Producing Functional Pea Protein. Alissa Schneider, B. Pam Ismail, 2020. Provisional Patent Filed Oct 30^th 2020