Modulating molecular interactions in pea protein to improve its functional properties

Authors: SHEN, YANTING - KANSAS STATE UNIVERSITY; WU, XIAORONG; LI, YONGHUI - KANSAS STATE UNIVERSITY

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2022
Publication Date: 5/6/2022
Citation: Shen, Y., Wu, X., Li, Y. 2022. Modulating molecular interactions in pea protein to improve its functional properties. Food Hydrocolloids. 8. Article 100313. https://doi.org/10.1016/j.jafr.2022.100313.
DOI: https://doi.org/10.1016/j.jafr.2022.100313

Interpretive Summary: Natural proteins exist in numerous structural arrangements, which are stabilized by various inter- and intra-molecular interactions. many factors (physical, chemical, & biological), such as sodium sulfite, urea, sodium dodecyl sulfate (SDS), and trypsin can interfere with those interaction and thus alter protein's structures and functional properties. The objectives of this study were to investigate the functional properties of pea protein isolate in terms of water/oil holding capacity, emulsifying and foaming properties, solubility, and gelation by modulating protein covalent and non-covalent interactions, to better understand the physicochemical features of the unfolded pea proteins related to their functional changes and potential food applications. Solubility of all the denatured proteins in this study increased significantly. Both urea and SDS unfolded proteins had higher water and oil holding capacity compared to the untreated control pea protein. The proteins unfolded with urea or SDS also showed better emulsification properties. The trypsin hydrolyzed protein exhibited the best foaming capacity and gelation properties among all the treatments. Principal component analysis indicated strong associations between molecular interactions and protein's functional and physicochemical properties.

Technical Abstract: Proteins exist in numerous spatial arrangements and are stabilized by various inter- and intra-molecular forces. Different denaturants such as sodium sulfite, urea, sodium dodecyl sulfate (SDS), and trypsin can interfere with protein molecule interactions, particularly disulfide bond, hydrogen bond, hydrophobic interaction, and peptide bond, respectively, which further alters protein secondary and tertiary structures and functional properties. The objectives of this study were to investigate the functional properties of pea protein isolate in terms of water/oil holding capacity, emulsifying and foaming properties, solubility, and gelation by modulating protein covalent and non-covalent interactions and understand the physicochemical characteristics (e.g., free amino group, free sulfhydryl, surface hydrophobicity, SDS-PAGE profile, secondary structures) of the unfolded pea proteins that are responsible for the functional changes. All the denatured proteins possessed significantly increased solubility. Both urea and SDS unfolded proteins had significantly higher water holding capacity and oil holding capacity with up to 5.01 and 5.09 g H2O /g, and 3.06 and 2.84 g oil /g compared with the control pea protein (4.12 and 1.29 g), respectively. The proteins unfolded with urea or SDS also showed improved emulsification properties. The trypsin hydrolyzed protein exhibited the highest foaming capacity and better gelation properties among all the treatments. Principal component analysis indicated strong associations between protein functional and physicochemical properties and molecular interactions.