Subunit composition affects formation and stabilization of o/w emulsions by 11S seed storage protein cruciferin. (November 2020)

• Record Type: Journal Article
• Authors: Withana-Gamage, Thushan S.; Hegedus, Dwayne D.; McIntosh, Tara C.; Coutu, Cathy; Qiu, Xiao; Wanasundara, Janitha P.D.
• Is Part Of: Food research international. Volume 137(2020)
• Publication Date: 2020-11
• Subjects: Cruciferin -- o/w Emulsions -- Hydrophobicity -- Protein solubility -- 11S globulins -- Arabidopsis thaliana -- Seed storage protein; Food -- Analysis -- Periodicals; Food industry and trade -- Periodicals; Food industry and trade -- Canada -- Periodicals; Food Technology -- Periodicals; Food -- Periodicals; Food-Processing Industry -- Periodicals; Aliments -- Industrie et commerce -- Périodiques; Aliments -- Industrie et commerce -- Canada -- Périodiques; Aliments -- Recherche -- Périodiques; Food industry and trade; Canada; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.foodres.2020.109387
• Languages: English
• ISSNs: 0963-9969

Abstract

Graphical abstract: Highlights: Cruciferin of identical or mixed subunits varied in oil/water emulsifying properties. CRUC hexamer had the lowest emulsifying ability at pH 7.4 without NaCl. pH 2.0-induced dissociation improved emulsifying properties across all cruciferins. Solubility and exposed hydrophobic sites relate to interface stabilization. Abstract: The 11S globulin cruciferin is the major storage protein in Brassicaceae/Cruciferae seeds and exists as a hexamer in its natural configuration. Arabidopsis thaliana cruciferin is composed of CRUA, CRUB and CRUC subunits. Wild type (WT) cruciferin and cruciferins composed only of identical CRUA, CRUB and CRUC subunits were examined for their ability to form and stabilize oil-in-water (o/w) emulsions. All proteins (0.9% at pH 7.4 and 2.0), except CRUC, formed stable canola oil or triolein emulsions with a dispersed phase volume fraction of 22–23%. A fine emulsion was formed by CRUB at pH 7.4 with droplet sizes of 6.8 and 8.6 μm for canola oil and triolein, respectively. The presence of 0.5 M NaCl reduced the level of adsorbed protein and protein load at the interface at pH 7.4, and resulted in emulsions that were less stable. Emulsions of CRUA and CRUB (pH 7.4, zero ionic strength, canola oil or triolein) had higher stability than emulsions with WT cruciferin up to 15 days after formation. CRUC formed a stable emulsion only at pH 2.0. The low solubility, low surface hydrophobicity and compact structure of the CRUC protein may contribute to its inferior emulsifying properties at neutral pH; however, acidic pH-induced dissociation of the hexameric assembly improved these properties. The abundance and exposure of hydrophobic residues in the hypervariable regions, extended loop regions, and solvent exposed surfaces of cruciferin are critical factors affecting o/w interface stabilization.