Oil-water interface and emulsion stabilising properties of rapeseed proteins napin and cruciferin studied by nonlinear surface rheology

Jack Yang, Penghui Shen, Anteun de Groot, Helene Mocking-Bode, Costas Nikiforidis, Leonard Sagis*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

Hypothesis
Two major protein families are present in rapeseed, namely cruciferins and napins. The structural differences between the two protein families indicate that they might behave differently when their mixture stabilises oil–water interfaces. Therefore, this work focuses on elucidating the role of both proteins in interface and emulsion stabilisation.
Experiments
Protein molecular properties were evaluated, using SEC, DSC, CD, and hydrophobicity analysis. The oil–water interface mechanical properties were studied using LAOS and LAOD. General stress decomposition (GSD) was used as a novel method to characterise the nonlinear response. Additionally, to evaluate the emulsifying properties of the rapeseed proteins, emulsions were prepared using pure napins or cruciferin and also their mixtures at 1:3, 1:1 and 3:1 (w:w) ratios.
Findings
Cruciferins formed stiff viscoelastic solid-like interfacial layers (Gs′ = 0.046 mN/m; Ed′ = 30.1 mN/m), while napin formed weaker and more stretchable layers at the oil–water interface (Gs′ = 0.010 mN/m; Ed′ = 26.4 mN/m). As a result, cruciferin-formed oil droplets with much higher stability against coalescence (coalescence index, CI up to 10%) than napin-stabilised ones (CI up to 146%) during two months of storage. Both proteins have a different role in emulsions produced with napin-cruciferin mixtures, where cruciferin provides high coalescence stability, while napin induces flocculation. Our work showed the role of each rapeseed protein in liquid–liquid multiphase systems.
Original languageEnglish
Pages (from-to)192-207
JournalJournal of Colloid and Interface Science
Volume662
DOIs
Publication statusPublished - 15 May 2024

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