Niosome-loaded cold-set whey protein hydrogels

• Alpha-tocopherol was encapsulated within sorbitan monostearate noisomal bilayers.
• The niosomes were added to either cross-linked or non-cross-linked protein solutions.
• The solutions were then gelled with glucono delta-lactone and subjected to analyses.
• Both niosomes charging and enzymatic cross-linking enhanced the gelation capability.
• Niosomes mediate protein supramolecules aggregation and assist protein refolding.

The α-tocopherol-carrying niosomes with mean diameter of 5.7 μm were fabricated and charged into a transglutaminase-cross-linked whey protein solution that was subsequently gelled with glucono delta-lactone. Encapsulation efficiency of α-tocopherol within niosomes was ≈80% and encapsulation did not influence the radical scavenging activity of α-tocopherol. Fourier transform infrared (FTIR) spectroscopy suggested formation of ε-(γ-glutamyl) lysine cross-linkages by transglutaminase and that enzymatic cross-linking increased proteins hydrophobicity. FTIR also proposed hydrogen bonding between niosomes and proteins. Dynamic rheometry indicated that transglutaminase cross-linking and niosomes charging of the protein solution enhanced the gelation process. However, charging the cross-linked protein solution with niosomal suspension resulted in lower elastic modulus (G′) of the subsequently formed gel compared with both non-cross-linked niosome-loaded and cross-linked niosome-free counterparts. Electron microscopy indicated a discontinuous network for the niosome-loaded cross-linked sample. Niosome loading into the protein gel matrix increased its swelling extent in the enzyme-free simulated gastric fluid.