Caffeine-loaded whey protein hydrogels reinforced with gellan and enriched with calcium chloride

Gellan gum and CaCl2 were exploited to modulate the textural and techno-functional properties of heat-set whey protein hydrogels. Enrichment with CaCl2 increased the amount of released caffeine from the protein hydrogel in conjunction with decreasing cohesiveness index and microstructural features modification. Gellan bundles as visualised by microscopic images conferred a remarkable reinforcing influence to gel samples; enrichment with gellan at 0.5 mg mL−1 increased the gel hardness value approximately 6.4 fold. Based on Fourier transform infrared (FTIR) spectroscopy it was suggested that gellan and CaCl2 enrichments decreased the β-sheet content of the protein gel matrix in favour of random coil structures. FTIR spectroscopy also proposed cation-π interactions between Ca2+ ions and electron-rich amide bonds of whey proteins, as well as interactions between carboxyl groups of gellan and the ε-amino group of lysine in β-lactoglobulin.