Gelation by bioactives: Characteristics of the cold-set whey protein gels made using gallic acid

A bioactive molecule, gallic acid (GA), was used to form cold-set whey protein gels. This method enables exploitation of the bioactive compound per se to gel whey proteins. Also, citric acid was used to crosslink whey proteins before gelation by GA. Compared with phosphoric acid (PA), gelation by GA prevented formation of intermolecular β-sheets and resulted in a porous microstructure. Also, the GA-induced gel had a lower firmness and water-holding capacity (WHC), but a higher swellability in pepsin-free simulated gastric fluid. Citric acid pre-crosslinking decreased the proportion of α-helix structures in favour of β-turns in the GA-induced gel. It also increased the size of ordered structures (α-helix and β-sheets), caused formation of larger protein aggregates and increased gel WHC. The PA-induced gel initially underwent a lower in vitro peptic disintegration; however, the disintegration of the PA-induced gel rapidly increased, surpassing those of GA-induced gels.