Iron‐encapsulated cold‐set whey protein isolate gel powder – Part 1: Optimisation of preparation conditions and in vitro evaluation

A central composite design with a quadratic model was used to investigate the effects of three independent variables involved in the synthesis of iron‐encapsulated cold‐set whey protein isolate gel (WPI) on encapsulation efficiency (EE) and L*, a*, b* colour characteristics. The optimal conditions for maximum EE with minimum colour alteration were determined as 6.8% WPI, 18.8 mM iron and pH 7. In an in vitro gastrointestinal assay, only about 28% of the encapsulated iron was released in the gastric condition (with pepsin at pH 1.2), compared to 95% in the intestinal condition (with pancreatin at pH 7.5).