Investigating casein gel structure during gastric digestion using ultra-small and small-angle neutron scattering

•The first study to monitor gastric devolution of casein gels using USANS and SANS.•Gels prepared in D2O exhibit earlier onset of gelation, are firmer yet more brittle compared to H2O.•Rennet-induced gel structure is sensitive to the acidic environment of the stomach.•Pepsin induces micelle swelling and promotes higher levels of protein digestion in the stomach.•Acidification and shear govern early gastric digestion kinetics.