Exploring the breakdown of dairy protein gels during in vitro gastric digestion using time-lapse synchrotron deep-UV fluorescence microscopy

•In vitro gastric digestions of dairy gels were monitored by synchrotron deep-UV microscopy.•Variations of tryptophan fluorescence allowed exploring pH gradients inside particles.•Syneresis of rennet gel led to compact protein aggregates under gastric acid conditions.•Consequently kinetics of pepsin hydrolysis were slower for rennet gel than acid gel.•Erosion is probably the predominant mechanism of dairy gel disintegration.