Acid-induced gelation of enzymatically cross-linked caseinates: Small and large deformation rheology in relation to water holding capacity and micro-rheological properties

Caseinate dissolved in different ionic milieus was used as model substrate for cross-linking by microbial transglutaminase and subsequent acid-induced gelation. The study follows up on previous research, where the molecular properties of cross-linked casein nanoparticles were linked to certain rheological characteristics acid gels (Raak et al., 2019, Food Hydrocoll 86:43–49), presents additional insight into physical gel properties. frequency dependency storage modulus followed a power law relationship, with exponent being linearly related phase angle. loss factor could be fitted second-order polynomial function, minimum which shifted lower at increasing extent. Strain sweep experiments showed less pronounced strain hardening behaviour reduced fracture extent, indicating flexibility number non-covalent bonds, respectively. water holding capacities good relationship properties, suggesting that serum drainage during centrifugation also affected behaviour. Additionally, diffusing wave spectroscopy particles interacted already prior gelation onset, presence Ca2+ ions increases particle size both caseinate solutions