Exploring the mechanisms of thermal aggregation resistance egg white: CMC concentration-mediated modification of protein structure and formation of microgel particles

Abstract

In industrial processes, heat-induced aggregation of egg white protein (EWP) severely hampers the development and application of liquid egg white products. This study aimed to fabricate thermally stabilized microgel particles of egg white protein (EMGP) via controlled phase separation using anionic polysaccharides, specifically carboxymethyl cellulose sodium salt (CMC). The underlying mechanisms, through which varying CMC concentrations impact the microstructural alterations and boost the resistance to thermal aggregation of EMGP, have been explored. The CMC concentration played a crucial role in modulating the competitive effects of phase separation and gelation in polysaccharide-protein mixed system, influencing the formation and structure of EMGP. The results demonstrated that EMGP with uniform size, high denaturation extent and compact structure were successfully obtained at optimal polysaccharide concentrations (1.5%, 2.0%, and 2.5% (w/v)). These structural modifications effectively inhibited protein unfolding and exposure of active sites during reheating, thereby enhancing the thermal stability of the EMGP. However, both insufficient and excessive polysaccharide concentrations compromised the formation of stable microgel particles. Moreover, thermal stability experiments demonstrated that the suspension of modified EMGP (5%, w/v) retained favorable flow characteristics after heating (100 °C, 30 min). In contrast, unprocessed natural EWP underwent gelation or particle degradation after reheating. Additionally, the particles exhibited excellent stability during storage. These findings offer valuable insights into the preparation of heat-stable EMGP, thereby expanding their potential applications in egg protein -based beverages.