Improved foaming properties and interfacial observation of sodium caseinate-based complexes: Effect of carboxymethyl cellulose

Proteins and their poly-complex/conjugates are well known to produce and stabilize foams due to the intrinsic amphiphilicity, tunable microstructures and surface adsorption behaviors. However, in-situ observations and in-depth understanding to their bulk, foaming and interfacial behaviors remain less charted especially when proteins are assembled in the multi-component food matrices. In this study, we reported that the carboxymethyl cellulose (CMC) represents an economic candidate to significantly enhance the foaming properties of sodium caseinate (SC) and its binary complex (sodium caseinate-tannic acid, SC/TA). The obtained complex (both SC/CMC and SC/TA/CMC) showed increased foam-ability, foam stabilities and reduced bubble sizes. In terms of the interfacial behaviors, micro-rheological test and dynamic interfacial data revealed that SC/TA/CMC foaming system exhibited viscous bulk phase, formation of elastic interface and more importantly the enhanced surface activity. To further investigate their nonlinear surface rheological characteristics , the large-amplitude oscillatory dilatational rheology was used, in which the surface dilatational modulus of SC/TA increased as CMC was added. More than providing a high-performance food surfactant , our study manifests that complex formed between polyphenols, proteins, and polysaccharides can be a viable platform to understand and design novel foaming agents in the food industry.