Sodium caseinate/cellulose nanofiber-stabilized Pickering emulsions: A study on lipid absorption regulation

This study aimed to develop a bio-based nano-additive (sodium caseinate/cellulose nanofibers (SC/CNF) complex) to modulate oil-in-water (O/W) colloid interfaces, which function as a fat control agent to slow lipid digestion. Edible protein (SC) was grafted onto CNF through facile electrostatic attraction, which reduces solvent and chemical usage. The physicochemical properties of SC/CNF showed that adding SC increased the interfacial bonding between CNF particles, resulting in higher interfacial pressure by forming dense and compact layers of SC/CNF. This characteristic improves the mechanical strength and colloidal stability of SC/CNF during water-oil stabilization. Further preparation of O/W Pickering emulsions stabilized by SC/CNFcomplexes was conducted using different parameters (for example SC concentration, dosage of SC/CNF, and O/W ratio) to investigate profile of free fatty acid (FFA) released during lipid digestion via simulated in vitro gastrointestinal tract (GIT) model. The results showed that the optimized emulsion stabilized by the SC/CNFcomplex rendered a lower value of free fatty acids (FFA) after undergoing in vitro simulated digestion. The lowest FFA release (31.18 %) was achieved under the following conditions: 1 % w/v (SC concentration), 1 % w/w (dosage of SC/CNF), and 20/80 (O/W) ratio. Low FFA release within the digestive system indicated that the nano-emulsions effectively regulated lipid digestion. The changes in physicochemical characteristics in terms of colloidal stability (particle size, microstructure, and surface charge) of the stabilized emulsions corresponding to the FFA released were studied during each digestion phase (including mouth, stomach, and small intestine). This study revealed that the SC/CNF complex is a promising nano-biomaterial that can function as a bio-functional food additive, particle stabilizer, and fat digestion controller. The unique characteristics of SC/CNF complexes in stabilizing oil-water emulsions present a potential interfacial mechanism for modulating lipid bioavailability. The innovation approach allows for the demand for green-label products, the development of healthier food options, and the pursuit of sustainable food solutions.