Sodium caseinate‐encapsulated propolis nanoparticles: Designing, production and characterisation

Background Incorporating propolis rich in various phenolics into a food‐grade matrix remains challenging due to its poor water solubility and limited physicochemical stability. The development of an effective delivery system such as sodium caseinate is of growing interest. Aim This study aimed to break down the structure of sodium caseinate, an edible and safe protein, embed a bioactive agent (propolis), and reassemble the matrix using different salts. The objective was to overcome the solubility and stability issues of propolis and evaluate the consistency of the resulting complex over a month. Methods Propolis extract was added to a 1% sodium caseinate solution using a hierarchical approach. Various concentrations (0.25%, 0.5% and 0.75%) were tested in triplicate. Particle size, entrapment efficiency, stability and water solubility of the complexes were assessed. Statistical analysis was performed using the SPSS software. Significant differences between means were determined by analysis of variance (completely randomised design), followed by Duncan's post hoc test. Major Findings At a molar ratio of 1:2 (propolis:caseinate), micellar structures were confirmed by TEM and 0.5% rCM‐pro was selected as the best treatment. Loading propolis into reassembled sodium caseinate markedly enlarged their mean particle size, increasing from 89.6 to 101.4 nm. A high entrapment efficiency of 99.65% was recorded for the encapsulated propolis. It also had a positive impact on preserving the complex quality, even after a month at 45°C. Furthermore, the water solubility of the rCM‐pro increased by 2.7‐fold. Industrial Implications Encapsulation not only protected the propolis extract from light and oxidation but also masked its herbal fragrance and unpleasant taste. This approach further supports the efficient design of delivery systems for hydrophobic nutraceuticals, enabling their incorporation into dairy products such as yoghurt, as well as a broad range of functional food and beverage applications.