Encapsulation of Acid Whey in Alginate Microspheres for Application in Skin Microbiome-Friendly Topical Formulations: Optimization Through a Design of Experiments Approach

Skin microbiome-friendly preparations are gaining increasing popularity in the cosmetics and pharmaceutical industries. Fermented plants, lysates, and heat-treated products are used as probiotic ingredients in cosmetics. This is due to the presence of <i>Lactobacillus</i> bacteria, such as acid or acid-rennet whey, which are natural probiotics that can positively impact the skin microbiome. However, due to technological difficulties, the direct use of whey as a cosmetic ingredient is limited. An optimized emulsification method was used to obtain alginate microspheres as carriers of whey. The process parameters were optimized using the Design of Experiments (DoEs) methodology. The effect of three key variables, including the type of probiotic raw material (whey from 1-cows, 2-goats, and 3-mixed), the alginate-to-raw material ratio (1-3%), and sonication time (0.5-1.5 min), on parameters such as encapsulation efficiency, bacterial survival, viscosity, and microspheres size was analyzed. The results obtained demonstrated that the optimal process parameters were the sonication time of 0.5 min and the alginate-to-whey mass ratio of 1.5% for all types of whey material studied. However, the most important factor influencing the properties and functionality of the microspheres was sonication time. The optimized whey-loaded microspheres were incorporated into a preservative-containing emulsion system, in which the viability of whey-derived bacteria was monitored over time. The whey encapsulation process effectively maintained the bacteria's probiotic properties, protecting their viability despite the presence of preservatives (at a level of 4.92 ± 0.9 log CFU/g after 30 days of formulation storage), thus confirming the feasibility of incorporating liquid whey into skincare formulations.