Enhancing the Gastrointestinal Survival of Microencapsulated Limosilactobacillus fermentum K73: Optimization Through Double Emulsification Followed by Spray Drying, and in Vitro Digestion Assessment

Abstract The growing interest in the health benefits of probiotics has led to increased demand for products containing these microorganisms, highlighting two key challenges: their survival in diverse food matrices and their survival within the gastrointestinal tract. Thus, this study aimed to optimize the formulation of microencapsulated Limosilactobacillus fermentum K73 with high oleic palm oil (HOPO) and whey, using double emulsification (W/O/W) and spray drying to enhance probiotic protection. Double emulsification was performed using high-shear homogenization at 11,000 rpm, dispersing the probiotic in oil as the first phase and then in whey as the aqueous phase. Spray drying was carried out at inlet and outlet temperatures 200°C and 90°C, respectively. The response variables were the zeta potential of the emulsions, bacterial cycle changes after drying and bile exposure, and powder moisture content. The optimal emulsion had a zeta potential of -23 mV, with bacterial cycle changes of 0.32 log CFU/mL after drying and 1.52 log CFU/mL after bile exposure, and a moisture content of 4.12%. Two synbiotics were prepared by adding a postbiotic from L. fermentum fermentation and a prebiotic (2’-fucosyllactose). In vitro digestion following the INFOGEST protocol showed synbiotics reaching the intestinal phase at 4.9–6.02 log CFU/mL. In conclusion, double emulsification combined with spray drying produced microencapsulates that survived gastrointestinal conditions at adequate concentrations, enabling their potential use for colonic delivery to evaluate effects on host health. Graphical Abstract