Probiotic Encapsulation: Bead Design Improves Bacterial Performance during In Vitro Digestion (Part 2: Operational Conditions of Vibrational Technology)

The development of functional foods is a viable alternative for the prevention of numerous diseases. However, the food industry faces significant challenges in producing functional foods based on probiotics due to their high sensitivity to various processing and gastrointestinal tract conditions. This study aimed to evaluate the effect of the operational conditions during the extrusion encapsulation process using vibrating technology on the viability of <i>Lactobacillus fermentum</i> K73, a lactic acid bacterium with hypocholesterolemia probiotic potential. An optimal experimental design approach was employed to produce sweet whey-sodium alginate (SW-SA) beads with high bacterial content and good morphological characteristics. In this study, the effects of frequency, voltage, and pumping rate were optimized for a 300 μm nozzle. The microspheres were characterized using RAMAN spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy. The optimal conditions for bead production were found: 70 Hz, 250 V, and 20 mL/min with a final cell count of 8.43 Log₁₀ (CFU/mL). The mean particle diameter was 620 ± 5.3 µm, and the experimental encapsulation yield was 94.3 ± 0.8%. The INFOGEST model was used to evaluate the survival of probiotic beads under gastrointestinal tract conditions. Upon exposure to in vitro conditions of oral, gastric, and intestinal phases, the encapsulated viability of <i>L. fermentum</i> was 7.6 Log₁₀ (CFU/mL) using the optimal encapsulation parameters, which significantly improved the survival of probiotic bacteria during both the encapsulation process and under gastrointestinal conditions compared to free cells.