Abstract
The efficacy of probiotics in providing health benefits may be related to their ability to survive at a sufficient concentration of 10(6) CFU/g during storage in food and colonization in the gastrointestinal tract. Microencapsulation is a viable method to improve the survivability of probiotics under harsh environmental conditions. In this research, microencapsulated Lactobacillus rhamnosus (MLR) was produced by a two-layer extrusion technique with sodium alginate and wild sage (Salvia macrosiphon) mucilage (SMM) in varying concentrations ranging from 0.2% to 0.8% as the first and second wall materials, respectively. The microencapsulation efficiency and second layer diameter of beads increased significantly with the increase in SMM concentrations. Microencapsulated Lactobacillus rhamnosus (LR) maintained its minimal concentration (6 log CFU/g) during 9 min at 72°C. The MLR-date yogurt (DY) sample had the lowest pH, highest acidity, and highest survival rate among the others at the end of storage. In simulated gastrointestinal conditions (SGC), the survival rates of free LR (FLR) and MLR were 45% and 47% on the 14th day of storage, respectively. In sensory properties, MLR had the highest score in odor and texture parameters but not in others. The MLR viscosity (666.3 mPa·s(-1)) and SEM images show a relatively denser structure for MLR. In conclusion, this study emphasized the potential of using double-layered beads to protect probiotics, providing valuable inspiration for developing new functional foods with higher survival ability in harsh conditions.