Ph.D. Dissertation:

Formulation of a low-fat synbiotic product (Cream Ardeh) containing inulin with the use of probiotic bacterial encapsulation technique

The survival of probiotics during the production, storage, and gastrointestinal passage of synbiotic dairy products is crucial in maintaining their health-promoting properties. In the first phase of this study, two probiotic strains, Lactobacillus acidophilus (La5) and Bifidobacterium bifidum (BB-12), were microencapsulated using an emulsion technique in sodium alginate (SA) and sodium caseinate (SC) matrices, each applied at two single concentrations and three combined ratios of 25:75 (SA1SC3), 50:50 (SA2SC2), and 75:25 (SA3SC1), with the aim of enhancing cell viability. Scanning electron microscopy (SEM) revealed spherical and uniform microcapsules with appropriate particle size and zeta potential for cell survival and colloidal stability. The results of encapsulation efficiency and simulated gastrointestinal tolerance (stomach and intestine, with and without bile salts) indicated that although encapsulation in the combined SA-SC matrix improved the survival of both probiotic strains B.bifidum (BB-12) exhibited significantly higher viability than L.acidophilus (La5) (p?0.05). Therefore, the B-SA3SC1 formulation was selected for use in the second phase to develop a synbiotic sesame-based cream. In the second phase, the effects of different inulin levels 5% (In1-BB12), 5.5% (In2-BB12), and 6% (In3-BB12) combined with microencapsulated B.bifidum (BB-12) were evaluated on the chemical, rheological, and sensory properties of a low-fat (15% fat) sesame cream. The results showed that inulin supplementation significantly increased total solids and ash contents, reduced syneresis, and stabilized pH, acidity, peroxide value, acid value, and microbiological quality during storage (p?0.05). The fatty acid profile demonstrated an improved unsaturated-to-saturated fatty acid ratio in the inulin and sesame-enriched treatments. The viability of B.bifidum (BB-12) in inulin-containing samples remained significantly higher than that of the control throughout 20 days of storage at 4 °C, maintaining viable counts above the minimum recommended level (p?0.05). Rheological analysis revealed that inulin addition increased viscosity, consistency, and yield stress in the synbiotic sesame cream samples, which followed the Power Law and Casson rheological models. Texture profile analysis showed that increasing inulin concentration enhanced hardness, cohesiveness, and gumminess, while reducing adhesiveness and springiness, consistent with the rheological findings. Sensory evaluation indicated that inulin had no significant effect on color and odor but improved taste, texture, mouthfeel, and overall acceptability compared to the control (p?0.05). Overall, the second phase results demonstrated that incorporating 6% inulin not only improved the nutritional value but also enhanced the rheological, textural, and sensory quality of the low-fat sesame cream. In conclusion, the findings indicate that emulsion-based microencapsulation is an effective strategy for enhancing the functionality of synbiotic products and ensuring targeted probiotic delivery to the colon. Moreover, combining this technique with a prebiotic fiber such as inulin not only preserved high probiotic viability during storage and improved the unsaturated/saturated fatty acid ratio but also increased rheological and structural stability, enhanced texture attributes such as hardness, cohesiveness, and gumminess, reduced adhesiveness and springiness, and improved mouthfeel and consumer acceptance. This study presents a successful example of integrating probiotic microencapsulation with fat-replacing prebiotic fibers to improve microbial stability, nutritional value, physical, and sensory characteristics in the development of low-fat synbiotic food products, providing a practical model for innovation in the food industry.

Keywords: Encapsulation, Lactobacillus acidophilus, Bifidobacterium bifidum, Prebiotic, Inulin, Synbiotic