Development and assessment of a functional probiotic yogurt formulation

Thesis Abstract

The escalating global demand for functional foods with health-promoting properties underscores the need for innovative dairy products that integrate probiotic benefits into widely accepted consumables like yogurt. Despite the recognized health advantages of probiotics, challenges persist in optimizing probiotic viability, sensory acceptability, and functional efficacy within yogurt matrices. This study aims to develop a novel probiotic yogurt formulation with enhanced viability and functional properties, and to evaluate its physicochemical, microbiological, sensory, and health-related attributes to ensure consumer acceptability and probiotic efficacy. The specific objectives include isolating and characterizing probiotic strains with high acid and bile tolerance, optimizing fermentation conditions for probiotic survival, assessing the physicochemical and sensory attributes of the formulated yogurt, and evaluating the probiotic's survivability during storage and its influence on host gut microbiota in vivo. The research adopts a mixed-methods design, integrating experimental laboratory analysis with a consumer sensory evaluation and an in vivo probiotic efficacy assessment. The study population comprises 50 isolates of probiotic bacteria sourced from fermented foods and gastrointestinal samples, subjected to phenotypic and genotypic characterization using API 50 CHL systems, 16S rRNA gene sequencing, and in vitro tolerance assays. A response surface methodology (RSM) approach guides the optimization of fermentation parameters—including temperature, inoculum size, and incubation duration—to maximize probiotic viability, analyzed through factorial ANOVA and regression modeling. Physicochemical analyses encompass pH, titratable acidity, viscosity, and syneresis, measured via standard AOAC methods, while texture and color are evaluated using instrumental rheometry and colorimetry. Sensory evaluation employs a structured hedonic and acceptance testing framework involving 100 consumer panelists, with data analyzed by descriptive statistics and non-parametric tests such as Kruskal-Wallis. Probiotic survivability during refrigerated storage (28 days) is monitored through plate counts on MRS agar, and in vivo efficacy is assessed in a randomized controlled trial involving 60 adult participants with low-grade digestive health issues, divided into probiotic and control groups. Gut microbiota composition is analyzed through 16S rRNA gene sequencing, and health markers like stool consistency and inflammatory markers are measured pre- and post-intervention. Anticipated findings include identifying probiotic strains with superior acid and bile tolerance, an optimized fermentation process yielding a high probiotic cell count (>10^8 CFU/mL), and a yogurt product with acceptable sensory qualities. It is expected that probiotic yogurt will demonstrate sustained viability during storage, improve gut microbiota diversity, and positively influence digestive health parameters. The study thus contributes novel insights into probiotic strain selection, formulation optimization, and functional efficacy within dairy matrices, expanding the current knowledge base on probiotic yogurt development and their health benefits. This research underscores the importance of integrating microbiological, sensory, and clinical assessments to develop functional foods that are both effective and consumer-friendly. The main conclusion suggests that carefully selected probiotic strains, combined with optimized fermentation and storage conditions, can produce a functional yogurt with significant health benefits. It recommends further longitudinal studies to confirm the long-term impacts of probiotic yogurt consumption on gut health and metabolic markers, and advocates for standardizing quality and efficacy parameters for probiotic dairy products based on the scientific findings.