Impact of fermentation time on sensory and nutritional quality of plant-based yogurts in local markets

Thesis Abstract

The rapid rise of plant-based dairy alternatives has intensified interest in how fermentation time affects both sensory acceptance and nutritional quality of plant-based yogurts in local markets, where consumer preferences and product labeling influence purchase decisions and public health outcomes. This study aims to determine how varied fermentation times influence sensory attributes (texture, aroma, flavor, mouthfeel, and overall liking) and nutritional profiles (protein and mineral bioavailability, carbohydrate and fat composition, and probiotic viability) of plant-based yogurts derived from almond, soy, and oat bases. Specifically, the objectives are to (i) quantify sensory differences across fermentation intervals (8, 12, 16, and 20 hours) using a trained panel and consumer acceptance testing (n = 120 per base), (ii) assess changes in macro- and micronutrient components and probiotic counts (lactic acid bacteria) with high-performance liquid chromatography (HPLC), gas chromatography–mass spectrometry (GC-MS), and plate counting, (iii) model relationships between fermentation time and sensory/nutritional outcomes via multivariate analysis (ANOVA/MANOVA, partial least squares regression), and (iv) identify consumer segments in local markets with distinct preferences using cluster analysis. A mixed-methods design combines quantitative sensory evaluation (n = 360 participants total for three bases across four fermentation times) and quantitative nutritional assays (n = 12 batches per base, analyzed in triplicate) with qualitative notes from panelists to contextualize sensory impressions. The research will be conducted in three phases product manufacture under standardized conditions with controlled starter cultures (Lactobacillus spp. and Streptococcus spp. as applicable), proximate and micronutrient analyses, and consumer testing in local retail environments to reflect real-world exposure. The study will employ a sensory methodology aligned with ISO 8586 and a nutritional protocol consistent with AOAC methods, complemented by probiotic viability assessments using colony-forming unit counts and 16S rRNA sequencing for identity confirmation. The theoretical framework integrates the Food Matrix Interaction Theory and the Theory of Planned Behavior to interpret how fermentation-driven matrix changes influence perceived quality and purchase intentions. Anticipated findings include a non-linear optimization of fermentation time where intermediate durations maximize sensory acceptance while preserving or enhancing critical nutrients and probiotic viability, with base-dependent trade-offs identified (e.g., almond-based yogurts showing greater textural improvement with longer fermentation but modest relative nutrient gains). The study is expected to contribute to knowledge by quantifying the precise fermentation-time–quality relationship across multiple plant bases, informing producers about optimal fermentation windows for market-specific sensory targets and nutritional claims, and offering evidence to guide regulatory labeling and health communication. The conclusions are likely to recommend fermentation windows that balance consumer satisfaction with nutritional quality, propose standardized production guidelines for local-market scalability, and suggest marketing strategies tailored to consumer segments uncovered in the local market survey. Policy-relevant recommendations will address labeling clarity for fermentation time and probiotic content, while methodological contributions will include a robust, replicable framework for evaluating fermentation kinetics and quality outcomes in plant-based dairy analogs.