Effects of Starter Concentration and Fermentation Time on Microbiological, Physicochemical, Nutritional, and Sensory...

The development of plant-based yogurt alternatives continues to expand in response to lactose intolerance, sustainability concerns, and demand for nondairy fermented products. Young coconut drink, derived from a mixture of coconut water and young coconut flesh, has been reported to contain fermentable sugars, minerals, and bioactive compounds that support microbial growth, suggesting its potential as a fermentation substrate. However, its fermentation characteristics remain underexplored. This study evaluated the effects of starter culture concentration (0.8% and 1%) and fermentation time (8 and 10 h) on the microbiological, physicochemical, nutritional, mineral, and sensory properties of young coconut drink-based yogurt. Yogurt was produced using Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus at 45°C. All formulations achieved lactic acid bacteria viability above 10⁷ CFU/g, indicating adequate LAB viability after fermentation. Starter concentration significantly influenced acidification, viscosity, proximate composition, carbohydrate utilization, and sensory acceptability, whereas fermentation time exerted a secondary effect. The formulation containing 1% starter fermented for 10 h exhibited the most balanced profile, combining desirable texture, acidity, and overall acceptability. This selected formulation showed a fatty acid profile dominated by medium-chain fatty acids, particularly lauric acid, a diverse amino acid profile characteristics of the plant-based matrix, and high mineral bioaccessibility (> 90%) for potassium, magnesium, and iron as determined by an in vitro gastrointestinal digestion model. Overall, young coconut drink-based yogurt demonstrates potential as a plant-based fermented beverage derived from locally available resources. However, further studies are required to enhance its nutritional profile and sensory characteristics.