Optimization of Mangrove Glucomannan Addition to Improve Physicochemical Properties of Kefir

Kefir is widely recognized as a functional fermented dairy product. However, its physicochemical stability, particularly pH, acidity, and syneresis, remains a challenge during processing and storage. The addition of functional polysaccharides, such as mangrove-derived glucomannan, has been proposed to improve kefir quality. This study aimed to investigate the effect of mangrove-derived glucomannan on the physicochemical properties of kefir. A Completely Randomized Design with different concentrations of mangrove glucomannan (0, 2, 4, 6, and 8% (v/v)) was applied, with four replications. The results showed that increasing glucomannan had a significant effect (P < 0.05) on total bacteria, pH, and titratable acidity. Mangrove-derived glucomannan significantly enhanced total bacterial counts in goat milk kefir (p < 0.05), increasing from 6.09 Log CFU/mL in the control to 7.45-7.80 Log CFU/mL at 2-8% concentrations. The treatments decreased pH from 3.66 (0%) to 3.35 (8%) (P < 0.05), while titratable acidity increased from 0.70% (0%) to 0.83-0.85% in the treatment groups (P < 0.05), confirming enhanced fermentation activity. Syneresis decreased at 2% glucomannan (0.93%) but increased slightly at higher concentrations, reaching 1.03% at 8% (P > 0.05). These findings indicate that glucomannan modulates kefir fermentation, as reflected in lower pH and higher acidity values.