Integrated Evaluation of the Fermentation Kinetics of Lactic Acid Bacteria in Tender Coconut Water Using Physicochemical Characterization and Mathematical Modelling.

Lactic acid bacteria (LAB) are widely used in food fermentation for their metabolic versatility and probiotic potential. Understanding their growth kinetics and metabolic behavior under controlled conditions is critical for process optimization. This study evaluated the fermentation performance and kinetic behavior of four LAB strains (Lact. paracasei CWKu14, Lact. rhamnosus CWKu-12, Lact. casei CWM15, and Lact. plantarum CWJ3) in tender coconut water (TCW) over 24 h. Changes in cell viability, pH, total soluble solids (TSS), sugar utilization, and organic acid production were monitored and analyzed using selected mathematical models. As cell density increased, all strains significantly reduced the pH and TSS of TCW. These changes were strain-specific; Lact. plantarum CWJ3 exhibited the highest cell viability (3.48 × 109 ± 0.18 × 109 CFU mL- 1) and the lowest final pH (4.11 ± 0.23). These strains preferentially consumed glucose and fructose over sucrose. Lact. plantarum CWJ3 and Lact. rhamnosus CWKu-12 showed higher monosaccharide utilization and lactic acid production rates. Lactic acid reached 7.11 ± 0.99-7.47 ± 1.08 mg mL- 1 after 24 h, whereas acetic acid remained low (≤ 0.18 mg mL- 1), indicating facultative heterofermentative metabolism with lactic acid dominance. The selected mathematical models fitted the experimental data well (R2 > 0.87). The Modified Logistic model best described microbial growth and sugar consumption, while the Modified Gompertz model best described acidification kinetics. Overall, Lact. plantarum CWJ3 and Lact. rhamnosus CWKu-12 showed superior fermentative efficiency, supporting their use as starter cultures, and indicating that mathematical modeling could be beneficial for strain selection in functional food development.