<![CDATA[This study aims to determine the optimal growth model for xylose fermentation using Debaryomyces hansenii with a substrate derived from oil palm empty fruit bunch (OPEFB) hydrolysate. An unstructured model was developed by observing the dynamics of Debaryomyces hansenii as biomass, xylose as the substrate, and xylitol as the product, utilizing both growth-associated and non-growth-associated product formation approaches. Four kinetic models for the specific growth rate (Aiba, Blackman, Monod, and Moser) were evaluated to fit the experimental data. The fitting process was performed by minimizing the Root Mean Square Error (RMSE) and validated using the coefficient of determination (R2) and the Normalized Root Mean Square Error (NRMSE). The evaluation results indicate that xylitol production by \textit{Debaryomyces hansenii} is predominantly decoupled from active cell growth and occurs primarily during the stationary phase. The Moser model proved to be the best-fitting model, exhibiting the lowest RMSE value (0.1789) and high predictive accuracy (R2 for biomass = 0.96; xylitol = 0.89). Parameter perturbation-based sensitivity analysis demonstrated that a 50\% increase in the maximum specific growth rate ($\mu_{max}$) and the ratio between the yield coefficients for xylitol production and biomass formation from the substrate (Y2) could double xylitol production by the end of fermentation, whereas a 50\% decrease in the maintenance coefficient (m) could increase the product concentration by more than two-fold.]]>
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