Titratable acidity and pH are important chemical traits for organoleptic quality of banana since they are related to sourness and sweetness. Banana fruit has the particularity of being ripened out of the plant after harvest and during postharvest maturation titratable acidity and pH of the pulp continue to change until consumption. A modeling approach was used to understand the mechanisms involved in changes in titratable acidity and pH of the pulp during maturation. Changes in pH were modeled by solving a set of equations representing acid/base reactions. Changes in titratable acidity were modeled by taking organic acid content (citrate, malate, oxalate, and phosphate) and mineral content (potassium, magnesium, chlorine) into account. The two models were built using data from three dessert banana cultivars with contrasting acidity. For each model, calculated values were compared to observed values. Sensitivity analysis was used to study the influence of the model parameters on pH and titratable acidity. These models allowed fairly good predictions of pH and titratable acidity, and shed some light on the determinants of acidity changes during banana maturation.