<p>Water content represents a critical quality parameter in all food products, yet its precise quantification remains challenging due to the potential loss of volatile compounds during heating and the risk of sample degradation or chemical transformation. Among various analytical techniques, Karl Fischer (KF) titration is one of the most widely accepted methods owing to its high specificity toward water based on a well-established redox reaction. Nevertheless, even KF titration may produce biased results in complex food matrices containing both carbohydrates and proteins. In such systems, the Maillard reaction—a non-enzymatic reaction between reducing sugars and amino groups—can occur upon heating. This reaction not only generates solid brown reaction products that may hinder water release but also produces water as a byproduct during its initial stages. Consequently, distinguishing between inherent moisture and water formed during heating becomes challenging. In this study, vaporization–coulometric Karl Fischer titration (vap-C-KF) was employed and compared with the conventional oven-drying method. Model systems were prepared by mixing maltodextrin and whey proteins in various ratios (1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1; w/w). A total of 330 measurements were performed, with each mixture analyzed in five replicates at five different temperatures: 125 °C, 145 °C, 155 °C, 165 °C, and 185 °C. The results were evaluated using descriptive statistics (maximum, minimum, median), standard deviation (SD), relative standard deviation (RSD),&#xa0;<i>F</i>-test, and ANOVA. Deviations from the optimal temperature significantly affected both the measured water content and extraction time. Furthermore, depending on the protein-to-maltodextrin ratio, it was estimated that between 0.34% and 0.80% of the total measured water content originated from the Maillard reaction.</p>