Measuring ingredients that absorb liquid, like flour, is typically done *before* mixing with liquids. While absorption does change the volume and weight of the ingredient *after* mixing, recipes account for this by specifying measurements at particular stages of preparation.
Recipes are designed with specific instructions for when to measure ingredients. For dry ingredients like flour, oats, or couscous, the measurement is taken in their dry, unmixed state. When these ingredients are combined with liquids, they naturally absorb some of that liquid, causing them to swell and increase in volume and weight. This absorption is a chemical process that alters the ingredient's properties, which is often the desired effect in the recipe.The recipe instructions will then guide you through the mixing process, often specifying the desired consistency or texture of the mixture. This allows you to visually assess the mixture and make minor adjustments if needed, rather than relying solely on the initial dry measurement. For example, a bread recipe might say to add more flour 'if the dough is too sticky.' This accounts for variations in flour type, humidity, and other factors that can affect absorption. The initial measurement provides a starting point, and the mixing instructions guide you to the final desired result.
When baking, use the 'spoon and level' method for measuring flour. Instead of scooping directly from the bag, which can compact the flour, gently spoon it into the measuring cup and then level off the top with a straight edge. This ensures a more accurate and consistent measurement, leading to better baking results.