Lab Technique · Entry 24 of 42
Dehydration (Gravimetric Moisture Analysis)
Slowly drying a sample to constant mass.
How it works in the lab
To measure moisture content, labs dry a weighed sample in an oven or desiccator, cool it in a sealed container, weigh it, and repeat until two successive weighings agree, the constant mass criterion that proves all removable water is gone. Weighing hot samples is avoided because convection currents make the balance read low, and desiccators prevent the dried sample from reabsorbing humidity from the air. The difference between initial and final mass, divided by the initial mass, is the moisture percentage.
Research Findings
The standard gravimetric method for determining a sample's moisture content.
Skills you gain in the lab and kitchen
- Drying a sample to constant mass
- Weighing only after cooling to avoid drift
- Storing dried samples away from humidity
- Calculating moisture percentage from mass change
- Being patient with low and slow drying
How it shows up in baking
Bakers dry meringues and fruit slices in a low oven until all the water is gone, and they know bread crumbs must be fully dried before grinding for crumbs or baking into toppings. Weighing ingredients after longProofing shows water lost to evaporation. The shared principle is that slow, complete drying followed by weighing gives a trustworthy measure of water content.
Recipes that demonstrate this technique
Each card shows exactly where the technique appears inside that recipe's method.