Densitometry

Densitometry is the technique for measuring optical density, extended in food laboratories to material density as well. Analysts use it to quantify compounds separated on chromatography plates, to check the opacity of packaging films, and to infer composition from X-ray images. Brewers and dairy chemists track fermentation progress and milk solids through density readings. Its strength is rapid, non-destructive quantification, provided instruments stay calibrated and samples are prepared consistently, making it a workhorse of routine quality control. Modern imaging densitometers automate what was once a tedious manual comparison of band intensities.