Bee bread is an important source of food for the bees and supplies the brood. Pollen that is not immediately consumed is mixed by the bees with saliva, honey, glandular secretions and enzymes contained therein and then stored in the honeycomb cells. This process of fermentation preserves the pollen and changes its composition.

To protect the stored supplies from fungi and bacteria, the bees also cover the honeycomb cells with a thin layer of propolis.