Foragers pack raw pollen pellets into comb cells, moisten them with nectar and glandular secretions, and pack it down tightly. Lactic-acid bacteria and yeasts already living in the hive then ferment the mix anaerobically over one to two weeks, producing bee bread (perga) — a more digestible, more nutritious, and far more shelf-stable food than raw pollen, thanks to a drop in pH and the breakdown of complex pollen-wall compounds.
Bee bread has roughly double the digestible protein of raw pollen for bees, because fermentation partly breaks down the tough, indigestible outer wall (exine) that protects each pollen grain.
Watch raw pollen packed into honeycomb cells ferment into bee bread: colour, acidity and lactic-acid bacteria all shift as days pass and hive temperature changes.
Fermentation rate depends on temperature; as effective ripening time increases, pH falls, lactic-acid bacteria multiply, and the pollen mass darkens from its raw plant colour toward deep amber-brown bee bread, eventually capped with honey.
Drag the days slider to advance ripening, change hive temperature to speed up or slow down fermentation, pick a pollen source to see its raw colour, and toggle honey capping. Watch the cutaway jar and comb cells respond live.
Because fermentation partly breaks down pollen's tough outer wall, bee bread is considerably more digestible and nutritious for bees than the raw pollen it was made from.