Do All Acorns Contain High Levels of Tannins?

Tannin Levels in Acorns

Tannins in acorns come from the bark and skin of the acorn shell. White oak acorns (Quercus alba) typically contain 0.5-1.5% tannins, while red oak acorns (Quercus rubra) can contain 1.5-3.5% tannins. The level of tannins also decreases with ripeness, with green acorns having higher tannin levels than mature acorns.

Processing Acorns for Food

To remove tannins from acorns, a leaching process is required. The simplest method is to boil the acorns in water, changing the water multiple times to remove the tannins. A more effective method involves soaking the acorns in a bucket of water for several hours, changing the water every 2-3 hours, and then rinsing and boiling them. This process can reduce tannin levels to around 0.1-0.5%. Another method involves using a combination of water and ash to leach tannins, but this method requires caution as excessive ash can be toxic.