To make acorn flour, you will need to follow several steps to remove the tannins and process the acorns into a usable flour. Here's a general guide:
Gather and select acorns: Find mature acorns from oak trees. Look for ones that are plump, brown, and free from visible damage or insect infestations.
Shell and sort the acorns: Remove the shells from the acorns by cracking them open using a nutcracker or a hammer. Discard any acorns that have wormholes or mold. Sort through the shelled acorns to ensure their quality.
Leach the tannins: Acorns contain bitter tannins that need to be leached out before they can be used for flour. There are a few methods to do this:
Water leaching: Place the shelled acorns in a large pot or a container and cover them with water. Change the water every few hours for 1-2 days or until the acorns taste less bitter. Alternatively, you can boil the acorns for 15-20 minutes, discard the water, and repeat the process until they become less bitter.
Cold leaching: Place the shelled acorns in a mesh bag and submerge them in a flowing stream or in a container filled with cold water. Allow the water to flow or change it regularly for several days until the acorns taste less bitter.
Note: Tasting small pieces of acorn throughout the leaching process will help you determine when the bitterness has been sufficiently reduced.
Dry the acorns: After leaching, spread the acorns on a baking sheet or a clean surface to dry. You can dry them in the sun, use a food dehydrator, or set your oven to a low temperature (around 150°F or 65°C) and place the acorns inside for a few hours until they are completely dry. Ensure they are dry and crispy before proceeding to the next step.
Grind into flour: Once the acorns are dry, grind them into a fine powder using a food processor, blender, or a grain mill. You can also use a mortar and pestle, although it will require more effort and time.
Sift and store: After grinding, sift the flour to remove any larger pieces or coarse bits. Store the acorn flour in an airtight container in a cool, dry place. It can be used in various recipes as a substitute for regular flour.
Remember, the process of making acorn flour can be time-consuming, but it can be a rewarding and enjoyable experience. It's important to note that some acorn species may require additional or specific steps, so it's always a good idea to consult reliable sources or experienced foragers for guidance on acorn preparation and consumption.