There are numerous ways to produce acorn flour, but the easiest and beginner-friendly method is cold-leaching.
Leaching is the process of extracting something. This something in this instance is tannin, found in all acorns. Although the amount of tannins in each acorn varies, red oaks generally have more tannins than white oaks. This year I decided to forage for acorns to make flour and I’d like the share the methods I took in order to make this delicious ingredient.
Table of Contents
But first, let’s address what you might be thinking – why would I bother making acorn flour? I’ll give you 3 reasons:
- Flavor
- Nutrition
- It’s free
Flavor
Before you dismiss the idea of making acorn flour, consider the flavor it adds to your dishes.
Acorn flour imparts a unique, nutty essence that sets it apart from conventional flours. The complex, earthy undertones bring a distinctive character to dishes, whether you’re baking bread, crafting pancakes, or experimenting with savory recipes. It also has a hint of sweetness, which lends itself to sweets and pastries as well.
Nutrition
Acorn flour isn’t just about flavor; it’s also nutrient dense with protein, fiber, and healthy fats. Acorn flour provides a wholesome alternative to traditional flours like wheat as it is also gluten-free.
All acorns are rich in vital nutrients, even though the precise nutrient profile varies depending on the species.
In a 1-ounce (28-gram) serving of dried acorns, you’ll find the following nutrient composition (1,2,3):
| Nutrient | Amount per 1 oz (28g) | % of Reference Daily Intake (RDI) |
|---|---|---|
| Calories | 144 | – |
| Protein | 2g | – |
| Fat | 9g | – |
| Carbohydrates | 15g | – |
| Fiber | 4g | – |
| Vitamin A | – | 44% of RDI |
| Vitamin E | – | 20% of RDI |
| Iron | – | 19% of RDI |
| Manganese | – | 19% of RDI |
| Potassium | – | 12% of RDI |
| Vitamin B6 | – | 10% of RDI |
| Folate | – | 8% of RDI |
It’s Free
Perhaps the most compelling reason to make acorn flour is that it’s essentially free. The oak trees scattered across California generously offer acorns during their mast events in the fall, inviting foragers to partake in a sustainable and cost-effective source of food.
Instead of relying solely on store-bought flours, consider the satisfaction of harvesting your own ingredients directly from nature.
By engaging in the foraging process and transforming raw acorns into flour, you not only access a unique culinary resource but also cultivate a deeper connection with the natural world. It’s a practice that aligns with sustainable living principles and introduces a sense of self-sufficiency into your kitchen.
But without wasting anytime, let’s get into it!
Prepping The Acorns
When foraging for acorns, keep in mind that not all nuts are created equal. Follow these guidelines to select prime acorns for your flour:
Inspect for Larvae & Rotten Acorns: Avoid acorns with tiny holes or signs of insect damage, as these may house oak moth larvae. A healthy acorn should be firm, without any signs of mold or rot. If the acorn inside is black, throw it out.
Color Matters: Choose acorns with vibrant, consistent coloration.
Dry Out Acorns: You should dry acorns as soon as you collect them. If you plan on storing your acorns for long-term storage, dry them out either in the sun with good air flow or with a dehydrator at the lowest setting. Removing the moisture in the acorns preserves them for longer and reduces the risk of spoilage. This step will take several days to weeks depending on which method you use.
The Cold Leach Method
Leaching is a crucial step in removing bitter tannins from acorns, rendering them palatable. Here’s how to go about it:
Crack and Collect: Shell the acorns, removing the nutmeat and papery skin layer; I like to use a meat mallet.
I like to keep my fresh acorn meat submerged in water to prevent it from oxidizing and turning brown.
Blend: Pour the acorn meat into a blender or vitamix with water and blend on high. It shouldn’t take long until the acorns are pulverized into tiny, grainy pieces.
The white layer in the middle is the starch that separates during the process which is normal.
Cold Soak: Place the acorn slush in a container (glass preferred) and immerse them in cold water. Change the water daily for several days until the bitterness is reduced. This batch of Cast Live Oak acorns was ready in about 5 days.
This is where you have to go by taste. Different acorns have different levels of tannins.
Taste a small piece of the acorn meat to ensure it’s not bitter. It be should taste slightly nutty.
Drying Out the Acorn Flour
Straining the Liquid: Squeeze the cloth around the flour as tightly as possible to extract as much water as possible. I used a low-quality cheesecloth from my local department shop and wished I had used a higher-quality one instead.
This pro tip comes from Chef Hank Shaw:
Let the water in the bowl settle for 1 hour. Carefully pour off the water and you will see a layer of what looks like beige house paint or melted coffee ice cream. This is acorn starch and fat. Use a spatula to scrape it into the container you are drying your acorns in.
Hank Shaw, Hunter Angler Gardener Cook
This is what the result is from the straining. You’ll begin to feel the texture of the flour now. However, there’s still liquid in it so we need to dry it out completely. No moisture. Unless you want to use the flour right away, then this step is not needed.
Dry Thoroughly: Once strained, spread the acorn pieces on a baking sheet to dry completely.
You can either use a dehydrator at the lowest setting (95 F), or if you live in a sunny area, you can sun-dry them.
You could technically use the oven at the lowest setting; my oven’s lowest was at 170 F. I do not recommend this method as this will roast the flour, and you would want this to be as clean as possible. The next time I make acorn flour, I’m skipping the oven and instead will sun dry them completely. Lesson learned.
Sift and Store: Sift the flour to remove any remaining coarse particles. You can grind whatever remains from sifting with a blender or spice/coffee grinder.
Store your acorn flour in an airtight container. If you want to store it longer-term, place the flour in the fridge or freezer for later use.
I store mine in quart Mason jars in the fridge or freezer. Stored this way, the flour will last for several years — which is good, because oaks don’t drop huge amounts of acorns every year.
Hank Shaw
Well there you have it! All homemade acorn flour. You may think to yourself that this is a ton of work – and in a way it is. Most of this process is a waiting game with a little leg work. But I promise you it’s all worth it once you taste the incredible meals you can make with this one ingredient. I hope this inspired you to go out and connect with your nearby ecosystems.
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