Acorns, beechnuts and hazelnuts
Nuts are the most energy-rich wild food in autumn. Hazelnuts can be eaten straight away, beechnuts should be roasted, and acorns must first be shelled, chopped and leached in water until they are no longer bitter. Mouldy and wormy nuts are thrown away. Caution: horse chestnut is poisonous – only sweet chestnut is edible.
- Collecting 1 hour, leaching acorns 1–3 days
Explained simply
In autumn there are little treasures lying everywhere in the woods: hazelnuts, beechnuts and acorns. Nuts are especially valuable because they have lots of fat – and fat gives the body lots of strength. A few nuts fill you up much more than a big pile of leaves.
Hazelnuts you can simply crack and eat. Beechnuts, the small triangular nuts of the beech, you had better roast, because many of them raw give you a tummy ache. Acorns are very bitter. You have to shell them, chop them small and soak them in water, changing the water, until they no longer taste bitter. That sometimes takes days.
And very important: chestnuts from the park are usually horse chestnuts – and they are poisonous! Only the sweet chestnut can be eaten. Its husk is like a hedgehog with lots of fine spines, and the nut has a little point on top. If you are not sure: do not eat it.
How it works
Nuts and seeds are supply packs for the seedling: they contain fat, starch and protein in a small space. That is why they have a much higher energy density than leaves, which consist mainly of water. Hazelnuts are especially rich in fat, acorns rather in starch. For emergency food, nuts are therefore the most valuable wild food in autumn.
Acorns contain lots of tannins. They taste bitter, make the mouth pucker and in larger amounts irritate stomach and gut. Tannins are water-soluble. The smaller the pieces, the larger the surface and the faster they dissolve. With cold leaching you change the water as soon as it turns brown; hot water speeds up the process but makes the flour bind less well.
Raw beechnuts are usually tolerated in small amounts; in larger amounts they can cause nausea, vomiting and stomach pain – in children sooner. Roasting makes them easier to digest, and the hard shell bursts more easily. Hazelnuts need no pre-treatment; roasting only improves the taste.
What really matters
Sorting is the most important step. Small holes in the shell show that a larva was inside – for example from the nut weevil or acorn weevil. Light, rattling or hollow nuts are empty or spoiled. A pot of water helps: what floats is usually hollow or wormy and is thrown away. Mould, dark spots or a musty smell mean: throw it away, because mould toxins are not destroyed by cooking.
Horse chestnut is the dangerous confusion. It stands in parks, avenues and beer gardens and is much more common than sweet chestnut. Differences: horse chestnut has large, palm-like divided leaves with five to seven leaflets, a thick green husk with a few strong spikes and usually a single, round, glossy brown nut with no point and a large pale patch. Sweet chestnut has single, long, narrow leaves with pointed teeth, a husk densely covered with fine, long spines and usually two to three nuts, flattened on one side, with a small point and a tuft.
For acorns you need patience and plenty of clean water. Plan one to three days for cold leaching and taste a small piece in between: only when it tastes mild and no longer puckering is it ready. Afterwards you dry and roast the pieces before grinding them into flour – damp flour goes mouldy quickly.
Safety: what to watch out for
Nut allergies are among the common and sometimes life-threatening food allergies. Anyone who is allergic eats no wild nuts. Many people with birch pollen allergy react to hazelnuts with tingling in the mouth. If the lips, tongue or throat swell, or breathing problems, a rash all over the body or dizziness start, that is an emergency: call 112 (in Austria also 144). Anyone who has been prescribed an emergency kit with an adrenaline auto-injector uses it according to medical instructions.
If horse chestnut poisoning is suspected, especially in children, call a poison information centre or the emergency number and bring remains. Typical are stomach and gut complaints such as nausea, vomiting and stomach pain. Do not induce vomiting.
Cracking with stones and cutting with a knife easily injure fingers. Put the nut on a firm, flat surface, hold it at the side with your fingertips and strike in a controlled way. Always score sweet chestnuts before roasting, otherwise they can burst in the heat.
When it makes sense – and when not
In autumn nuts are the best wild food in Central Europe: easy to find, easy to recognise, energy-rich and storable. Hazelnuts and roasted beechnuts are quickly ready to eat. Acorns are worthwhile mainly when you stay in one place for longer and have water, fire and time – on the move the effort is usually too great.
Yields vary greatly: in mast years beech and oak bear a great deal, in other years almost nothing. On top of that there are competitors such as squirrels, wild boar and birds. So never plan firmly on wild nuts. Take only a share, too; the nuts are winter food for many animals and seed for new trees.
Good to know
Acorns were used as a staple food in many parts of the world, and in hard times in Central Europe they were roasted as a coffee substitute. Leached acorn flour can be made into porridge and – mixed with grain flour – into flatbread, because acorn flour alone hardly holds together.
Dried hazelnuts and beechnuts keep a long time in their shells in a dry, airy place. They may only be packed airtight when really dry, otherwise they go mouldy. Acorn flour keeps only a few weeks because of its fat content; if it smells rancid, it is thrown away.
Step by step
Collect and sort
Pick up freshly fallen nuts from the ground. Sort out anything with holes (worm damage), mould, dark spots or no weight. A water test helps: nuts that float in a pot of water are usually hollow or wormy.
- 1
Collect and sort
Pick up freshly fallen nuts from the ground. Sort out anything with holes (worm damage), mould, dark spots or no weight. A water test helps: nuts that float in a pot of water are usually hollow or wormy.
- 2
Recognise and avoid horse chestnut
Check leaves, husk and nut: horse chestnut has palm-like leaves, a few thick spikes and round, shiny nuts with no point – poisonous. Sweet chestnut has single toothed leaves, densely fine-spined husks and nuts with a point and a tuft.
When in doubt every chestnut is a horse chestnut – do not eat it.
- 3
Crack hazelnuts
Hazelnuts are ripe when the shell is brown and they come out of the husk easily. Crack them between two stones and eat the kernel straight away or roast it briefly. Spit out kernels with dark spots or a bitter, musty taste.
- 4
Roast beechnuts
Free the small, three-sided beechnuts from their prickly husk, roast them in a pan or on a flat stone over the embers while stirring until the shell bursts and they smell nutty. Then peel. Eat only a few raw, give children none raw.
- 5
Shell and chop acorns
Cut acorns open or crack them with a stone, remove the shell and the thin brown inner skin. Throw away discoloured kernels. Chop the kernels coarsely or crush them between stones – the finer, the faster the leaching.
- 6
Leach out the tannins
Cold: put the chopped acorns in a cloth in clean water and change the water several times a day as soon as it turns brown – this takes one to three days. Hot: boil them in water, pour off the brown water, repeat with fresh hot water, often five to ten times.
- 7
Taste whether still bitter
Chew a small piece: if it still tastes bitter or makes your mouth pucker, keep leaching. Only when it tastes mild and slightly nutty is it ready.
- 8
Dry, roast, grind
Squeeze out the leached pieces, dry them in a thin layer and then roast them in the pan. Grind them into flour between stones. You can use acorn flour for porridge or – mixed with other flour – for flatbread. Store dry and airy.
Common mistakes
- Confusing horse chestnuts with sweet chestnuts
- Soaking acorns only briefly and eating them bitter
- Not sorting out wormy and mouldy nuts
- Eating many raw beechnuts
- Storing damp nuts airtight – they go mouldy
Quick view
Materials
Airy collecting bag or basket
Collect each species separately so nothing unknown gets mixed in
No plastic bags for long periods – greens sweat and spoil
Knife (fixed or locking blade)
Cut away from your body.
Rules on carrying knives differ by region – check local rules.
Metal pot (stainless steel, aluminium, titanium)
Hot – scalding risk.
Cotton cloth / T-shirt
For leaching and straining
Removes coarse particles only – no disinfection.
Lighter, matches or ferro rod
For boiling and roasting
Observe local fire bans.
Suitable for
- Autumn (September to November)
- Energy-rich emergency food with fat and starch
- Building a store: keeps long when dried
Not suitable for
- People with nut or tree pollen allergy
- Eating raw acorns
- Large amounts of raw beechnuts, especially for children
- Mouldy or discoloured nuts
Prerequisites
- Recognising oak, beech and hazel reliably
- Being able to tell horse chestnut from sweet chestnut
- Enough clean water for leaching
- No nut allergy
Safety
- Throw away mouldy, discoloured, musty-smelling or hollow nuts – mould toxins are not destroyed by cooking. Never eat acorns raw or bitter: the tannins irritate stomach and gut.
How it works
Nuts store fat and starch for the seedling – that is why they supply much more energy than greens. Acorns contain lots of water-soluble tannins that taste bitter and irritate the stomach. The finer you chop them, the faster the tannins dissolve in the water. Roasting makes beechnuts easier to digest.
Advantages
- Lots of energy from fat and starch
- Easily recognised trees
- Storable
Disadvantages
- Only in autumn
- Acorns need lots of water and time
- Allergy risk
- Large variation from year to year
Deep knowledge
Background
Acorns were a staple food in many cultures, and in hard times acorn flour was used in Central Europe too, to stretch flour or roasted as a coffee substitute. FM 3-05.70 describes acorns as edible after the bitter tannins have been removed by repeated soaking or boiling.
Beech and oak do not bear equally every year: in so-called mast years the ground is full of nuts, in other years you find hardly anything. The poisonous horse chestnut is much more common in parks and avenues than the sweet chestnut, which grows mainly in mild regions.
Variants
- Cooking sweet chestnuts
- Score reliably identified sweet chestnuts crosswise on the curved side and roast them or boil them for about 20 minutes, then peel. Unscored they can burst in the heat.
- Drying a store
- Store hazelnuts and beechnuts in their shells in an airy, dry place. Leached, well-dried acorn flour keeps for a few weeks in a sealed jar.
Common mistakes
- Confusing horse chestnuts with sweet chestnuts
- Soaking acorns only briefly and eating them bitter
- Not sorting out wormy and mouldy nuts
- Eating many raw beechnuts
- Storing damp nuts airtight – they go mouldy
Limits and risks
- No detailed nutrition figures
- Not a complete tree identification guide
Material alternatives
Derived from material properties: a substitute must have all relevant properties. Observe the notes on the substitute.
- Airy collecting bag or basket
- Metal pot (stainless steel, aluminium, titanium) (Hot – scalding risk.), Single-wall stainless steel bottle (Heat only single-wall bottles without paint/plastic; remove the lid before heating.), Double-wall insulated bottle (Never heat directly.), PET bottle (clear, max. 2 litres) (Do not heat or place in a fire.), Food-grade water container (Only use containers that never held chemicals or fuel.), Airtight food-grade storage container (Fill only when clean and completely dry; never use containers that previously held chemicals.), Collapsible water container or bag (Protect from sharp objects.), Measuring jug, Food-grade water bag (Use only for drinking water, never for chemicals or fuel.), Fermentation jar or crock (Use only food-grade containers of glass, food-safe glazed stoneware or food-grade plastic – no metal containers for acidic food.), Resealable food bags (Use only bags intended for food; do not use with boiling water unless the manufacturer explicitly allows it.), Rigid collecting container (box, basket or mug) (One species per container – never mix in anything unknown)
- Metal pot (stainless steel, aluminium, titanium)
- Single-wall stainless steel bottle (Heat only single-wall bottles without paint/plastic; remove the lid before heating.)
- Lighter, matches or ferro rod
- Ferro rod (Practise before you need it.), Fire striker and hard stone (Carbon steel, not stainless.), Bow drill set (bow, spindle, hearth board, bearing block) (Use only dry wood.), Burning lens / magnifier (Never leave lying in the sun – fire risk.), Fire piston (Maintain the seal.), Pump drill (spindle, flywheel, crossbar, cord) (Fix the flywheel firmly and centrally – a loose disc can fly off.)
Results come exclusively from structured entries. No improvised instructions are generated.
Sources
Headquarters, Department of the Army (USA) (2002): FM 3-05.70 Survival
Acorns: removing tannins by soaking or boiling; beechnut and hazelnut as food
Bundesinstitut für Risikobewertung (BfR) (2017): Risiko Pflanze – Einschätzung und Hinweise
Horse chestnut and other poisonous plants, poisoning risks
U.S. Food and Drug Administration (FDA) (2012): Bad Bug Book: Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins, 2nd edition
Natural toxins in food, mould toxins
Gesundheitsportal Österreich (gesundheit.gv.at), Bundesministerium für Soziales, Gesundheit, Pflege und Konsumentenschutz: Vergiftungsinformationszentrale (VIZ)
Poison emergency line in Austria