1 Principles
Why food spoils and how to stop it
A harvest arrives in a few weeks; you eat for twelve months. Preserving is what turns a summer garden into a year of food.
Bacteria, moulds and yeasts need water, warmth, a mild pH and time. Enzymes in the food itself also keep working. Every method removes one or more of these:
| Method | What it removes | Good for | Keeps | Fuel / effort |
|---|---|---|---|---|
| Cold storage | Warmth | Potatoes, roots, cabbage, apples, squash | 2–8 months | None, needs a cool place |
| Drying | Water | Fruit, beans, grain, herbs, mushrooms, lean meat, fish | 6–12 months+ | Sun or low heat |
| Salting, curing | Available water | Meat, fish, vegetables | Months | Lots of salt |
| Smoking | Water at the surface, adds antimicrobials | Fish, meat (after salting) | Weeks to months | Wood, attention |
| Fermenting | pH (lactic acid) | Cabbage, cucumbers, most vegetables | Months, cool | Salt only |
| Vinegar, sugar | pH, available water | Vegetables, fruit | 1 year+ | Vinegar or sugar, some heat |
| Canning | All microbes (heat) plus air (seal) | Almost everything, if done right | 1–2 years+ | Jars, lids, fuel, a pressure canner for low-acid food |
Preserve only sound, fresh food. Preserving slows spoilage, it never reverses it. Wash hands, tools and containers; cleanliness decides success more than any recipe.
2 Stores
Grain, beans and dry goods: keep them for years
Dry food lasts as long as it stays dry, cool, dark and sealed from insects and rodents.
Dry enough
Grain and beans below about 13 % moisture: a grain cracks between the teeth, a bean shatters under a hammer rather than squashing. Damp grain heats, moulds and can grow toxic moulds (aflatoxin).
Kill insects
Freeze for 3–4 days at −18 °C, or spread thinly in an oven at 60 °C for 30 minutes. Or seal airtight with oxygen absorbers or a layer of dry ice (CO₂) at the bottom, lid loose until it has evaporated.
Seal
Food-grade buckets with gasket lids, metal bins, glass jars, Mylar bags inside buckets. Rats chew through plastic bags and thin buckets; metal is safest.
Store cool and off the floor
On pallets or shelves, away from walls, in the coolest dry room. Every 10 °C cooler roughly doubles shelf life.
Rotate and inspect
Eat oldest first, check monthly for insects, mould smell, condensation, droppings.
| Food | Sealed, cool, dry | Note |
|---|---|---|
| Whole wheat, rye, maize, dry beans, lentils | 10–30 years | Old beans cook slowly; soak longer, add a pinch of baking soda. |
| White rice, pasta, rolled oats | 5–30 years | Brown rice only 6–12 months (its oil goes rancid). |
| White flour | 1–2 years | Wholemeal flour 3–6 months: store grain, grind as needed. |
| Salt, sugar, honey, spirits | Indefinite | Honey crystallises: warm gently. Never give honey to babies under 1 year (botulism). |
| Vegetable oil, nuts | 1–2 years | Rancid smell: discard. Keep dark and cool. |
| Commercial cans | 2–5 years+ | Discard bulging, leaking, deeply dented or rusted-through cans. |
3 Water out
Drying: the oldest method
Warm, dry, moving air does the work. Heat without airflow cooks the food; airflow without warmth takes too long and it moulds.
| Food | Prepare | Air temp | Done when |
|---|---|---|---|
| Herbs, tea leaves | Bunches hung upside down in shade | ≤ 35–40 °C | Crumbles |
| Apples, pears, plums, berries | Slice 5–8 mm, dip apples in lemon water or salt water (1 tsp per L) to stop browning | 55–60 °C | Leathery, no moisture when squeezed |
| Beans, peas, carrots, cabbage, greens | Blanch in boiling water 2–5 min, then cool; beans for storage just dry on the plant | 50–60 °C | Brittle, snaps |
| Mushrooms | Slice, do not wash (brush) | 40–50 °C | Crisp |
| Tomatoes | Halve, salt lightly | 55–60 °C | Leathery; in humid climates store under oil or freeze |
| Jerky (lean meat) | Trim all fat, slice 5 mm, salt or marinate, heat to 71 °C (poultry 74 °C) first | 60–70 °C | Bends and cracks, does not snap |
| Fish | Split, salt first (see salting); unsalted only in cold, dry, windy climates (stockfish) | Cool wind | Hard, stiff |
Pack dried fruit loosely in a jar for a week and shake daily. If drops of moisture appear on the glass, dry it longer. Then store airtight in the dark.
Drying at low temperature does not kill bacteria in meat. Heat it to 71 °C first (boil strips in the marinade 5 minutes, or bake), then dry. Fat goes rancid: trim it all. Wild game can carry parasites; see meat safety.
4 Salt
Salting and curing meat and fish
Salt draws water out and makes what is left too salty for most bacteria. Salt is worth stockpiling: 20–30 kg per household per year if you preserve with it.
Salt fish
Clean
Gut, remove the head, split flat along the backbone, scrape out the blood line. Work cold and fast.
Layer in salt
About 1 kg of coarse salt per 3 kg of fish. A layer of salt, fish skin down, salt, fish, finishing with salt, in a box with drain holes. Keep below 10 °C.
Wait
1–3 weeks depending on thickness, re-stacking every few days. The flesh becomes firm and translucent.
Air-dry
Brush off salt, dry in the shade in wind, bring in at night and in rain. Weeks. Hard, dry salt fish keeps a year or more.
To eat
Soak 24–48 hours in cold water, changing it 3–4 times, then cook.
Salt pork, bacon, ham
Traditionally done in the cold months, 2–5 °C. Rub every surface with salt (about 3–5 % of the meat's weight, plus curing salt if you have it), pack in a clean crock or bag, turn and rub daily. Rule of thumb: 1 week per 2.5 cm of thickness. Then rinse, dry, and hang in a cool, airy place or smoke. Barrel salt pork is packed in salt and covered with a strong brine; it keeps a year in a cool place and is soaked before cooking.
Sausages, whole hams and anything cured slowly without air can grow botulism. Nitrite curing salt prevents it. There are two very different kinds: concentrated "curing salt #1 / Prague powder" (used at about 2.5 g per kg of meat) and European "nitrite curing salt" (used as the entire salt, about 20–30 g per kg). Mixing them up is dangerous: nitrite overdose is poisonous. Weigh it, follow the packet exactly, keep it labelled and away from table salt. Without nitrite, stick to cold temperatures, plenty of salt, thin pieces and hot smoking or cooking.
5 Smoke
Smoking: hot or cold
Smoke dries the surface and coats it with antimicrobial compounds. Always salt or brine first.
Hot smoking · 60–90 °C
Cooks and smokes at once, a few hours. Fish until the flesh flakes and reaches 63 °C inside; meat and sausage 71 °C; poultry 74 °C. Keeps about a week cool, longer if very dry. Easiest: a barrel or metal box over a small fire.
Cold smoking · below 30 °C
Days to weeks of thin smoke, food does not cook. Only for well-salted, cured food (salt fish, bacon, ham). The fire is 3–5 m away, smoke travels through a buried pipe or trench and cools before reaching the smoke box. Keeps months.
Wood
Hardwoods: beech, oak, alder, apple, cherry, hickory, maple. Dry wood smouldering, not flaming. Never pine, spruce or other conifers (bitter, sooty), painted, treated or unknown wood.
Dissolve about 80–100 g salt per litre of water (a raw egg or potato should just float). Soak fillets 30 min to 2 hours depending on thickness, rinse, let the surface dry in a breeze until tacky (1 hour), then smoke.
6 Acid
Fermenting: sauerkraut and friends
Lactic acid bacteria already on the vegetables turn sugars into acid. Salt keeps rot bacteria out while they work. No heat, no fuel, and fermented food keeps vitamin C through winter.
Sauerkraut
- Remove outer leaves (keep two clean ones) and the core. Shred the cabbage 2–3 mm thin. Weigh it.
- Add 20 g of salt per kg of cabbage (1.5–2.5 %). Non-iodised salt ferments best, but any plain salt works.
- Squeeze and knead with clean hands until the cabbage is limp and a puddle of juice forms.
- Pack into a crock or jar a handful at a time, pressing hard until juice covers it. Lay the kept leaves on top, then a weight (a water-filled bag or jar). Everything must stay under brine; top up with 2 % brine (20 g salt per litre) if needed.
- Cover loosely (gas must escape) at 18–22 °C. Bubbles for 1–2 weeks; taste from week 1. When sour enough, move to below 10 °C: keeps 6 months or more.
| Vegetable | Method | Salt |
|---|---|---|
| Cabbage, kale, turnip, kohlrabi | Shredded, own juice | 2 % of weight |
| Cucumbers (small, firm) | Whole in brine with dill, garlic, a grape or oak leaf for crunch | 35–50 g per L water |
| Carrots, beans, beetroot, cauliflower, peppers | Chunks in brine | 20–30 g per L water |
| Beetroot kvass, turnip | Chunks in brine, drink the liquid | 20 g per L water |
- A flat white film on the surface (kahm yeast) is harmless: skim it off.
- Fuzzy mould (blue, green, black, pink), slimy or mushy vegetables, or a rotten, putrid smell: discard all of it. Sour is normal, rotten is not.
- Vegetables above the brine are what spoil. Keep them submerged.
7 Acid and sugar
Vinegar pickles, jam, syrup
Quick and reliable, as long as you stick to the ratios.
Vinegar pickles
Vinegar with at least 5 % acidity. Never more water than vinegar (1:1 at most). Pour boiling over packed vegetables and seal. For shelf storage, water-bath them for 10–15 minutes; otherwise keep cool and eat within months. Make vinegar yourself from apple juice or wine left open with a "mother" for 1–3 months; homemade strength is unknown, so use it for fridge pickles only.
Jam
About equal weights of fruit and sugar, boiled hard until it sets: a drop on a cold plate wrinkles when pushed. Sugar above 60 % stops microbes. Pour into hot clean jars, seal, water-bath 10 minutes. Low-sugar jam must be kept cold.
Fruit in syrup, juice
Fruit is naturally acidic, so it can be water-bath canned. Juice: heat to 80–85 °C, fill hot bottles, seal; or ferment into cider and wine, which keep longer and trade well.
Honey
Never spoils if kept sealed (it absorbs water from the air). Preserves fruit covered in it. See bees.
8 Heat and seal
Canning: safely, or not at all
Jars are heated to kill microbes, then seal as they cool. The acidity of the food decides which method is safe.
Water-bath canning (high-acid food)
Prepare
Canning jars without chips, new flat lids (or glass lids with new rubber rings). Wash in hot soapy water, keep jars hot.
Fill
Leave headspace: 6 mm for jam, 12 mm for fruit, tomatoes and pickles. Run a clean knife inside to release air bubbles. Wipe the rims.
Close
Lid on, band finger-tight only (air must escape).
Boil
Jars on a rack or folded cloth in a deep pot, covered by 2.5 cm of water. Start timing when it reaches a full rolling boil. Add 5 minutes above 300 m altitude, 10 above 1,000 m.
Cool and check
Lift out, leave 12–24 hours without touching. The lid must be sucked down and not flex when pressed. Unsealed jars: refrigerate and eat soon, or reprocess within 24 hours.
Pressure canning (low-acid food)
Pressure canner (not a pressure cooker: too small, gauge unreliable). Put 5–8 cm of water in, jars on the rack, lid locked. Vent steam for a full 10 minutes, then close the vent. Time from when pressure is reached: 10 psi (69 kPa) weighted gauge up to 300 m altitude, 15 psi above. Keep the pressure steady; if it drops below, restart the time. When done, turn off heat and let it depressurise on its own, then wait 10 minutes before opening.
| Food (tested times) | Method | 0.5 L jar | 1 L jar |
|---|---|---|---|
| Jam, jelly | Water bath | 10 min | - |
| Applesauce | Water bath | 15 min | 20 min |
| Crushed tomatoes + 1 tbsp lemon juice per 0.5 L | Water bath | 35 min | 45 min |
| Green beans | Pressure | 20 min | 25 min |
| Carrots | Pressure | 25 min | 30 min |
| Potatoes, cubed | Pressure | 35 min | 40 min |
| Dry beans (soaked, boiled 30 min), meat, chicken | Pressure | 75 min | 90 min |
- Never water-bath or oven-can vegetables, beans, meat, fish or soup. No exceptions for "grandma's recipe".
- Use tested times only (USDA Complete Guide to Home Canning, Ball, national food agencies; keep one on paper). Do not can thick purées (pumpkin), flour-thickened sauces or fat-rich mixtures: heat does not penetrate reliably.
- Discard without tasting: bulging or unsealed lids, liquid spurting out, foam, cloudy liquid, off smell. Botulism can also show no signs at all.
- As an extra safety step, boil home-canned low-acid food for 10 minutes before eating.
- Symptoms 12–72 hours after eating: double or blurred vision, drooping eyelids, slurred speech, trouble swallowing, weakness spreading downward, difficulty breathing. Life-threatening: needs antitoxin and breathing support. See Medical.
9 Cold
Root cellar and clamp
The ground a metre or two down stays near 8–10 °C all year; in winter a cellar with a cold-air vent drops to 0–5 °C. Most roots keep for months with no fuel at all.
| Crop | Temp | Humidity | How | Keeps |
|---|---|---|---|---|
| Potatoes | 4–7 °C | High (90 %) | Dark, in sacks or crates. Below 4 °C they turn sweet, light turns them green. | 5–8 months |
| Carrots, beetroot, parsnips, swede, celeriac | 0–4 °C | Very high (95 %) | Tops cut to 1 cm, unwashed, in boxes of damp sand or sawdust. | 4–6 months |
| Cabbage | 0–2 °C | Very high | Hang by the root or wrap in paper. Smells: best in a separate space. | 3–4 months |
| Apples, pears | 0–4 °C | High | Unbruised, wrapped singly in paper. Away from vegetables: their ethylene gas sprouts potatoes and makes carrots bitter. | 2–6 months |
| Onions, garlic | 0–10 °C | Dry (60–70 %) | Cured dry skins, in nets or braids. Not in the damp cellar: an attic or cold room. | 6–9 months |
| Squash, pumpkin | 10–15 °C | Dry | Cured, stem on, not touching. A cool bedroom or under a bed. | 3–6 months+ |
No cellar? Build a clamp
Site
Well-drained spot, dig a shallow ditch around it to shed water.
Base
A 15 cm layer of straw on the ground (or on a mesh sheet against rodents).
Pile
Dry, unwashed, undamaged roots or potatoes in a cone or ridge up to about 1 m high.
Cover
20 cm of straw, then 15–20 cm of soil, patted smooth. Leave a tuft of straw sticking out at the top every 1–2 m as a chimney for moisture.
Use
Open from one end on a mild day, take what you need for a week or two, close it again carefully.
A barrel or dead chest freezer buried to the lid in the ground and covered with straw bales; an unheated garage, stairwell or north-facing shed; a pit lined with straw. Protect every store from mice and rats with metal mesh, and check it every week for rot: one bad apple really does spoil the rest.
10 More
Eggs, fat and pemmican
Water-glassed eggs
Clean, unwashed fresh eggs (the natural coating seals the shell), no cracks. Stir about 30 g of hydrated lime (calcium hydroxide, "builder's lime") into 1 L of water. Submerge eggs pointy end down in a crock, cover, keep cool and dark. Keeps 8–12 months. Rinse before use and crack each one into a separate cup first.
Rendered fat
Cut pork or beef fat small, melt slowly with a little water over low heat for hours, strain through cloth into clean jars. Lard and tallow keep months cool and dark, a year or more cold. Cooked meat buried completely in fat (confit) keeps weeks in a cold cellar.
Pemmican
Lean meat dried until brittle, pounded to powder, mixed with an equal weight of hot rendered fat (optionally dried berries), pressed into cakes. Complete, compact, keeps many months to years if kept cool.