Pickling and Fermenting
Cooking Skills: Vegetables 2
Chapter 6 · Pickling and Fermenting
Skill goal
Pickle vegetables in vinegar and ferment cabbage safely, and know the signs of a good and a bad ferment.
Shopping list for this chapter
The basics
Pickling and fermenting both keep vegetables for longer and give them a sharp, tangy flavour, but they work in different ways. Pickling uses acid (vinegar) and the fridge. Fermenting uses salt and time to let friendly bacteria make their own acid. The first is quick and safe for beginners. The second is slower and needs careful rules.
Pickling or fermenting?
| Vinegar pickle | Ferment (sauerkraut) | |
|---|---|---|
| Where the sourness comes from | The vinegar you add | Bacteria turning the vegetable's sugars into lactic acid |
| Time | An hour to a day | One to two weeks or more |
| Salt | A little, for flavour | Measured by weight (about 2%), essential for safety |
| Keeping | Fridge, about 1 week | Fridge for some weeks after fermenting (taste and smell tell you) |
| Risk level | Low if cleaned and refrigerated | Higher: needs measuring, submerging, and knowing when to discard |
| Flavour | Sharp, bright, crisp | Complex, tangy, softer |
Vinegar pickles
- The brine: roughly equal parts vinegar and water, plus a spoon of sugar and a teaspoon of salt per 300 ml. Stronger vinegar makes a sharper, longer-lasting pickle.
- Cut thin so the brine reaches the middle quickly. Dense vegetables (carrot, cauliflower) can be blanched briefly first.
- Pack tightly and cover completely with brine.
- Add flavour: mustard seeds, peppercorns, garlic, dill, chilli, bay.
- Keep cold. These are refrigerator pickles, not shelf-stable preserves.
Fermenting
- Weigh the salt: about 2% of the weight of the vegetables. Too little and unwelcome microbes can grow; too much and the ferment stalls.
- Keep it under the brine. Anything above the surface can grow mould.
- Leave room for gas and don't seal tightly.
- Keep it cool and out of the sun, at about 18 to 21°C. Warmer is faster, but less predictable.
- Taste after a week. It should smell pleasantly sour, like a fresh pickle. It is done when you like it.
- Know when to bin it: fuzzy or coloured mould, a rotten smell or a slimy texture. When in doubt, throw it out.
Try it
Level 1 · Start here
Refrigerator pickled vegetables
The easiest pickle: raw vegetables in a hot brine. It is ready in an hour and improves over a day or two.
Ingredients (4 portions)
- 200 g mixed vegetables (carrot, cucumber, radish, cauliflower, green beans), cut thin
- 150 ml white wine or cider vinegar
- 150 ml water
- 1 tbsp sugar
- 1 tsp salt
- 1 tsp mustard seeds or peppercorns
- 1 garlic clove, sliced (optional)
- Wash the vegetables and cut into thin sticks, slices or small florets so they pickle quickly. Pack them tightly into a clean jar with the spices and garlic.
- Heat the vinegar, water, sugar and salt in a small pan until the sugar and salt dissolve. Pour the hot brine over the vegetables, covering them completely.
- Cool to room temperature, then close the jar and refrigerate. Eat after 1 hour, though they taste better after a day.
- Keep in the fridge and eat within about 1 week.
Jars and keeping
Clean jars: wash jars, lids and utensils in hot soapy water and rinse well; for vinegar pickles you can also run them through a dishwasher hot cycle. Use non-reactive containers (glass or food-grade plastic or ceramic), because acid and salt corrode some metals.Quick pickles are not preserved: keep them in the fridge in a covered jar and eat within about 1 week. They are safe because of the acid and the cold, not because they have been canned. Don't leave them on the worktop for days.
Level 1 · Practice
Quick pickled red onions
Pink pickled onions lift tacos, salads, curries and sandwiches. The acid turns them a bright magenta in minutes.
Ingredients (6 portions)
- 2 red onions, thinly sliced
- 100 ml red wine vinegar or cider vinegar
- 100 ml water
- 1 tbsp sugar
- 1 tsp salt
- 1 bay leaf (optional)
- Pack the onion slices into a clean jar.
- Warm the vinegar, water, sugar and salt until dissolved. Pour over the onions so they are submerged.
- Leave for 30 minutes at room temperature, then refrigerate. They are good within the hour and best after a day.
Keeping
Quick pickles are not preserved: keep them in the fridge in a covered jar and eat within about 1 week. They are safe because of the acid and the cold, not because they have been canned. Don't leave them on the worktop for days.
Level 2 · Quick slaw
Kimchi-style slaw (quick, not fermented)
Real kimchi is fermented for days and usually contains fish sauce. This is a quick vegetarian version with the same flavours, no fermenting and no fish.
Ingredients (4 portions)
- ½ Chinese leaf or white cabbage, shredded
- 1 carrot, in matchsticks
- 3 spring onions, sliced
- 1 tbsp salt
- 1 tbsp grated fresh ginger
- 2 garlic cloves, grated
- 1 tbsp chilli flakes (gochugaru, if you can find it)
- 1 tbsp soy sauce
- 1 tsp sugar
- 1 tbsp rice vinegar
- Toss the cabbage with the salt and leave for 30 minutes. It will release a lot of water. Rinse briefly, then squeeze it dry.
- Mix the ginger, garlic, chilli flakes, soy sauce, sugar and rice vinegar into a paste.
- Mix the paste with the cabbage, carrot and spring onions (wear gloves for the chilli).
- Leave for at least 1 hour, then keep in the fridge in a covered container and eat within 3 days.
A real ferment later
Once the sauerkraut method below makes sense, you can ferment kimchi: that needs more careful safety rules than this recipe.
Level 3 · First ferment
Sauerkraut
Cabbage, salt and time. The salt draws out water to make a brine, and the good bacteria already on the cabbage turn it sour. Weigh the cabbage and the salt: guessing is how ferments go wrong.
Ingredients (10 portions)
- 800 g small white cabbage (about 800 g after removing the outer leaves and core)
- 16 g salt (about 2% of the cabbage weight)
- 1 tsp caraway seeds (optional)
- Remove the outer leaves and the core. Shred the cabbage finely, weigh it, and weigh out 2% of its weight in salt (800 g of cabbage needs 16 g).
- In a large bowl, massage the salt into the cabbage for 5 to 10 minutes, until it goes limp and releases a lot of liquid. Mix in the caraway.
- Pack the cabbage firmly into a clean jar, pressing down so the brine rises over the cabbage. Leave a gap of 3 to 4 cm at the top. Put a weight on top (a small clean jar filled with water, or a fermenting weight) so that everything stays under the brine.
- Cover loosely and leave at 18 to 21°C, out of the sun, for 1 to 2 weeks. Press it down daily and taste after a week. When it is tangy enough, close the lid and keep it in the fridge.
Fermenting
Fermenting safety: the guidance I found (mostly from US university extension services and fermenting guides, not from the UK Food Standards Agency) is consistent on these points. Use about 2% salt by weight (a range of 1.5% to 3% is quoted), weigh the salt, and keep every piece of vegetable under the brine, especially in the first 7 to 10 days, because surface mould grows where vegetables touch the air. Ferment at about 18 to 21°C. Throw the whole batch away if you see fuzzy or coloured mould, or if it smells rotten or feels slimy. Don't taste anything you are unsure of. A sour, tangy smell and bubbles are normal. If anyone eating it is pregnant, elderly, very young or has a weakened immune system, check current official advice on unpasteurised fermented foods first.Gas pressure: fermenting makes gas. Never screw a lid on tight and leave it: use an airlock lid, or leave the lid loose, or open it briefly once a day. Don't fill a jar to the brim.
Clean jars: wash jars, lids and utensils in hot soapy water and rinse well; for vinegar pickles you can also run them through a dishwasher hot cycle. Use non-reactive containers (glass or food-grade plastic or ceramic), because acid and salt corrode some metals.
Experiments
Experiment
Salt level in a quick pickle
Less, a lot, none.
- Make three small jars of pickled carrots with no salt, 1 teaspoon of salt, and 2 teaspoons per 300 ml of brine. Taste after a day.
Look for: Without salt the pickle tastes flat; the right amount seasons it; too much is harsh. This is for flavour: vinegar pickles are kept safe by the cold and the acid.
Experiment
Vinegar strength
More vinegar, less vinegar.
- Make two jars of pickled onions: one with equal vinegar and water, and one with twice as much water as vinegar. Taste after a day.
Look for: The stronger brine is sharper and crisper; the weaker one is milder and softer. Neither is wrong: write down which you prefer.
Experiment
Jar size
Air at the top.
- Make two ferments of the same amount of cabbage, one in a jar that is nearly full and one in a larger jar with plenty of headspace. Keep both under the brine.
Look for: A fuller jar means less air above and less risk of surface mould, but less space for gas and brine to rise. A lot of headspace is a place for trouble: choose a jar that is about three-quarters full.
Experiment
Fermenting time
Taste at 3, 5, 7 and 10 days.
- Take a clean spoonful from the sauerkraut at each time and taste it, then press the cabbage back under the brine.
Look for: At 3 days it is only slightly sour; at 7 to 10 days it is properly tangy. Fermenting longer gives a stronger flavour. Stop when you like it, then refrigerate.
Tasting notes
| What I tried | Method or amount | What I saw | What I thought | Will I do it again? |
|---|---|---|---|---|
| Refrigerator pickled vegetables | ||||
| Quick pickled red onions | ||||
| Kimchi-style slaw | ||||
| Sauerkraut | ||||
| Salt level | ||||
| Vinegar strength | ||||
| Jar size | ||||
| Fermenting time |
Troubleshooting
| Problem | Likely cause | What to do |
|---|---|---|
| Limp pickles | Cut too thick, or brine not hot | Cut thinner; pour on the brine hot; use fresh crisp vegetables |
| Cloudy brine | Normal in a ferment; cloudy quick pickles can mean spoilage | In a ferment, cloudy is normal; in a vinegar pickle that has been kept too long, throw it away |
| Sauerkraut not bubbling | Too cold, or too little salt or time | Move somewhere warmer (about 20°C) and wait a few days |
| White film on top | Possibly harmless yeast, or mould | If fuzzy, coloured or doubtful, throw the whole batch away |
| Mushy sauerkraut | Too warm or too much time | Use a cooler place; refrigerate sooner next time |
| Too salty | Too much salt or no rinsing | Rinse before eating; weigh salt precisely next time |
Pickling and fermenting safety
Clean jars: wash jars, lids and utensils in hot soapy water and rinse well; for vinegar pickles you can also run them through a dishwasher hot cycle. Use non-reactive containers (glass or food-grade plastic or ceramic), because acid and salt corrode some metals.Quick pickles are not preserved: keep them in the fridge in a covered jar and eat within about 1 week. They are safe because of the acid and the cold, not because they have been canned. Don't leave them on the worktop for days.
Fermenting safety: the guidance I found (mostly from US university extension services and fermenting guides, not from the UK Food Standards Agency) is consistent on these points. Use about 2% salt by weight (a range of 1.5% to 3% is quoted), weigh the salt, and keep every piece of vegetable under the brine, especially in the first 7 to 10 days, because surface mould grows where vegetables touch the air. Ferment at about 18 to 21°C. Throw the whole batch away if you see fuzzy or coloured mould, or if it smells rotten or feels slimy. Don't taste anything you are unsure of. A sour, tangy smell and bubbles are normal. If anyone eating it is pregnant, elderly, very young or has a weakened immune system, check current official advice on unpasteurised fermented foods first.
Gas pressure: fermenting makes gas. Never screw a lid on tight and leave it: use an airlock lid, or leave the lid loose, or open it briefly once a day. Don't fill a jar to the brim.
Checkpoint: can you do this now?
- I can make a vinegar pickle and I know it must stay in the fridge.
- I know why I weigh salt for a ferment and keep everything under the brine.
- I can tell safe signs (sour smell, bubbles) from unsafe ones (mould, slime, rot).
- I know not to seal a ferment tightly.
- I know when to throw a batch away.
Next chapter
Cooking Skills: Vegetables 2, chapter 7 is Dips, Purées and Sauces: smooth textures and sauces from scratch.