Sweetcorn likes a long, hot summer, and a Scottish one often falls short, so a good year's cobs deserve more than a single meal. This golden relish mixes the kernels with red and green peppers, celery, onion, vinegar, sugar, mustard and turmeric. The tested recipe uses about 8 to 10 cobs, and a short spell in a pan of boiling water is what lets the sealed jars keep in the cupboard.
- Makes
- about 4 to 5 x 470ml (US pint) jars, or about 9 x 240ml (half-pint) jars
- Cooking time
- about 10 minutes' simmering, then 15 minutes' processing in boiling water (20 minutes above about 300m)
- Keeps
- best used within a year, unopened, in a cool, dark, dry place
- In season
- late summer into early autumn in Scotland, until the first frosts
Ingredients
- 8–10 cobs of sweetcorn, to give 1.2 litres (about 850g) of kernels
- 300ml red peppers, diced
- 300ml green peppers, diced
- 300ml celery, chopped
- 150ml onion, diced
- 600ml vinegar, 5% acidity (white distilled or cider)
- 175g white sugar
- 1¼ tbsp canning or pickling salt
- 1¼ tsp celery seed
- 1¼ tbsp mustard powder
- a rounded ½ tsp turmeric
- optional, to thicken: 2 tbsp plain flour mixed with 2 tbsp water
Go by the 1.2 litres of kernels rather than the cob count, measure the chopped vegetables in a measuring jug, and check the vinegar label says 5% acidity.
Method
- Wash the jars and keep them hot until you fill them, and prepare new two-piece canning lids following the maker's directions.
- Put a rack in the bottom of a canner or a deep pan, half fill it with clean warm water and heat it to about 82°C (hot but not boiling) ready for the hot jars.
- Husk the cobs, boil them for 5 minutes, then dip them in cold water.
- Cut the whole kernels from the cobs and measure out 1.2 litres.
- Put the peppers, celery, onion, sugar, vinegar, salt and celery seed in a large stainless steel or unchipped enamel pan (not copper, brass or iron) and bring to the boil.
- Simmer for 5 minutes, stirring now and then.
- Take out 60ml of the hot liquid and mix the mustard powder and turmeric into it.
- Stir the mustard mixture and the corn into the pan and simmer for another 5 minutes.
- If you want a thicker relish, blend the flour and water to a smooth paste, stir it in and keep stirring often.
- Fill the hot jars with the hot relish, leaving about 1.25cm of space below the rim.
- Wipe the rims with a clean, damp paper towel and put on the lids and screw bands.
- Don't skip this bath. Stand the jars on the rack in the hot water, then pour in boiling water around them, not directly onto them, until it is at least 2.5cm above the lids.
- Cover the pan and bring it to a vigorous boil on the highest heat.
- Once it is boiling, time 15 minutes (20 minutes above about 300m), with the lid on. If the water stops boiling, bring it back to a full boil and start the timing again from the beginning.
- Turn off the heat and wait 5 minutes.
- Lift the jars out onto a towel or rack, at least 2.5cm apart. Don't tighten the screw bands or press the lids until the jars are completely cool.
- Leave them undisturbed for 12–24 hours, then check the seals (see below), label with the date and store.
Why the vinegar matters so much with corn
Sweetcorn has almost no acid of its own. All fresh vegetables except most tomatoes are low-acid foods, and a mix of vegetables only becomes an acid food when the recipe includes enough vinegar. The acid has to reach a minimum, even level right through the jar to stop botulism bacteria growing. In this relish that balance is set by the proportion of 5% vinegar to corn, peppers, celery and onion.
So keep every quantity as written, and halve or double the whole batch only. Don't cut the vinegar or sugar, don't use a vinegar whose acidity isn't stated, and don't add chillies, garlic, extra corn or other vegetables: each one changes the balance the recipe was tested at. A tested recipe matters far more for corn than for fruit. There's more on this in the guide to mixing fruit and veg in preserves.
Picking cobs for relish
Many modern varieties crop well in a cooler climate, but in a cool summer late-sown cobs may not have time to ripen, so cold gardens need an early-ripening variety; see the best sweetcorn varieties for Scotland. Watch the frost dates for your area as autumn closes in.
To check a cob, peel back a little of the husk and pierce a kernel with your thumbnail. Watery juice means it isn't ripe; creamy juice means it's ready. Once picked, sweetcorn loses sweetness as its sugars turn to starch, so make the relish on the day you pick. The full sweetcorn growing guide covers sowing, pollination and harvesting.
Jars, lids and the boiling-water bath
The processing time applies only to pint jars (about 470ml) and half-pint jars (about 240ml), with two-piece canning lids (a flat lid and a screw band). These are US pints; a British-pint jar (568ml) is bigger. Larger jars, clip-top jars and old jam jars with twist-off lids have no processing time for this relish. There's more on closures in the guide to jars for preserving.
Check your garden's height above sea level before you start (an Ordnance Survey map shows it): above about 300m, the bath needs 20 minutes rather than 15.
Because the jars spend 15 minutes in boiling water, they don't need sterilising first; wash them and keep them hot. The sterilising guide covers preserves that are hot-filled without a bath.
Without the bath, hot-filled jars have no tested keeping time, so keep them in the fridge and eat the relish within a few days.
Checking the seal
When the jars have cooled, take off the screw bands and test each lid:
| Test | Sealed | Not sealed |
|---|---|---|
| Press the centre of the lid | Stays down | Springs back up |
| Tap it with a teaspoon | Clear, ringing note | Dull sound |
| Look across it at eye level | Curves slightly downwards | Flat or bulging |
A jar that hasn't sealed can go in the fridge; eat it within a few days. Or reprocess it within 24 hours: check the jar rim for tiny nicks, change the jar if needed, fit a new lid and process for the full time again (15 minutes, or 20 above about 300m).
Storing and opening
| Stage | Where | How long |
|---|---|---|
| Sealed | Clean, cool, dark, dry place (10–21°C), away from a cooker, hot pipes and sunlight | Best used within a year |
| Opened | Fridge | Within a few weeks to a month or two |
Store the jars without their screw bands, which keeps the lids dry and shows a broken seal straight away. Before opening, check each lid still curves downwards. Don't taste relish from a jar with a loose lid, dried streaks down the outside, liquid that spurts out, an unnatural smell or mould.
Damp corrodes metal lids and can break the seals, so a damp shed is a poor store. If jars have to go somewhere that might freeze, such as an unheated garage in winter, wrap them in newspaper and pack them in a heavy box: freezing doesn't spoil the relish, but it can soften it, and a jar that comes unsealed will spoil. More on spoilage signs is in how long preserves keep.
Common questions
Can I use frozen sweetcorn?
Yes. Use 850g of frozen kernels in place of the fresh corn, and skip boiling the cobs. Everything else stays the same.
Can I add chilli or garlic?
No. Extra vegetables lower the acid in the jar, and the processing time may no longer keep the relish safe. Stir chilli sauce into a spoonful at the table instead.
Can I use less sugar or vinegar?
No. The vinegar makes low-acid corn acid enough for the boiling-water bath to work. With less of it, the processing time may no longer keep the relish safe. The sugar is part of the same tested balance, so keep that as written too.
Can I use malt vinegar?
Better not. White distilled and cider vinegar at 5% acidity are the recommended vinegars for pickling, so check the label says 5%. Never use a vinegar whose strength isn't stated.
Can I use ordinary table salt?
Canning or pickling salt is best. The anti-caking agents in other salts can make the liquid cloudy.
Do I have to use the flour?
No. It is optional and only thickens the relish.
Sources
Show the 11 sources
- Recipe proportions based on: Pickled Corn Relish (National Center for Home Food Preservation, University of Georgia; adapted from the USDA Complete Guide to Home Canning, 2015): all ingredient quantities and yield (halved), 5% vinegar, boiling the ears 5 minutes and dipping in cold water, cutting whole kernels, frozen corn as a replacement, simmering order and times, mustard and turmeric mixed into ½ cup of the liquid, optional flour paste, ½ inch headspace, processing times (15/20 min) for half-pints and pints
- Using Boiling Water Canners (National Center for Home Food Preservation): rack, half-filling with warm water heated to 180°F (82°C) for hot packs, pouring boiling water around not onto the jars, at least 1 inch of water over jars, highest heat and lid on, timing from the boil, restarting if the boil stops, 5-minute wait, 1 inch spacing, 12–24 hours undisturbed, not tightening bands or pressing lids until completely cool
- Cooling Jars and Testing Jar Seals (National Center for Home Food Preservation): removing screw bands, press, tap and eye-level seal tests, reprocessing within 24 hours with a new lid and the same time, unsealed jars in the fridge and eaten within several days
- Storing Home-Canned Foods (National Center for Home Food Preservation): clean, cool, dark, dry place at 50–70°F (10–21°C), away from hot pipes, a range and sunlight, best used within a year, storing without ring bands, damp corroding lids and breaking seals, wrapping jars in newspaper in heavy cartons where they may freeze, freezing softening food but not spoiling it unless jars unseal, spoilage signs, not tasting from unsealed or spoiled jars
- Sterilization of Empty Jars (National Center for Home Food Preservation): pre-sterilising needed only for jars processed for less than 10 minutes
- Ensuring Safe Canned Foods (National Center for Home Food Preservation): all fresh vegetables except most tomatoes are low-acid; mixtures stay above pH 4.6 unless the recipe has enough vinegar
- General Information on Pickling (National Center for Home Food Preservation): 5% white distilled or cider vinegar; don't alter vinegar, food or water proportions or use vinegar of unknown acidity; minimum, uniform acid level to prevent botulinum growth; canning or pickling salt, as anti-caking agents cloud the liquid
- Home Canning Equipment for Making Pickles (University of Nebraska–Lincoln Extension): stainless steel or unchipped enamel pans; no copper, brass or iron
- Sweetcorn: grow your own (RHS): long, hot summers vs modern varieties in a cooler climate; cobs may not ripen in a cool summer; early-ripening varieties in cold areas; thumbnail ripeness test; sugars turn to starch after picking
- Storing Home-Canned Jams and Jellies (National Center for Home Food Preservation): opened jars kept in the fridge (about 1 month for jam)
- 25 dirt-cheap ways to garden organically and save (Garden Organic): opened chutney kept in the fridge (3–4 months)