Preserves 101: How to sterilize jars and preserve fruit for long-lasting jams, chutneys and sauces (2024)


Preserves 101: How to sterilize jars and preserve fruit for long-lasting jams, chutneys and sauces (1)

Make summer fruit and veggies last through winter with these simple preserving techniques, including low-sugar options for fruit bottling and jams.

Words: Nicola Galloway

It is possible to preserve with small amounts of sugar, and even no added sugar in some cases. The key is following precise preserving and bottling techniques.

The preserving pan is out and slowly bubbling away in the background while we go about our day. The apricots that usually kickstart the preserving season gave us a very small harvest, so instead of many jars of compote it is 6 jars of precious jam for the cooler months. My orchidist friend Craig suggests the ‘tree needs a good haircut’ of which it will have once the last fruit are plucked from the longest branches – if we can beat the birds to them! 🐦🍑 I am not sure quite where this pan came from originally but it is my prized preserving/jamming pan as it has a heavy and wide base. This allows for more surface area for moisture evaporation via steam and the heavy base safe guards against burnt jam. Pictured is my Low-sugar Fruit Conserve using seconds berries from the market. Find the base recipe in my Homegrown Kitchen cookbook 📖 www.homegrown-kitchen.co.nz #homegrownkitchen #homegrown #seasonalfood #localfood #summer #reducefoodwaste #newzealand

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JARRING QUESTIONS: WHICH JARS TO USE?

Agee and Perfit jars are most often used for preserving and can be used repeatedly, with sealable lids available from most supermarkets.

Preserves 101: How to sterilize jars and preserve fruit for long-lasting jams, chutneys and sauces (2)

It is also possible to reuse food jars such as pasta sauce, gherkin, jam and chutney jars. As long as the rubber seal on the inside of the lid is in good condition, it can be re-used safely.

CORRECTLY SEALED JARS & STORAGE

It is essential that lids are correctly sealed before storing. After the jars have been processed using one of the techniques described (see preserving methods below), completely cool and check that the “button” on the lid is down or, if there is no button, that the lid is curving into the jar creating a vacuum seal. If not sealed correctly do not store the jar – eat fresh or freeze contents instead.

Preserves 101: How to sterilize jars and preserve fruit for long-lasting jams, chutneys and sauces (3)

Always store sealed jars of preserves in a cool dark place such as a pantry as heat fluctuations can cause the seals to expand and retract, potentially spoiling the contents.

STERILIZING JARS

The “water bath” preserving method explained below doesn’t require pre-sterilizing of jars as they will be heated to boiling point during processing. For the “open pan” method, often used for smaller batches of preserves such as chutney and jam, it is essential jars are sterilized correctly before use.

Oven sterilization. Clean jars in hot soapy water, rinse and arrange on an oven tray. Place in a 120°C oven for 10 minutes until jars are dry. Meanwhile boil the lids for 10 minutes, then drain and air dry on a dish rack. Remove jars one at a time from the oven to fill with piping hot sauce, jam or chutney. Secure the lids and place jars on a wooden bench or board to cool.

Boiling sterilization. Place jars and lids in a large pot, cover with cold water and bring to a boil, then simmer for 10 minutes. Carefully remove with jar tongs, drain and air dry on a rack. Do not use a tea towel to dry as lint can contaminate the jar.

WATER-BATH PRESERVING

Preserves 101: How to sterilize jars and preserve fruit for long-lasting jams, chutneys and sauces (4)

Water-bath preserving is the process of immersing jars of produce in a bath of cold water that is then slowly brought to the boil and held at a high heat for some time. Water-bath preserving units can be purchased, or make one using a large pot with a small wire rack or plate in the base to sit the jars on.

Step 1: Fill jars with prepared sauce or pack snugly with fruit and syrup to 1cm from the top of the jar.
Step 2: Screw on lids and place in the water bath with 1cm space between jars for water to circulate.
Step 3: Fill the water bath or pot with cold water to cover the top of the jars by 1cm, or to the shoulder of taller jars.
Step 4: Cover (if possible) and bring to a gentle boil.
Step 5: Once the water just reaches a boil, turn down to low and hold at this heat for 10 minutes.
Step 6: Carefully remove jars using jar tongs and leave to cool on the bench. Once jars are completely cooled check lids are correctly sealed. Store in a cool, dark pantry or cupboard.

OPEN-PAN PRESERVING

This is similar to the overflow method although less messy as the jars aren’t quite filled to the top. Use this technique when making a small batch of chutney or sauce.

Step 1: Reheat jam or chutney if needed.
Step 2: Sterilize jars (see sterilization methods above).
Step 3: Using oven gloves, hold hot jars and fill with piping hot chutney or jam to within 5mm from the top. Use a damp cloth to wipe the jar rim.
Step 4: Screw on sterilized lids and leave to cool completely on the bench. Check that the lids are sealed correctly. Store jars in a cool, dark pantry or cupboard.

Note: These preserving techniques are only recommended for fruit, including tomatoes. They are not suitable for non-acidic vegetables, or fish and meat.

This is an extract from our special edition In Your Backyard: Living Lightly

In Your Backyard: Living Lightlyis filled with practical advice on making small steps to a lighter footprint.Order online here.

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Preserves 101: How to sterilize jars and preserve fruit for long-lasting jams, chutneys and sauces (2024)

FAQs

Preserves 101: How to sterilize jars and preserve fruit for long-lasting jams, chutneys and sauces? ›

Oven sterilization.

How do you sterilise jars for jams and preserves? ›

Wash your jars and the lids in hot soapy water, but do not dry them. Instead, leave them to stand upside down on a roasting tray while they're still wet. Pop the tray of clean, wet jars and lids in to a preheated oven at 160-180ºC for about 15 mins.

Do I need to sterilize jars before canning jam? ›

Jars do not need to be sterilized before canning if they will be filled with food and processed in a boiling water bath canner for 10 minutes or more or if they will be processed in a pressure canner. Filled jars that will be processed in a boiling water bath canner for less than 10 minutes need to be sterilized first.

How long do you boil jars to sterilize jam? ›

Wash the jars, lids and bands in hot, soapy water; rinse well. Put the jars on a rack in a pot of water. Boil 10 minutes, then reduce the heat and simmer until ready to use. Meanwhile, put the lids and bands in a separate saucepan of simmering water until ready to use (do not boil).

What happens if you don't sterilize canning jars? ›

According to The National Center for Home Food Preservation, jar sterilization is not required for safe preserving if you'll be processing your filled jars in a boiling water bath canner for 10 minutes or more. That's because harmful microorganisms will be destroyed during processing.

Can you sterilize canning jars without boiling? ›

I prefer to use the oven sterilization method (as opposed to the hot water method) which is as follows: Preheat your oven to 275 degrees. Wash each canning jar or mason jar and lid with hot soapy water then rinse but don't dry them. Place each clean jar on a baking tray and place in the oven for 10 minutes.

Does boiling water sterilize jars? ›

Step 4 - Sterilise Your Jars With Boiling Water

Fill the pan with cold water until the jars are covered. Bring to the boil and keep at the maximum temperature for 10 minutes, turn the heat off and cover the pan to keep the jars warm until you are ready to fill them.

Do you need to sterilize jars for chutney? ›

Ideally, you should sterilise your jars in the oven just before you use them. You can then ladle your hot jam or chutney straight in, being careful not to drip it on the rim of the jar. Remember to always leave a bit of space at the top of your jar too (ideally 1cm to 2cm).

Do you put homemade chutney in jars hot or cold? ›

Fill the hot dry jars right to the top – preserves shrink slightly on cooling and a full jar means less trapped condensation. Seal the jars while still hot. This rule applies to all jams, jellies, pickles and chutneys.

How do you sterilize jars for relish? ›

Place jars and lids in a deep saucepan over high heat. Cover with cold water. Bring to the boil. Reduce heat to medium and boil for 10 minutes.

Are ball mason jars sterile when you buy them? ›

Even when you purchase new jars in a box covered in plastic wrap, those jars are still not in a sterile environment. In addition to contamination by microorganisms that cannot be seen, packaged jars may accumulate dust, small bits of debris and even chips of glass in the case of breakage.

Can I sterilize canning jars in the dishwasher? ›

Put the jars you are sterilizing in the dishwasher with the openings facing down. It might sound obvious, but it's fine if other dirty dishes from your regular life happen to be in there, too. Run the dishwasher in the sanitize cycle. Bear in mind that the sanitize cycle might run longer than typical wash cycles.

Why do you boil mason jars before canning? ›

By subjecting the jars to boiling water, you effectively eliminate any lurking microorganisms that could compromise the quality and safety of your preserved foods.

Do you need to sterilize jars for refrigerator jam? ›

Then I learned about refrigerator jam, which is just what it sounds like: jam you store in the fridge instead of the pantry. You don't need to sterilize anything, you can skip the pectin and you can cook it in batches of any size, from as small as a pint of perfect strawberries to as large as a bushel of blueberries.

How long do you sterilize jam jars in the microwave? ›

Sterilising in the microwave

For a small number of jars, this can be a handy way of sterilising. Wash jars and rinse them before standing them upright in your microwave and microwaving them on full power for 60 seconds. Lids can be sterilising by submerging them in a pan of boiling water for 10 minutes.

How to seal jam jars in boiling water? ›

Place lids on jars, screw on rings and lower jars back into the pot of boiling water. The water should cover the jars; if not, add more. Boil jars for 10 minutes. Transfer jars to a folded towel and allow to cool for 12 hours; you should hear them making a pinging sound as they seal.

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