How to Sterilise Jam Jars
Before even contemplating the idea of making jams or chutneys, you must first ensure that you have all the essential tools and equipment to hand. This will boost your chances of success!
When making jams and preserves, you can store your finished concoctions in used jars or brand new shop bought ones. Just ensure that before you pot your preserves, your jars are scrupulously clean. It’s important to kill all bacteria and organisms so that the contents remain fresh and well preserved.
There are several ways in which you can sterilise your jam jars. This guide will explain the dishwasher and oven methods. Both will ensure your jars dry off thoroughly after washing and remain hot, ready for potting your preserve of choice.
- Heat your oven to 140°C / 275°F or Gas Mark 1. While your oven is heating up, thoroughly wash your jars and their lids in warm, soapy water. Rinse off all traces of soap suds and leave to drain, but don’t dry completely.
- Prepare a baking tray with a sheet of baking paper and place on your wet jars. Ensure they are all separated evenly on the tray.
- Place the tray into the oven and heat the jars for 20 minutes. Meanwhile, place the washed lids into a saucepan of boiling water and boil for 20 minutes.
- Your jam jars and lids are now sterilised and ready for potting! Make sure that you always pot preserves in warm jars because cold glass will crack when it comes in contact with heat.
If you’re lucky enough to own a dishwasher, this method is a very convenient way to sterilise your jam jars. A dishwasher’s drying cycle leaves glass and cutlery very hot, which is perfect for potting preserves.
- If you’re using recycled jam jars, just swirl out any traces of jam or chutney with water before loading into the dishwasher.
- Set your dishwasher to the highest possible setting and allow the jars to go through a full cycle so that the glass is as clean as a whistle, bone dry, and hot to touch.
- If your jam is not cooked yet, you can keep your clean jars in a warm oven before you’re ready to start potting.
How to Make Jam
Making jam involves cooking boiling fruit until it reaches a setting point. There are various stages jam goes through whilst cooking, and there are various tests that can be done to ensure a perfect consistency for spreading. Any jam recipe can be used with this method.
Stage 1: Cooking the Fruit
- Place your chosen fruit, as per the recipe you are working from, into a preserving pan and cook gently with or without sugar. If you are cooking raspberries (a delicate fruit), add the sugar to the pan before cooking.
- For any citrus fruits or blackcurrants, blueberries and cranberries, these fruits have tougher skin and peel so ensure you thoroughly cook to soften and then add in the sugar until it dissolves.
- Add in pectin according to your recipe.
Stage 2: Rapid Boil
- Increase the heat to the highest possible setting and allow the fruit to boil rapidly; this is called a ‘full rolling boil’. This stage will appear very vicious and you’ll know once the jam has reached this stage because the bubbles will not stir out.
- Keep boiling for the required time. This will allow the sugar to react with the pectin for the desired setting texture at the end.
Stage 3: Skimming
While your jam is boiling rapidly, you’ll notice scum setting on the top and around the sides of the mixture. Remove the scum as soon as you spot it rising to the surface. The best utensil for this job is a slotted metal spoon. Removing scum will ensure a smooth overall texture; otherwise it’ll bond with any peel or pulp when cooling down in the jar later.
Stage 4: Testing
At this point, study your mixture and check whether the jam is beginning to set. The mixture will begin to thicken around the sides and the bubbles will appear less frothy; they’ll be larger and pop slowly. Now you can test the jam – there are two methods for this: the flake test and the wrinkle test. These tests can be done once every 3 - 5 minutes.
- Flake Test: Use a clean wooden spoon to scoop up a small amount of jam. Allow to cool slightly before tilting back into the pan. If the last bit of jam falls in a flake rather than a liquid stream, the jam is set and ready!
- Wrinkle Test: Before you start making your jam, place a few plates into the fridge or even the freezer. When you’re ready to test the jam, take a cold plate and place a teaspoonful of jam and place on top. Allow to cool slightly then run your finger through the jam. If the surface wrinkles, then you have a perfectly set jam.
How to Make Savoury Preserves (Chutneys and Relishes)
A typical chutney or relish is thick and chunky. Vegetables are mainly used in these preserves which contain a large quantity of water; when cooked, the water releases into the mixture which could completely ruin the end product. It’s important to gently cook out the water for a thick consistency, while the sugar and vinegar will preserve the vegetables.
Stage 1: Prep
- Gather all the ingredients stated in the recipe you’ve chosen. Chutneys and relishes contain small chunks, so chop up your vegetables, dates, nuts etc. into approximately 1cm cubes.
- Grate any citrus rind and whole spices into powder using a pestle and mortar or a coffee grinder. Make sure all your ingredients are prepared before so everything cooks evenly.
Stage 2: Cooking
- Simmer all the ingredients in a large preserving pan over a low heat. Keep an eye on the mixture and ensure it doesn’t start boiling. Stir often until the sugar has completely dissolved.
- Increase the heat and continue to simmer the mixture until it begins to thicken. This is a lengthy process and can take approximately 1 hour to feel the mixture becoming thicker.
- Stir occasionally to help it along and scrape any bits stuck at the bottom of the pan.
Stage 3: Testing
- After about one hour, your preserve is ready to test. Take a clean wooden spoon and drag the mixture from one side of the pan to the middle; if the mixture slides back immediately, it needs a little longer to simmer.
- Test again after about 15 minutes until a clear channel is left when you drag your spoon through. A little liquid in sight is okay.
Stage 3: Pureeing
As with making most sauces, this step requires reducing the cooked mixture into a puree. You can either pass the mixture through a sieve or a blender. You can choose whether you want a completely smooth chutney/relish or a thicker mixture with cubes of ingredients remaining.
How to Pot Your Preserves
Potting Sweet Preserves
You must pot your jam into warm, sterilised jam jars as soon as it’s reached its setting point. Make sure you have all your potting equipment at the ready: jars, ladle, funnel, wax circles, and lids.
- In the event of any spillages, place your jars onto a baking tray and position the funnel on top of a jam jar. Start to spoon in the jam one ladleful at a time until the jam reaches 1cm from the top. Try to be as neat as possible; you don’t want jam around the top or the lid may stick on!
- Once all your jars are filled, place a wax circle on the top of each surface and cover with cellophane wrap or seal with sterilised lids. If you’re using jar lids, place on top loosely and seal completely when the mixture is cooler.
Potting Savoury Preserves
Potting your chutneys, pickles etc. is the same as potting jam except you’ll require vinegar-proof lids.
- Spoon your savoury preserve into sterilised jars and leave a 1cm - 2cm gap from the top. If you have a chunkier, thicker chutney mixture, press the contents down to remove any air gaps. A metal teaspoon is probably the best utensil for this job as you can get to the bottom of the jar.
- Screw your lids on once all the jars are filled and tighten once the contents have cooled.