Sterilising glass jars is essential in the process of home preserving, as any bacteria present is likely to spoil your food, or worse, make you ill. Whether you are making chutney, jams or marmalade, having clean jars and lids is a must. Here are five fool-proof methods of sterilising jars ready for home preserving.
Before sterilisation, it’s essential to ensure that your glass jars are clean. Wash them thoroughly with hot, soapy water and rinse them well. Pay close attention to any corners or crevices where food particles may hide.
Five Ways of Sterilising Glass Jars
1. Boiling Glass Jars
- Choose a pot large enough to accommodate all the jars you plan to sterilise. Place a dishcloth or towel at the bottom of the pot to create a protective barrier between the jars and the direct heat.
- Arrange the clean jars upright in the pot, making sure they don’t touch each other or the sides of the pot. Leave enough space between them to allow water circulation.
- Fill the pot with enough water to completely submerge the jars by at least 1 inch. Place the pot on the stove over medium-high heat and bring the water to a rolling boil. Boil for 20 minutes.
- Using tongs, carefully remove the jars from the boiling water, ensuring not to touch the inside or rims. Place them upside down on a clean dishcloth or towel to allow excess water to drain.
Allow the jars to cool completely before touching or sealing them. Once cooled, inspect the jars for any signs of cracks or imperfections. Discard any jars that are damaged.
2. Dishwasher Method of Sterilising Jars
- Arrange the clean glass jars and their lids in the dishwasher, spacing them out evenly and making sure they’re secure.
- Check your dishwasher’s settings to see if it has a sterilising or high-heat option. If available, select that setting for maximum sterilisation. Alternatively, you can choose the hottest and longest cycle available on your dishwasher.
- Add dishwasher detergent as usual and start the sterilising cycle. Once the sterilising cycle is complete, let the jars stay in the dishwasher until they are completely dry. If you open the dishwasher after the cycle, it can introduce moisture and compromise the sterilisation process.
The jars should be hot and dry when you fill them, so you might need to keep them warm in an oven afterwards.
3. Oven Method of Sterilising
- Preheat the oven to 140°C. Thoroughly wash the jars with hot soapy water.
- Arrange the wet, clean jars on a baking sheet or oven-safe tray, leaving space between each jar for proper heat circulation. This allows the heat to evenly sterilise the jars.
- Place the jars in the preheated oven and let them heat for about 20 minutes. This duration is sufficient to kill any lurking bacteria inside the jars. Adjust the time slightly if using larger or smaller jars.
- Using oven mitts or heat-resistant gloves, carefully take out the tray from the oven. Place it on a heat-resistant surface, and allow the jars to cool completely before handling them.
The lids should be boiled for the same amount of time. Keep the jars warm in the oven until you are ready to use them.
4. Microwave Method of Sterilising Jars
- Ensure that your glass jars and lids are microwave-safe. Look for labels or any indications provided by the manufacturer to ensure they can withstand microwave heat.
- Thoroughly wash the glass jars and their lids with hot, soapy water. Rinse them well to remove any soap residue, ensuring they’re clean and free of debris.
- Fill each jar with about 1 inch of water to create a steamy environment during the sterilisation process. Place the lids loosely on top of the jars without tightening them. Place the jars in the microwave and microwave them in short intervals. Start with 1-minute intervals at high power. The exact time needed may vary depending on the wattage of your microwave and the size of the jars.
- After each interval, carefully remove the jars using oven mitts or heat-resistant gloves to avoid burns. Gently swirl the water inside the jars to distribute the heat evenly and prevent hotspots. Then, place the jars back in the microwave for the next interval.
- Continue microwaving the jars in intervals, checking the water temperature and rotating the jars until the water reaches boiling point. Once boiling, allow the jars to sit in the microwave for a few additional minutes to ensure thorough sterilisation.
- Carefully take the jars out of the microwave using oven mitts or heat-resistant gloves as they will be hot. Empty the water from the jars and place them on a clean towel or drying rack to air dry completely before filling them with food.
Take care not to put metal lids in a microwave. Lids will need to be sterilised and boiling them is the quickest method.
5. Sterilising Solution
It is also possible to soak jars in a sterilising solution, however there is a chance of it tainting the flavour of the preserve. If using a sterilising solution, follow manufacturers’ advice.
I have a preferred method when sterilising jars for home preserving, and that is a combination of boiling and oven. I boil the jars and the lids as described, then place the jars upside down on a baking tray in a hot oven for 20 mins. I then turn down the heat, pop the lids in with the jars, and keep warm until needed.
Do you like preserving food at home? Share your preferred way of sterilising glass jars!