How to Sterilise Baby Jars in the Oven

If you're batch-cooking baby purees or storing homemade porridge jars, you'll need a reliable way to sterilise the glass jars before filling them. Oven sterilisation is a straightforward method that uses dry heat to kill bacteria. No special equipment needed beyond what you already have in your kitchen.

This guide covers the exact temperature, timing and technique for sterilising baby food jars in a standard UK oven. We've based this on NHS food safety guidelines and tested the method with common baby food storage jars available in the UK.

What You'll Need

Glass jars with metal lids: Use heatproof glass jars designed for food storage. Babymoov Babybols are a popular choice. They're 120ml glass jars with airtight lids, purpose-built for baby food portions. Avoid jars with plastic components, printed labels that might peel, or cork lids.

A baking tray: Line it with baking paper to stop the jars rolling and to catch any condensation. A standard oven tray works fine.

Sterilised tongs or oven gloves: You'll need to handle hot jars without touching the rim or inside. A pair of clean kitchen tongs washed in hot soapy water works, or use dedicated Munchkin bottle tongs if you have them.

Cooling rack (optional): Helps air circulate around the jars once they come out of the oven, keeping them sterile until you're ready to fill them.

Step-by-Step: Oven Sterilisation Method

Step 1: Wash the Jars Thoroughly

Start by washing each jar and lid in hot soapy water. Use a baby bottle brush to reach the bottom and sides, then rinse thoroughly under clean running water. You don't need to dry them. Any residual water will evaporate in the oven. The wash removes visible food residue; the oven handles the invisible bacteria.

Step 2: Preheat the Oven to 140C

Set your oven to 140 degrees Celsius (gas mark 1). This is the recommended baseline for dry heat sterilisation of glassware. Some guides suggest 160C fan-assisted, but starting at 140C reduces the risk of thermal shock, where rapid temperature changes cause glass to crack.

Don't put the jars into a cold oven. Let it reach 140C first, then load the jars. Putting cold glass into a hot oven is one of the most common causes of jar breakage during sterilisation.

Step 3: Arrange Jars Upside Down on the Tray

Place the washed jars upside down on the lined baking tray, leaving about 2cm between each jar for air circulation. Put the metal lids on the tray separately. Don't screw them onto the jars during heating, as trapped air can cause pressure build-up.

Spread the jars out rather than stacking them. Each jar needs direct heat contact to reach sterilising temperature throughout. Crowded trays create cold spots where bacteria might survive.

Step 4: Heat for at Least 20 Minutes

Slide the tray into the middle of the preheated oven and set a timer for 20 minutes. This is the minimum. The jars need time to reach and maintain 140C throughout the glass, not just on the surface.

The NHS guidance for dry heat sterilisation specifies 160C for 45 minutes or 170C for 20 minutes for laboratory glassware. For domestic baby food jars at 140C, 20 to 30 minutes gives a comfortable safety margin. If you're uncertain, go with 30 minutes.

Step 5: Remove and Fill While Hot

Using tongs or oven gloves, carefully remove the tray from the oven. Handle each jar by the base. Never touch the rim or inside, as this reintroduces bacteria.

This is the critical step: fill the jars with your prepared baby food while they are still hot. You have roughly 15 minutes before the jars cool below sterilising temperature and bacteria from the air can settle on the surface. Work quickly but carefully.

Spoon or pour your puree, porridge or mash directly into each jar. Seal with the metal lid immediately. If you're using plastic snap-on lids (like the Babymoov ones), wait until the jar cools slightly (about 5 minutes) so the plastic doesn't warp.

Step 6: Cool, Label and Store

Place the filled, sealed jars on a drying rack and let them reach room temperature. Label each one with the contents and date. A simple sticker or masking tape works. Once cool, refrigerate any jars you'll use within 48 hours, or freeze the rest for up to 3 months.

How Long Do Sterilised Jars Stay Sterile?

An empty jar that's been properly oven-sterilised stays sterile for about 4 hours if left sealed and undisturbed. Once you remove the lid or touch the rim, the clock starts. Fill within 15 minutes for best results. If a jar has been sitting open for more than an hour, re-sterilise it before use.

For batch-cooking sessions, sterilise all your jars at once, then work through them systematically. Line up your jars on the tray, prepare your food while the oven heats, and have everything ready to go the moment the timer goes off.

Oven and Other Sterilisation Methods

Oven sterilisation is one of four common methods for baby feeding equipment. Here's how it compares:

Steam sterilisers (electric or microwave) are faster, typically 5 to 8 minutes per cycle, and designed specifically for baby bottles and accessories. If you're sterilising bottles daily, a dedicated baby steriliser is worth the investment. But for glass food storage jars in bulk, the oven handles more jars at once.

Cold water sterilisation using Milton sterilising tablets takes 15 minutes and works for items that can't go in the oven, like silicone weaning sets, plastic containers and teething toys. Keep a Milton solution bowl ready alongside your oven method for mixed batches.

Boiling works in a pinch but risks cracking glass jars from direct heat contact, and it's harder to maintain a consistent temperature across all items. The oven provides more even, controlled heat.

Common Mistakes to Avoid

Putting cold jars into a hot oven. Thermal shock is the number one cause of jar breakage. Always preheat the oven fully before loading.

Screwing lids on during heating. Trapped air expands when heated and can pop lids off or crack the glass. Heat jars and lids separately.

Touching jar rims with bare hands. Even freshly washed hands carry bacteria. Always use tongs or handle jars by the base after sterilisation.

Filling jars after they've cooled. Once the jar drops below sterilising temperature, airborne bacteria settle on the surface. You have a narrow window. Fill while hot.

FAQ

What temperature do you sterilise baby jars in the oven?

Heat your oven to 140 degrees Celsius (gas mark 1) for standard glass jars. Some guides suggest 160C fan-assisted, but 140C is the safer baseline that reduces thermal shock risk. Never exceed 170C.

How long should you leave jars in the oven to sterilise them?

Leave the jars in the oven for at least 20 minutes at 140C. The jars need to reach and maintain sterilising temperature throughout, so don't rush this step. Some parents leave them for up to 30 minutes for extra reassurance.

Can you put plastic baby food containers in the oven to sterilise them?

No. Oven sterilisation is only suitable for heatproof glass jars and metal lids. Plastic baby food containers should be sterilised using cold water with Milton tablets or a dedicated steam steriliser instead.

Is oven sterilisation as effective as a steam steriliser?

Yes, when done correctly at the right temperature and duration, oven sterilisation kills the same harmful bacteria as steam sterilisation. The NHS confirms that dry heat sterilisation at 160C for 45 minutes, or 170C for 20 minutes, achieves effective sterilisation of glassware.

How do you fill sterilised jars without contaminating them?

Fill the jars while they are still hot from the oven, ideally within 15 minutes. Use sterilised tongs to handle them, and pour or spoon food directly in. If the jars cool below sterilising temperature, bacteria can settle on the surface before you fill them.

Last reviewed: August 31, 2026 · Evidence-based content · Contains affiliate links

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