Sterilisation

Sterilising Glass Bottles and Jars

Sterilising glass bottles and jars is an important step before use, especially when you are using them for food grade products. Without sterilisation, it is almost impossible to account for all possible contaminants that could be in glass, no matter the storage method. Dust could have found its way inside, traces of mould could be growing in moisture, or if the items are left exposed, insects could have made their way in and out without anyone knowing.

The good news is that there are many simple options when it comes to sterilising your glass jars and bottles to ensure that they are suitable for your product.  Glass is easy to clean and due to its transparent nature, it is very apparent when something is amiss. Once sterilised, it will remain so provided it is stored in suitable conditions.

The recommended methods of sterilising glass bottles and jars are the following:

• Hand washing
• Dishwasher
• Heat sterilisation
• Microwave steaming

Hand washing

Much as you would wash any household crockery or drinking implements, hot, soapy water and a sponge is an effective way of ensuring that the bottles and jars are clean and usable. In cases where they seem particularly contaminated, such as with layers of dust, it is recommended to rinse the items out both before and after the washing process.

Please note that it is important the bottles and jars are thoroughly drained and dried out, as the presence of moisture can lead to the growth of mould over time.

Dishwasher

If you have a dishwasher to hand, this can be an effective way of cleaning and sterilising bottles and jars. Dishwashers are efficient when it comes to removing all contaminants from the surface of the glass. Their process of heating the objects inside as a means of drying them is useful for killing off any lingering bacteria.

Please note that dishwashers operate on a fixed cycle, and any particularly stubborn contaminants that are not removed will not be identified by the dishwasher, so the bottles and jars may need additional inspections before they are put to use.

Heat sterilisation

Exposing your glass to sustained heat is a reliable way to kill off any bacteria that might be lingering inside bottles and jars. An oven is a suitable place to accomplish this, although the heat will not remove any debris inside the jar already, so it is recommended to remove this either by hand washing or with a dishwasher first. Heat the glass up to 150C for 15-20 minutes and any bacteria inside will have been killed off. Please be sure to use oven gloves when handling the glass afterwards, as glass retains heat for longer than plastic.

Please note that any cracks or chips in glass before it is placed in the oven are liable to expand, causing the glass to shatter violently. Always check for any signs of damage before using the heat sterilisation method.

Microwave steaming

Placing a small amount of water inside your bottles and jars and then putting them inside a microwave and setting it on full power for a minute or two will kill any bacteria inside. A microwave works by superheating water particles exclusively, so this method relies on you creating a steamed environment to sterilise the inside. It is worth noting that if there is no water inside, this method is less effective.