Looking at airport rules such as those for Heathrow
Can I carry liquid baby food, prepared milk, soya milk, rice milk or
sterilised water through security?
Yes, if you are travelling with a
baby or infant you can carry a reasonable amount of liquid and
liquidised food for the baby or infant infant for your journey. To
assist security screening, please do not carry these items in a flask.
Spare supplies must be packed in your hold baggage.
You can either
carry the liquids as part of your liquid bag allowance in which case
the standard liquid rules apply or alternatively separately in
containers over 100ml. Following x-ray screening, security officers
may also need to carry out additional checks on these items.
If you are intending to carry supplies to last longer than those required for the flight, it is likely you will have to pack these extra items in your checked-in luggage depending on the airports you are travelling from or through.