Yes you can express your milk and store it for her.
Certain precautions to follow.
Express breastmilk frequently atleast for a week before you travel.
All this milk should be labelled with date and time of pumping and stored in the deep freezer.
A 5 month old baby can take a lot of milk at one feed so you will need to save larger amounts for her.
Once the milk needs to be used you can thaw it by keeping it in a container of hot water. Once thawed the milk cannot be refrozen and needs to be used up within 24hours.
Kindly avoid bottle feeding and feed instead using a bowl and spoon or bottle with spoon