smoothies with banana extracts

Is it okay to use extracts ? On the day with the bananas and milk if you just cut the banana up and freeze them, then add the frozen banana to a glass of milk flavored with the extracts (such as banana , strawberry,almond or vanilla (etc)then just blend til thick with a couple ice cubes . You could freeze the bananas the night befor and have them ready to blend into a smoothie on the banana day.

What are the ingredients of your extracts?