Keep them in cold lemony water until needed, drain and squeeze well.
I have stored the whole cleaned flowers and the banana blossom heart in the fridge in cold lemony water for 2 days. They turned light brown, if you don't mind it the taste should be the same.
Good luck with it! Please be gentle, this is my very first guide ever. Thank you for watching. Please let me know if you have any yummy recipes for it! 🍴