The Youtuber Melisa Maker revealed a great and very inexpensive way to do that. In fact, each day she sprays the mattress with baking soda.
All you need is about 200 g of baking soda. Leave it for 30 minutes, and then vacuum the mattress. Your bed will not only be a healthier “environment” for you, but it will also smell wonderful.
Practice vacuuming mattresses and before and after cleaning with baking soda.
Watch this video to see how she does it: