I like to do long hikes in black bear country. I don't really go on multiday trekking trips, just day trips but often need to bring food along. I know that backpackers often keep their food in bear vaults but since I don't spend the night, I am only really interested in not smelling to the bear, not keeping them from getting to my food while I'm sleeping. I was wondering if a dry sack, like this ![enter image description here](https://i.stack.imgur.com/FlkeM.jpg)

would seal the contents so they don't smell outside, just like they keep water from getting in. The advantage of this vs. a bear vault is that the extra air can be bled out for a minimal size of the cargo in the backpack.