Can bears smell food inside dry sacks?

Question

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

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.

Answer 1

No, it will not. A bear will smell your food regardless of what container you put it in. A dry bag may reduce the distance from which a bear can smell your food, but will not make it impossible to smell your food.

It's extremely uncommon – especially for black bears – for a bear to attack a person to try to steal their food. Unattended food is a big risk, but if the food is in your pack, it's not a significant problem. The bear may smell it, but it'll also smell you and hopefully hear you, and generally decide it's not worth the risk.

For day hikes I don't think special food protection against bears is necessary. Being aware of your surroundings and making sure bears hear you coming will be much more effective.

Answer 2

Bears have a seriously sensitive nose. I can't remember the correct values, but they have magnitudes more smell receptors than a bloodhound (I just looked it up, a bear's nose is estimated to be 7 times more sensitive than a bloodhound.

You can minimize what can be smelled by using ziplock bags and placing those in uncoated stainless steel containers. Stainless steel electrochemically absorbs many food smells.