Get a rat sack or a bear can. Or an Ursack - though if you ever go to areas where bear cans are required that won't help you, you'll still need to rent an approved bear can.

Leaving your food in ziplocs doesn't help. They're not odor proof at all. I have been able to vacuum pack coffee in foodsaver vac bags, which are nylon, and keep coffee odor from permeating the contents of my bear can; however, my nose is not as sensitive as a raccoon's or bear's and so I will never trust any bag to be completely odor proof - including the OP sacks they sell at REI.

You have auto insurance, life insurance, medical insurance and you fasten your seatbelt - you need to protect your food in the wilderness. I've never had a bear touch my canister but I'm certainly not about to go without it.