Bears have a very good sense of smell and can usually smell foods and smells from a mile or 2 miles away.
So while a Ziploc bag can help seal in some of the food smells the bears can likely smell the food coming through the Ziploc bag.
So keep all food out of sight from bears and possibly high up in a tree to avoid bears from getting to it.
Keep food stored inside your trunk of your car or inside a camper or RV if you're in a camper or RV.
Never store food inside your tent because the bears could come into your tent while asleep and attack you for the food.
Bears just like dogs have a good sense of smell and can smell just about anything that is sealed.