Plastic containers work well for storing foods, but the common problem is the food odor that gets left behind. Coffee carries with it a strong scent, and if you store coffee grounds in the container for an extended period of time. the plastic absorbs the smell. To prevent the next foods you store in the container from absorbing the coffee smell and taste, deodorize the plastic with safe household elements.
Wash the plastic with warm, soapy water to remove any coffee residue. Rinse the plastic when done and smell.
Sprinkle baking soda into the plastic cup or container, cover and let sit overnight. The baking soda is a natural odor absorbent that will pull out the coffee odor.
Pour about 1 cup white vinegar into the plastic bowl. The vinegar is also a deodorizing element, and will foam when mixed with the baking soda. Cover the container or cup and shake to thoroughly clean the plastic. Discard the mixture and rinse the plastic.
Soak the plastic in a 50/50 solution of water and white vinegar for about one hour if any odor remains. Wash the plastic with soapy water afterward, rinse and dry the plastic.