To neutralise lingering food smells in plastic containers, you can use baking soda and wash them thoroughly with hot water.
*Disclaimer: Alfa Cleaners do not recommend or endorse any particular brand, detergent or cleaning agent. The above is provided for information only. You must determine yourself whether any of the possible cleaning agents are suitable and safe. Alfa Cleaners will not be held responsible for the use or misuse of any of this information.