The invention provides a canister used for food product such as coffee and a packaging system comprising the same. At least 50% of the surface area of the canister sidewall is flat except it is deviated with 1-4 concaved grooves. The canister is made of a polymeric material at a usage of no more than 1.0 grams per cubic inch of the volume of the canister. When sealed, the canister can maintain its shape under a top load of at least 2.0 pounds per cubic inch of its volume and a vacuum pressure of at least 18 kPa caused by higher external pressure compared to internal pressure.
