A vent assembly includes a bag construction configured to contain a food product such as a popcorn charge. The bag construction is formed of at least one sheet of polyester film material and configured to expand from a collapsed configuration to an expanded configuration when the food product is heated in a microwave oven. The vent assembly includes a first portion of the bag construction and a second portion of the bag construction that is configured to be folded against the first portion. The second portion includes a venting structure formed in the sheet of polyester material. An adhesive is applied to at least one of the first portion or the second portion. The adhesive is configured to adhere the first portion to the second portion so that the vent is at least partially sealed while the bag construction is in the collapsed configuration and to release the first portion from the second portion as the bag construction expands to the expanded configuration to allow the vent to at least partially open.