the present invention relates to a food package for cooking , storing and heating of ready - to - eat food . the food package comprises a food container , a plastic film for sealing the food package from ambient air and being provided with an opening , said food package further comprising an openable and resealable valve membrane of a thermoelastic material covering said opening , wherein an adhesion between the valve membrane and the surface it is applied on is lower in a first area than in a second area , wherein said first area extends in a direction at least between said opening of said plastic film and an edge of said valve membrane , such that a canal may be created between said opening and a valve membrane periphery during cooking and / or heating of said ready - to - eat food , wherein the valve membrane has a production machine direction of the thermoelastic material which has a relationship to said direction of said first area such that an angle therebetween is within an interval of 60 ° to 90 °.