Abstract: The present invention relates generally to the field of beverage capsules. In particular, the present invention relates to a biodegradable top membrane of a beverage capsules. The biodegradable top membrane of a beverage capsule is pierceable by injection means of a beverage preparation machine which are adapted to inject an extraction liquid under pressure inside a closed chamber containing a mass of soluble and/or extractable food material. Remarkably, the top membrane possesses the necessary physical properties to be useful for beverage capsules while being biodegradable. The biodegradable top membrane for a beverage capsule comprises at least one polyhydroxyalkanoate (PHA).