In this sense, antioxidants, free radical scavengers and oxygen scavengers can be incorporated into the packaging materials to produce active materials. Their function is to interrupt the free radical chain reactions by reacting with ROS by hydrogen donation, hence preventing the ROS attack to the unsaturated molecules present in foods. Antioxidant materials are particularly interesting in those systems where a specific quantity of oxygen is beneficial for making some packaged products appear fresher and more desirable to the consumer, i.e., red meat fresh appearance.