Food additives are substances of natural origin or obtained by chemical synthesis. Among these additives, food antioxidants play an essential role in preserving food quality by neutralizing free radicals and inhibiting oxidation reactions, which helps prevent food spoilage and maintain its freshness, taste, and nutritional value. In addition, dietary antioxidants may also be beneficial to health. This is particularly the perception that consumers have in relation to antioxidants of natural origin, such as plant extracts. In this paper, we have focused on the case of rosemary extract as a food additive, authorized in many countries, including the United States and Europe, under the code E392. Through the examination of patent documents available in specialized databases and using appropriate keywords, our research made it possible to go back in time to show, first, the uses of rosemary extract and, second, the exploitation of rosemary extract in the field of food. We selected 411 relevant documents (granted patents and patent applications), of which almost 40% were filed in China. The first patent found was published in 1984, and it concerned a method to obtain a highly effective antioxidant suitable for preventing the oxidation of food from rosemary. This patent was followed by others who claimed, among other things, more effective methods to extract rosemary. More recently, innovations have focused on the synergistic effect of rosemary extract with other compounds, particularly for antimicrobial action in food preservation.