In the food and feed industry, large amounts of agro‐industrial basic materials are used for the formulation of end‐products meant for human or animal nutrition. These basic ingredients and the final end‐products often have to fulfil special requirements regarding nutritional and anti‐nutritional factors (ANFs). A special need therefore exists for the identification and characterization of these factors. As there is increasing interest in the use of legume seeds as protein and energy sources in various foods and feedstuffs, a number of methods for the immunochemical detection and quantification of proteinaceous ANFs in legumes have been developed. Current knowledge of the immunochemical detection and analysis of antigenic proteins in legume seeds and some of the phenomena of these proteinaceous ANFs in young animals are described in this paper.