Perennial Sainfoin Seeds As an Emerging Plant-Based Food: Effects of Thermal Processing on Nutritional Quality, Sensory Properties, Toxicity, and Immunoreactivity

Sainfoin (Onobrychis viciifolia L.) seeds exhibit a high nutrient density, containing approximately 42% protein, 9% fat, and 45% dietary fiber. This study investigated the potential of sainfoin seeds as a food source by subjecting them to conventional processing methods, including hot air and blanching, as well as infrared treatment, which is known for its energy efficiency. The impact of processing on amino acid, tocopherol, and fatty acid profiles, as well as hydroxymethylfurfural (HMF) content, was assessed. Additionally, sensory attributes were evaluated using descriptive sensory analysis. Cellular toxicity and macrophage-mediated immunoreactivity, together with the effects of thermal processing, were assessed using in vitro models relevant to human physiology. The seeds contained significant levels of γ-tocopherol and exhibited amino acid profiles—particularly arginine and isoleucine—comparable to those of plant foods such as soy and nuts, with approximately 88% of their fatty acids being unsaturated. Hot-air treatment resulted in the formation of HMF, which was not detected in the other treatment groups and was also associated with more pronounced changes in sensory characteristics compared with the other processing methods. Either raw or processed seeds exhibited no cytotoxicity or marked macrophage-mediated inflammatory response under the tested in vitro conditions, supporting their preliminary potential for incorporation into food products.