Amaranth (Amaranthus caudatus L.): Nutritional Composition, Bioactive Compounds, Processing Technologies, Food Applications, and Future Perspectives

Amaranth (Amaranthus caudatus L.) is an Andean pseudocereal with a nutritional profile characterized by its protein, dietary fiber, and bioactive compound content, adequate balance of essential amino acids, and the presence of bioactive compounds with antioxidant, anti-inflammatory, and cardiometabolic properties. This review analyzes the main processing methods applied to amaranth, including milling, roasting, popping, rolling, extrusion, germination, fermentation, encapsulation, and component isolation, describing how these technologies modify its nutritional, functional, and technological properties. It also examines its applications in various food categories, such as baked goods, extruded snacks, fermented beverages, symbiotic foods, and gluten-free formulations, highlighting its potential as a functional food ingredient for developing functional foods and nutraceuticals. Furthermore, this study discusses the technological and industrial challenges associated with its processing, including structural, sensory, and scalability limitations, within the context of the growing global demand for healthy and sustainable foods. Finally, the study identifies knowledge gaps and research priorities to optimize processing conditions, improve sensory acceptability, and enhance industrial value, thereby supporting further evaluation of its integration into food production systems.