Quinoa (Chenopodium quinoa Willd.) as a Functional Food Ingredient: Bioactive Compounds, Processing Effects and Bio accessibility

Quinoa (Chenopodium quinoa Willd.) has transitioned from a regional Andean staple to a globally traded pseudocereal valued for its nutrient density, gluten-free status, and adaptability to diverse agroecologies. Beyond macronutrient quality, current quinoa research increasingly emphasizes bioactive compounds that may support “functional food” positioning, including phenolics (free and bound forms), flavonoids, betalains (in pigmented genotypes), triterpenoid saponins, bioactive peptides released during processing or digestion, and fibre-associated polysaccharides. At the same time, translational progress depends on resolving a persistent tension: many health-relevant phytochemicals are sensitive to processing, while consumer acceptance often requires processing precisely to reduce bitterness and improve texture, digestibility, and shelf stability. This review synthesizes recent advances on quinoa’s bioactive composition, the mechanisms by which key compound classes may contribute to antioxidant, cardiometabolic, and gut-microbiome–related outcomes, and the extent to which these compounds remain bioaccessible after domestic and industrial transformations. Evidence shows that germination, fermentation, and selected non-thermal treatments can enhance certain phenolics and functional attributes, whereas some thermal operations may either decrease labile compounds or improve extractability depending on matrix changes. Emerging work on quinoa proteins highlights modification strategies that improve solubility, emulsification, and gelation, enabling applications in gluten-free bakery, pasta, beverages, dairy alternatives, and hybrid foods. Finally, this review identifies research gaps that limit clinical translation and product standardization, including cultivar-by-environment variability, insufficient human trials with well-characterised quinoa matrices, and limited harmonization in analytical workflows for bioactive quantification and bioaccessibility.