Effect of pearling and altitude on quinoa grain composition and protein digestibility

This study examined how pearling intensity and cultivation altitude jointly influence the nutritional composition, in vitro protein digestibility, and saponin content of quinoa ( Chenopodium quinoa Willd.) produced at 2000, 2500, and 3000 m a.s.l. in Colombia. Grains were subjected to four abrasion levels (0%, 10%, 30%, and 50%), and their proximate composition, amino acid profile, vitamin content, saponin concentration, and protein digestibility were determined. The antimicrobial activity of pearling residues was also assessed. Pearling at ≥30% decreased saponin content to <0.11%, meeting safety requirements for human consumption and increasing protein digestibility by 11.56%. However, this treatment also led to substantial reductions in fat, fiber, ash, vitamins, and essential amino acids. Although altitude significantly affected several nutritional attributes, it had no measurable impact on saponin levels. Pearling residues exhibited antimicrobial activity, indicating their potential as bioactive byproducts. Overall, moderate pearling effectively enhances quinoa digestibility and reduces antinutritional compounds while generating residues with possible applications in food and pharmaceutical sectors. • Pearling strongly modulates quinoa nutritional composition and digestibility • ≥30% pearling reduces saponins below 0.11% while increasing protein digestibility • Ppearling causes significant losses of lipids, fiber, minerals and vitamins • Altitude affects nutrient profiles but not saponin reduction efficiency