In Peru, chronic malnutrition is associated with low protein intake and quality. While plant proteins from seven-seed flour (7SF) used in nutritional beverages offer a sustainable alternative, there is no standardized formulation in terms of protein value, quality, and digestibility. Previous research lacks an analysis of optimal formulations that consider the quantity, quality, and digestibility of proteins in 7SF mixtures. This study aimed to optimize the formulation of 7SF through mixture design (MX), considering protein content and quality (PDCAAS). Also, in vivo digestibility was assessed to verify its potential as a protein source in human diets. The aminoacid profiles of cereals, andean grains, and legumes were analyzed to identify similar profiles by principal component analysis. MX was carried out in Desing Expert software taking into account: protein content ≥ 15%, PDCAAS ≥ 0.85 and low costs. Three best mixtures obtained (without repeating flours with similar amino acid profiles) were selected for sensory and viscosity evaluation. Tarwi and barley were excluded due to specific aminoacid deficiencies and costs, while soybean content was reduced due to cultural factors and protease inhibitors.Sensory evaluation only showed difference in consistency.The final formulation selected included kiwicha (0.251), faba bean (0.05), pea (0.221), soybean (0.327), maca (0.05), rice (0.05) and wheat (0.05). This optimal formulation underwent in vivo digestibility evaluation using Holtzman rats over a period of 9 days to assess protein quality parameters. Digestibility tests revealed an apparent digestibility of 48.53 ± 13.71, a true digestibility of 37.52 ± 12.37, a biological value of 75.05 ± 0.33 and a nitrogen balance of 0.20 ± 0.09. The protein quality of the 7SF formulation without heat treatment showed lower biological values compared to previous studies, which establishes a basis for future research focused on improving the formulation or treatments to optimize digestibility and biological utilization.