Quinoa has more proteins than the other grains mentioned (Table 2), and its grains contain all the essential amino acids (tryptophan has the lowest concentration). The presence of essential amino acids has also been confirmed in the less well known varieties of quinoa, such as those pertaining to Coastal ecotypes from central and southern Chile (Miranda et al., 2012a). As mentioned, quinoa is similar to rice in terms of culinary uses, transportation and storage, but once processed quinoa grain offers superior nutritional quality. In most countries, rice is consumed mainly as “white rice”. White rice differs from the wholemeal rice because it has been dehusked, a process which results in a significant reduction in protein content (Table 3). On the other hand, in the case of quinoa, while peeling and/or washing is often necessary to remove the saponins from the epicarp (few varieties are sweet or lacking in saponins), far fewer proteins are lost than in the case of rice, where 16–17% of high quality proteins are lost during the peeling process. In contrast, with quinoa, removal of the outer seed layer , which is rich in saponins, fibre and flavonoids, but protein-poor, results in the consumable grain gaining roughly.
The nutritional value of quinoa recognized in every literature review over the last 20 years can only be confirmed and enriched further by more research. The high quality proteins contained in its seeds are little affected by the cultivation conditions, particularly in water-deficit situations. This makes the plant very resilient, a useful quality where agriculture faces problems of aridity, degraded or salinized soils, and even excess greenhouse gas emissions. The 20 amino acids often maintain their proportions in different cultivation conditions, with little impact on the quality of their proteins. Their minerals (P, K, Ca, Mg, Mn, Zn), oils, vitamins (B1, B2, B3, C, E) and flavonoids seem to combine with each other synergetically, to give this plant highly nutritional and antioxidant qualities, maintained even under processing at high temperatures. Its advantages over rice, its similar culinary uses and post-harvest processes, and its low water demand, suggest that quinoa grains could be at least a partial replacement for rice, with excellent benefits for human health, in both deficit populations and in populations where nutrition problems arise from excess.