Quinoa: Protein and Nonprotein Tryptophan in Comparison with Other Cereal and Legume Flours and Bread

Abstract

Making composite flours with nonwheat cereals or supplementing its flour with protein-rich sources, such as legume flours, especially in countries in which the production of wheat is insufficient, can improve the nutritional value of bread. This chapter describes the techniques used to analyze protein and nonprotein tryptophan, reports their contents in cereal and legume flours, and compares the concentrations of this amino acid in these flours. It also highlights the importance of nonprotein tryptophan in calculating the nutritional value of foods. In addition, quinoa is taken into consideration as an alternative protein source whose nutritional value is similar to that of milk. Quinoa is a dicotyledonous indigenous plant of the Andes growing at an altitude higher than 4000 m. It is still widely cultivated in South America, and it is considered an excellent pseudocereal for its nutritional characteristics. Its use should be promoted to enrich the nutritional value of bakery products. Tryptophan is present in cereals and legumes not only as protein tryptophan but also as nonprotein tryptophan. The determination of nonprotein tryptophan in cereals and legumes is very important because this fraction is easily absorbable at the gastrointestinal level, increasing its availability for brain serotonin synthesis. © 2011 Elsevier Inc. All rights reserved.