Chemical composition and nutritional evaluation of quinoa (Chenopodium quinoa Willd.)

Quinoa is an Andean pseudocereal that contains 14.6% protein (fresh wt). This protein is of an exceptionally high quality and is particularly rich in histidine and lysine (3.2 and 6.1% of protein composition, respectively). Raw debittered quinoa shows PER values 78-93% those of casein and when cooked its PER values can reach 102105% those of casein. The albumins + globulins are the major protein fraction of quinoa (44-77% of total protein) and a low percentage of prolamins (OS-7.0%) indicates that quinoa may be free of gluten. The fat content of quinoa is 5.6% (fresh wt) with the essential fatty acids, linoleic and r-linolenic acids, accounting for 5563% of the lipid fraction. Quinoa oil is particularly stable due to relatively high concentrations of natural antioxidants, namely 690-754 ppm of a-tocopherol and 760930 ppm of y-tocopherol in the raw oil, falling to 450 and 230 ppm, respectively, in the refined oil. Given the high quality of its oil, and the fact that some varieties show fat concentrations up to 9.5%, quinoa could be considered as a potentially valuable new oil crop. Starch accounts for 52-60% of grain weight, but the amylose content of this starch is low, 1 l-12%. The majority of the starch granules are between 0.7 and 3.2 pm, but unlike other small granule starches such as rice, quinoa initiates gelatinization at a much lower temperature (about 58°C). Polyamine concentrations in quinoa at 22 18-2690 nmol/g fresh wt may contribute to, but are unlikely to be solely responsible for, its “earthy” taste. On the basis of 100 g dry wt, quinoa has more riboflavin (0.39 mg), a-tocopherol(5.37 mg), and carotenes (0.39 mg) than barley, rice, or wheat, but only a fifth as much niacin ( 1.06 mg). In terms of a 100-g edible portion, quinoa supplies 0.20 mg B6 (10% of RDA), 0.61 mg pantothenic acid (9-15% RDA), 23.5 pg folic acid ( 12% RDA), and 7.1 pg biotin (7-24% RDA); other vitamins are present at levels below 10% RDA. On the basis of 1 kg dry wt, quinoa has more Ca (1487 mg), Fe (132 mg), K (9267 mg), Mg (2496 mg), Cu (5 1 mg), Mn (100 mg) and Cl(1533 mg) than other cereals; the Na:K ratio is 1:76. In terms of RDAs and depending on age and sex, a 100-g edible portion of quinoa supplies 27-40% of the Fe, 23-76% of Mg, 47-200% of Cu, 1 l-16% of P, 15-19% of K, lo-15% of Zn, and only l-2% of Na. The major antinutritional factors in quinoa are saponins, which can be removed by washing or abrasive dehulling; they do not exceed 0.0 1 g in a 100-g edible portion. Quinoa leaves contain more fat (1.8%), ash (3.3%), fiber (1.9%) nitrates (0.4%), vitamin A (2085 pg RE/lOO g), vitamin E (2.9 mg (u-TE/lOO g), Mg (83 mg/lOO g), and Na (289 mg/lOO g) than spinach leaves on a fresh weight basis, but only half the