Comparative study on chemical and lipid composition of two varieties of quinoa seeds (Chenopodium quinoa L.)

The seeds of two varieties of quinoa (Chenopodium quinoa L.), white and black, were analysed for their chemical composition and a detailed study of their lipids was carried out as well. The chemical composition of the seeds was as follows: protein content - 15.7% and 14.5%, lipids - 5.9% and 6.6%, carbohydrates - 65.6% and 64.6%, starch - 40.2% for both varieties, water soluble sugars - 7.2% and 5.5%, and minerals - 2.4% and 2.3%, respectively. The oil content was about 6.0%, but high amounts of biologically active compounds in the seed oils of black quinoa were noted (tocopherols - 1102 mg/kg, phospholipids - 7.6% and sterols - 3.4%), while in the seed oils of white quinoa tocopherols were 365 mg/kg, phospholipids - 11.9% and sterols - 2.1%. Linoleic and oleic acids dominated in both oils, followed by palmitic and linolenic acid. Unsaturated fatty acids predominated in the lipid fraction where the content of polyunsaturated fatty acids was 53.1% (white quinoa) and 49.4% (black quinoa), followed by monounsaturated fatty acids - 30.7% and 33.5%, respectively. In the tocopherol fraction of the oils the main component was - tocopherol, followed by α- tocopherol. The main component of the sterol fraction was - sitosterol (80.1% and 75.7%). Phospholipids in the seeds of the two varieties of quinoa had similar composition. Despite some differences in the chemical and lipid composition, these quinoa seeds were established to be a valuable source of proteins, carbohydrates and healthy lipid-soluble bioactive components for human nutrition.