The total phenol and total flavonoid amounts of raw and roasted quinoa grains were measured between 135.63 (control) and 176.75 mgGAE/100 g (15 min) to 332.86 mg/100 g (control) and 421.43 mg/100 g (15 min), respectively. Also, antioxidant activity values of quinoa grain extracts were established between 14.15 mmol/kg (control) and 14.84 mmol/kg (15 min). Although gallic acid contents of quinoa grains are detected between 3167.98 (5 min) and 3726.00 mg/100 g (control), catechin amounts of quinoa seeds were identified between 11.73 mg/100 g (15 min) and 24.15 mg/100 g (10 min). The oleic and linoleic acid amounts of the oils of raw and roasted‐quinoa grains were identified between 26.68% (15 min) and 37.80% (control) to 37.31% (control) and 51.81% (10 min), respectively. Total phenol, flavonoid amounts and antioxidant activity values of roasted quinoa grains increased with the roasting time. In general, the amounts of oils increased with the increase of roasting time, whereas the amounts of other fatty acids decreased. Practical applications Quinoa seeds possess nutritional properties due to phytochemicals. Quinoa seeds are ground to make a variety of baked goods, or they can be puffed to produce breakfast foods and snacks. Quinoa seeds are consumed in cooked rice, soups, yoghurt, and salads. Roasting can affect the amounts of phytochemical of edible seeds. Quinoa seed, considered as an alternative oilseed crop due to the quality and quantity of the lipid fraction, is rich in essential fatty acids (linoleic and alpha‐linolenic acids).