RESUMO
In this study, the effect of malting process on the antioxidant compounds and antioxidant capacity of quinoa seeds was studied. The optimal germination conditions were germination temperature of 23 °C, degree of steeping of 36% and germination time of 3 days. Under these conditions, green quinoa malt was obtained and subsequently roasted at different temperatures (100-190 °C). Results showed maximum increases in phenolic compounds, Maillard reaction products and antioxidant activity (DPPH radical scavenging and reducing power) in samples roasted at 145 °C for 30 min, whereas a more intensive thermal treatment (190 °C) diminished the levels of all evaluated variables. Thus, malting with a moderate thermal treatment could be considered as an effective process to enrich antioxidants in quinoa grains for their further use as functional ingredient in the production of gluten-free foods and beverages.
RESUMO
Quinoa (Chenopodium quinoa) seed has gained a great interest in the last years, mainly due to its nutritional properties and its content of antioxidant substances with health-promoting properties in humans. In this work, the effect of germination time and fermentation on the levels of antioxidant compounds (ascorbic acid, tocopherol isomers and phenolic compounds) and antioxidant activity of quinoa seeds was evaluated. Fermentation was carried out naturally by the microorganisms present in the seeds or by inoculation with two Saccharomyces cerevisiae strains (used for baking and brewing). Ascorbic acid and total tocopherols were significantly increased (p ≤ 0.05) after 72 h of germination process in comparison with raw quinoa seeds, whilst fermentation caused a decrease in both types of compounds. Phenolic compounds and antioxidant capacity were improved using both bioprocesses, being this effect more noticeable for germination process (101 % of increase after three days of germination). Germination and fermentation proved to be desirable procedures for producing enriched ingredients with health-promoting antioxidant compounds in a natural way.