Enhancement of the rancidity stability in a marine-oil model by addition of a saponin-free quinoa (Chenopodium quinoa Willd.) ethanol extract

11 pages, 3 tables, 4 figuresThis research focused on the antioxidant capacity of quinoa (Chenopodium quinoa Willd.), being its basic objective to analyze the retention of this property in the case that a previous saponins removal by water washing was undertaken. Chemical analyses related to saponin content and antioxidant behavior were carried out on ethanolic extracts of two quinoa ecotypes (Ancovinto and Cancosa) and compared to quinoa that was not subjected to saponins extraction; comparison to positive control (BHT‐including condition) was also achieved. Lower contents on total polyphenols, total flavonoids and γ‐tocopherol, and antioxidant activity (DPPH assay) were observed in saponin‐free quinoa extracts from both ecotypes when compared with their saponin‐including counterpart. Further, the effect of the different kinds of quinoa extracts was comparatively analyzed in a marine‐oil heated model system. As a result, saponin‐free quinoa extracts led to marked lipid oxidation inhibition assessed by the determination of conjugated dienes, peroxides, thiobarbituric acid reactive substances, and polyenes, this effect being similar to the one produced by saponin‐including quinoa extracts. Consequently, the water‐washing process did not produce a detrimental effect over the inhibitory capacity of lipid oxidation of quinoa grain when evaluated in a lipid‐food system with high degree of unsaturation (i.e., marine‐oil model)Author M. Miranda acknowledges receiving a Chilean CONICYT scholarship. This work was supported by the Consejo Superior de Investigaciones Científicas (CSIC) through the Research Project 2013‐70E001Peer reviewe