Effect of germination on selected phytochemicals and antioxidant activity of quinoa (Chenopodium quinoa)

Abstract

Quinoa (Chenopodium quinoa) is a pseudo-cereal native of the Andean region of South America and has gained importance due to its potentially good nutrient content and natural antioxidants. In this research undertaking, quinoa seeds were subjected to germination and subsequent tray drying at 40ºC to study the changes in polyphenols, tannins, saponins and antioxidant activity during different germination stages. The total phenolic content (TPC) of germinated quinoa samples ranged from 150.8±2.26 mg GAE/100 g to 171.2±1.69 mg GAE/100 g with the highest value for the 48 h germinated sample. The total tannin content was highest (343±1.41 mg TA/100 g) in raw sample which decreased by 14% during 48 h of germination. Total saponin content decreased from 1.597 g SE/100 g to 0.938 g SE/100 g during 48 h germination. There was a significant two-fold increase in digestible starch during germination. The antioxidant activity was determined using 3 methods: DPPH scavenging activity, Ferric Reducing Antioxidant Power (FRAP) and ABTS reducing capacity. The DPPH scavenging activity of the germinated sample was found to have increased by 7.5% compared to the raw sample. Moreover, the antioxidant activity of the 48 h germinated sample was found to be higher than the standard ascorbic acid. The antioxidant activity of the 48 h germinated sample determined by FRAP (412.85 mg AAE/100 g) accounts for a 48.68% increase. The % ABTS reducing capacity of 48 h germinated sample was 86.65% higher than the raw quinoa seeds. Germination of quinoa improved the phenolic content and antioxidant activity of quinoa seeds and decreased the saponin content. Germinated quinoa can be ideally used in functional food formulations.