Evaluation of the influence of germination conditions on the phytochemical content and antioxidant activity of quinoa by response surface methodology

Resumen del trabajo presentado al VI Congreso Mundial de la Quinua y III Simposio Internacional de Granos Andinos, celebrado en Universidad Nacional del Altiplano de Puno (Perú) del 21 al 24 de julio de 2017.

Quinoa (Chenopodium quinoa) is a crop indigenous to the Andean region that has recently been introduced in North America, Europe, Asia and Africa due to its ability to adapt to a wide range of environmental conditions. Quinoa is receiving growing attention across the world due to its excellent nutritional value and high phytochemical content. Numerous studies have demonstrated the health-promoting effects of quinoa consumption, which have been linked to its high concentration of a wide range of bioactive compounds, most of them exhibiting antioxidant activity. Quinoa has been traditionally consumed as cooked seeds or used as an ingredient of bakery products. However, little is known on the effect of germination process on bioactive compounds and functional properties of quinoa. The objective of this study was to evaluate the influence of germination on gamma-aminobutyric acid (GABA) content, phenolic composition and antioxidant activity of quinoa by using response surface methodology. Since germination time and temperature are key factors affecting the bioactivity of sprouts, the impact of different times (12, 21, 42, 63 and 72h) and temperatures (12, 14, 20, 26 and 28°C) were analyzed using a 22 central composite rotational design. Non germinated quinoa showed a total phenolic content (TPC) and oxygen radical absorbance capacity (ORAC) of 270 mg GAE/100g and 1085.75 mg TE/100g, respectively. Germination caused a marked increase of both parameters, being the optimal conditions 42 h and 20° C, which increased 1.8- and 1.3-fold the TPC and antioxidant activity, respectively, in quinoa sprouts. GABA content was modified during germination, from values of 22.41 mg/100g in quinoa seeds to values in the range 17.97-122.32 mg/100g in the sprouts, depending on the germination conditions. The regression model obtained for GABA was not significant (R2 < 0.75) within the time and temperature ranges studied. However, the highest GABA concentration was found in quinoa sprouts obtained at 63 h and 26°C, which was 5.5-fold higher than that observed in seeds. The phenolic profile of sprouts obtained in the optimal conditions was studied by HPLC-DAD-ESI/MS. These sprouts exhibited greater concentration of both flavonoids and non-flavonoids compounds than seeds. Flavonols such as kaempferol-O-dirhamnosyl-galactopyranose and quercetin-O-glucuronide increased sharply during germination. Hydroxycinnamic compounds such as trans-p-coumaroylhexoside, trans-feruloylhexoside, and sinapoylhexoside acids were found in quinoa sprouts but not in quinoa seeds. In conclusion, germination in selected conditions is a valuable technological process to enhance the content of bioactive compounds and the antioxidant activity of quinoa. The consumption of fresh quinoa sprouts or their incorporation as ingredients into foods can provide beneficial effects in human health, and can diversify the quinoa food market.

This research was cofunded by the Ministry of Economy and Competitiveness (Spain) and the European Union through the project number AGL2013-43247-R. E. Peñas thanks to Ramón y Cajal Programme and Professor L. Paucar-Menacho to Consejo Nacional de Ciencia y Tecnologia (Peru) for financial support (Grant number 118-2013-CONCYTEC-FONDECYT).

Peer Reviewed