Optimization of germination conditions by response surface methodology to obtain oat healthy products

Póster presentado a la EuroFoodChem XIX Conference, celebrada en Budapest (Hungria) del 4 al 6 de octubre de 2017.Oat is gaining a great attention worldwide due to its excellent nutritional value increasing its demand among informed population. Numerous scientific studies have demonstrated the health-promoting effects of oat consumption, which are linked to its high concentration of bioactive compounds, most of them exhibiting antioxidant properties. Oat is usually consumed as flakes and more recently as milk-like beverages. Germination is a natural process that enhances the biologically active compounds of grains and, hence, their health attributes. However, less is known about the effect of germination on the composition of phenolic compounds and antioxidant capacity of oat. The objective of this study was to optimize germination conditions by using response surface methodology (RSM) in order to maximize the content of free phenolic compounds and antioxidant properties of the final germinated product. Free, bound and total phenolic compounds (FPC, BPC and TPC, respectively) were determined by the Folin-Ciocalteau method in methanolic and alkaline extracts and the antioxidant capacity was evaluated by different methods in germinated grain extracts (ORAC, FRAP, TEAC and DPPH) or in the whole germinated grain (QUENCHER-DPPH). Since germination time and temperature are key factors affecting the bioactivity of sprouts, the impact of time interval (24-216h) and temperatures (12-20°C) were analyzed using a 22 central composite rotational design. Non germinated oat showed a TPC, FPC and BPC of 805, 464 and 332 mg GAE/100g, respectively, and an ORAC value of 618 mg TE/100g. The regression models obtained exhibited large determinant coefficients (R2 > 0.85) showing their suitability to explain the variation on experimental data, with exception to BPC, where the developed model was not significant. A desirability function was used to obtain optimal germination conditions to enhance the antioxidant properties of the grains, which corresponded to 160-216h at 20 ºC. Under these conditions, 1380-1641 mg GAE/100g, 668-858 mg GAE/100g, 2484-3092 mg TE/100g, 58.7-61.0 mmol Fe/100g, 1073-1142 mg TE/100g, 31%, and 29-33% reduction, were obtained for FPC, TPC, ORAC, FRAP, TEAC, DPPH and DPPH-QUENCHER, respectively. In conclusion, germination is suggested as a valuable process to improve the content of free phenolic compounds and the antioxidant activity of oat. The oat sprouts obtained can be consumed as fresh product in soups or salads but also can be dehydrated and used as functional ingredients that can be incorporated into novel foods diversifying the oat food market and providing health-promoting benefits to consumers.This research was cofunded by the Ministry of Economy, Industry and Competitiveness (Spain) and Emilio Esteban S.A. through a CDTI projects number IDI-20150913. E. Peñas thanks to Ramón y Cajal for financial support.Peer Reviewe