The objective of this work was to assess the effects of hydrothermal treatments and the environmental and genetic variability on the isoflavone aglycones concentration in soybean [Glycine max (L.) Merrill] grains. The study was carried out with the soybean cultivars BR 36, FEPAGRO RS-10, and BRS 155, cultivated in three locals of Paraná State (Londrina, Capanema, and Palmas), during 1999/2000 soybean season, submitted to hydrothermal treatments at 40, 50 and 60°C for 12 and 18 hours. Higher concentrations of total isoflavones (280 mg/100 g) were observed in grains harvested in Palmas, where the average temperature during pod filling was 19ºC. In Londrina (23ºC), there was lower concentration of isoflavones (140 mg/100 g). The cultivar BRS 155 presented the highest content of total isoflavones in Palmas and in Londrina. Non-treated grains of BRS 155 showed in average 4.0 mg/100 g of aglycones, which increased to 52 mg/100 g, after hydrothermal treatments. The treatment at 50ºC for 12 hours was the most effective in developing isoflavone aglycones. At 60°C, there was a decrease of the aglycones, due to inactivation of b-glycosidases. Malonyl forms, which are thermal unstable, were reduced at higher temperatures.
Glycine max; glycosides; functional foods; heat treatment
