|Gonzalez-de mejia, Elvira|
Submitted to: Food Research International
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/9/2009
Publication Date: 8/1/2010
Citation: Paucar-Menacho, L.M., Berhow, M.A., Mandarino, J., Chang, Y., Gonzalez-De Mejia, E. 2010. Effect of time and temperature on bioactive compounds in germinated Brazilian soybean cultivar BRS 258. Food Research International. 43:1856-1865. Interpretive Summary: This research has shown that the use of soy-seed germination in food preperation enhances several key nutritional factors in soy. These factors can be used to develop new and improved soy foods and ingredients with altered levels of health enhancing components. A number of compounds found in soy have been shown to have important health benefits. Most soy products are prepared from the dry mature soybean. When the soybean is allowed to germinate before it is processed into flour and other products, however, the levels of a number of beneficial compounds can be increased. Using a new mathematical model, the effects of germination on a number of phytochemicals in soybeans from the cultivar BRS 258 were examined. An optimal germination time and temperature of 63 hours at 30 degrees C enhanced the levels of soy isoflavones, saponins and the protein lunasin, while decreasing the levels of the antinutritive proteins BBI, lectin and lipoxygenase. This could result in new foods and formulations for soy ingredients in foods.
Technical Abstract: The consumption of soybeans and soybean products has increased in the last few years due to the functional properties of bioactive compounds such as lunasin, Bowman Birk Inhibitor (BBI), lectin, saponins, and isoflavones. The objective of this study was to determine the effect of germination of soybean seeds cultivar BRS 258 on its bioactive compounds. Germination was carried out in a germination chamber with paper trays. Samples were frozen at –30°C, freeze-dried and milled to produce germinated soybean flour. Isoflavone and saponin determinations were analyzed by high performance liquid chromatography. Lunasin, BBI and lectin were analyzed by ELISA and western blot. The effects of the variations in germination time and temperature were analyzed using the Response Surface Methodology (RSM), with a 33 central composite rotational design. The independent variables studied were time and temperature. The germination conditions of soybean BRS 258 modified the concentrations of bioactive compounds within the ranges studied. It increased the concentration of lunasin, isoflavone aglycone, saponin glycosides, and decreased the concentration of BBI, lectin and lipoxygenase. Optimal increases in the concentrations of the isoflavone aglycones (daizein and genistein) and the saponin glycosides were observed with a 63 h germination time at 30°C. Both germination time and temperature had an influence on the composition and concentration the bioactive compounds in germinated soybean flour.