104C-22 |
The effect of planting time and location on the isoflavone content of different soybean (Glycine max) cultivars |
V. B. FIGALLO, Department of Nutrition and Food Sience, University of Maryland, 0112 Skinner Building, College Park, MD 20742, W. J. Kenworthy, Department of Natural Resource Sciences and Landscape Architecture, University of Maryland, 1112 H.J. Patterson Hall, College Park, MD 20742, and M. M. GIUSTI, Department of Nutrition and Food Science, University of Maryland, College Park, 0112 Skinner Building, College Park, MD 20742. There is evidence to suggest that diets containing high amounts of soybean isoflavones are associated with overall low cancer mortality rates, particularly in cancers of colon, breast and prostate. The importance of understanding the environmental factors that affect the isoflavone formation in the soybeans is essential for the correct selection of special cultivars for specific purposes. Our objective was to evaluate the effect of the planting time and location in the qualitative and quantitative composition of isoflavones in different soybean cultivars selected for special traits. Twenty-four soybean cultivars were grown randomly at two different locations in Maryland (Wye and Poplar Hill Farms). Two different planting times were analyzed for each variety. Methanol (80% in water) was used for isoflavone extraction from the seeds using flavone as internal standard. The samples were filtered and the solvent evaporated. Isoflavone extracts were re-suspended in 16% acetonitrile, and analyzed by HPLC. Cultivars were analyzed for isoflavone content and profile. Experiments were done by duplicate. HPLC conditions were optimized to achieve separation of daidzein, glycitein and genistein and their 9 derivatives. Genistein derivatives were present in highest proportion in all cultivars followed by daidzein and glycitein-related isoflavones. The effect of location was significant for most cultivars, with soybeans grown in Poplar Hill exhibiting higher concentrations of isoflavones than Wye Farm location. There was also an effect of planting time, with soybeans seeded after barley showing higher isoflavone concentrations than plants seeded during the full season (complete period). Planting time and location had an impact on soybean recoveries and profiles. Selection of planting time and location affect the concentration of isoflavones in the seeds. Our results suggest that it may be possible to have double planting during a growing season (barley or similar followed by soybeans) and still obtain seeds with high isoflavone content.
Session 104C, Fruit & Vegetable Products: Vegetables (Processed)
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