CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Determination of DPPH radical scavenging activity in fermented soybean enriched with isoflavones
Autor/es:
MARAZZA, J.; NAZARENO, M.A.; GARRO, M.S.; SAVOY DE GIORI, G.
Lugar:
San Miguel de Tucumán, 15-17 de setiembre
Reunión:
Simposio; III International Symposium on Lactic Acid Bacteria. Second Argentinean LAB Net Meeting Internacional; 2009
Institución organizadora:
CERELA-CONICET
Resumen:
The development of new natural healthy products that improve the health of consumers is the main goal of the food industries. Isoflavones (IS) are non steroidal compounds that are able to produce several beneficial effects on consumers. The prevention of heart disease, reduction of serum cholesterol and antioxidant activities is some of the many properties attributed to IS consumption. Soybean are a major source of IS and contain two principal forms, inactive b-glucosides (dadizin and genistin) and active IS aglycones (dadizein and genistein), which are released from b-glucosides by action of microbial gut b-glucosidases. Lactic acid bacteria with b-glucosidase activity could by used to increment the content of IS with biological activity. The aims of this study were a) increase the amount of active aglycones by fermentation of soymilk with L. rhamnosus CRL981, b) determinate the total soluble phenolic content in fermented soybean and c) evaluate their antiradical activity. Soymilk was fermented during 24 h at 37C and samples were taken at 0, 3, 6, 9, 12 and 24h. The IS content was determined by HPLC. The total soluble phenolic content was determinate by spectrophotometric analysis using Folin-Ciocalteu assay. The antiradical activity, expressed as a percentage of antiradical activity (%ARA), was determined spectrophotometricaly using DPPH radical. At the end of fermentation, 54.7% of daidzin and 100% of genistin were hydrolyzed by action of alpha-glucosidase enzyme upon isoflavone glucosides. The total soluble phenolic content in fermented soymilk did not change during fermentation showing a value of 106.2 ug of galic acid equivalents per milliliter of soymilk. With respect to antiradical activity soymilk showed an increase reaching a value of 41.8%ARA at 24h of fermentation. This increase in the % ARA along fermentation is consequence of increase of aglycones content which is able to scavenge the free radical present in the reaction mixture. The fermentation of soymilk with L. rhamnosus CRL981 allowed the increase of the content of biologically active IS. Also, we demonstrated that IS are able to scavenge the free radical preventing the tissue and cell damage produce by them during oxidative stress conditions. The use of lactic acid bacteria with alpha-glucosidase activity would allow the elaboration of soybean products enriched in isoflavones with beneficial effects to consumers.