Effect of flour extraction and baking process on vitamins B1 and B2 content and antioxidant capacity of traditional rye bread

Resumen del póster presentado al IFT Annual Meeting, celebrado en New Orleans (L.A, USA), del 28 de junio al 1 de julio de 2008.The milling and bread making processes can affect B vitamins, phenolic compounds, reduced glutathione, tocopherols and tocotrienols known by their role on antioxidant capacity. Therefore, the effect of rye flour extraction rates and baking process on thiamin and riboflavin content was analyzed by HPLC. Moreover, the antioxidant capacity of traditionally rye bread was studied. Rye flour with extraction rate of 100% (F -100%) and 92% (F-92%) were taken for bread baking whilst commercially available white wheat with flour extraction rate of 70% was used as reference. The antioxidant properties of dough and bread extracts were evaluated as Trolox EquivalentAntioxidant Capacity (TEAC), Peroxyl Radical Scavenging Capacity (PRTC), Superoxide Dismutase (SOD)-Iike activity. Moreover, the reducing capacity of both extracts was provided by Folin -Ciocalteu reagent (FCR). Thiamin concentration was 10.9 and l0.8% higher in rye dough formulated with F-100% thanF-92% and wheat dough, respectively. Regarding riboflavin content 16% higher concentration was noted in rye dough madeJrom F-100% t11an F-92%. Wbeat dough riboflavin content was at least four-fold lower than rye doughs. Moreover, rye breads baking process reduced thiamin (20%) and riboflavin (30%) contents. Higher thiarnin reduction (56%) was noted in wheat bread whilst riboflavin contentwas reduced only 10% compared to wheat dough. Changes of thiamin content during baking were weakly correlaied with TEAC (r=0.68), PRTC (r=0.47), SOD-Iike activity (r=0.69) and FCR reducing capacity (r=0.71) while changes in riboflavin content were strongly correlated with TEAC (r=0.96), PRTC (r=0.92) and FCR reducing capacity (r=0:98). A 200g portian daily intake of bread F-100% might provide about 40% and 22% of thiamin and riboflavin, respectively for adolescents and adults. Moreover, a lack of reduction of antioxidant capacity during rye bread baking was observed and this was almost three-fold higher in rye than wheat bread. Therefore, rye breads should be highly recommended for human nutrition.Peer reviewe