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SKROVANKOVA, S., SIKOROVA, P.: Vitamin B2 (ribofl avin) content in cereal products. Acta univ. agric. et silvic. Mendel. Brun., 2010, LVIII, No. 5, pp. 377–382 Vitamin B2 (ribofl avin) is a water-soluble essential vitamin. Nowadays an increased risk for ribofl avin defi ciency may be seen in people on special diets (diabetes mellitus), smokers or heavy alcohol drinkers. In the Czech diet the main sources of the vitamin intake are milk and dairy products followed by cereals and meat. Cereals are good source of this vitamin as it is widely and regularly consumed in different forms. Analyses of the vitamin B2 content in diff erent types of cereal products (fl ours, breads, pastries, breakfast cereals, cooked pasta) of Czech origin using HPLC with reversed phase and UV detection were done. The vitamin B2 content of chosen cereal products decreased in this progression: enriched wholemeal breakfast cereals (the best source of the vitamin), enriched wheat fl ours, breads – rye and wholemeal wheat breads, whole wheat and spelt fl ours, wheat bread, cooked whole wheat and rye spaghetti, wheat and multigrain pastries and fi nally scoured wheat fl ours. vitamin B2, ribofl avin, cereal products, HPLC/UV Vitamin B2 – ribofl avin is a water-soluble essential vitamin which is needed in the metabolism of amino acids, fatty acids, and saccharides. It also activates vitamin B6 (pyridoxine) and folic acid and helps to create niacin. Ribofl avin exerts its biological function through two coenzymes – fl avine adenine dinucleotide (FAD) and fl avine mononucleotide (FMN) which participate in oxidation-reduction reactions in numerous metabolic pathways exemplifi ed by the oxidation of reduced NADH, the oxidation in the tricarboxylic acid cycle, and in the –oxidation of fatty acids (Ball, 2006). Humans cannot synthesize this vitamin and thus it must be obtained from their diet through absorption in the small intestine. The recommended daily intake (RDI) of ribofl avin, related to protein and energetic intake, is from 1.2 to 1.7 mg per day in the Czech Republic (Velisek, 2009). Nowadays an increased risk for ribofl avin defi ciency may be seen in people on special diets (diabetes mellitus, peptic ulcer disease, weight loss), smokers, heavy alcohol drinkers and women using certain types of birth control. Therefore the solution could be the diet enriched with some of common vitamin sources as products with whole cereals or ribofl avin enriched products, e.g. bread and pastries. These products could be enriched by ribofl avin (E 101) up to 50 % of RDI, cereal mixtures and pasta even up to 100 % of RDI. Vitamin fortifi cation of foods is referred in Regulation No. 446/2004. This vitamin can be also used as a colorant which is referred in Regulation No. 304/2004. Great natural food sources of vitamin B2 include: entrails – liver, nuts, yeast, cheese, eggs, milk, lean meat and wholemeal cereals. In the Czech diet the main sources of the vitamin intake are milk and dairy products followed by cereals and meat (Hlubik and Opltova, 2004). Cereals are good source of this vitamin as it is widely and regularly consumed in different forms – fl our for home culinary purposes and technological production of cereal products, bread, pastries, breakfast cereals, pastas, and biscuits, especially for common cereals – wheat and rye. The aim of this work was therefore to determine ribofl avin content in common cereal products of the Czech origin. Ribofl avin is stable, not destroyed by heat or oxidation, unless exposed to ultraviolet radiation (420–560 nm). So it is a highly photosensitive compound. Knowledge of its photochemical behaviour 378 S. Skrovankova, P. Sikorova in aqueous solution over an appropriate pH range is needed to predict the shelf-life. The choice of the optimum pH is crucial for liquid preparations. Ahmad et al. (2004) determined that ribofl avin solutions are most stable to UV and visible radiations at pH 5–6. Ribofl avin content could be also decreased according to character of foods, technological and culinary processes (Leskova et al., 2006), e.g. scouring and dissolution in cooking water (Al-Khalifa and Dawood, 1993). Vitamins (vitamin B2) in cereals occur especially in germ and aleuronic layer, so losses are connected to cereal scouring, primarily its level (Hagg and Kumpulainen, 1994). Scoured cereal products without bran then contain up to ten times less B-complex vitamins than bran products. Losses of ribofl avin due to baking are quite small (up to 10 %). The signifi cant losses of this vitamin (35–55 %) are in cooked products due to leaching into water (Ayranci and Kaya, 1993; Velisek, 2009). Freezing doesn’t signifi cantly aff ect ribofl avin contents in breads (Hagg and Kumpulainen, 1994). In foodstuff s, the vitamin B2 may be presented in free and phosphorylated forms, tightly bound but non-covalently to proteins. For vitamin extraction there can be used an acid hydrolysis or an enzymatic treatment (takadiastasa, trypsin, clarasa) (Ndaw et al., 2000). For vitamin determination several methods have been reported – microbiological assay (Golbach et al., 2007), electrochemical method and High Performance Liquid Chromatography (Arella et al., 1996, Tang et al., 2006). The most widely used method in the determination of vitamin B2 is HPLC using reverse phase with fl uorescence (Andres-Lacueva et al., 1998; Cataldi et al., 2003) and UV (Hőller et al., 2003) detection. MATERIAL AND METHODS

Vitamin B<sub>2</sub> (riboflavin) content in cereal products