Nutritional composition, biological activity and technological properties of new slovakian black oat varieties

Black and red cereal grains, rich in anthocyanins, have recently gained a lot of interest in the food industry due to health benefits. The aim of this study was to evaluate the nutritional composition (crude protein, starch, ash, fat, beta-glucans), biological activity (antioxidant activity, total polyphenols, carotenoids and anthocyanins) and technological properties (farinograph, amylograph and extensograph) of new Slovakian black oat varieties Hucul and Norik. Technological properties were observed by incorporation of whole-grain oatmeal flour to standard wheat flour T-650 in amount 3, 6 and 9%. The grains of selected varieties were grinded and resulting whole-grain oatmeal flour was used for analyses. The crude protein content was in both varieties in amount similar to 11%; starch content similar to 44% and ash content in amount similar to 2.6%. The Norik variety showed a higher content of fat - 5.80%, beta-glucans - 4.29%, and total carotenoids - 7.47 mu g.g-1. In Hucul variety was detected a higher content of total polyphenols - 0.19 mg GAE.g(-1)(GAE - gallic acid equivalent) and anthocyanins - 22.00 mu g.g(-1). The antioxidant activity (DPPH method) was approximately at the same level in both evaluated varieties - 3 mg TEAC.g(-1) (TEAC - Trolox equivalent antioxidant capacity). There were several differences in mineral composition between observed varieties. The Norik variety showed higher content [mg.100 g(-1)] of Fe - 5.94, K - 397.56, Na - 6.33 and P - 365.51, while in Hucul variety it was detected higher content of S - 142.89 and Zn - 2.05. Other mineral compounds were not significantly different. Amylograph device shown that with an increasing addition of black oat flour, the amylograph maximum fell down with the best value at 9% addition with compared to standard flour - 1593 AU. Farinograph values on the contrary, showed the good quality of standard flour but parameter water absorption was better with addition of oat flour due to non-starch polysaccharides presented in oat. Extensograph device showed that increasing addition of oat flour decreased resistance to extension. Colorant cereals generally can increase biodiversity in agriculture, and can be attractive raw materials for production foods with added value.