Polyphenols and vitamin E as potential antioxidants in barley and malt
2011
Dabina–Bicka, I., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology | D. Karklina, D., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology | Kruma, Z., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology
Barley (Hordeum vulgare L.) is an ancient and important cereal grain crop. Whole grain products are recommended for healthy diets as being recognized sources of dietary fiber and antioxidant substances – such as polyphenols and vitamin E. The aim of current research is to compare the content of total phenolic compounds (TPC) and vitamin E of different barley varieties and malt types. One flaky, malting barley variety ‘Klass’, four hull-less barley lines from Latvia and theirs corresponding malt and for comparison four types of industrial malt – Pilsner, Munich, light, caramel and black malt were used for analyses. The total phenolic content was determined by spectrophotometer according to the Folin-Ciocalteu colorometric method with some modifications. Total phenolics were expressed as gallic acid equivalents (mg GAE gE-1 dry weight). During research vitamin E content was detected according to standard method AOAC 971.30. All barley varieties and malt samples exhibited significant content of vitamin E, and contained significant levels of phenolic compounds. The content of vitamin E in all barley samples was similar and average increase during malting was 34% for all varieties. Increase of content of vitamin E during malting can be explained by synthesis of vitamin E in germination process of grains. Content of vitamin E in malt depends on kilning temperature: higher kilning temperature, higher losses of vitamin E. A significant increase in TPC (from 2.017 to 3.406 mg GAE gE-1 DW) in all malt samples were observed after malting, i.e. steeping, germinating and kilning samples showing greater effect. It increases during malting probably not only by the modification or release of phenolic compounds, but also by the formation of new antioxidants, such as Maillard reaction products.
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