Analysis of polyphenols in cereals may be improved performing acidic hydrolysis: A study in wheat flour and wheat bran and cereals of the diet |
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Authors: | Sara Arranz Fulgencio Saura Calixto |
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Institution: | Department of Metabolism and Nutrition, ICTAN, CSIC, José Antonio Novais, 10, 28040, Madrid, Spain |
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Abstract: | Most analytical studies on polyphenols in cereals refer to compounds determined in aqueous-organic extracts and alkali hydrolysates, but an appreciable amount of polyphenols bound to cell wall constituents may remain insoluble in the residues of extraction and alkali hydrolysis. The main objective of this work was to determine if sulphuric acid hydrolysis may release significant amounts of polyphenols to be considered for analytical and nutritional studies. HPLC/MS analyses of polyphenols were performed in methanol–acetone extracts, alkali and sulphuric acid hydrolysates of wheat flour, bran and a pool of cereals of the diet. The amount of polyphenols found in the acidic hydrolysates (200–1600 mg/100 g) was higher than in alkali hydrolysates (0.2–372 mg/100 g). Lower amount of polyphenols were found in the methanol–acetone extracts (44–160 mg/100 g). Hydroxybenzoic, caffeic, cinammic, ferulic and protocatechuic acids were the main constituents of the hydrolysates. The contribution of cereals to the intake of dietary polyphenols in Spain was estimated around 360 mg/person/day (65 mg of extractable and 295 mg nonextractable polyphenols). |
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Keywords: | Acidic hydrolysis Alkali hydrolysis Cereals Dietary polyphenols |
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