Hydroxycinnamic Acids and Ferulic Acid Dehydrodimers in Barley and Processed Barley

• Published in: Journal of agricultural and food chemistry Vol. 49; no. 10; pp. 4884 - 4888
• Main Authors: Hernanz, Dolores, Nuñez, Verónica, Sancho, Ana I, Faulds, Craig B, Williamson, Gary, Bartolomé, Begoña, Gómez-Cordovés, Carmen
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-10-2001
• Subjects: Biological and medical sciences; Cereal and baking product industries; Chemical Fractionation; Chromatography, High Pressure Liquid; Coumaric Acids - analysis; Dimerization; Food industries; Fundamental and applied biological sciences. Psychology; Genetic Variation; Hordeum - chemistry; Hordeum - genetics; Hydrogen-Ion Concentration; Hydrolysis; Hydroxybenzoates - analysis; Mass Spectrometry; Characterization; Barley; Fractionation; Genetic variability; Distribution; Cereal; Processed food; Cinnamic acid(4-hydroxy 3-methoxy); Cinnamic acid(hydroxy)
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf010530u

Hydroxycinnamic acid content and ferulic acid dehydrodimer content were determined in 11 barley varieties after alkaline hydrolysis. Ferulic acid (FA) was the most abundant hydroxycinnamate with concentrations ranging from 359 to 624 μg/g dry weight. p-Coumaric acid (PCA) levels ranged from 79 to 260 μg/g dry weight, and caffeic acid was present at concentrations of <19 μg/g dry weight. Among the ferulic acid dehydrodimers that were identified, 8-O-4‘-diFA was the most abundant (73−118 μg/g dry weight), followed by 5,5‘-diFA (26−47 μg/g dry weight), the 8,5‘-diFA benzofuran form (22−45 μg/g dry weight), and the 8,5‘-diFA open form (10−23 μg/g dry weight). Significant variations (p < 0.05) among the different barley varieties were observed for all the compounds that were quantified. Barley grains were mechanically fractionated into three fractions:  F1, fraction consisting mainly of the husk and outer layers; F2, intermediate fraction; and F3, fraction consisting mainly of the endosperm. Fraction F1 contained the highest concentration for ferulic acid (from 77.7 to 82.3% of the total amount in barley grain), p-coumaric acid (from 78.0 to 86.3%), and ferulic acid dehydrodimers (from 79.2 to 86.8%). Lower contents were found in fraction F2, whereas fraction F3 exhibited the lowest percentages (from 1.2 to 1.9% for ferulic acid, from 0.9 to 1.7% for p-coumaric acid, and <0.02% for ferulic acid dehydrodimers). The solid barley residue from the brewing process (brewer's spent grain) was ∼5-fold richer in ferulic acid, p-coumaric acid, and ferulic acid dehydrodimers than barley grains. Keywords: Barley; brewer's spent grain; ferulic acid; p-coumaric acid; ferulic acid dehydrodimers