Pentoses and Hydroxycinnamic Acids in Brewer's Spent Grain

In this work, the total pentose (xylose and arabinose) and hydroxycinnamic acid (ferulic and p -coumaric acids) in eight lots of brewer's spent grain preserved by different methods (freeze-drying, oven drying and freezing) has been determined. The total acid-extractable pentose content of the samples varied between 13·0 and 19·5% dry weight for xylose, and 7·2 and 9·6% dry weight for arabinose, whereas the total alkali-extractable hydroxycinnamic acid content varied between 0·17 and 0·24% dry weight for ferulic acid, and between 0·068 and 0·121% dry weight for p -coumaric acid. Significant differences (p<0·05) between lots were found for ferulic and p -coumaric acids. With respect to the different preservation methods, significant differences (P<0·05) were only seen in arabinose content. The content of pentoses and hydroxycinnamic acids in brewer's spent grain has been compared with those from other agro-food residues whose use is also proposed for the enzymatic release of these compounds.