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. (C) 2002 Elsevier Science Ltd.