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Title
Fractionation of the main components of barley spent grains from a microbrewery
Authors
Gholamali Z. Dehnavi Jose L. Laucerica Dani RodriguezMilagros Beaton Mohammad J. Taherzadeh and Carlos Martin
Received
December 12, 2010
Published
Volume 45 Issue 5-6 May-June
Keywords
barley spent grains, acid hydrolysis, alkaline delignification, acetosolv
Abstract
The chemical composition of barley spent grains generated in a microbrewery and their fractionation by acid hydrolysis and delignification were investigated. The material contained high amount of carbohydrates (60%), while its lignin content was lower than that reported for other sorts of barley spent grains. Different dilute-acid hydrolysis methods were evaluated for separating the main components of the spent grains, without affecting the sugars generated by starch hydrolysis. The utilization of a two-step dilute-acid hydrolysis approach allowed to hydrolyse starch in a first step, at 100 ºC, and hemicelluloses in a second step, at 121 ºC. Acetosolv and alkaline delignification were used for solubilising the lignin fraction. A higher lignin solubilisation (95% of the lignin contained in the raw material) was achieved after alkaline delignification, whereas only 34% of the initial lignin was removed by direct acetosolv. When the acetosolv treatment was combined with acid hydrolysis, lignin solubilisation increased to 74%. Lignin was precipitated from the liquors at recovery rates from 40 to 93%, as depending on the hydrolysis/delignification method used.
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