초록
<P><B>Highlights</B></P><P>► We studied dilute-acid pretreatment of barley straw at low combined severity (−1.6 to 1.1). ► We monitored the production of fermentable sugars and the release of five inhibitory compounds. ► We optimized the pretreatment conditions at 170°C, 0% sulfuric acid and 60min. ► We used the ratio of Σsugars/Σinhibitors to evaluate the suitability of barley straw hydrolysates for fermentation purposes. ► We discussed the effect of the concentrations of the inhibitors on ethanol and hydrogen fermentability.</P> <P><B>Abstract</B></P><P>The production of fermentable substrates from barley straw under various process conditions was studied. Pretreatment included chemical pretreatment with dilute-acid followed by enzymatic hydrolysis; the pretreatment conditions were expressed in a combined severity factor, CS, which ranged in the present study from −1.6 to 1.1. Considering the production of fermentable sugars and the release of inhibitory compounds, the optimal pretreatment conditions were 170°C, 0% sulfuric acid and 60min, corresponding to CS −0.4. Under these conditions, 21.4g glucose/L, 8.5g xylose/L, and 0.5g arabinose/L were produced, while 0.1g HMF/L, 0.4g furfural/L, 0.0g levulinic acid/L, 0.0g formic acid/L, and 2.1g acetic acid/L were released. The ratio of Σsugars/Σinhibitors proved to be a good tool for evaluating the suitability of a hydrolysate for fermentation purposes.</P>