We will present a combined hydrolysis factor (CHF) that combined pretreatment temperature, time, and chemical loading to characterize the severity of acidic pretreatments, such as dilute acid and Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL).  With this factor, we can use a low temperature and extended time without reduce pretreatment severity and therefore enzymatic saccharification.  We demonstrated the benefit of this approach for reducing inhibitor formation using SPORL.  Comparing analytical results for SPORL pretreatment of Douglas-fir at two different temperatures shows that the apparent activation energy of sugar degradation is higher than hemicellulose hydrolysis, approximately 161 kJ/mole versus 100 kJ/mole.  Thus, we demonstrated that we can balance the production of degradation products against hemicellulose hydrolysis and therefore the resultant substrate enzymatic digestibility (SED) by changing pretreatment temperature and duration.  Specifically, pretreatment at 165�C for 75min significantly reduced furan formation compared with the pretreatment at 180�C for 30 min while maintaining the same SED.  Obtaining high SED with Douglas fir is also limited by lignin content.  Fortunately, the bisulfite in SPORL provides delignification activity.  By combining kinetic models for hemicelluloses hydrolysis, sugar degradation, and delignification, the performance of pretreatment can be optimized with respect to temperature, duration, acid, and bisulfite loading.  The kinetic approach taken in this study is effective to design viable low temperature pretreatment processes for effective bioconversion of lignocelluloses.

Using low temperature to balance enzymatic saccharification and furan formation during SPORL pretreatment of Douglas-fir

247th National Meeting (2014)

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