Comparison of dilute acid pretreatment of agave assisted by microwave versus ultrasound to enhance enzymatic hydrolysis.

A comparison between microwave and ultrasound irradiations in the agave pretreatment using dilute sulfuric acid as catalyst was assessed for the first time. Pretreatments were performed using a Taguchi Orthogonal Array L9 (34) to improve the hemicellulose removal and the agave digestibility. The results showed that under optimal conditions, the hemicellulose removal was superior in the pretreatment assisted with microwave (77.5%) compared to ultrasound (28.2%). Enzymatic hydrolysis yield of agave pretreated with microwave (MWOC) was 2-fold higher than agave pretreated with ultrasound (USOC). The relatively mild conditions of pretreatment with MWOC allowed to obtain a hydrolyzed free of inhibitors with a high glucose concentration (47.7 g/L) at low solids loading (10% w/v). However, these conditions did not have a significant effect over the agave pretreated with ultrasound. The pretreatment assisted with MWOC allowed to reduce time and temperature of the process compared to pretreatment with conventional heating.