title: Ultrasonic pretreatment of corn slurry for saccharification: a comparison of batch and continuous systems.
abstract: The effects of ultrasound on corn slurry saccharification yield and particle size distribution was studied in both batch and continuous-flow ultrasonic systems operating at a frequency of 20 kHz. Ground corn slurry (28%w/v) was prepared and sonicated in batches at various amplitudes (192-320 microm(peak-to-peak (p-p))) for 20 or 40s using a catenoidal horn. Continuous flow experiments were conducted by pumping corn slurry at various flow rates (10-28 l/min) through an ultrasonic reactor at constant amplitude of 12 microm(p-p). The reactor was equipped with a donut shaped horn. After ultrasonic treatment, commercial alpha- and gluco-amylases (STARGEN 001) were added to the samples, and liquefaction and saccharification proceeded for 3h. The sonicated samples were found to yield 2-3 times more reducing sugars than unsonicated controls. Although the continuous flow treatments released less reducing sugar compared to the batch systems, the continuous flow process was more energy efficient. The reduction of particle size due to sonication was approximately proportional to the dissipated ultrasonic energy regardless of the type of system used. Scanning electron microscopy (SEM) images were also used to observe the disruption of corn particles after sonication. Overall, the study suggests that both batch and continuous ultrasonication enhanced saccharification yields and reduced the particle size of corn slurry. However, due to the large volume involve in full scale processes, an ultrasonic continuous system is recommended.
authors.affiliation: Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011-3080, USA. melissam@iastate.edu
authors.forename: Melissa
authors.initials: M
authors.lastname: Montalbo-Lomboy
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Khanal
authors.forename: J Hans
authors.initials: JH
authors.lastname: van Leeuwen
authors.forename: D Raj
authors.initials: DR
authors.lastname: Raman
authors.forename: Larson
authors.initials: L
authors.lastname: Dunn
authors.forename: David
authors.initials: D
authors.lastname: Grewell
mesh_terms: D002241:Carbohydrates / Q000138:chemical synthesis* / Q000528:radiation effects*; D010936:Plant Extracts / Q000737:chemistry* / Q000528:radiation effects*; D013010:Sonication; D003313:Zea mays / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D002241:Carbohydrates; D010936:Plant Extracts