Ultrasonication of Sugary -2 Corn for Enhanced Enzymatic Hydrolysis

This study investigates the potential application of high powered ultrasonics as a liquefaction pretreatment of sugary-2 corn slurry. Ground sugary-2 corn ( Zea Mays L. ) slurry was treated with ultrasonics at 20kHz and amplitudes of 192-320 µ m pp (peak-to-peak) for 5, 10, 15, 20 and 40 seconds. After sonication, enzymes (Stargen TM 001) were added to the samples to hydrolyze the starch into fermentable sugars. It was found that the reducing sugar released in the treated samples were 6-fold higher than in the non-treated samples. Scanning electron microscopy images revealed that the sugary starch was partially gelatinized during sonication. This observation was confirmed by polarized-light microscopic images, where deformed “Maltese crosses” were found. The swelling rate of sonicated samples was nearly 66 times higher than when applying conventional heating. This result confirms better gelatinization capability of ultrasonics compared to conventional heating. The maximum relative net energy gain (additional chemically released energy) of the sonicated samples was at 5s of sonication time with a power setting between 248-330W. The findings in this study indicated ultrasonics as a promising pretreatment step in sugary-2 corn hydrolysis

Ultrasonic Pretreatment of Corn Slurry in Batch and Continuous Systems

The effects of ultrasonication of corn slurry, on particle size distribution and enzymatic hydrolysis was studied for the dry-grind mill ethanol industry. Two independent ultrasonic experiments were conducted at a frequency of 20 kHz; in batch and continuous systems. The ground corn slurry (33% m/v) was pumped at flow rates 10-28 L/min in continuous flow experiments, and sonicated at constant amplitude (20µmpeak-to-peak(p-p)). Ultrasonic batch experiments were conducted at varying amplitudes of 192-320µmp-p. After ultrasonication, StargenTM001 enzyme was added to the samples and a short 3h hydrolysis followed. The treated samples were found to yield 2-3 times more reducing sugar compared to the control (untreated) samples. In terms of energy density, the batch ultrasonic system was found to deliver 25-times more energy than the continuous flow systems. Although the experiments conducted in continuous system released less reducing sugar than the batch system, the continuous system was more energy efficient. The particle size of the sonicated corn slurry (both batch and continuous) was reduced relative to the controls (without treatment). The reduction of particle size was directly proportional to the energy input during sonication. The study suggests that both batch and continuous flow ultrasonic systems enhances enzymatic hydrolysis yield, reduces particle size of corn slurry and could be a potential effective pretreatment for corn slurry