PRETREATMENT OF CORN FIBER BY PRESSURE COOKING IN WATER

The pretreatment of corn fiber using liquid water at temperatures betw een 220 and 260 degrees C enhances enzymatic hydrolysis. This paper de scribes the laboratory reactor system currently in use for cooking of corn fiber at temperatures ranging from 200 to 260 degrees C. The corn fiber at approx 4.4% solid/liquid slurry was treated in a 2-L, 304 SS , Parr reactor with three turbine propeller agitators and a Proportion al-Integral-Derivative (PID), controller that controlled temperature w ithin +/- 1 degrees C. Heat-up times to the final temperatures of 220, 240, or 260 degrees C were achieved in 50 to 60 min. Hold time at the final temperature was less than 10 s. A serpentine cooling coil, thro ugh which tay water was circulated at the completion of the run, coole d the reactor's contents to 180 degrees C within 2 min after the maxim um temperature was attained. Ports in the reactor's head plate facilit ated sampling of the slurry and monitoring the pH. A continuous pH mon itoring system was developed to help observe trends in pH during pretr eatment and to assist in the development of a base (2.0 M KOH) additio n profile to help keep the pH within the range of 5.0 to 7.0. Enzymati c hydrolysis gave 33 to 84% conversion of cellulose in the pretreated fiber to glucose compared to 17% for untreated fiber.