Factory Trials To Optimize The Application Of Dextranase In Raw Sugar Manufacture: Part I

Application of commercial dextranase to hydrolyze dextran in U.S. sugar manufacture is still not optimized, partly because of confusion about which enzyme to use, and how and where to add the enzyme. Until recently, there was no uniform method to measure the activity of dextranases, but several factories are now successfully using the Eggleston factory titration method to 1) compare economically equivalent activities of different dextranases, 2) measure the activity of delivered batches, and 3) monitor the changing activities on factory storage. An approximate 14 to 20-fold difference in activity existed between the "non-concentrated" and "concentrated" forms of commercial dextranases used in 2004. Factory trials to optimize dextranase applications were conducted in the 2004 Louisiana processing season. As a previous laboratory study showed dextranase applications to syrup were uneconomical, only juice applications were studied. Results are reported from a factory that applies dextranase to a 5 min retention time tank adjacent to a mixed juice tank receiving juice from the 1st and 2nd mills. Higher dosages of dextranase were required in the factory than in laboratory. Working solutions of "concentrated" dextranase were required to improve contact between the enzyme and substrate (dextranase/dextran), and are more cost-effective than applying a "non-concentrated" dextranase undiluted. Working solutions can be easily prepared with tap or distilled water and are stable up to 24 h maximum; if prepared with a 24 degrees Brix raw sugar solution they are stable for 140 h. Greater levels of dextran improve hydrolysis by dextranase because of lower enzyme/substrate contact ratios. The factory had relatively high levels of antibody dextran (>1000 ppm/degrees Brix) in juice, and the application of 6 ppm (normalized to the original enzyme activity) of 2 or 5-fold working solutions of "concentrated"dextranase (52,000 DU/ml) were successful in hydrolyzing 70-94% dextran.