Submitted to: International Sugar Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/2/2006
Publication Date: 9/1/2006
Citation: Eggleston, G., Monge, A., Montes, B., Steward, D. 2006. Factory trials to optimize the application of dextranase in raw sugar manufacture: part i. International Sugar Journal. 108(1293):529-537 Interpretive Summary: Unfortunately, the application of dextranase (an enzyme)to break down long chains of unwanted dextran in U.S. sugarcane factories is still not optimized because of misinformation about which enzyme to use, and how and where to add the enzyme. Factory trials were conducted to provide more optimum conditions. Working solutions of "concentrated" dextranase, which can be diluted with either tap or distilled water or sugar solutions, are required to improve contact between the dextranase and dextran in factory tanks and are more cost-effective than adding "non-concentrated" dextranases directly. The factory had relatively high levels of dextran in extracted cane juice and the addition of 6 parts per million of the working solutions were very successful in breaking down 70 to 94% dextran.
Technical Abstract: Application of commercial dextranases to break down dextran in U.S. sugar manufacture is still not optimized, partly because of misinformation 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 previous laboratory studies showed dextranase applications to syrup were uneconomical, only juice applications were studied. This paper reports trials at a factory that applies dextranase to a 5 min retention time tank adjacent to the mixed juice tank near the first and second mills. Working solutions of “concentrated” dextranase were required to improve contact between the enzyme and substrate (dextranase/dextran) in factory tanks/pipes and are more cost-effective than adding “non-concentrated” dextranases directly. Working solutions can be easily prepared with tap or distilled water (2- or 5-fold dilutions) and are stable for up to a maximum of 24 hours; if prepared with a 24 oBrix raw sugar solution they are stable for 140 hours. Greater amounts of dextran improve breakdown by dextranase because of lower enzyme/substrate contact ratios. The factory often had relatively high levels of antibody dextran (>1000 ppm/oBrix) in juice, and the addition of 6 ppm (normalized to the original enzyme activity) of 2- or 5-fold or working solutions of “concentrated”dextranase (52,000 DU/ml) were successful in breaking down 70-94 % dextran.