The application of commercial dextranases to break down dextran in U.S. sugar manufacture is still not optimized, partly because of misinformation about where to add the enzyme and which enzyme to use. Furthermore, there is no uniform method to measure the activity of commercial dextranases by producers/vendors/distributors, which has meant that direct comparison of activities is not possible. In this study, a simple titration method to determine the relative activity of dextranases was identified and modified for easy factory use. All activities were confirmed with an accurate IC-IPAD method using a NaOH/NaO Ac gradient. Most commercial dextranase enzymes in the U. S. are from a fungal source: Chaetomium gracile or erraticum, and are available in "non-concentrated" or "concentrated" forms. An approximate 8-10 fold difference in activity exists between the two concentration forms, and activity variations exist within each form. In 2002/03 only "non-concentrated" dextranases were applied in Louisiana to either last evaporator bodies (usually < 10 ppm/syrup) or juice. "Non-concentrated" and "concentrated" dextranases studied at juice pH 5.4-5.8, showed similar maximum activity at 48.9°C or 120°F, as monitored by IC. Dextranase activities, in lastevaporator syrup temperature (~63°C or 145°F) and Brix (-65°) conditions, were dramatically reduced (activity began to decrease after 25-30°Brix). Overall, juice applications were more efficient and economical than adding them to evaporator syrups. Application of "non-concentrated" dextranase to evaporator syrup was uneconomical. However, "concentrated" dextranase can be applied to syrup at levels as low as 10 ppm/solids (equiv. to 45 ppm/juice) to remove up to -37% dextran which is useful to consider when severe dextran problems occur. Heating juice to 48.9°C in the presence of all dextranases, dramatically removed more dextran (3380 ppm/°Brix) from a juice than at the current ambient temperature of application (32.2°C or 90°F) and was much more economical. For a "non-concentrated" dextranase, after 10 min at 10 ppm/juice and 48.9°C, -46.3% dextran was removed compared to 13.6% at 32.2°C. For the "concentrated" dextranase, after only 10 min at only 4 ppm/juice, 66.6% dextran was removed at48.9°C and was considered an overdose, compared to 29.6% at 32.2°C. Dextranase was shown to work in the presence of dithiocarbamate biocide in juice, and factory studies are being undertaken to check that no adverse dextran formation is occurring at 48.9°C. Under factory storage conditions, over a grinding season (90 days), the activity of "concentrated" dextranase decreased only slightly (~9%), whereas "non-concentrated" dextranase activity had approximately halved (-46%), and even reduced in activity when stored under refrigeration.
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