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item Eggleston, Gillian

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2003
Publication Date: 3/1/2004
Citation: Eggleston, G., Monge, A. 2004. Optimization of factory applications of dextranases in the U.S.(abstract). Zuckerindustrie. 129(3):192

Interpretive Summary:

Technical Abstract: Although the use of commercial dextranases to breakdown dextran in sugar manufacture was pioneered by Australian researchers in the 1970s, applications in the U.S. sugar industry are still not optimized. This is partly because of misinformation about where to add the enzyme and which enzyme to use. Furthermore, there is no national or international method to measure the activity of dextranases, which has meant that direct comparison of activities is not possible. In this dextranase optimization study, a simple method to determine the relative activity of dextranases was identified, which is based on titration and and could be easily undertaken at factories. All the relative activities were further confirmed with ion chromatography with integrated pulsed amperometry detection (IC-IPAD) using a sodium hydroxide/sodium acetate gradient method. Most commercial dextranase enzymes in the U.S. are from a fungal source: Chaetomium gracile or Chaetomium erraticum, and are available in 'non-concentrated' or 'concentrated' forms. Up to an approximate 10-fold difference in activity exists between the two concentration forms, and variation in activities also exist among enzymes within each form. In 2002/03 non-concentrated dextranases were applied in Louisiana sugarcane factories, and applications varied considerably with each factory. In 2002, most applications were in last evaporator bodies at very low ppm levels (usually less than 10ppm), although more were made to the juice in 2003. Non-concentrated and concentrated dextranases studied at pH 5.4-5.8, showed similar maximum activity between 110-130 degrees F, as monitored by the accurate IC-IPAD method. Syrups in last evaporator bodies have temperatures ~145 degrees F and Brixes ~65, but enzyme activity had decreased dramatically at this temperature and Brix (decrease in activity began after 25-30 Brix). Laboratory studies on the application of a non-concentrated dextranase to a final evaporator syrup containing 7230 ppm/Brix dextran (measured with a modified ICUMSA Haze method) at 145 degrees F, indicated that only levels of 80ppm on solids removed ~25% dextran and reduced viscosity after 20 mins, which is not economical and confirms initial factory studies. In comparison, a concentrated enzyme, under the same conditions, at 10ppm on solids removed 37% dextran. Both the activity of the non-concentrated and concentrated dextranases was relatively low at the ambient temperature (~90 degrees F) of juice. Heating the juice to 120 degrees F, markedly removed more dextran from a factory deteriorated juice (3380 ppm/Brix dextran) than at 90 degrees F. For the non-concentrated juice, after 10 mins at 10ppm on juice and 120 degrees F, ~46.3% dextran was removed compared to 13.6% at 90 degrees F. For the concentrated juice, after only 10 mins at only 4 ppm on juice, 66.6% dextran was removed at 120 degrees F compared to 29.6% at 90 degrees F. Factory studies are currently being undertaken to check that no adverse dextran formation is occurring at the optimum temperatures. Storage characteristics of the dextranases are described, as well as the economic costs of different additions.