Submitted to: International Sugar Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/1/2007
Publication Date: 2/1/2008
Citation: Eggleston, G., Montes, B., Monge, A., Guidry, D. 2008. Optimization of alpha-amylase application in raw sugar manufacture. part I: characterization of commercial alpha-amylases. International Sugar Journal. 110(1310):97-104. Interpretive Summary: Unfortunately, the application of amylase (an enzyme) to break down long chains of unwanted starch in U.S. sugarcane factories is still not optimized because of misinformation about which enzyme to use, and how to add the enzyme. Factory trials were conducted to provide more optimum conditions for amylase applications to factory staff. Working solutions of high activity amylase were required to improve contact between the amylase and starch in factory tanks and are more cost-effective than adding amylase undiluted. There is also an important discussion on concern about the use of engineered high temperature stability alpha-amylases, developed for much larger markets than the sugar industry, and possible carry-over activity into raw and refined sugars, molasses, and food products.
Technical Abstract: In recent years there have been warnings by some U.S. refineries that there may be a penalty for high starch concentrations in raw sugar if starch control is not improved. Most commercial amylases used by the U.S. sugar industry to control starch have intermediate temperature stability (up to 85 degrees C with an optimum ~70 degrees C), and are produced from Bacillus subtilis. There is neither a uniform/standard method to measure the amylase activity in the sugar industry nor a regulatory body to issue or regulate standard activity methods and units for any commercial enzyme. A method incorporating PhadebusTM blue starch tablets was modified to simulate conditions in typical last evaporators, i.e., pH 6.4 and 65.5 degrees C, where amylases are mostly currently applied. A wide range of activity existed for amylases (59.0 to 545.3 KNU/ml) that did not reflect their comparative unit costs, i.e., activity per U.S. dollar only differed 4-fold from 40.7 to 161.8 KNU/ml/$. Results from a survey on current Louisiana amylase applications show a wide variation in why, when, and how commericial alpha-amylases are applied, as well as how starch is measured. Concern about the use of engineered high temperature stability (up to 115 degrees C) amylases from Bacillus licheniformis and stearothermophilus, developed for much larger markets than the sugar industry, and possible carry-over activity into raw and refined sugars, molasses, and food products, are discussed. Part II of this study (Eggleston et al, 2007b) reports the optimization of amylase application at factories.