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United States Department of Agriculture

Agricultural Research Service

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Research Project: Further Improving the Levels of Starch in Raw Sugar in Louisiana

Location: Commodity Utilization Research

2013 Annual Report


1a.Objectives (from AD-416):
To develop a factory method to measure carry-over activity in raw sugars and then to test if there is any carry-over activity in the raw sugars produced in the 2011. Also continue a factory study started in 2011 at Alma factory, Louisiana, to ascertain the dosage limit of high temperature stable amylase from Bacillus licheniformis before carry-over activity occurs in raw sugar. Polysaccharide analyses of high viscosity factory products will also be conducted to ascertain the actual action of the amylase.


1b.Approach (from AD-416):
A large number of enzyme companies will be contacted to find more concentrated and cheaper amylases for the Louisiana sugarcane industry, and their relative activities measured. The effect of storage time (up to 6 months) on amylase activity will also be measured. Polysaccharide analysis will be undertaken by Dr. Greg Cote at USDA-ARS-NCAUR in Peoria, IL. The viscosity of massecuite and molasses will be measured with an oscillatory deformation rheometer. Starch will be measured using the iodometric method used at the refinery. A Phadebus® (cross linked starch that turns blue in the presence of amylase and water) method to test stains in clothing for amylase activity from saliva will be used as a start to develop a method to measure carryover amylase activity in raw sugars. For the factory study, 0, 5, 8, 11, 14, 18 and 21 ppm Bacillus licheniformis amylase will be dosed into the flash heated limed juice (FHLJ) just before entering the clarifier at Alma factory. For every dose level studied, at least six samples of FHLJ and clarified juice (CJ) will be taken every 20 min, taking into the 97 min Retention Time (Rt) in the clarifier. Syrup will also be collected and crystallized at the USDA-ARS-SRRC pilot plant. Syrups, and raw sugars from both the factory and pilot plant will be checked for carry-over amylase activity.


3.Progress Report:

In recent years, starch impurity concentrations in sugarcane have been increasing. Approximately 18% starch was found to partition into raw sugar and 82% into molasses. By developing a new method to accurately remove the surface molasses layer from raw sugar crystals it was calculated that the true starch partition coefficient was approximately 7%. Thus, most starch occurs in the molasses around the crystal and not inside the crystal. Special attention needs to be applied to the centrifugation process in the factory and refinery to minimize the starch in sugars. Despite the increases in starch concentrations delivered to sugarcane factories, the retention times across factories have not changed. As a result, considerable insoluble (granular) starch has been observed using both microscopic and chemical techniques, in syrups and in some raw sugars, particularly those with high soluble starch content. Approximately 2.7 ppm/Brix starch was solubilized per minute using syrup pan boiling. Current iodometric starch methods in the sugar industry mostly measure soluble starch and do not take into account all the insoluble starch present. As the insoluble starch detrimentally affects amylase applications and viscosity, we are currently developing a method to accurately measure both insoluble and soluble starch in raw and affined sugars, as well as other sugar products. Commercial amylases used in Louisiana sugarcane factories were also shown markedly vary in activity per unit dollar and in their storage characteristics.

Agricultural Research Service' Principal Investigator is monitoring activities.


Last Modified: 4/16/2014
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