Sugar Industry Technologists Sixty Third Annual Technical

Conference, Vancouver, Canada, May 16 -19, 2004

 

Plants trials of non-toxic XYZ 1 clarifying reagent for

polarization analysis of sugar

 

By

 

Dr. Shu Juan Yu, professor

                E-mail : lfshjyu@scut.edu.cn

 

                     Dr. Chung Chi Chou, visiting professor

                  E-mail : drchouusa@yahoo.com

           Website:esugartech.com
 

South China University of Technology (SCUT)

Guangzhou, China

 
Introduction
 

For over 100 years lead sub-acetate, considered to be the most effective analytical clarifying reagent for sugar solution, has been used for clarification of sugar containing solution in preparation for polarization measurement. However, lead is listed as a toxic hazardous material by the U.S. Environmental Protection Agency (EPA) requiring strict handling and disposal procedures. Lead affects the central nervous system, and the most acute cases of lead poisoning can lead to death. Lower exposures are associated with coma, convulsions, and damage to the brain, kidneys, and bone marrow. Trace lead level in blood have been associated with reduced intelligence, impaired hearing, and decreased growth.

 

The U.S. sugar refiners have discontinued used of lead sub-acetate reagent by switching to high wave length polarimetry method since early 1990’s. This high wave length polarimetric method, approved by International Commission on Uniform Method of Sugar Analysis (ICUMSA), was based on work published by Chou and/or Altenberg (1, 2, 3,). Some U.S. raw sugar producers have used ABC clarifying reagent. Sugar processing Research Institute has successfully developed diethylaminoethyl (DEAE) based XYZ clarifying reagent (4). However the reagent is found to be too expensive for used in developing countries. In addition, since the work was done in USA, lead acetate reagent can not be used as control for comparison due to strict EPA requirements.

 

In this paper, the results of tests of a modified XYZ 1 reagent in two factories, in China and India respectively, have been presented. The less expensive XYZ 1 reagent has been found, as compared to result using lead sub-acetate reagent as control, to be an effective alternative clarifying reagent for lead sub-acetate for process control purposes.

 

Procedures

 

The experimental procedures are a modified ICUMSA method derived from a Baddley Chemicals, Inc. procedure used for routine pol analysis in various sugar mills.  The following are guidelines as described in the Dr. GAO’s paper (4)

 

Raw sugar (A or B sugar)

 

Weigh 26.00g of raw sugar into a 100ml volumetric flask; add 70ml water to dissolve then carefully fill it to the mark and stir.  Pour the solution into a 150ml dry beaker and cover with a watch glass (take the Brix if purity is tested). 

Add 2-5g of XYZ, or other reagents, and stir for one minute, cover with a watch glass.

 Seat a stem less funnel on a 150ml beaker and filter the solution through a Whatman #91 filter paper.  Cover the funnel with a watch glass while filtering.

 Discard the first 10ml of filtrate; then collect a volume sufficient for pol analysis.

 Rinse the monitor tube 3 times with the clarified solution; then fill it without trapping any air bubbles.

 Put the tube in the Automatic Polarimeter and read the figure displayed.  Repeat the reading at least 3 times for each sample.

 

Massecuite and molasses (including the c sugar)

 

Dilute 13.00g of material with water to the mark of a 200ml flask and stir, cover with a watch glass.

 Pour 100ml into a 150ml dry beaker and measure the Brix by an Automatic Refractometer.

 Add 5-8g of a clarifying reagent (10-15g for final molasses) and stir 1 minute, covered with a watch glass.

 Filter as above and measure according to the procedure for raw sugar analysis. 

 

Syrup

 

Dilute 26.00g of syrup with water to the mark of a 200ml flask and stir, covered with a watch glass.

 Pour 100ml into a 150ml dry beaker and measure the Brix.

 Add 2-6g of a clarifying reagent and stir 1 minute, covered with a watch glass.

 Filter and measure according to the above procedure

 

Mixed, clarified juice and other juices

 

Pour 100ml of juice into a 200ml beaker and measure the Brix. 

Add 4-7g of a clarifying reagent and stir 1 minute, covered with a watch glass. 

Filter and measure according to the above procedure.

 

Results

 

The original XYZ formulation, a DEAE based clarifying reagent, was compared with a non- lead commercial clarifying agent as reported by GAO (4). The result is shown in table 1.

 
Except for two outliers samples, the XYZ reagent exhibits a superior capacity for removal of color and turbidity from sugar solution, and found to be a good alternative clarifying reagent for lead sub acetate in polarizing sugar.
 
However, the DEAE based original XYZ reagent is rather expensive to manufacture. Consequently further work was done to modify and reformulate the reagent resulting in the development of XYZ1 and XYZ 2 reagents. Since lead- sub acetate reagent is not available in USA for comparison test with the modified XYZ new products, arrangement was made to do the test in cane sugar mills in developing countries where lead sub-acetate reagent is still being used for daily routine polarization test.
 
Table 2 to Table 6 is routine polarization results of various process samples of a sugar mill in China using lead sub-acetate reagent. Each sample is also analyzed using new XYZ non- toxic reagent for comparison. The difference between results from lead sub-acetate reagent and XYZ1 and XYZ 2 respectively are also shown in the Tables. The process samples tested include mixed juice, clarified juice, evaporated syrup, “A” massecuite, “A” “B” “C” molasses and B/S (final) molasses. The results clearly indicate that new XYZ reagents give comparable results as those of lead sub-acetate reagent, with the exception of low purity samples, such as “C” and B/S molasses.
 
Table 2 is the comparison test results of mixed juices for 13 samples. The results of both XYZ 1 and XYZ 2 compares favorably with those of lead sub-acetate reagent. For process control purpose, both new XYZ reagents can be used for polarization of sugar solution as a replacement for the lead sub-acetate reagent.
 
Table 3 is the test results of 15 clarified juices using lead sub-acetate reagent vs. new XYZ reagents. The difference between the two reagents are well within the variation in process parameters and experimental error indicating that the new XYZ reagent is a very good replacement for the lead sub-acetate reagent.
 
Table 4 and 5 are pol readings of evaporated syrup and “A” massecuite respectively using the new XYZ reagents as compared to the results obtained by the lead sub- acetate reagent. Again the difference in the polarization readings among all three reagents for all 30 samples is very close. It can be concluded that the lead sub-acetate reagent can be replaced by the new XYZ reagent for polarizing sugar.
 
Table 6 is the comparison of polarization readings of B/S molasses (final molasses) using various reagents. It can be seen that there are significant difference in polarization readings obtained by the new XYZ reagents and lead sub-acetate reagent respectively for all 15 samples tested. The major reason is that the XYZ reagent is not capable to remove sufficient turbidities from the low purities B/S molasses solution for accurate measurement of polarization. Clearly to polarize B/S molasses solution Lead sub acetate reagent is still needed at the present time.
 
Table 7 is the work performed by a sugar cane mill in India to evaluate the new XYZ reagent vs. lead sub-acetate reagent for mixed juice, clarified juice, evaporated syrup, “A” molasses, “B” molasses , “C’ washed molasses, B/S molasses, Bagasse extract and press mud. These India work confirmed that the new XYZ reagent is not applicable for polarizing low purities process streams, such as “B” molasses, “c” molasses and B/S molasses.
 
 

Conclusion

 
Lead poison is a significant concern among US health care professionals. The guidelines for safe lead levels in blood have been revised repeatedly over the years, from 60 mcg/dl before 1970 to 25 mcg/dl in 1985 to 10 mcg/dl. Unfortunately, in spite of these concern regarding safety of worker and protection of ground/drinking water, dusty dry lead sub-acetate reagent is still being used for polarizing sugar in most developing countries.
 
To help improve the safety of worker and to protect the ground water from contamination with lead waste, new non toxic reagents XYZ 1 and XYZ 2 are developed to replace lead sub-acetate reagent for polarizing sugar. From this study it appears that the new XYZ reagents can be used as substitute of lead sub-acetate reagent for polarization measurement of most process streams, except low purity materials such as “B” molasses, “C” molasses, and B/S molasses. The cost of the new XYZ reagent is comparable to that of lead sub-acetate on per samples basis.
 
There is no doubt that the use of toxic lead sub-acetate reagent in the sugar industries would be banned by governments in each countries in the future for worker’s safety and to protect environment.
 

Reference

 

(1)  Chou, C. C.   1987. Alternate methods of polarizing sugar. Proc. Sugar Ind. Technol. pp 1-25.

 
(2) Altenburg, W. and Chou, C. C.  1991.  An alternative method of raw sugar
      polarization. Proc. Sugar Ind. Technol. pp 187-196.
 

(3) Altenburg, W. and Chou, C. C.  1993. Update of Near Infrared polarization of Raw Sugar. Proc.

      Sugar Ind. Technol. pp 73-93.

 

(4) Gao, Dawei, Chou, C. C.  and Kuebei, M. 2000. A new clarifier for the polarization analysis of

      sugar solution. Proc. Sugar Ind. Technol. pp 171-181.

 
 

last updated 12/01/04