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Cane Analysis - Pol and brix - (Lance Holden)

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By Holden, Lance
Posted on 2008-06-30    Last edited on 2010-01-13

A Non-Fibre Method of Cane Analysis using the Wet Disintegrator

Background:

The first people to use the wet disintegrator are believed to be the Hawaiian Sugar Technologists.
The use of the wet disintegrator then spread to other countries, including Australia.
Mr.Dennis Foster of Sugar Research did extensive testing with the wet disintegrator and independent testing was also done by B.S.E.S. and C.S.R. Mill Technologists.

The weaknesses in all of their Analysis formulas was the fact that it was necessary to have either a fibre, or a moisture content of the cane, in order to determine the %Pol and Brix content.


Dry fibre, and moisture analysis are time consuming analyses, and even if we had these figures, it would be necessary to assume a figure for hygroscopic water.

In 1961, Bureau of Sugar Experiment Stations Mill Technologists did extensive research on a Press Method of determining the dry fibre content of cane samples.

Although their research yielded excellent results, the method was “mothballed”

Being on good terms with these people ( B.S.E.S. Techs.), I was able to obtain a copy of their Research Results for my perusal.

Some time later, while working in a fruit cannery, I devised a formula for fruit analysis.

I realized immediately that the formula should also work with sugar cane.

It was so simple: we did not need a fibre content; we did not need a moisture; we did not have to assume a hygroscopic water figure. All of these problems were taken care of in a simple formula.

I applied the formulas (for Brix and Pol) to the Bureau results and was amazed at the precision that was obtained.

I submitted my paper to the International Sugar Journal,and it was subsequently published in the August 1971 edition of this publication.

Required Equipment:

(1) Jeffco Cutter-Grinder (2) Water-cooled wet disintegrator with 7 inch blades
(3) Hydraulic Press capable of 1500 psi pressure.
(4) Filter aid & Buchner vacuum filtration equipment
(5) High Precision Refractometer (preferably), or alternatively, a high precision Density Meter. (for Brix of the filtered Press Juice and the filtered disintegrator extract)
(6) Saccharimeter with a 400 mm Pol tube

Method of Analysis:

About 10 kg of the cane sample are treated in a Jeffco Cutter-Grinder.
The ground up cane is then thoroughly mixed by the cone and quarter method.

Two kg are transferred to the disintegrator drum, followed by 8 kg of deionised water.
The cane-water mixture is then spun for 30 minutes.

While the disintegrator is spinning, a 2 kg aliquot of the cane is transferred to the juice press and pressed at 1500 p.s.i. for a 5 minute drainage time.

The collected Press Juice is then treated with high grade filter aid and vacuum filtered using Buchner filtration equipment. The first part of the filtration is discarded .
The final portion of the filtered Press Juice is then analysed for Brix using the chosen Instrument.

After 30 minutes the disintegrator is turned off and a portion of the slurry is removed and cooled and strained through a suitable sieve.
Approximately 2 litres of the extract from the sieved slurry is treated with high grade filter aid and filtered using Buchner filtration equipment.
NOTE: It is important to discard the first of the filtrate, as there could be adsorption of moisture from the vessel.

If the Precision Refractometer is chosen for Brix analysis, the following procedure is recommended for the % Pol determination of the filtered disintegrator extract:

Pol in Extract Determination:

Exactly 500 ml of the filtered extract are transferred to a 500 ml volumetric flask which has been previously dried and tared.
The weight of the 500 ml  of filtered extract is then determined.
A portion of the filtered extract is then clarified with Horne’s dry lead and filtered.
It is then read in a 400 mm pol tube

Let % Pol of the Filtered Extract = p
Therefore, p = Pol % filtered Extract =

Formula_1


Let J = the Brix of the filtered Press Juice


Let P = the %Pol of the Cane

Let B = the Brix of the Cane

Then

P = Pol % Cane =

Formula_2

Where  p = Pol% filtered extract


B = Brix of Cane =

Formula_3

Where b = the Brix of the filtered extract


If you want more information please e-mail to the Author, viz., Lance Holden at lanhol@iprimus.com.au

Bibliography
Holden L., 1971, The "Holden" method of determining brix and pol in sugar cane, ISJ, August 1971, 228-
232

NOTE: In the formula Pol % filtered Extract: %Pol is derived from the fundamental method of dividing the calculated polariscope reading  in a 200 mm tube by the number of sucrose normal weight per 100 ml of undiluted extract.
See below for a clearer explantion:
%Pol of sugar solution = (N.W. x Pol reading in a 200 mm tube) divided by the weight of 100 ml of undiluted solution. We have, in this instance, a 400 mm tube, so we halve the normal weight to 13. We have 500 ml ofundilutedextract, so we divide this weight by 5. Then 5 x 13 = 65.




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