Lynne Wong's PhD thesis

found that the amount of absorbed water on the fibre was dependent on the cane variety
and the concentration of the solution used. They also did an experiment with pure
cellulose in a 20% sucrose solution and found a value of 8%.
Foster (1963) used a different method to determine Brix-free water in cane fibre. Cane (2
kg) was weighed into a wet disintegrator, and reduced to a slurry with water (6 kg). A
sample of the extract was taken for Brix reading. The extract was then removed until the
slurry mass was 4000 g. To this was added an exact mass of 1500 g of 67.00° Brix sucrose
solution. After five minutes of further mixing in the disintegrator, the resultant Brix was
measured, and the actual mass of solvent plus Brix could be calculated. Subtracting this
mass from 4000 g, gave the mass of fibre plus Brix-free water. He obtained values of 25 to
40% Brix-free water on fibre.
Mangion and Player (1991) ensured that all the adsorbed water was removed from a prewashed,
essentially sucrose-free fibre sample, and then contacted this fibre with a sucrose
solution of known concentration. They employed a method that used eight grams of fibre
sample weighed into a pre-weighed jar. The fibre was vacuum dried at 80 °C, and 825
mbar for 3 hours to avoid any heat damage of the fibre prior to analysis. After which, the
sample mass was determined, and 150 g of a 10° Brix sucrose solution was added and well
mixed to ensure all fibre was wetted by the sucrose solution. Mixing was effected from
time to time for one and a half hours. The sample was then filtered through a covered
Whatman 91 filter paper prior to the Brix measurement. The Brix of the original sucrose
solution was also measured. The Brix-free water of the fibre was calculated by means of
the following equation:
-1
% Brix-free water = [100 w 4 (1 – p 3 p 4 )]/w 3
where w 3 and w 4 are the mass of fibre sample and the mass of sucrose contact solution
respectively, and p 3 and p 4 are the Brix of the sucrose solution before and after mixing with
the fibre sample.
Mangion and Player (1991) found from over 250 data points, an average of 20.6% Brixfree
water in present day cane varieties with a standard deviation of 2.2 units.
Qin and White (1991) adopted the same method and reasoned that with unit mass of fibre
added to 20 times its mass of sucrose solution, if the Brix-free water was 20% and the
initial sucrose solution was 10° Brix, one could only expect an increase of 0.1 unit Brix,
which was a small change and very difficult to measure with any accuracy. If the contact
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