Lynne Wong's PhD thesis

The extraction of fibres starting first with the tops, followed by green leaves, peeled stalk,
rind and dry leaves, could be completed within one week. All the samples (12 x 5) were
separated into fibre and pith/fines, dried and sealed in plastic bags pending dry sieving at a
later stage.
The optimum conditions for fibre extraction from the various components of the sugar
cane plant depend on the type of sample processed: the sample mass used and the
disintegrating time vary, as detailed in the following section.
3.4.3.1 Cane stalk
The peeled cane stalks were cut longitudinally into thin sticks (about 6-8 pieces depending
on the diameter of the stalk), and put through a Jeffco cutter-grinder. About 500 g of the
sample was then placed in a Jeffco wet disintegrator followed by 4 L of water. The
disintegrator was operated at 8000 rpm for 30 seconds. The fibres were then inspected to
see whether they were well separated and soft; if not, the disintegration was continued
until good separation was obtained. After all the cutter-ground stalks had been processed
in this manner, the resulting fibres and pith were washed free from gummy matter and
rinsed under tap water, using a 38 μm sieve to catch the sample. Retting of the sample was
then effected overnight in a bucket of water.
The determination of Brix-free water in fibres involves contacting the fibres with a 10°
Brix sucrose solution and measuring the increase in the Brix of the resulting solution. In
order to ensure that any increase in Brix is due to the preferential absorption of the water
by the fibres and not the elution of the residual Brix in the fibres into the solution, the
fibres must be washed free of sucrose. Hence after retting, the sample which consisted of a
mixture of fibres and pith, was well washed by filling the cup of the Pinette Emidecau
press with some of the sample, which was then washed with 3 L of tap water. The
washing was repeated two more times. The water in the sample was pressed out by using a
pressure of 20 MPa and the cake was weighed. To test for residual Brix in subsequent
washing, if the mass of the cake was for example 180 g, then (150 x 180)/16=1687.5 mL
water were used to wash the sample. The wash liquid was tested for Brix by using a
refractometer, and the Brix value was required to be less than 0.01. If not, the washing and
testing was repeated until the Brix of the washings was less than 0.01. The volume of
water calculated above to wash the sample, and to test for residual Brix in the washing, is
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