Lynne Wong's PhD thesis

Data in Tables 2.9 and 2.11 show that dry trash raised the analytes (HPIC sucrose, Clerget
sucrose, Brix and pol) of press juice. Unfortunately, moisture content of the dry trash used
in the first case was not determined, whereas in the second case, the dry trash had 7.1 and
15.1% moisture, which indicates that the Brix-free water value of the dry trash used was
about or greater than 15%. Experiment should have been performed with added moisture
to the dry trash and determine at what moisture level, the analytes of the press juice cease
to be raised, when the dry trash is crushed with clean cane. Data in Table 2.10 show that a
dry trash sample of 29.8% moisture raised the Brix of press juice, this was probably due to
experimental error, as only Brix was raised. In the fourth trial of dry trash addition to
clean cane (Table 2.2), the dry trash sample had 17.88% moisture (Table 2.5), and it raised
only the pol level in mixed juice, indicating that the Brix-free water value of the dry trash
is below 17.88%. The fact that dry bagasse of 10.7 and 22.2% moisture (Table 2.12)
raised the analytes of press juice would indicate that the Brix-free water of the bagasse
sample used was about or greater than 22.2%. This was probably due to the presence, in
the bagasse sample, a high proportion of pith, which has a higher Brix-free water value
than other components of sugar cane plant. The above indicates that the Brix-free water in
dry trash might be involved below a critical moisture level in raising the analytes of press
juice and mixed juice.
To test this assertion, the sugar cane plant of four cane varieties and of three ages has been
successfully separated into fibres of its component parts by means of a simple method
specially developed for the purpose, for determination of Brix-free water capacity and
sorption behaviour. The use of a 1.18 mm sieve ensures complete separation of fibres
from pith, of which the ratio gives an indication of the milling quality of the cane variety.
The four cane varieties under study show fibre/pith ratio approaching to one, indicating
good millability.
An analytical method has been developed to determine the Brix-free water in fibres
obtained from the various component parts of sugar cane plant. It involves contacting the
dried fibre sample with a sucrose solution; the subsequent Brix-change in the contact
solution gives a measure of the Brix-free water value of the sample. The method makes
use of a distilled water blank to compensate for any residual sucrose in the sample, and
good separation of fibre and fines in the sample is essential to obtain reproducible results.
The vacuum drying method of the fibre sample prior to the Brix-free water determination
left residual moisture in the samples, which average 1.12% for the nine cane component
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