Lynne Wong's PhD thesis

are: cane tops, dry and green leaves, soil, rocks, cane roots, etc. Cane top is defined as the
top part of the cane stalk above the actively growing apical internode with attached green
leaves. Some authors use the word “trash” as a collective term for all extraneous matter, or
more frequently, as the dry leaves associated with cane stalks. To avoid confusion, the
term extraneous matter will be used in this thesis as the collective name and its individual
components, by their specific names such as tops, green leaves, dry leaves, soil, etc. The
term trash, if used, will refer to the dry leaves associated with cane stalks.
1.3.1 Direct measure of extraneous matter in cane
A method exists to determine directly the amount of extraneous matter in a cane supply.
This is carried out on a consignment of 5-6 tonnes of cane after the separation of all noncane
materials, i.e. trash, green leaves, tops and young shoots to determine their respective
masses. The number of samples handled in a day is limited and the results obtained are far
from being representative of the total mass of cane crushed during the day. As this method
is too time-consuming and costly to be practicable, factories do not systematically
determine extraneous matter in cane, and its exact level is therefore unknown. A more
common practice nowadays is to use a smaller sample size of about 400 kg taken by a
loader from a cane consignment. Fig 1.5 shows such a test being carried out with the
removed non-cane placed on both sides and cleaned cane in the middle. Results obtained
on a single cane consignment over a fortnight showed mean extraneous matter of 8.3%
ranging from 4.7% to 11.5% at one factory, and 24.0% with a range from 17.2% to 34.0%
at another factory (Wong Sak Hoi et al., 1999).
In South Africa, Cargill (1976) described sampling and analytical procedures involving a
grab sampler positioned next to a main cane carrier for estimating the amount of tops and
trash in a cane consignment. A sample size of 100 kg is recommended (Anon., 1985b).
Wong Sak Hoi et al. (1999) devised a rapid and reliable method of estimating extraneous
matter in a cane consignment, by using grab samples of cane bundles containing about 40
cane stalks. The method was found to yield reasonably accurate estimate of extraneous
matter in cane. Results obtained at one factory on sample involving 40 cane stalks taken
from a consignment of 400 kg, was compared with the true value of the whole
consignment. Statistical analysis of ten such paired-comparisons showed a mean
coefficient of variation of 11.6.
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