Lynne Wong's PhD thesis

leaves increased the level of impurities in the juice but had little influence on the sucrose
retention in the bagasse, while the opposite was true for dry trash, as they showed that
green leaves contain twice as much soluble solids as did the same quantity of dry matter
from dry leaves. This laboratory scale experiment had the merit of adding accurately
measured amount of extraneous matter to clean cane, and determining the quality of the
resulting cane, bagasse and juice. There was no evidence to suggest that the prevailing
experimental conditions would be different from those which may be expected under
industrial conditions.
Tsai et al. (1961) also used an experimental mill to crush mixtures of various types of
extraneous matter with clean cane, and found the purity of the crusher juice extracted
dropped by 0.5 – 0.6 unit for each unit of extraneous matter added irrespective of whether
it was dry trash, green leaves, tops, roots, dead stem or soil. With a similar experimental
mill, Legendre and Irvine (1974) studied the effects of a mixture of 40% dry trash and 60%
cane tops in increments of 0, 5, 10, 20 and 30% by mass of cane on milling quality such as
fibre % cane, juice extraction and purity of juice extracted. Hemaida et al. (1977) also
investigated the effects of dry and green leaves at 0, 2.5, 5.0 and 7.5% cane on mixed juice
extraction, bagasse % cane, sucrose lost in bagasse % cane and mixed juice purity. All the
above workers also estimated the theoretical sugar recovery and sucrose loss in molasses.
1.5.3 Effects of cane quality on cane processing in Mauritius
The analysis of factory performance data conducted by Wong Sak Hoi and Autrey (1997)
over the period 1960 to 1996 showed that the increase in extraneous matter in cane has
increased sucrose losses in filter cake, bagasse and molasses. This is in contrast to the fact
that over the same period sucrose extraction at the milling plant (mill extraction) has
actually been improved as a result of heavy investment in cane preparation equipment and
in milling tandems, and by the application of more imbibition water % fibre. One
favourable aspect of the extra trash in cane is the increase in the mass of bagasse % cane
by 4 units, which is good for energy production. However, this advantage is outweighed
by the capital investment in the installation or modification of various factory equipment
such as the feed table, heavy duty shredders, juice screening system and modern boilers,
and by higher maintenance costs to off-set the effect of extraneous matter on factory
performance.
22