Lynne Wong's PhD thesis

Figure 3.19. Stalk cake washed
free from Brix (top) and three
fractions after wet-sieving.
Figure 3.20. Rind sample before
and after cutter-grinding.
Figure 3.21. Rind cake washed
free from Brix (top) and three
fractions after wet-sieving.
3.4.4 Characterisation of the sugar cane component parts
3.4.4.1 Gross calorific value
The gross calorific value (GCV) of the extracted fibres was measured with a Parr model
1241 adiabatic oxygen bomb calorimeter (Fig 3.22).
Samples of the four cane varieties R 579, R 570, M 1557/70 and M 1400/86 of the same
age (about 52 weeks old) were obtained. After the nodes were rejected, rind was peeled
off the stalk, and fibres were extracted from both rind and stalk. The combined rind fibre
and fines, as well as stalk fibre, stalk pith and dry leaf were examined. Long fibres in rind,
stalk and dry leaf were cut into fine particles with a pair of scissors, before drying at
105 °C for three hours in a drying oven. Each sample, when required, was removed from
the oven, pressed into a pellet and burnt in the adiabatic oxygen bomb calorimeter to
determine its GCV.
The calorific value of fibre (or bagasse) is determined by burning a weighed sample in an
adiabatic bomb calorimeter under controlled conditions and is computed from the
temperature observations made before and after the combustion, with allowances being
made for the thermometer and thermochemical reactions. Benzoic acid pellets weighing
between 0.9 and 1.25 g were used to calibrate the calorimeter.
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