Lynne Wong's PhD thesis

Figure 3.2. Cane stalk.
Figure 3.3. Cross-section of stem.
(Van Dillewijn, 1952) (Van Dillewijn, 1952)
The juice-containing parenchyma cells are thin-walled and contribute only to a small part
of the total fibre in the cane. The vascular bundles on the other hand contain many small
thick-walled cells which surround the large vessels and sieve tubes. The vessels carry
water from the roots and the sieve tubes conduct sugary juices from the leaves. High
tensile strength in the vascular bundles appears to impart good milling quality to the cane
variety.
The fibrous residue of the sugar cane stalk after crushing and juice extraction is known as
bagasse, it consists mainly of cellulose, pentosans and lignin. Paturau (1989) enumerated
two important types of fibrous residue occurring in bagasse: a) the tough, hard-walled,
cylindrical cells of the rind and vascular tissues (true fibre); and b) the soft, thin-walled,
irregularly shaped parenchymatous cells of the inner stalk tissue (pith). The vessel
segments, also associated with the vascular bundles, because of their non-fibrous character
and because any depithing steps (the separation of pith from fibres) will remove a large
portion of the cells, are often, but not always, considered as a pith fraction.
The fibrous physical composition of bagasse can be summarized as shown in Table 3.2.
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