Exerpts from The Biology of Saccharum spp. (Sugarcane),
Office of the Gene Technology Regulator, Australian Gov't.
The Biology of Saccharum spp. (Sugarcane)
Byproducts of sugar production
Several by-products are produced from crushing sugarcane at the
sugar mill. In Cuba, it has been estimated that up to 31 products are
produced from sugarcane. These include refined sugar, raw sugar,
molasses, alcohol, rum, yeast, bagasse, syrups, dextran, confectionary,
crude wax, and glucose (as reviewed by Allen et al. 1997). One hundred
tons of sugarcane is estimated to produce 14.3 t raw sugar, 27.2 t
bagasse, 5.2 t filter cake, 2.6 t molasses and 50.7 t waste water
(Allen et al. 1997).
Ethanol
A
pilot plant is being constructed in QLD to explore the production of
ethanol from bagasse (O'Hara et al. 2009), however, in some countries,
sucrose is being fermented to produce ethanol (Schubert 2006). In 2006
in Brazil, 47% of the sugarcane crop was used for ethanol production,
yielding 17.8 million litres (summarised in Goldemberg &
Guardabassi 2009). In 2006, around 40% of fuel used in cars in Brazil
was ethanol (Orellana & Neto 2006).
Bagasse
Bagasse
is the fibrous portion of sugarcane that remains after the juice has
been removed. It consists of two types of fibre: the long fibres in the
rind, and the shorter, softer fibres in the pith of the cane stem,
which constitute 55% of bagasse dry weight. Bagasse cellulose fibres
are longer (1–1.5 mm) than hardwood fibres (0.7–1 mm), but shorter than
softwood fibres (2.5–5 mm) and are suitable for papermaking.
Bagasse
is used to make paper in many countries. The pith material of the stem
is considered a contaminant for papermaking and it must be removed for
high quality paper making.
Eco friendly plates, bowls, takeout containers and other packaging products produced with sugarcane fiber in Florida.
Internationally,
bagasse has also been used to make particleboard, a construction panel
that can be used for cabinets and laminate flooring (Nelson 1998). More
recently panels have been prepared using bagasse as the basis for both
the resin and the fibres in the board (Hoareau et al. 2006).
Bagasse
is used as an animal feed but its use is limited by low digestibility,
even for ruminants. Steam treatment of the bagasse improves its
digestibility so that it can be used in the fattening of cattle (Pate
1982; Playne 1984; de la Cruz 1990; de Medeiros & Machado 1993;
Allen et al. 1997; UN Industrial Development Organisation 2002).
Bagasse has also been used as food for shrimp (Freeman et al. 1992).
Bagasse
is burnt for heat to produce steam as a source of power to run the
sugar mills, with excess energy directed to the electricity grid
(Sreenivasan et al. 1987; Mackintosh 2000).
Bagasse is also an
effective bio-sorbent and may be used in waste water management. For
example, chromium, cadmium, nickel and dyes, common pollutants found in
synthetic waste water, are effectively adsorbed by bagasse (Khattri
& Singh 1999; Krishnani et al. 2004; Khan & Amin 2005).
Molasses
Molasses
is the thick syrupy residue left after the sucrose has been removed
from the clarified sugar juice (syrup). The ‘C’ molasses (final or
blackstrap molasses) is used for alcohol fermentation, as a stock feed
supplement and as a fertiliser for cane fields (Sreenivasan et al.
1987; Sansoucy et al. 1988; Mackintosh 2000).
Rum is produced by fermentation of molasses using yeast (Saccharomyces cerevisiae) (Purseglove 1972).
Other products
Trash is the plant material left after harvesting of the sugarcane stalks.
In
northern QLD it is generally retained in the field as mulch. Baled
trash is used as garden mulch and as a low-grade cattle feed in the
south-east QLD growing region (Dawson 2002).
Sugarcane
wax comprises both the waxy coating on the outside of the stalk,
concentrated mainly at the nodes, and the lipids found throughout the
cells (Allen et al. 1997). Sugarcane wax is used in cosmetics and
pharmaceutical products and it has also been used to lower cholesterol.
Sugarcane
ash, the residue produced when the sugarcane bagasse is burnt as fuel
in the boilers, and filter mud, the solids left after filtering the
cane juice, are often used as fertilisers on sugarcane farms
(Qureshi et al. 2000). It is estimated that 1 t of sugarcane crushed in
QLD produces 0.01 t of sugarcane ash and 0.05 t of mill mud (Qureshi et
al. 2000). These provide a good supply of many plant nutrients,
although nitrogen may need to be added (Calcino 1994).
In
Australian banana plantations, sugarcane ash has been shown to enhance
the growth of bananas by suppressing nematodes, possibly due to
improved soil health (Broadley et al. 2004).
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