Sugarcane, or
sugar cane, is any
of six to thirty-seven species (depending on taxonomic system) of
tall
perennial grasses of the genus
Saccharum (family
Poaceae, tribe
Andropogoneae).
Native to warm
temperate to tropical regions of India
and Asia, they have stout, jointed, fibrous stalks that are
rich in sugar, and measure two to six meters
(six to nineteen feet) tall. All sugar
cane species interbreed, and the major commercial
cultivars are complex
hybrids.
Brazil
produces
about one-third of the world's sugarcane.
Cultivation and uses
Sugar cane is grown in over 110 countries with an estimated total
production of 1,591 million
metric tons
in 2007, more than six times the output of
sugar beet.
In 2005, the world's largest producer of
sugar cane was Brazil, followed by
India. Sugar cane products include table sugar,
Falernum,
molasses,
rum,
cachaça (the
national spirit of Brazil), and
ethanol. The
bagasse that remains after sugar cane
crushing may be burned to provide heat and electricity. It may
also, because of its high cellulose content, serve as raw material
for
paper,
cardboard,
and eating utensils that, because they are by-products, may be
branded as "
environmentally
friendly."
History of sugarcane
- For a longer history, see History of sugar.
Sugarcane is indigenous to tropical
South
Asia and
Southeast Asia.
Different
species likely originated in different locations with S.
barberi originating in India and S.
edule and S. officinarum coming from New Guinea
. Crystallized sugar was reported 5,000 years
ago in India.
Around the
eighth century A.D., Arabs introduced sugar to
the Mediterranean
, Mesopotamia, Egypt
, North Africa, and Spain
. By
the tenth century, sources state, there was no village in
Mesopotamia that did not grow sugar cane.
It was
among the early crops brought to the Americas by the Portuguese
.
Boiling houses in the 17th through 19th centuries
converted sugarcane juice into raw
sugar.
These houses were attached to sugar plantations in the western
colonies. Slaves often ran the boiling process, under very poor
conditions. Made of cut stone, rectangular boxes of brick or stone
served as furnaces with an opening at the bottom to stoke the fire
and remove ashes. At the top of each furnace were up to seven
copper kettles or boilers, each one smaller and hotter than the
previous one. The cane juice began in the largest kettle. The juice
was then heated and lime added to remove impurities. The juice was
skimmed, then channeled to successively smaller kettles. The last
kettle, which was called the 'teache', was where the cane juice
became syrup. The next stop was a cooling trough, where the sugar
crystals hardened around a sticky core of molasses. This raw sugar
was then shoveled from the cooling trough into
hogsheads (wooden barrels), and from there into the
curing house.
Sugarcane
is still extensively grown in the Caribbean
. Christopher
Columbus first brought it during his second voyage to the Americas, initially to the island of
Hispaniola
(modern day Haiti
and the
Dominican
Republic
). In colonial times, sugar formed one side
of the
triangular trade of New
World raw materials, European manufactures, and African
slaves.
France
found its
sugarcane islands so valuable, it effectively traded its portion of
Canada, famously dubbed "a few acres
of snow," to Britain for their return of Guadeloupe
, Martinique
and St.
Lucia
at the end of the Seven
Years' War. The Dutch
similarly
kept Suriname
, a sugar colony in South
America, instead of seeking the return of the New Netherlands (New York).
Cuban
sugarcane
produced sugar that received price supports from and a guaranteed
market in the USSR
; the
dissolution of that country forced the closure of most of Cuba's
sugar industry. Sugarcane remains an important part of the
economy of Belize
, Barbados
, Haiti, along with
the Dominican
Republic, Guadeloupe, Jamaica
, and other islands.
Sugarcane
production greatly influenced many tropical Pacific islands, including Okinawa
and, most particularly, Hawai i
and Fiji
. In
these islands, sugarcane came to dominate the economic and
political landscape after the arrival of powerful European and
American agricultural businesses, which promoted immigration of
workers from various Asian countries to tend and harvest the crop.
Sugar was the dominant factor in diversifying the islands' ethnic
makeup, profoundly affecting their politics and society.
Brazil is the biggest grower of sugarcane, which goes for sugar and
ethanol for gasoline-ethanol blends
(
gasohol) for transportation
fuel. In India, sugarcane is sold as
jaggery, and also refined into sugar, primarily for
consumption in tea and sweets, and for the production of alcoholic
beverages.
Cultivation
Sugarcane cultivation requires a
tropical
or
subtropical climate, with a minimum
of of annual moisture. It is one of the most
efficient photosynthesizers in the
plant kingdom. It is a C-4 plant, able to
convert up to 2 percent of incident solar energy into biomass.
In prime
growing regions, such as India, Peru
, Brazil, Bolivia
, Colombia
, Australia, Ecuador
, Cuba, the
Philippines
, El Salvador
and Hawaii, sugarcane
can produce for each square meter exposed to the sun.
Although sugarcanes produce seeds, modern stem cutting has become
the most common reproduction method. Each cutting must contain at
least one bud and the cuttings are sometimes hand-planted.
In more
advanced countries like the United States
and Australia, billet planting is common. Billets
harvested from a mechanical
harvester are
planted by a machine which opens and recloses the ground. Once
planted, a stand can be harvested several times; after each
harvest, the cane sends up new stalks, called
ratoons. Successive harvests give decreasing
yields, eventually justifying replanting. Two to ten harvests may
be possible between plantings.
Sugarcane is harvested by hand and mechanically. Hand harvesting
accounts for more than half of production, and is dominant in the
developing world. In hand harvesting the field is first set on
fire. The fire burns dry leaves, and kills any
lurking,
venomous snakes, without
harming the water-rich stalks and roots. Harvesters then cut the
cane just above ground-level using
cane
knives or
machetes. A skilled harvester
can cut of sugarcane per hour.
Photo of three trailer truck filled
with plant cane
Mechanical harvesting uses a sugarcane
combine (or chopper harvester), a
harvesting machine originally developed in
Australia. The Austoft 7000 series was the
original modern harvester design that has now been copied by other
companies including
Cameco and
John Deere. The machine cuts the cane at
the base of the stalk, strips the leaves and deposits the cane into
a transporter, while blowing the thrash back onto the field. Such
machines can harvest each hour, but machine-harvested cane must
rapidly arrive at the processing. Once cut, sugarcane begins to
lose its sugar content, and damage to the cane during mechanical
harvesting accelerates this decline.
Pests
The cane grub can inflict substantial reduce yield by eating roots;
it can be controlled with
Confidor or
Lorsban. Other important pests are the
larvae of some
butterfly/moth species, including the
turnip moth, the
sugarcane borer (
Diatraea
saccharalis), the Mexican rice borer (
Eoreuma
loftini); leaf-cutting ants,
termites,
spittlebugs (especially
Mahanarva
fimbriolata and
Deois flavopicta), and the
beetle Migdolus fryanus also are significant
pests. The planthopper insect
Eumetopina flavipes acts as a
phytoplasma vector, which causes the
sugarcane disease
ramu stunt.
Processing
Manually extracting juice from
sugarcane
Sugar crystals
Evaporator with baffled pan and foam
dipper for making ribbon cane syrup.
Three Rivers Historical Society Museum at Browntown, South
Carolina
Traditionally, sugarcane processing requires two stages. Mills
extract raw sugar from freshly harvested cane, and sometimes bleach
it to make "mill white" sugar for local consumption.
Refineries, often
located nearer to consumers in North
America, Europe, and Japan
, then
produce refined white sugar, which is 99 percent sucrose. These two stages are slowly merging.
Increasing affluence in the sugar-producing tropics increased
demand for refined sugar products, driving a trend toward combined
milling and refining.
Milling
Small
rail networks are a common method of
transporting cane to a mill. Refineries test newly arrived cane for
Brix and trash percentage.
The mill washes, chops, and uses revolving knives to shred the
cane. Shredded cane is repeatedly mixed with water and crushed
between rollers; the collected juices (called
garapa in Brazil) contain 10–15 percent sucrose, and
the remaining fibrous solids, called
bagasse, are burned for fuel. Bagasse makes a sugar
mill more than energy self-sufficient; surplus bagasse goes in
animal feed, in paper manufacture, or to generate electricity for
sale. The cane juice is next mixed with
lime to adjust its
pH to 7.
This mixing arrests sucrose's decay into glucose and fructose, and
precipitates some impurities. The mixture then sits, allowing the
lime and other suspended solids to settle. The clarified juice is
concentrated in a
multiple-effect evaporator to
make a syrup about 60 percent sucrose by weight. This syrup is
further concentrated under vacuum until it becomes
supersaturated, and then seeded with
crystalline sugar. On cooling, more sugar crystallizes from the
syrup. A
centrifuge separates the sugar
from the
molasses. Additional
crystallizations extract more sugar; the final residue is called
blackstrap.
Raw sugar is yellow to brown. Bubbling
sulfur dioxide through the cane juice before
evaporation bleaches many color-forming impurities into colorless
ones. This
sulfitation produces sugar known as "mill
white", "plantation white", and "crystal sugar". Such sugar is the
most commonly consumed in sugarcane-producing countries.
Refining
Sugar refining further purifies the raw sugar. It is first mixed
with heavy syrup and then centrifuged in a process called
'affination'. Its purpose is to wash away the sugar crystals' outer
coating, which is less pure than the crystal interior. The
remaining sugar is then dissolved to make a syrup, about 70 percent
solids by weight.
The sugar solution is clarified by the addition of
phosphoric acid and
calcium hydroxide, which combine to
precipitate
calcium phosphate. The
calcium phosphate particles entrap some impurities and absorb
others, and then float to the top of the tank, where they can be
skimmed off. An alternative to this "phosphatation" technique is
'
carbonatation,' which is similar, but
uses
carbon dioxide and calcium
hydroxide to produce a
calcium
carbonate precipitate.
After filtering any remaining solids, the clarified syrup is
decolorized by filtration through
activated carbon.
Bone
char is traditionally used in this role. Some remaining
color-forming impurities adsorb to the carbon. The purified syrup
is then concentrated to supersaturation and repeatedly crystallized
in a vacuum, to produce
white
refined sugar. As in a sugar mill, the sugar crystals are
separated from the molasses by centrifuging. Additional sugar is
recovered by blending the remaining syrup with the washings from
affination and again crystallizing to produce
brown sugar. When no more sugar can be
economically recovered, the final molasses still contains 20–30
percent sucrose and 15–25 percent glucose and fructose.
To produce
granulated sugar, in
which individual grains do not clump, sugar must be dried, first by
heating in a rotary dryer, and then by blowing cool air through it
for several days.
Ribbon cane syrup
Ribbon
cane is a subtropical type that was once widely grown in the
southern United
States, as far north as coastal North Carolina
. The juice was extracted with horse or
mule-powered crushers; the juice was boiled, like
maple syrup, in a flat pan, and then used in the
syrup form as a food sweetener. It is not currently a commercial
crop, but a few growers find ready sales for their product .
Most U.S.
sugarcane production occurs in Florida
and Louisiana
, and to a lesser extent in Hawaii and Texas
.
Production
|
Top Ten Sugarcane Producers — 11 June 2008 |
| Country |
Production
(Tonnes)
|
Footnotes |
|
514,079,729 |
|
|
355,520,000 |
|
|
106,316,000 |
|
|
64,365,682 |
|
|
54,752,000 |
P |
|
50,680,000 |
|
|
40,000,000 |
F |
|
36,000,000 |
|
|
27,750,600 |
|
|
25,300,000 |
F |
|
1,557,664,978 |
A |
P = official figure, F = FAO
estimate, * = Unofficial/Semi-official/mirror data, C = Calculated
figure
A = Aggregate (may include official, semi-official or
estimates);
Source: Food And Agricultural Organization of United
Nations: Economic And Social Department: The Statistical
Division |
In India,
the states of Uttar
Pradesh
(38.57 %), Maharashtra
(17.76 %) and Karnataka
(12.20 %) lead the nation in sugarcane
production.
In the
United States, sugar cane is grown commercially in Florida, Hawaii, Louisiana, and Texas.
Cane ethanol
Ethanol is generally available as a by-product of sugar
production.
It can be used as a
biofuel alternative to
gasoline, and is widely used in cars in Brazil. It is a promising
alternative to gasoline, and may become the primary product of
sugarcane processing, rather than sugar.
A textbook on renewable energy describes the energy
transformation:
At present, 75 tons of raw sugar cane are produced
annually per hectare in Brazil. The cane delivered to the
processing plant is called burned and cropped (b&c), and
represents 77% of the mass of the raw cane. The reason for this
reduction is that the stalks are separated from the leaves (which
are burned and whose ashes are left in the field as fertilizer),
and from the roots that remain in the ground to sprout for the next
crop. Average cane production is, therefore, 58 tons of b&c per
hectare per year.
Each ton of b&c yields 740 kg of juice (135 kg of
sucrose and 605 kg of water) and 260 kg of moist bagasse (130 kg of
dry bagasse). Since the higher heating value of sucrose is 16.5
MJ/kg, and that of the bagasse is 19.2
MJ/kg, the total heating value of a ton of
b&c is 4.7 GJ of which 2.2 GJ come from the sucrose and 2.5 from the
bagasse.
Per hectare per year, the biomass produced corresponds
to 0.27 TJ. This is equivalent to 0.86 W per
square meter. Assuming an average insolation of 225 W per square
meter, the photosynthetic efficiency of sugar cane is
0.38%.
The 135 kg of sucrose found in 1 ton of b&c are
transformed into 70 liters of ethanol with a combustion energy of
1.7 GJ. The practical sucrose-ethanol
conversion efficiency is, therefore, 76% (compare with the
theoretical 97%).
One hectare of sugar cane yields 4000 liters of ethanol
per year (without any additional energy input, because the bagasse
produced exceeds the amount needed to distill the final product).
This however does not include the energy used in tilling,
transportation, and so on. Thus, the solar energy-to-ethanol
conversion efficiency is 0.13%.
Sugarcane as food
In most countries where sugarcane is cultivated, there are several
foods and popular dishes derived directly from it, such as:
- Raw sugarcane: chewed to extract the juice
- Sugarcane Juice: Combining fresh
juice, extracted by hand or small mills, with a touch of lemon and ice to make a popular drink, known variously
as ganne ka rass, guarab, guarapa,
guarapo, papelón, aseer asab, Ganna
sharbat, mosto and caldo de cana
- Jaggery: Solidified
molasses, known as Gur or Gud in India,
traditionally produced by evaporating juice to make a thick sludge
and then cooling and molding it in buckets. Modern
production partially freeze dry the juice to reduce caramelization
and lighten its color. It is used as sweetener in cooking
traditional entrees, sweets and desserts.
- Molasses: as a sweetener and as a syrup accompanying other foods,
such as cheese or cookies
- Rapadura: a candy
made of flavored brown sugar in Brazil, which can be consumed in
small hard blocks, or in pulverized form (flour), as an add-on to
other desserts
- Rum: especially in the Caribbean
- Syrup: a traditional sweetener in soft
drinks, now largely supplanted (in the US at least) by high-fructose corn syrup, which is
less expensive
- Rock candy: crystalized cane
juice
Nitrogen fixation
Some sugarcane varieties are known to be capable of fixing
atmospheric
nitrogen in association with a
bacterium,
Acetobacter
diazotrophicus. Unlike
legumes and other
nitrogen fixing plants which form
root
nodules in the soil in association with bacteria, Acetobacter
diazotrophicus lives within the intercellular spaces of the
sugarcane's stem.
See also
References
- Link and reference involving U.N. FAO production
figures
- Sharpe, Peter (1998). Sugar Cane: Past and
Present. Illinois: Southern Illinois University.
- Watson, Andrew. Agricultural innovation in the early
Islamic world. Cambridge University Press.
p.26–7.
- Eumetopina flavipes and Ramu
Stunt
- da Rosa, A, Fundamentals of Renewable Energy Processes, 2005,
Elsevier, ISBN 978-0-12-088510-7, pp. 501-502
- Z. Dong et al., A Nitrogen-Fixing Endophyte of Sugarcane Stems (A
New Role for the Apoplast), Plant Physiology, 1994, Vol 105,
Issue 4 1139-1147
- R. M. Boddey, S. Urquiaga, V. Reis and J. Döbereiner, Biological nitrogen fixation associated with sugar
cane, Plant and Soil, Volume 137, Number 1 / November,
1991
- Bailey, L. H. and Bailey, E. Z. 1976. Hortus Third: A
Concise Dictionary of Plants Cultivated in the United States and
Canada. MacMillan Publishing Company, New York
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