Posted by: Rob Viens | April 22, 2012

Sugarcane Fields Forever

Happy Earth Day! Although it didn’t exist in the 19th century, I’m sure Darwin would be a fan of anything that celebrates biodiversity (among other things).

April 22nd found Darwin continuing on the road to Rio, this time in the rain.  Today’s diary entry describes the route to Itaborai.  As an example, here is part of Darwin’s description of life on the road:

“As usual started sometime before daylight & proceeded to Madre de Dios [Rio Bonito] where we breakfasted, had it not been for the torrents of rain this would have been a very interesting ride; the country is richly cultivated, the Sugar Cane being the chief produce. — The woods contained numbers of beautiful birds; the hedges were decorated by several species of passion flowers. — Madre de Dios, like all the villages is extremely foreign looking & picturesque. — The houses are low & painted with gay colours; the tops of the windows & doors being arched takes away the still effect so universal in an English town. — One or two handsome Churches in the centre of the village completes the picture. — It continued to rain & we started for our sleeping place, Fregueria de Tabarai. [Itaborai].” (Apr 22)

Macaé excursion – April 22

Map of Darwin's Expedition – April 22, 1832

More cultivated fields – this time its Brazil’s other major crop – sugarcane. So today, a few words on the sweet grass that we love so much.

Along with being the world’s top producer of coffee (see Brazil’s Magic Beans), Brazil is also #1 in the production and exportation of sugarcane – the source of 80% of all the world’s sugar (the other 20% comes from sugar beets).  This does not include other sweeteners such as the corn industry’s attempt to replace sugar with high fructose corn syrup. According to the United Nations, sugarcane is the largest crop in the world – we do love our sugar!

Sugarcane stalks (from Wikipedia Commons):

sugarcane stalks

As noted above, sugarcane is a general name for several species of grass (Poaceae family) – specifically it is comprised of grasses in the genus Saccharum. These grasses have the unique property of storing high concentrations of sugar (in this case sucrose) in their stalk. The stalk, which can grow up to about 20 feet tall, often contains around 15% soluble sugar.

Sugarcane evolved in southeast Asia and was first cultivated and processed in India over  5,000 years ago. (India is still the second largest producer of sugarcane today.) Starting in about the 8th century, sugarcane cultivation started to move westward into the Middle East, North Africa, and the Mediterranean region. As Europeans came to the New World, sugarcane came with them and eventually became a major crop in the New World Tropics. It is still grown in many of these regions today.

Harvesting the Sugar-Cane in Minas Geraes, Brazil (from the Marianne North Online Gallery)
Harvesting sugarcane in Brazil

Like coffee in Brazil and cotton in the US, sugarcane was a major diver of the slave trade, as cheap labor was instrumental for providing cheap sugar.

Once it is harvested, the sugarcane is processed and converted in to cane sugar and dried to produce granulated sugar (more or less the sugar you buy in the store). The more common white variety of cane sugar goes through an addition series of refining that removes any remaining impurities (but uses fun things like calcium hydroxide and phosphoric acid to do it). In its liquid form, cane sugar can be processed and concentrated to also produce molasses, which in turn can be fermented to make rum and other local forms of alcohol (for example, Cachaça in Brazil).

Cane Sugar (from Alibaba.com)

cane sugar

Today sugarcane is also a major source of ethanol (for use in biofuels) in Brazil.  One estimate suggests that 1 hectare of sugarcane can be used to produce 4,000 litres of ethanol per year (and its a grass, so it grows back again). In addition, the leftover fibrous material left over from the production of cane sugar (called bagasse) is often burned and used for cooking or generating electricity In addition, it can be allowed to break down into natural gas which can also be captured and burned as a fuel source.  It is amazing how versatile this little “sugar grass” can be!

Sugarcane, like so many of the crops that are important to humans, has been artificially selected and bred by humans for favorable properties (e.g., sugar concentration, ease of growth) and/or crossbreed to produce more productive hybrids.  Although he may not have been thinking about it much at the time, this artificial selection was an important concept for Darwin as he considered the evidence or where new species come from. In fact, he devoted the first chapter of Origin of Species to artificial selection – using it to set the stage for the new concept of natural selection. (RJV)

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