The European Union, the United States, and Russia are the world's three largest sugar beet producers, although only the European Union and Ukraine are significant exporters of sugar from beet. Beet sugar accounts for 30% of the world's sugar production.
In the United States, genetically modified sugar beets resistant to glyphosate, (marketed by Monsanto as Roundup) a herbicide, are slated to be planted for the first time in the spring of 2008. Sugar from the biotechnology-enhanced sugarbeet has been approved for human and animal consumption in the European Union. This action by the EU executive body allows unrestricted imports of food and feed products made from (H7-1) glyphosate-tolerant (Roundup Ready) sugarbeets.
In most temperate climates, beets are planted in the spring and harvested in the autumn. At the northern end of its range, growing seasons as short as 100 days can produce commercially viable sugarbeet crops. In warmer climates, such as in California's Imperial Valley, sugarbeets are a winter crop, being planted in the autumn and harvested in the spring. In recent years, Syngenta AG has developed the so-called tropical sugar beet. It allows the plant to grow in tropical and subtropical regions. Beets are planted from a small seed; 1 kg of beet seed comprises 100,000 seeds and will plant over a hectare of ground (1 lb will plant about an acre).
Up until the latter half of the 20th century, sugarbeet production was highly labor-intensive, as weed control was managed by densely planting the crop, which then had to be manually thinned with a hoe two or even three times during the growing season. Harvesting also required many workers. Although the roots could be lifted by a plough-like device which could be pulled by a horse team, the rest of the preparation was by hand. One laborer grabbed the beets by their leaves, knocked them together to shake free loose soil, and then laid them in a row, root to one side, greens to the other. A second worker equipped with a beet hook (a short handled tool something between a billhook and a sickle) followed behind, and would lift the beet and swiftly chop the crown and leaves from the root with a single action. Working this way he would leave a row of beet that could then be forked into the back of a cart.
|Top Ten Sugar Beet Producers - 2005|
(million metric ton)
UN Food & Agriculture Organisation (FAO)
Today, mechanical sowing, herbicide application for weed control and mechanical harvesting has removed this reliance on workers.
Harvesting is now entirely mechanical. The beet harvester chops the leaf and crown (which is high in non-sugar impurities) from the root, lifts the root, and removes excess soil from the root in a single pass over the field. A modern harvester is typically able to cover six rows at the same time. The beet is left in piles at the side of the field and then conveyed into a trailer for delivery to the factory. The conveyor removes more soil -a farmer would be penalized at the factory for excess soil in his load.
If beet is to be left for later delivery, it is formed into clamps. Straw bales are used to shield the beet from the weather. Provided the clamp is well built with the right amount of ventilation, the beet does not significantly deteriorate. Beet that is frozen and then defrosts, produce complex carbohydrates that cause severe production problems in the factory. In the UK, loads may be hand examined at the factory gate before being accepted.
In the US, the fall harvest begins with the first hard frost, which arrests photosynthesis and the further growth of the root. Depending on the local climate, it may be carried out in few weeks or be prolonged throughout the winter months. The harvest and processing of the beet is referred to as "the campaign", reflecting the organization required to deliver crop at a steady rate to processing factories that run 24 hours a day for the duration of the harvest and processing (for the UK the campaign lasts approx 5 months). In the Netherlands this period is known as "de bietencampagne", a time to be careful when driving local roads in the area the beets are grown. The reason for this is the naturally high clay content of the soil, causing slippery roads when soil falls from the trailers during transport.
Sebewaing, Michigan is known as the sugar beet capital of the world. Sebewaing lies in the Thumb region of Michigan, both the region and state are major sugar beet producers. Sebewaing is home to one of three other Michigan Sugar Company factories, and is home to the "Michigan Sugar Festival".
After harvesting, the beets are hauled to the factory. Delivery in the UK is by hauler or, for local farmers, by tractor and trailer. Railways and boats were once used in the UK, but no longer. Some beet was carried by rail in the Republic of Ireland, until the 2006 shutdown of sugar beet production in the country due to the end of subsidies.
Each load entering is weighed and sampled before tipping onto the reception area, typically a "flat pad" of concrete, where it is moved into large heaps. The beet sample is checked for
From these the actual sugar content of the load is calculated and the grower's payment determined.
The beet is moved from the heaps into a central channel or gulley where it is washed towards the processing plant.
Diffusers are long (many metres) vessels in which the beet slices go in one direction while hot water goes in the opposite direction. The movement may either be by a rotating screw or the whole unit rotates and the water and cossettes move through internal chambers. There are three common designs of diffuser, the horizontal rotating 'RT' (from Raffinerie Tirlemontoise, the manufacturer), inclined screw 'DDS' (De Danske Sukkerfabrikker), or vertical screw "Tower". A less common design uses a moving belt of cossettes and water is pumped onto the top of the belt and pours through. In all cases the flow rates of cossettes and water are in the ratio one to two. Typically cossettes take about 90 minutes to pass through the diffuser, the water only 45 minutes. These are all countercurrent exchange methods that extract more sugar from the cossettes using less water than if they merely sat in a hot water tank. The liquid exiting the diffuser is called raw juice. The colour of raw juice varies from black to a dark red depending on the amount of oxidation which is itself dependent on diffuser design.
The used cossettes, or pulp, exits the diffuser at about 95% moisture but low sucrose content. Using screw presses, the wet pulp is then pressed down to 75% moisture. This recovers additional sucrose in the liquid pressed out of the pulp, and reduces the energy needed to dry the pulp. The pressed pulp is dried and sold as animal feed, while the liquid pressed out of the pulp is combined with the raw juice or more often introduced into the diffuser at the appropriate point in the countercurrent process.
During diffusion there is a degree of breakdown of the sucrose into invert sugars and these can undergo further breakdown into acids. These breakdown products are not only losses of sucrose but also have knock-on effects reducing the final output of processed sugar from the factory. To limit (thermophilic) bacterial action the feed water may be dosed with formaldehyde and control of the feed water pH is also practised. There have been attempts at operating diffusion under alkaline conditions but the process has proven problematic - the improved sucrose extraction in the diffuser offset by processing problems in the next stages.
Next, carbon dioxide is bubbled through the alkaline sugar solution, precipitating the lime as calcium carbonate (chalk). The chalk particles entrap some impurities and absorb others. A recycling process builds up the size of chalk particles and a natural flocculation occurs where the heavy particles settle out in tanks (clarifiers). A final addition of more carbon dioxide precipitates more calcium from solution; this is filtered off, leaving a cleaner golden light brown sugar solution called thin juice.
Before entering the next stage the thin juice may receive soda ash to modify the pH and sulphitation with a sulfur-based compound to reduce colour formation due to decomposition of monosaccharides under heat.
There are variations on the above system, with different recycling and crystallisation paths.
Commercially, if the syrup has a Dextrose Equivalency above 30 DE, the product has to be hydrolyzed and converted to a high-fructose syrup, much like high-fructose corn syrup, or iso-glucose syrup in the EU.
Although beets have been grown as vegetables and for fodder since antiquity (a large root vegetable appearing in 4000-year old Egyptian temple artwork may be a beet), their use as a sugar crop is relatively recent. As early as 1590, the French botanist Olivier de Serres extracted a sweet syrup from beetroot, but the practice did not become common. The Prussian chemist Andreas Sigismund Marggraf used alcohol to extract sugar from beets (and carrots) in 1747, but his methods did not lend themselves to economical industrial-scale production. His former pupil and successor Franz Karl Achard began selectively breeding sugar beet from the White Silesian fodder beet in 1784. By the beginning of the 19th century, his beet was approximately 5–6 percent sucrose by weight, compared to around 20 percent in modern varieties. Under the patronage of Frederick William III of Prussia, he opened the world's first beet sugar factory in 1801, at Cunern in Silesia.
The development of the European beet sugar industry was encouraged by the Napoleonic Wars. In 1807 the British began a blockade of France, preventing the import of sugarcane from the Caribbean. Partly in response, in 1812, Frenchman Benjamin Delessert came up with a sugar extraction process suitable for industrial application, and in 1813, Napoleon instituted a retaliatory embargo. By the end of the wars, over 300 sugar beet mills operated in France and central Europe.
The first U.S. sugar beet mill opened in 1838, but the first commercially successful mill was established by E. H. Dyer in 1879.
Sugar beet plants are susceptible to rhizomania ("root madness") which turns the bulbous tap root into many small roots making the crop economically unprocessable. Strict controls are enforced in European countries to prevent the spread, but it is already endemic in some areas. Continual research looks for varieties with resistance as well as increased sugar yield. Sugar beet breeding research in the United States is most prominently conducted at various USDA Agricultural Research Stations, including one in Fort Collins, Colorado, headed by Linda Hanson and Leonard Panella, one in Fargo, North Dakota, headed by John Wieland, and one at Michigan State University in East Lansing, Michigan, headed by J. Mitchell McGrath.
Other economically important members of the Chenopodioideae subfamily: