Sugar beet, a cultivated plant of Beta vulgaris, is a plant whose tuber contains a high concentration of sucrose. It is grown commercially for sugar production. Sugar beets and other B. vulgaris cultivars such as beetroot and chard share a common wild ancestor, the sea beet (Beta vulgaris maritima).[1]
The European Union, the United States, and Russia are the world's three largest sugar beet producers,[2] although only the European Union and Ukraine are significant exporters of sugar from beets. The U.S. harvested 1,004,600 acres (4 065 km²) of sugarbeets in 2008.[3] Beet sugar accounts for 30–35% of the world's sugar production.[4]
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Sugar beet is a hardy biennial plant that can be grown commercially in a wide variety of temperate climates. During its first growing season, it produces a large (1–2 kg) storage root whose dry mass is 15–20% sucrose by weight. If the plant is not harvested at this time, then during its second growing season, nutrients in the root will be used to produce flowers and seeds and the root will decrease in size. In commercial beet production, the root is harvested after the first growing season.
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, planted in the autumn and harvested in the spring. In recent years, Syngenta 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).
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 two or three times with a hoe 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 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 beets that could be forked into the back of a cart.
| Top Ten Sugar Beet Producers - 2005 (million metric tons) |
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|---|---|
| France | 29 |
| Germany | 25 |
| United States | 25 |
| Russia | 22 |
| Ukraine | 16 |
| Turkey | 14 |
| Italy | 12 |
| Poland | 11 |
| United Kingdom | 8 |
| Spain | 7 |
| World Total | 242 |
| Source: UN Food & Agriculture Organisation (FAO)[5] |
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Today, mechanical sowing, herbicide application for weed control and mechanical harvesting have displaced this reliance on manual farm work. A root beater uses a series of blades to chop the leaf and crown (which is high in non-sugar impurities) from the root. The beet harvester 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 beets are dumped into trucks as the harvester rolls down the field, and then delivered to the factory. The conveyor then removes more soil.
If the beets are to be left for later delivery, they are formed into clamps. Straw bales are used to shield the beets from the weather. Provided the clamp is well built with the right amount of ventilation, the beets do not significantly deteriorate. Beets that freeze and then defrost 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 over the course of a 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 the 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 approximately 5 months). In the Netherlands this period is known as "de bietencampagne", a time to be careful when driving on local roads in the area while the beets are being grown. The reason for this is because the naturally high clay content of the soil tends to cause slippery roads when soil falls from the trailers during transport.
Sebewaing, Michigan is known (to Americans) 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 Michigan Sugar Company factories. The town sponsors an annual "Michigan Sugar Festival".
Arthur Stayner, because of his energetic work in experimenting with the growing of sugar beets in alkali soils, is regarded as the "father and founder of the movement that made the manufacture of sugar in Utah a success."[6]
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After they are harvested, beets are hauled to a factory. In the UK, beets are transported by a hauler, or by a tractor and a trailer by local farmers. Railways and boats are no longer used. Some beets were carried by rail in the Republic of Ireland, until the shutdown of sugar beet production in 2006 after the end of the government subsidies.
Each load is weighed and sampled before it gets tipped 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 elements, 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.
After reception at the processing plant, the beet roots are washed, mechanically sliced into thin strips called cossettes, and passed to a machine called a diffuser to extract the sugar content into a water solution.
Diffusers are long vessels of many metres in which the beet slices go in one direction while hot water goes in the opposite direction. The movement may either be caused by a rotating screw or the whole rotating unit, and the water and cossettes move through internal chambers. There are three common designs of diffuser: the horizontal rotating 'RT' (Raffinerie Tirlemontoise, manufacturer), inclined screw 'DDS' (De Danske Sukkerfabrikker), or vertical screw "Tower". Modern tower extraction plants have a processing capacity of up to 17,000 metric tons per day.[7] A less common design uses a moving belt of cossettes, with water pumped onto the top of the belt and poured 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, exit 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. The final byproduct, Vinasse, is used as fertilizer or growth substrate for yeast cultures.
During diffusion, there is a degree of breakdown of the sucrose into invert sugars. 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 practiced. There have been attempts at operating diffusion under alkaline conditions, but the process has proven problematic. The improved sucrose extraction in the diffuser is offset by processing problems in the next stages.
Carbonatation is a procedure which removes impurities from raw juice before it undergoes crystallization. First, the juice is mixed with hot milk of lime (a suspension of calcium hydroxide in water). This treatment precipitates a number of impurities, including multivalent anions such as sulfate, phosphate, citrate and oxalate, which precipitate as their calcium salts and large organic molecules such as proteins, saponins and pectins, which aggregate in the presence of multivalent cations. In addition, the alkaline conditions convert the simple sugars, glucose and fructose, along with the amino acid glutamine, to chemically stable carboxylic acids. Left untreated, these sugars and amines would eventually frustrate crystallization of the sucrose.
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.
The thin juice is concentrated via multiple-effect evaporation to make a thick juice, roughly 60% sucrose by weight and similar in appearance to pancake syrup. Thick juice can be stored in tanks for later processing, reducing load on the crystallization plant.
Thick juice is fed to the crystallizers. Recycled sugar is dissolved into it, and the resulting syrup is called mother liquor. The liquor is concentrated further by boiling under a vacuum in large vessels (the so-called vacuum pans) and seeded with fine sugar crystals. These crystals grow as sugar from the mother liquor forms around them. The resulting sugar crystal and syrup mix is called a massecuite, from "cooked mass" in French. The massecuite is passed to a centrifuge where the liquid is removed from the sugar crystals. The remaining syrup is rinsed off with water and the crystals are dried in a granulator using warm air.
The remaining syrup is fed to another crystallizer from which a second batch of sugar is produced. This sugar ("raw") is of lower quality with a lot of color and impurities and is the main source of the sugar that is dissolved again into the mother liquor. The syrup from the raw is also sent to a crystalliser. From this, a very low-quality sugar crystal is produced (known in some systems as "AP sugar") that is also redissolved. The syrup separated is molasses, which still contains sugar but contains too much impurity to undergo further processing economically.
Actual procedure may vary from the above description, with different recycling and crystallisation processes.
In a number of countries, most notably the Czech Republic, sugar from sugar beet is used to make a type of rum which is now known as tuzemak. On the Åland Islands, a similar drink is made under the brand name Kobba Libre. In some European countries, especially in the Czech Republic and Germany, sugar beet is also used to make rectified spirit and vodka.
An unrefined sugary syrup can be produced directly from sugar beet. This thick, dark syrup is produced by cooking shredded sugar beet for several hours, then pressing the resulting sugar beet mash and concentrating the juice produced until it has the consistency similar to that of honey. No other ingredients are used. In Germany, particularly the Rhineland area, this sugar beet syrup (called Zuckerrüben-Sirup or Zapp in German) is used as a spread for sandwiches, as well as for sweetening sauces, cakes and desserts.
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.
In Saint John, New Brunswick, sugar beet molasses is used as a de-icing product on the Harbour Bridge. The molasses has a lower melting point (-34 Celsius) than road salt and reduces corrosiveness.[8]
Many road authorities in North America now use de-sugared beet molases as de-icing or anti-icing products in winter control operations. The molases is typically combined with liquid chlorides and can either be applied directly to road surfaces or used to treat the salt spread on roads. The addition of the liquid to rock salt has several benefits; it reduces the bounce or scatter of the rock salt (keeping it where it is needed), it lowers the freezing point of the salt brine mix (so the de-icers remain effective at lower temperatures) and it reduces the activation time of the salt to begin the melting process. The molases used for this application is a waste product created when sugar beets are used to make commercial grade sugar. Reference: http://www.cas.org/newsevents/connections/beetmolasses.html
Betaine can be isolated from the by-products of sugar beet processing. Production is chiefly through chromatagraphic separation, using techniques such as the "simulated moving bed".
Uridine can be isolated from sugar beet. Uridine in combination with omega-3 fatty acids has been shown to alleviate depression in rats.[9][10]
There are plans by BP and Associated British Foods to use agricultural surpluses of sugar beet to produce biobutanol in East Anglia in the United Kingdom.
The feedstock-to-yield ratio for sugarbeet is 56:9. Therefore it takes 6.22 kg of sugarbeet to produce 1 kg of ethanol (approximately 1.27 l at room temperature).
A large root vegetable in 4000-year-old Egyptian temple artwork may be a beet. Although beets have been grown as vegetables and for fodder since antiquity, their use as a sugar crop is relatively recent. As early as in 1590, the French botanist Olivier de Serres extracted a sweet syrup from beetroot, but the practice was not widely used. The Prussian chemist Andreas Sigismund Marggraf used alcohol to extract sugar from beets (and carrots) in 1747, but the methods did not lend themselves to industrial scale production.
Marggraf's 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 (dry) 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 beet sugar industry in Europe rapidly developed after the Napoleonic Wars. In 1807, the British began a blockade of France, which prevented the import of sugarcane from the Caribbean. Partly in response, in 1812 Frenchman Benjamin Delessert devised a process of sugar extraction suitable for industrial application. In 1813, Napoleon instituted a retaliatory embargo. By the end of the wars, over 300 sugar beet mills operated in France and central Europe.
Sugar beet was not grown on a large scale in the United Kingdom until the mid-1920s when 17 processing factories were built, following war-time shortages of imported sugar cane. One factory had, however, been built by the Dutch at Cantley in Norfolk in 1912. Sugar beet seed from France was listed in the annual catalogues of Gartons Agricultural Plant Breeders from that firm's inception in 1898 until the first of their own varieties was introduced in 1909.
The first sugar beet mill in the U.S. opened in 1838, and the first commercially successful mill was established by E. H. Dyer in 1879.
An injunction in the base Center for Food Safety v. USDA in September 2010 prevented farmers from planting Roundup Ready sugar beets across the United States until a remedial environmental impact report could be filed, prompting some fear of a sugar shortage.[11]
Sugar beet is an important part of a rotating crop cycle.
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. It is also susceptible to the beet leaf curl virus which causes crinkling and stunting of the leaves.
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:
In the United States, genetically modified sugar beet, engineered for resistance to glyphosate, a herbicide marketed as Roundup, was developed by Monsanto. Glyphosate controls weeds by interfering with the 5-enolypyruvylshikimate-3-phosphate 5-enolypyruvylshikimate-3-phosphate (EPSP) synthase enzyme, which is involved in the production of amino acids. These amino acids, tryptophan, tyrosine and phenylalanine,[12] are synthesized in plants and bacteria, not humans or animals.[13] Glyphosate-resistant sugar beet contains a biosynthetic gene that protects it from the effects of glyphosate when it is applied to the crop as a means to control weeds. In 2005, the United States Department of Agriculture-Animal and Plant Health Inspection Service (USDA-APHIS) deregulated glyphosate-resistant sugar beet after it conducted an Environmental Assessment and determined glyphosate-resistant sugar beet were highly unlikely to become a plant pest.[14]
Sugar from glyphosate-resistant sugar beet has been approved for human and animal consumption in the European Union and the United States. Studies have concluded that sugar from glyphosate-resistant sugar beet has the same nutritional value as sugar from conventional sugar beet (not genetically modified or non-GMO).[14] Potential weed resistance and scientific evidence of super weeds has hindered public acceptance of glyphosate-resistant sugar beet.
Glyphosate-resistant sugar beet plays an important role in the United States' sugar industry. The United States imports 10% of its sugar from other countries, while the remaining 90% is extracted from domestically grown sugar beet and sugarcane. Of the domestically grown sugar crops, half of the extracted sugar is derived from sugar beet, and the other half is from sugarcane. After deregulation in 2005, glyphosate-resistant sugar beet was extensively adopted in the United States. By the 2010 growing season, 95% of sugar beet acres were planted with glyphosate-resistant sugar beet seed.[15]
The ability to effectively and efficiently control weeds in glyphosate-resistant sugar beet is one of the many reasons why glyphosate-resistant sugar beet has been widely adopted in the United States. Elimination of weeds is important in sugar beet fields because they compete with the crop for water, nutrients and light. Weeds may be chemically controlled using glyphosate (Roundup) without harming the crop. After planting sugar beet seed, weeds emerge in fields and growers apply glyphosate to control them. Glyphosate is commonly used in field crops because it controls a broad spectrum of weed species[16] and has a low toxicity.[13]
Prior to glyphosate, growers used other herbicides to control weeds in conventional sugar beet fields. While these chemicals are still available in small quantities, they are not as effective as glyphosate and require stricter application procedures. They also tend to injure the sugar beet crop.
Since herbicide options are limited in conventional sugar beet fields, growers rely on different methods to control their weeds. One method to reduce weed populations is mechanical control. Mechanical control uses tillage equipment to move soil and disturb weeds.[17] Tillage equipment is necessary in both glyphosate-resistant and conventional sugar beet fields, but it is used more frequently in conventional systems. This may be problematic because greater use of tillage equipment directly correlates to higher input production costs as more fuel is required to run the equipment.
In addition to greater use of tillage equipment in conventional sugar beet fields, hand labor is another useful approach to control weeds. Each year, thousands of migrant workers travel around the United States to work in agricultural fields, including sugar beet fields. The widespread adoption of glyphosate-resistant sugar beet however has decreased the demand for migrant workers. Unlike conventional sugar beet, there is greater weed control in glyphosate-resistant sugar beet fields and migrant workers are no longer needed.[18]
Glyphosate-resistant sugar beet allows growers to achieve higher yields and more recoverable white sucrose than conventional sugar beet. Higher yields are achieved from greater weed control in glyphosate-resistant sugar beet field.[14]
Many weeds in the United States and worldwide are resistant to glyphosate.[19] Resistance develops when growers use the same herbicide, or mode of action, every year to control their weeds. Applying different herbicide modes of action reduces the risk of resistance.
The introduction of glyphosate-resistant sugar beet may contribute to the growing number of glyphosate-resistant weeds because sugar beet may be rotated with other glyphosate-resistant crops, such as soybean. If using all glyphosate-resistant crops, growers may control their weeds every year solely using glyphosate - a weed control strategy that is not recommended because it increases the likelihood of resistance.
Monsanto has developed a program to encourage growers to use different herbicide modes of action to control their weeds in all cropping systems. Growers receive financial support when purchasing multiple herbicides.[20]
On January 23, 2008 the Center for Food Safety, the Sierra Club, and the Organic Seed Alliance and High Mowing Seeds filed a lawsuit against USDA-APHIS regarding their decision to deregulate glyphosate-resistant sugar beet in 2005. The organizations expressed concerns regarding glyphosate-resistant sugar beets' ability to potentially cross pollinate with conventional sugar beet.[21]
On September 21, 2009 U.S. District Judge Jeffrey S. White, U.S. District Court for the Northern District of California, ruled that USDA-APHIS had violated Federal law in deregulating glyphosate-resistant sugar beet without adequately evaluating the environmental and socio-economic impacts of allowing commercial production.[21]. The USDA estimated a sugar shortage would cost consumers $2.972 billion in 2011.[22]
On August 13, 2010 Judge White revoked the deregulation of glyphosate-resistant sugar beet and declared it unlawful for growers to plant glyphosate-resistant sugar beet in the spring of 2011. As a result of this ruling, growers were permitted to harvest and process their crop at the end of the 2010 growing season, yet a ban on new plantings was enacted. After the ruling, glyphosate-resistant sugar beet could not be planted until USDA-APHIS filed an Environmental Impact Statement. The purpose of an Environmental Impact Statement is to determine if environmental issues have negative effects on humans and the environment, and it may take two to three years to complete the study. After the Environmental Impact Statement is completed, USDA-APHIS may petition to deregulate glyphosate-resistant sugar beet.[21][23]
After Judge White's ruling, USDA-APHIS prepared an Environmental Assessment seeking partial deregulation of glyphosate-resistant sugar beet. The Assessment was filed based on a request received from Monsanto and KWS SSAT AG, a German seed company. Both companies, as well as the sugar beet industry employees and growers, believed a sugar shortage would occur if glyphosate-resistant sugar beet could not be planted. As a response to this concern, USDA-APHIS developed three options in the Environmental Assessment to address the concerns of environmentalists, as well as those raised by the industry. The first option was to not plant glyphosate-resistant sugar beet until the Environmental Impact Statement was completed. The second option was to allow growers to plant glyphosate-resistant sugar beet if they obtained a USDA-APHIS permit and followed specific mandates. Under the third and final option, glyphosate-resistant sugar beet would be partially deregulated but monitored by Monsanto and KWS SSAT AG. USDA-APHIS preferred the second option.[20][24] They placed the Environmental Assessment in the Federal Register on November 4, 2010 and received public comment for thirty days.[21][24]
On February 4, 2011 the USDA-APHIS announced glyphosate-resistant sugar beet had been partially deregulated and growers would be allowed to plant seed from spring 2011 until an Environmental Impact Statement is completed. USDA-APHIS developed requirements that growers must follow if handling glyphosate-resistant sugar beet and will monitor growers throughout the partial deregulation period. The requirements are classified into categories which include planting glyphosate-resistant sugar beet for seed production, planting for sugar production, and transporting sugar beet across state lines. Failure to follow the requirements set by USDA-APHIS may result in civil or criminal charges and destruction of the crop.[21] The lawsuit is an ongoing case and changes are expected to continue until the Environmental Impact Statement is complete.
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