What Is Refining Of Sugar

[Vannessa Rataj]

Canesugar mills traditionally produce raw sugar, which is sugar that still contains molasses, giving it more colour (and impurities) than the white sugar which is normally consumed in households and used as an ingredient in soft drinks and foods. Raw cane sugar does not need refining to be palatable. It is refined for reasons such as health, color, and the requirement for a pure sugar taste. Raw sugar is stable for transport and can be from mills to locations for processing into white sugar. Cane sugar mills / factories often produce a partially refined product called 'Plantation White' for their local market, but this is inferior to white sugar made by refineries.[1]

Beet sugar factories can also produce raw sugar, but this has an unpleasant taste. There is no separate raw sugar stage to the process; the sugar extract from the beet is, after cleaning, crystallised directly into white sugar.[1]

The origins of the art of refining sugar seem to stem from Khorasan in Persia. Next, the Venetians produced a primitive form of refined sugar, resembling sugar candy. Approaching the end of the 16th century, the art of refining sugar had spread to Germany, Fifty years later, the Dutch started their refineries, which soon dominated the European market.[2] The risks involved in large refineries stimulated developments in the insurance industry.

In the early modern era (AD 1500 to 1800) the sugar refinery process consisted of some standard steps. First the raw sugar was put in a copper boiler and mixed with bullock's blood and lime-water. The mixture was then left to stand for a night in order to dissolve. In the morning, a fire was lit under the pan or boiler. The albumen of the blood then coagulated and entangled the mechanical impurities of the sugar, forming a scum that was constantly removed. The simmering was then continued till a sample of the mixture appeared transparent. It was then rapidly boiled down till such consistency that it could form threads between one's finger and thumb. At which point the fire was damped. The second step was granulation. For this, the syrup was transferred to a vessel called a cooler, where it was agitated with wooden oars till it granulated. The third step was to put the granulated sugar in molds.[3]

The first sugar refineries were located in coastal cities throughout western Europe. They did not necessarily have to be in a port city, because at the time goods were generally transloaded from a ship onto a barge before reaching their destination. Sugar refineries are often located in heavy sugar-consuming regions such as North America, Europe, and Japan. Since the 1990s, many state-of-the art sugar refineries have been built in the Middle East and North Africa region, e.g. in Dubai, Saudi Arabia and Algeria. The world's largest sugar refinery company is American Sugar Refining with facilities in North America and Europe.

The sugar refineries that were built from about 1500 AD to 1800 did not require purpose built buildings. Ideally, they were located on a broad street along a broad canal with a good quay, so resources could be brought in at low cost by barge and by road. The refinery also had to stand somewhat free from other buildings. It required wind to dry the produce and to keep it from sweating, especially in Summer. The chimneys also had to significantly stick out above the surrounding buildings.[4] From about 1800 the Industrial Revolution changed the refining process by introducing steam power and all kinds of machinery. It led to the construction of specialized building that could be recognized by having a large number of very shallow floors.

The pre-1800 refinery was extensively described in the Netherlands, because the Dutch Republic dominated the trade in and refining of sugar for a long time. In Holland, the ideal refinery was at least 150 Rijnland feet (0.3140 m) long and 30 feet wide. The warehouse of the refinery would be on the street/canal side. It had to be at least 30 feet wide, 40 feet long and 20 feet high, with enough natural light and two 10 feet doors to let pass 2000-3000 pound barrels. The warehouse needed a windlass for vertical transport and a scale to weigh at least 1,800 pounds.[5] Ideally, the warehouse and the refinery were separate buildings, but with the high real estate prices in Holland, this was rare.[6]

Behind the storage for raw materials was the drying house, also called drying stove or oven.[8] One or two houses were for drying the sugar loaves, two more were for making candy. These drying rooms were 10 feet long, 12 feet wide and 30 feet high. Each contained an iron stove burning on coal. It was set in brick, and fed from outside the room.

The post 1800 industrial sugar refinery was characterized by using gravity to transport sugar downwards through the building as it went through several refining steps. In combination with some other features, this led a recognizable type of 19th century sugar refinery building. Examples were buildings of: the Domino Sugar Refinery, the Boston Sugar Refinery, the Amsterdamsche Stoom Suikerraffinaderij, the Wester Suikerraffinaderij and the Nederlandsche Suikerraffinaderij.

The refining process was also extensively described in 1793. In 1833 another description referred to it as 'The old, or German Method, by Blood, Eggs, Clay etc.[13] At the time refineries produced different kinds of sugar. Loaf sugar was the highest quality. Next came lump sugar, followed by bastard sugar.[14] Bastard sugar was made from the drainings of loaf and lump sugar.[15] It was generally ground and sold as powder sugar.[16] Sugar candy consisted of very large crystals formed around threads. It was either white or brown, depending on the quality of the sugar that was used.[17]

The second step was to filter and store the cleared liquor. For that it was brought to the cleared juice cistern by feeding it into a copper tube (or trough) that ended above a filter that was placed over the cistern. This filter was a piece of cloth in a basket and caught things like egg scales, nails, pieces of wood etc.[24] At the time, the cleared juice cistern, was simply called cistern.[21] It also served to hold the cleared juice while the first two pans were cleaned.

The fourth step cooling, was not applicable to sugar candy. For loaf sugar the third or fourth pan were used as cooling pans. For lump sugar three pans were used for cooling.[27] As soon as a pan of sugar was 'done' (i.e. boiled), it was transferred to a cooling pan. when it had sufficiently cooled, the sugar would form a crust. Ideally, the next batch of boiled sugar was done at this exact moment and was then added to the cooling pan. A cooling pan could be filled with up to five batches.[26] Also see granulation above.

Filling the molds was the fifth step. Sugar candy was made by drying the sugar by heat. For this it was brought to the drying house by transport bucket. Here the sugar was put in candy pots.[28] The operation to put the sugar in the transport buckets and to fill the pots could take about two-three minutes. Ideally, the second pan was by then ready to fill the transport buckets.[29] If candy sugar was made, the drying room could contain about 150 pots of candy made from the raw sugar of four pans after about 6 hours of work. The drying room was then cleaned, shut off, and the fire in its stove was lit.[30]

If sugar loaves or lump sugar was made, the sugar was brought to the filling room, see image: Filling molds in 1793. Here, the molds were filled. These had a conical shape with a hole in the tip, which was stopped by a piece of cloth.[31] In the filling room, the molds were filled and then placed on their pointy end, starting in a corner of the room. They were then stacked up to each other while the outer rows were supported by prefixes voorzetsels, i.e. broken molds that were not fit for any other purpose.[28]

The day after, the molds were brought to one of the upper floors.[32] Here the stop of the forms was removed, and over a few days syrup leaked out and was gathered into collection pots. The forms were then put on top of a box, where sugar that stuck to the outside of the form was scraped off and collected. The loaves were carefully ticked out of the molds.[33]

The British refining industry started in about 1544, when two sugar refineries were established in London. These were also known as 'sugar houses'. At first, their success was limited because of the strong competition from Antwerp. After the fall of Antwerp in 1585, the sugar refining industry in London expanded.[34] The first sugar refinery in Bristol was started in 1607, when Robert Aldworth founded a single pan refinery.[35] Sugar trade and refining would become the main source of prosperity for Bristol in the 18th century. At one time, there were some 20 refineries in Bristol.[36] In Liverpool, the first sugar refinery was established in 1667.[37]

The sugar refinery industry in Scotland started in 1667. By 1715 there were refineries on the Atlantic coast in Glasgow and on the North Sea coast in Leith. However, the real center of the Scottish refining industry would be established in Glasgow's outport Greenock. Here, the first sugar refinery was established in 1765. Up till 1826 five others followed. By 1869 there were 14 sugar refineries in Greenock, with the two largest processing 14,000 tons of sugar per week. Four more sugar refineries were also located on the River Clyde, and two were in Leith.[38] Glasgow was an important center for the production of the very heavy machinery required for cane sugar mills.[39] This probably contributed to the growth of Greenock as a center for sugar refining, which required lighter, but comparable machinery.

After World War I, the British Sugar refining industry went downhill. The war made the government see the dangers of completely relying on cane sugar imports, and so the cultivation of sugar beet, processed in beet sugar factories was promoted. In 1973 the accession of the UK to the European Union meant that the British refining industry had to deal with European legislation, which favored production in Europe. In 2010 Tate & Lyle sold its sugar refining business to American Sugar Refining, which was also allowed to use the name for these activities.[42]

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