Sugar
Sugar is any of a number of sweet, colourless, water-soluble chemicals found in seed plant sap and mammalian milk that comprise the simplest group of carbohydrates. The most common sugar is sucrose, a crystallized tabletop and commercial sweetener used in meals and beverages. Sugar is a chemical term for all carbohydrates that have the general formula Cn(H2O)n. Sucrose is a disaccharide, or double sugar, consisting of one glucose molecule connected to one fructose molecule. Sucrose is represented by the formula C12H22O11 (following the generic formula Cn[H2O]n1) because one molecule of water (H2O) is lost in the condensation step linking glucose to fructose.
Sucrose is found in practically all plants, but only sugarcane (Saccharum officinarum) and sugar beets have high enough concentrations to support economic recovery (Beta vulgaris). The former is a huge grass that grows in tropical and subtropical climates, while the latter is a root crop that grows in temperate climates. Sugarcane has 7 to 18% sugar by weight, while sugar beets contain 8 to 22% sugar by weight. Sucrose from either source (or two lesser sources, the sugar maple tree and the date palm) is the same molecule, delivering 3.94 calories per gramme, as do all carbs. Other components isolated with sucrose cause differences in sugar products.
Sugarcane was the first cultivated sugar crop, evolving from wild types in the East Indies—most likely New Guinea. During the Napoleonic Wars, France sought an alternate indigenous source of sugar to prevent her ships from running blockades to sugarcane sources in the Caribbean, and the sugar beet was created as a crop in Europe. Sugarcane cannot be preserved once harvested due to sucrose breakdown. As a result, cane sugar is often generated in two stages: raw sugar production in cane-growing nations and refining into food goods in sugar-consuming countries. Sugar beets, on the other hand, can be preserved and are hence typically converted into white sugar in a single stage.
Sugar cane
Cane harvesting and distribution
Sugarcane is often collected during the cooler months of the year, while it is harvested all year in Cuba, the Philippines, Colombia, and other good locations. Long machetes are used to harvest up to two-thirds of the globe’s cane crop by hand. However, automated harvesting has increased since the 1940s. Cane is burned before or after harvest to drive out rats and snakes and to burn off leaves and rubbish that dull knife blades, but environmental concerns are causing some areas to collect whole unburned cane.
Harvested cane is delivered to the facility using a variety of methods, including oxcarts, trucks, railway carriages, and barges.
The typical economic distance between a field and a plant is 25 kilometres (15 miles). Keeping the period between cutting and processing as short as possible encourages cane degradation and better sugar output.
Cane is weighed and sampled for analysis upon arrival at the factory gate (if factors other than weight are used for payment). Cane is stored in the mill yard in as tiny quantities and for as short a time as possible. Factories operate around the clock, with only one or two days off every month for cleaning. Although payment is often dependent on weight and sucrose content, other quality parameters like moisture, litter, and fibre content are also considered. Payment is usually shared, with 60–65 per cent going to the producer and 35–40% going to the processor.
Production Of Raw Sugar
The extraction of cane juice by milling or diffusion; clarification of the juice; concentration of the juice to syrup by evaporation; crystallisation of sugar from the syrup; and separation and drying of the crystals are the fundamental phases in sugarcane processing.
Extraction of juice
Sugarcane is loaded onto a movable table by hand or crane after it has been weighed. The table transports the cane to one or two sets of revolving blades, which chop the cane into chips to expose the tissue and open the cell structure, preparing the material for efficient extraction of the drug. Knives are frequently followed by a chipper, which shreds the chips for finer cane processing. The chipped (and shredded) cane is then fed into the crusher, a set of roller mills that crushes the cane cells and extracts the juice. The crushed cane is pressed against a countercurrent of water known as the water of maceration or imbibition as it passes through a succession of up to eight four-roll mills. Dilute juice is created by combining streams of juice taken from cane with maceration water from all mills. Residual juice is juice from the last mill in the series that does not get a current of maceration water.
Extraction by diffusion is an alternative to extraction by milling. Cane is processed by revolving blades and a shredder is pushed through a multicell, countercurrent diffuser in this method. Sugar extraction is higher by diffusion (an average rate of 93 per cent against 85-90 per cent by milling), but nonsugar extraction is also higher. Diffusion is thus most commonly used in areas with high cane quality, such as South Africa, Australia, and Hawaii. A smaller “bagasse diffuser” is occasionally used to boost extraction from partially milled cane after two or three mills. (Bagasse is residual cane fibre after the juice has been extracted.)
The disposal of the vast amounts of water consumed by diffusers is an expensive environmental issue. Diffusion cane factories must operate their primary, secondary, and tertiary water-treatment facilities.
Clarification
Heat, lime, and flocculation aids are used to purify the juice from the extraction mills or diffusers. The lime is a calcium hydroxide suspension, frequently in a sucrose solution, that creates a calcium saccharate compound. Heat and lime destroy enzymes in the juice and raise the pH from its natural acid level of 5.0-6.5 to neutral. Because sucrose inverts or hydrolyzes, to its components glucose and fructose at acid pH (less than 7.0), and all three sugars degrade quickly at high pH, pH control is critical throughout the sugar manufacturing process (greater than 11.5).
The neutralised juice is heated to 99-104 °C (210–220 °F), injected with flocculants such as polyacrylamides, and pumped to a continuous clearing vessel, a huge, enclosed, heated tank in which clear juice runs off the upper part and mud settles below. Defecation is the process of settling and separating. Muds are pumped to rotary vacuum filters, where residual sucrose is washed away by a revolving filter and a water spray. Meanwhile, clarified juice is routed through three to five multiple-effect evaporators.
Concentration
Steam is used to heat the first of a sequence of evaporators in the multiple-effect system, which was created for the American sugar industry in 1843. The juice is heated and drawn to the next evaporator, which is heated by the first evaporator’s vapour. The procedure is repeated until the clear juice, which contains 10-15% sucrose, is concentrated in evaporator syrup, which contains 55–59 per cent sucrose and 60–65 per cent by weight total solids. Nonsugars deposit on the evaporator’s walls and tubes, forming scale and limiting heat transfer efficiency. If another set of evaporators is not available for scale removal, the entire manufacturing operation is frequently forced to stop.
Crystallization
molasses blackstrap
Badagnani
The syrup from the evaporators is transferred to vacuum pans and supersaturated under vacuum. When fine seed crystals are introduced, the sugar “mother liquor” produces a solid precipitate that is approximately 50% by weight. Crystallization is a continuous process. The first crystallisation, which produces A sugar or A strike, leaves behind A molasses, a residual mother liquor. The A molasses is concentrated to produce a B strike, and the low-grade B molasses is concentrated to produce C sugar and blackstrap molasses. Blackstrap contains roughly 25% sucrose and 20% invert (glucose and fructose); at these amounts, the sugar cannot be economically extracted through crystallisation.
