Sugar was first manufactured from sugar cane in India, and its manufacture has spread from there throughout the world. Chemically, sugar is the substance sucrose, which can behydrolysed in acidic solution (i.e. below pH 7) to form the monosaccharides glucose and fructose as follows. sucrose + H2O →glucose + fructose Sucrose is purified from raw sugar (97.5% sucrose) in a four step process as follows:
Step 1 – Affination
The raw sugar is mixed with a saturated syrup and then centrifuged to extract the crystals. Surface impurities (molasses) dissolve in this syrup and are removed.
Step 2 – Carbonization
The sugar is redissoved and calcium hydroxide and carbon dioxide are added to the solution. These react according to the following equation Ca(OH)2 + CO2 →CaCO3 + H2O Color, gum and amino acid impurities precipitate out with the calcium carbonate.
Step 3 – Char filtration
Activated charcoal is added to the syrup, removing color and inorganic ash.
Step 4 – Crystallization
The solution is boiled under vacuum and the crystal growth monitored to produce particular sizes of crystal.
The sugar is made into a variety of different products (raw sugar, golden syrup, treacle, soft brown sugar, coffee crystals, 1A sugar, castor sugar, liquid sugar) with varying amounts of glucose, fructose and inorganic impurities. Pollution is minimized by ensuring complete fuel combustion, monitoring liquid and gaseous effluents. The solid mud from carbonization is buried on site.
REFINED SUGAR PRODUCTS
Granulated sugar containing 99.93% sucrose and sold as castor sugar (fine crystals) and 1A sugar is the major refined product. Soft brown sugar is a specialty product with a Characteristic flavor, produced by crystals used from a selected syrup with a high reducing sugar and ash content. Coffee crystals are made from the same syrup as brown sugar, but are crystallized over a much longer period of time giving much larger crystals.
Several grades are produced in liquid form with quality to meet customer requirements. This sugar is produced at 67o Brix (% solids) at which density it is unlikely to crystallize. Liquid sugar is utilized in industry.
to split sucrose into glucose and fructose. Golden syrup contains about 27% sucrose and 47% reducing sugar with 3% ash and 18% water. The high reducing sugar component inhibits crystallization and allows a table syrup to remain in liquid form. Treacle is produced in the same manner from a similar syrup except that char decolourisation is not used.
Golden syrup and treacle are produced from selected syrups by inverting1 a portion of the syrup using invertase (an enzyme) or acid hydrolysis