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High Fructose Corn Syrup vs Sugar - Manufacturing Process
Sweetener Manufacturing Process
Sweetener Processing Comparison Chart
High Fructose Corn Syrup | Table Sugar |
| Corn refiners make high fructose corn syrup from corn starch, which must be separated from other components of the kernel. Cleaned, shelled corn is soaked in warm water containing 0.1% to 0.2% sulfur dioxide, which softens the kernels and facilitates separation of the various components: starch, hull, protein and oil. The soaked corn is milled to release the oil-containing germ, which is separated from the components by hydrocyclones. The resulting starch, hull and protein components are then finely ground and screened to remove the hull. The resulting slurry is passed to a continuous centrifuge to separate the starch and protein components. The starch is washed and concentrated in a series of hydrocyclones. The enzyme alpha-amylase is added to a slurry of starch and water to liquefy or reduce the particle size of the starch to produce glucose polymers. Enzymes are nature's catalysts to get things done. This step is followed by saccharification with the enzyme glucoamylase, which breaks the glucose polymers down to their basic building blocks. The resulting glucose mixture is filtered and clarified by centrifugation, carbon filtration and ion exchange. A small amount of magnesium is added to the purified glucose solution. Glucose isomerase, an enzyme, is used to convert a portion of the glucose to fructose. The resulting mixture is 42% fructose, 53% glucose and 5% higher sugars. The mixture is refined with carbon filters and ion exchange. The fructose content of the resulting syrup is enriched by chromotographic separation, accomplished by passing the syrup through a column of adsorbent containing calcium or other cation that attracts the fructose portion of the syrup. This step produces a syrup that is about 90% fructose, which is then blended with the 42% fructose syrup to produce one that is 55% fructose, 42% glucose and 3% higher sugars. The final syrup is refined by carbon filtration and ion exchange and then evaporated to 77% solids for shipping.(1) | Sugar cane is milled to extract the juice. Sugar beets are sliced, soaked in hot water, which may contain sulfur dioxide, chlorine or ammonium bisulfite as a disinfectant, and pressed to extract the juice. Damaged beets may require the addition of an enzyme such as dextranase to aide in sugar extraction. The cane or beet juice is then strained and clarified with heat and lime (calcium oxide or calcium hydroxide); small quantities of soluble phosphate may also be added. In sugar beet processing, the juice may be mixed with sulfur dioxide to prevent color formation and adjust pH. A heavy precipitate forms and is separated from the limed juice by gravity or centrifugation. The precipitate can be reprocessed to extract any remaining sugar. In the beet sugar refining process, the mixture is passed through resin-filled columns to separate the sugar from the non-sugars. Using a chromatographic separation process, it is possible to recover up to 90% of the sugar in beet molasses. Evaporation is the next step, which occurs in an evaporator station and vacuum pans. The syrup is then clarified again by adding lime, phosphoric acid, and a polymer flocculent, then aerated and filtered. To crystallize the sugar, some mills seed the vacuum pans with isopropyl alcohol and ground sugar. Once the sugar crystals are dried and cooled, the sugar is again refined by washing and clarification. Two clarification methods are commonly used: pressure filtration and chemical treatment; chemical clarification is the preferred method. Two chemical methods are commonly used: phosphatation and carbonation; both processes require the addition of lime. The next step is decolorization. The two most common color adsorbants are granular activated carbon and bone char, manufactured from degrease cattle bones. The decolorized sugar liquor moves through heaters, multiple effect evaporators, vacuum pans, and then ultimately is “seeded” to form crystals. Next, the crystals are washed in a centrifuge and then dried, screened, conditioned, and stored until packaging. The refined cane or beet sugar may be further processed into invert sugar by dissolving it in water to make liquid sucrose, and then adding hydrochloric acid and sodium hydroxide, or enzymes to hydrolyze the bond between glucose and fructose.(2) |
1. See generally White PJ and Johnson LA, “Corn Sweeteners,” in Corn Chemistry and Technology, 2nd Edition (2003); Alexander RJ, “Production and Description,” in Sweeteners: Nutritive (1998); and Corn Refiners Association, “Manufacture,” in Nutritive Sweeteners from Corn, 8th Edition (2006).
2. See generally Environmental Protection Agency, AP 42, Compilation of Air Pollutant Emission Factors, Vol. 1, § 9.10.1.1 Sugarcane Processing (5th ed.) and 9.10.1.2 Sugarbeet Processing. Galloway JH. History of sugar – Domestication to the 17th Century, abstracted from Annals of the Ass’n of Am. Geographers., Vol. 86, No. 4, at 682-706 (Dec. 1996); Chou CC. 2000. Sugar refining processes and equipment, in Handbook of Sugar Refining: A Manual for the Design and Operation of Sugar Refining Facilities.
