STARCH SWEETENERS

Starch sweeteners are an important outlet for wheat starch and in many plants starch is not dried at all. In stead the refined A-starch slurry is further processed into starch syrups.

For wheat starch the glucose is particular important. Basic and typical units of operation are:

1. LIQUEFACTION. The refined A-starch slurry is pH-adjusted and enzymes are added. The prepared slurry is heated by direct steam in a steam jet. The liquefaction is typically a two stage process. The combination of heat and enzymes gelatinizes and thins the starch. The enzyme does the work by cutting the long starch molecules into pieces by hydrolysis. A low DE hydrolysate is formed and at this point the starch has been converted into a maltodextrin. (DE= Dextrose Equivalent).
2. SACCHARIFICATION. The low DE hydrolysate is pH and temperature adjusted once again and new enzymes added to produce glucose with a higher DE. Glucose of different composition can be made depending on the enzymes added and the process applied - even products close to pure dextrose.
3. PROTEIN FILTRATION. New technology allows cross-flow membrane filtration of the hydrolysate. By dia-filtration glucose may be recovered from the filter residue leaving a protein rich mud to be discharged as animal feed.
4. CARBON TREATMENT. The glucose hydrolysate is heated and treated with activated carbon to remove impurities and colour bodies and then filtered.
5. ION EXCHANGE. The glucose hydrolysate is demineralised with ion exchange resins in a "merry go round" arrangement. Cation resins remove various ions as sodium, calcium, traces of iron and some amino acids. Anion resins remove ions like chloride, sulphate, phosphate and most residual amino acids.
6. EVAPORATION. The refined glucose syrup is concentrated by evaporation to its final commercial dry matter content. The syrup is now ready for drumming off or for road tanker transport.
7. A MULTITUDE OF SWEETENERS. By varying the procedures a range of commercial products can be made and the pure dextrose syrups may even form basis for further processing into High Fructose Syrups utilizing sophisticated techniques like enzymatically isomerising and chromatography.

APPLICATION.

Being a pure renewable natural polymer, starch has a multitude of applications.

Commercial wheat starch is used in the manufacture of sweeteners, sizing of paper and textile and as a food thickener and stabilizer.

Nine million t per annum of starch and starch sweeteners are manufactured in the European Union and one third is originating from wheat.

In the European Union 40% of native and modified starches is consumed by the paper industry being the most important outlet at present.

Increasing amounts of grain, however, is supposed to be consumed by the new bio-fuel industry. In USA this development has already started on maize as raw material. In Europe wheat is the prime candidate.