High Fructose Corn Syrups are produced from refined very high DE glucose syrups. An enzymatic process using isomerase fixated on a resin facilitates the conversion of glucose to fructose. By using more resin columns in parallel the enzyme activity is completely exhausted before a refill.

The isomerase catalyses the formation of 42% fructose in equilibrium with glucose. This syrup may be refined and evaporated as such and it is an excellent all-purpose sweetener.

In order to obtain a more perfect match with sucrose based liquid sugar (cane and beet sugar) the fructose content has to be increased to 55% by enrichment. A stream of HFCS-42 is fractionated. Previous attempts to do this by crystallisation have never gained industrial acceptance. The fractionation is done more elegantly by chromatography. By auto-matically switching the injection point an endless ring column is simulated and the HFCS-42 is fractionated in fructose and glucose. Water or condensate is used to eluate the column. The fructose fraction is backmixed with the HFCS-42 to make up an HFCS-55. In this way a perfect match with traditional sucrose based liquid sugar is obtained. The HFCS-55 finds widespread use as sweetener in soft drinks.

The fructose fraction from the chromatographic column can of course be refined and evaporated to a syrup separately as HFCS-90 finding applications in low calorie foods.