I was surprised, I got feedback so quickly, I thought I was asking into the void.
The production of HFCS-55 goes through this process:
- Corn kernels are ground into corn starch
- α-Amylase enzyme hydrolyzes α-bonds in starch, producing oligosaccharides
- Glucoamylase breaks down oligosaccharides into glucose
- Xylose isomerase converts glucose to ~42% fructose and ~50% glucose
- Liquid chromatography purifies fructose to ~90% concentration
- 90% fructose solution mixed with 42% fructose to create 55% fructose "High Fructose Corn Syrup"
I was really curious about the "liquid chromatography"
I think I finally found the answer when I ran across this PDF document, entitled: AmberLiteTM Uniform Particle Size Ion Exchange Resins - Chromatographic Separation of Fructose and Glucose with AmberLiteTM CR99 Ion Exchange Resins -
Technical Manual and the section on "3.1 The Chromatographic Mechanism"
[...] Inside the bead, the dissolved sugars interact with the calcium ions held by the resin. Fructose, glucose and water form weak ligand complexes with the calcium ion. A stronger interaction in the fructose/calcium ion complex than in the glucose/calcium ion complex is the basis of the mechanism of separation of fructose from glucose1. This mechanism of separation is called ligand exchange chromatography.
While technically it is a cation exchange column using Ca2+, the interaction between fructose/glucose and the Ca ions, is an affinity relationship. The footnote from the DuPont technical manual clears this up:
1 Chromatographic separation resins do not “exchange” ions as do the resins used in deashing and mixed bed polishing. They function by adsorbing and “slowing” fructose as it moves down the column. The syrup doesn’t exchange ions in the process.
I also found a nice webpage from PuroLite, that goes through the process.
This sweetener is produced by passing a 42% fructose solution through a calcium form strong acid cation resin to effect a separation and create a 75-90% fructose solution which can be blended back with additional 42% fructose to produce a 55% fructose purity.
Owing to a greater number of sites available for hydrogen bonding, the fructose molecule will form a coordination complex with calcium ions fixed onto a strong acid cation resin. This results in a preferential affinity of the resin for the fructose molecule over the glucose molecule and hence a chromatographic separation of the two sweeteners as they pass through the resin bed. From a feed solution containing a purity of 42% fructose by weight, the fructose in the product fraction can reach in excess of 99% purity.
When producing 55% fructose, the optimum productivity and efficiency of the system is achieved by enriching to an 85-90% fructose concentration.
some other highlights:
In the 1970s, the technology was developed for continuous chromatographic separation of fructose utilizing a simulated moving bed (SMB) separation system.
let me know if I missed anything.