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Efficient, low-cost production method for the natural sweetener 5-Ketofructose (5-KF)


5-Ketofructose (5-KF) is the perfect sweetener. Thanks to the inventive method it is now possible to produce the substance efficiently and cost-effectively. For the first time, a natural product produced from renewable raw materials and without any unpleasant aftertaste is made available. It optimally supports diabetic diets without changing the flavour of the meals or drinks.
Recombinant cells of Gluconobacter oxydans are used for its production. Not only can these cells convert fructose to 5-KF in a highly effective manner, but also express enzymes that break down low-cost substrates available in large amounts. 


According to a recent study by the Robert Koch Institute over 50 % of all Germans suffer from overweight; obesity-related diseases have doubled worldwide since 1980. This high body-mass-index is also associated with an increased risk of type 2 diabetes. Especially teenagers and young adults are increasingly affected. Sweeteners have no calories that are digested by the human body and their sweetness factor is high without affecting insulin levels. Therefore, they are of particular interest to people with diabetes.  Moreover, they are considered appropriate for low-sugar diets. However, most of the sugar sub­stitutes are produced synthetically and not all of them can be consumed without side effects.


There are only a few natural sugar substitutes available on the market. The comparatively expensive sweetener Stevia has a high sweetening power, but it also has a slightly bitter aftertaste. Plus, the production conditions in Asia are not well controlled; no crucial breakthrough has been reported so far. 5-KF is not yet available on the mar­ket as its production used to be either complicated or inefficient – and definitely costly. As 5-KF is ideally suited as a sweetener and global demand is expected to rise in the future, it is more crucial than ever to provide an efficient and low-cost production method.


The method developed by scientists at RWTH Aachen University, the University of Bonn and Forschungszentrum Jülich is based on the use of recombinant Gluconobacter oxydans strains, enabling low-cost pro­duction of 5-KF. And that is not all. In a fed-batch process with a highly concentrated solution of fructose it is possible to produce 5-KF in a single step, because fruc­tose dehydrogenase (FDH) is overexpressed in the strain. Product yield and concentration are much higher com­pared to conventional methods. Process efficiency and product purity can be optimized even further through additional measures. The use of mixed cultures will allow users to adjust the process to different substrates through the expression of necessary enzymes during the process. Methods for purification of the product are currently under development.

The comparison with the wild type (white symbols) is an impressive proof of how the conversion of fructose to 5-KF can be significantly enhanced in the recombinant strain (black symbols) through the addition of FDH [RWTH].
The comparison with the wild type (white symbols) is an impressive proof of how the conversion of fructose to 5-KF can be significantly enhanced in the recombinant strain (black symbols) through the addition of FDH [RWTH].


  • Natural sweetener from readily available, renewable resources
  • No unpleasant aftertaste
  • Very effective single-stage process
  • Product yield > 90%
  • High product concentrations
  • Procedure can be adapted to various carbohydrate substrates
  • Low-cost, natural sweetener


Currently, there is no natural sweetener without undesired aftertaste that is available at affordable prices. 5-Keto­fructose (5-KF) has all of these qualities. With a new fer­mentation method, substrates (e.g. sucrose, glucose or starch), that are inexpensive and available in large amounts, can be used for the direct production of 5-KF.

Find out more

Elena Herweg, Marie Schöpping, Katja Rohr, Anna Siemen, Oliver Frank, Thomas Hofmann, Uwe Deppenmeier, Jochen Büchs,
"Production of the potential sweetener 5-ketofructose from fructose in fed-batch cultivation with Gluconobacter oxydans",
Bioresource Technology, Volume 259, 2018, Pages 164-172, ISSN 0960-8524.

Siemen, A., Kosciow, K., Schweiger, P. et al.,
"Production of 5-ketofructose from fructose or sucrose using genetically modified Gluconobacter oxydans strains",
Appl Microbiol Biotechnol (2018) 102: 1699.

Anne Böse, M.Sc.
Ettlinger Straße 25
76137 Karlsruhe | Germany
Phone +49 721-79004-0
boese(at) |
Development Status
Proof of concept / TRL3
Patent Situation
EP (WO 2018/229161 A1) pending
US (WO 2018/229161 A1) pending
Reference ID
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