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Institute of

AT Agricultural Technology


Digestion of agricultural raw materials and residues

Lead Institute AT Institute of Agricultural Technology

Investigation and validation of methods for the extraction of free sugars from agricultural raw materials and residues, evaluation of new technologies

Sugars from biomass are essential building blocks for the production of biobased chemicals. A comprehensive knowledge of their recovery is necessary in order to evaluate and develop efficient conversion processes.

Background and Objective

As in conventional refineries, the first process step in a biorefinery usually is the fractionation of biomass into the individual components. Carbohydrates are one of the main components of plant biomass. In free form, their underlying sugar building blocks are essential intermediates for the fermentative production of many bio-based bulk chemicals. This conversion works relatively efficiently with carbohydrates such as starch from corn or sucrose from sugar beets, but to prevent food competition, these raw materials are of very limited availability for the biorefineries. Alternative sources of carbohydrates are cellulose and hemicellulose, the main components of most agricultural products, especially of harvest residues such as straw, chaff or sugar beet pulp.

But cellulose and hemicellulose cannot simply be transferred to the required sugars, since they are usually bound in complex, very resistant composite structures. For the efficient use of raw materials, it is therefore necessary to convert in free sugars by digestion techniques. For this saccharification physical, chemical and biotechnological processes can be used. In the past, various methods and integrated processes have been developed. However, due to cost reasons, these have not been implemented in large scale plants yet.

In addition to the analysis and evaluation of existing and new digestion processes, a focus of our work lies in the development and optimization of new digestion methods and method combinations for efficient saccharification of agricultural raw materials and residues. We take into account both the specific requirements of the substrates as well as the requirements of the biotechnological or chemical catalytic follow-up processes.


The central elements of our work are:

  • Analysis and evaluation of known and development of new saccharification process
  • Substrate-specific development of saccharification methods and strategies taking into account the follow-up processes

For this purpose, we use a variety of technologies and analytical methods:

  • Mechanical-physical pretreatment using mills (analytical purposes: ultra-centrifugal and  ball mills; process development: hammer-, knife- and rotor beater mills)
  • Biomass composition analysis: According to NREL and other methods using both conventional and ion chromatographic methods which allow the qualitative and quantitative determination of all carbohydrates and potential degradation products
  • Saccharification of agricultural raw materials and residues with various high-pressure autoclaves (50 mL to 5 L; electric, steam and superheated microwave heating)
  • Optimization and evaluation of digestion methods, especially for high substrate concentration, optimization of choice and dosage supporting chemicals and enzymes by methods of statistical experimental design


Permanent task 1.2011 - 12.2025

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