Biomasses such as red and white clover, lucerne and ryegrass are important raw materials in a new research project at Aarhus University, where the ambition is to increase the production of protein to meet the growing demand for animal-based foods.

This increases the demand for proteins for animal feeds. In Denmark, soybean meal from South American is the most important source of feed protein. This import, however, has been criticized from many sides and research projects such as the one at Aarhus University are looking for suitable alternatives to the use of soybean as a protein source for farm animals.

One of the aims of the project, which has received 17m DKK from BioBase (a research initiative coordinated by DCA – Danish Centre for Food and Agriculture), is to optimise the extraction of proteins and other high-value components from green biomasses and undertake chemical, biochemical and biological evaluations of the protein fractions produced in laboratory and pilot-scales. The project, which involves scientists from several departments at Aarhus University, will also be looking at the possibilities of replacing animal-based protein in food products with green biomass proteins.

- The research project will serve as a platform for future large-scale national and international project within the biorefining of green biomass but could be applied to other types of biomass also, according to Professor Knud Erik Bach Knudsen, Department of Animal Science, who manages the project.

The project will also construct a technology platform for protein extraction and exploitation of by-products from the process.

The pilot-scale facility that will be established will produce two primary streams: a liquid phase (grass juice) that contains solubilized proteins, carbohydrates, minerals, etc., and a solid phase consisting of the fibrous fraction (grass pellets).

The scientists will extract the proteins and other compounds from the liquid fraction by precipitating proteins using heat and/or pH adjustment. The fraction is subsequently dried to a storable product. The stability of proteins from green biomass and of mixed products contain proteins from the green biomass will be studied in a separate work package. The nutritional quality of proteins from green biomass and mixtures will be evaluated in experiments with monogastric animals. This is done using rats and ileum-cannulated pigs and will also provide information concerning the nutritive value for humans.

- The solid fraction will be dewatered and dried to a grass pellet that can be used in the feeding of cattle or sows or as a raw material in a central biorefinery since the fresh green biomass is harvested at an early stage of development and is therefore only slightly lignified. The grass pellets will therefore be relatively easy to ferment in the gastrointestinal tract. Compared to the starting material, the protein content will be roughly halved, resulting in a fibre-rich energy feed that will be comparable to beet pulp and citrus pulp but will have a higher protein content. Such a feed will be interesting as a rumen-friendly feed supplement for dairy cows, as an energy-rich but still bulky feed for sows, but may also be used as complete rations for nursing cows, sheep, horses, etc., explains Knud Erik Bach Knudsen.

Another part of the project will carry out assessments of the fibrous fraction resulting from the protein extraction process.

- We need to examine the fibre-rich streams from the protein extraction process. This will be done using chemical methods, and we will carry out in-vitro digestibility tests simulating the digestive processes of ruminant and non-ruminant species to assess their potential use for cattle and sows, explains Knud Erik Bach Knudsen.

For further information please contact: Professor Knud Erik Bach Knudsen, Department of Animal Science, telephone: +45 87158063, email: knuderik.bachknudsen@agrsci.dk

Facts: The "High-quality protein from green biomass - Green protein" is one of four research platforms of the BioBase research initiative, which is coordinated by DCA – Danish Centre for Food and Agriculture.

The project will run until the end of 2017. Project participants are the Department of Animal Science, the Department of Engineering and the Department of Molecular Biology and Genetics at Aarhus University.