Zeinab Solati has conducted her Ph.D. thesis in BioValue’s project 1. Below is a short summary of her findings and information on the defense.


PhD title: Production of protein in grassland species and innovative cropping systems: quantity and quality for extraction

Large amounts of protein for animal production is imported into the EU as a result of insufficient European manufacture of animal feed protein of required quality especially for monogastric animals. This high dependency on imported protein has raised both environmental and economic concerns. Therefore, there is a need in Europe for identifying the most appropriate alternative sources to imported protein. Some of the highest protein yields per hectare are found in legume and grass species. However, they are not directly consumable by monogastrics i.e poultry and pig. Integration of protein production into a biorefinery producing other high value products e.g. fuels and chemicals can provide the possibility to extract and concentrate high quality protein and concurrently improve the economy of biorefinery.

The main objective of this study was to investigate the crude protein yield and the extractable true protein concentration and yield in different plant species and under different managements (i.e. harvest date, leaf and stem separation) in order to provide the basis for a biorefinery industry. Extractable true protein was determined according to the Cornell Net Carbohydrate and Protein System (CNCPS), which fractionates the crude protein into fractions of high to low solubility. It was assumed that the soluble crude protein fractions can be easily extracted in a biorefinery whereas extraction of cell wall-bound protein will demand pre-treatment techniques i.e. physical disintegration, utilizing enzymes, etc.

Pure grasses festulolium, cocksfoot, tall fescue and reed canary were superior to annual crops in optimized rotations and traditional crops common in Danish agriculture e.g. barley, maize and wheat with regard to crude protein yield and extractable protein per hectare. However, pure legumes such as red clover showed higher amount of extractable protein per hectare compared to perennial ryegrass and tall fescue across the spring. Unfertilized grass-legume mixtures showed similarities to intensively fertilized pure grasses with regard to extractable true protein per hectare. As the unit mass of biomass production increases with maturity, harvest of plant material should take place where the highest biomass yield is achieved. Nevertheless, the quality of protein in terms of solubility and thus extractability declined with maturity. This shows that the time of harvest may be a compromise between the high biomass yield and extractable protein concentration (per kg of DM) and thus should take place where an economic balance is met. While there was little to no difference in concentration of easily extractable protein between leaf and whole plant of grasses, legumes had notably higher easily extractable protein concentration in leaf than in their whole plant. The later the maturity stage of the plant, the larger the difference was. This indicates that in legume species, extraction of protein from the leaf rather than the whole plant can positively improve the extractable true protein on a mass basis and that extraction of protein from the leaf rather than the whole plant may be used as an appropriate strategy to mitigate the adverse effect of maturity on extractable protein on a mass basis.

The new research findings contribute to the identification of the most appropriate species for the European protein production and decision making with regards to appropriate field managements. These findings provide the basis for a biorefinery industry and can be utilized along with other supplementary data (i.e. valorization of biomass by-products, cost of crop production, quality of protein in terms of essential amino acids, etc.) for identifying the most suitable species for domestic protein production.

We hope that you will participate at Zeinab’s defense:

Time: Friday, September 15th 2017 at 10 AM

Place: Auditorium, Foulum, Blichers Allé 20, 8830 Tjele

Main supervisor: Senior researcher Uffe Jørgensen, Aarhus University

Contact information: Zeinab Solati, e-mail: Zeinab.solati@agro.au.dk

Defense title: Production of protein in grassland species and innovative cropping systems: quantity and quality for extraction