ORGANOFINERY: FROM GREEN CROPS TO PROTEINS, ENERGY AND FERTILISER

Summary

Difficulties with the supply of organic protein feed; low crop yields and low value of leguminous forage crops and a lack of organic fertiliszers are nowadays threesome of the major challenges faced by farms with monogastric animals. Thus, forcing the organic farmers to import feed and manure forom conventional farms. The main idea of the OrganoFinery project is to develop a green biorefinery concept where the same organic crop is utilizsed for animal feed, fertilizser and energy production in the form of methane, coping in this way with those challenges.
One of the aims of the project includes the identification of crops that can be grown on organic arable farms, where there is generally a significant lack of nitrogen. Particularly legumes are interesting as they can biologically fix N, producing large amounts of protein without the addition of N fertilizer. Red clover, clover grass, alfalfa and oil seed radish are being studied.
Right after the harvest, the biomasses are separated in a green juice and a press cake using a screw press. Organic protein feed is produced by lactic acid fermentation of the green juice. The extraction of proteins is based on an already developed technique to extract proteins from alfalfa. The method for separation of proteins from alfalfa was developed by AAUs subcontractor Biotest Aps in a joint Biorefinery program (FØSU grant 2101-08-0041). After the fermentation, two fractions are obtained: 1) the protein paste, with non-denatured proteins suited for development of a protein feed additive for poultry and 2) the brown juice, which is studied together with the press cake as a substrate for anaerobic digestion. Moreover, the digestate obtained after the anaerobic digestion is evaluated as organic fertilizser for the crops.
The protein yields obtained during the separation-fermentation process are in the range of 7 kg of crude protein from one tonne of fresh biomass. Crude protein contents up to 45 % DM are obtained in the protein pastes. Furthermore, the amino acid composition showed more favourable composition than the traditional soy protein for poultry feed.