Demonstration-scale protein recovery by lactic acid fermentation from grass clover – a single case of the production of protein concentrate and press cake silage for animal feeding trials

There is an increasing interest in green biorefineries for the utilization of green biomass to provide a variety of valuable products. Proteins can be extracted from green biomasses such as alfalfa, clover, or grass and separated into protein-rich concentrates suitable for feeding to monogastric animals. Press cake suitable for feeding ruminant animals is also produced. Full implementation of such a green biorefinery requires knowledge and experience of production at demonstration scale. Moreover, product evaluation in animal-feeding trials requires a large amount of product. There has been collaboration in Denmark between several partners from industry and academia to assess the practicality and scalability of a green biorefining plant producing protein concentrate and press cake silage from organic grass clover at the scale of ca. 10 tons per hour fresh biomass input. Lactic acid fermentation of the pressed green juice was successfully performed to precipitate proteins and stabilize the juice. Despite minor difficulties, the demonstration-scale biorefining plant was operative for four days, processed 444 tons of grass clover, and resulted in the overall production of 1 ton of dried protein concentrate, 7 tons of protein paste, and 223 tons of press cake silage. The protein concentrate was rich in essential amino acids and was tested in feeding trials with poultry; the press cake silage, rich in processed fibers and fiber-associated proteins, was tested in feeding trials with dairycows