Lactic acid fermentation for refining proteins from green crops and obtaining a high quality feed product for monogastric animals

Nowadays, the organic farming sector is growing at a fast pace in Europe while needs to face the lack of organic protein sources and in particular, feeding monogastric animals is becoming more and more urgent. Green biorefinery concepts might become the suitable solution for the production of organic protein-rich feeds from green crops. In this context, red clover, clover grass, alfalfa and oilseed radish were studied as possible feedstocks for the development of an organic biorefinery system in Northern Europe. For this purpose, the green crops were processed into a nitrogen-rich protein concentrate, a fiber-rich press cake, and a residual stream of soluble nutrients (brown juice). The process, which involved a novel protein refining technique using lactic acid fermentation, yielded between 6 and 13 kg of dry organic protein product per ton of fresh crop. The protein products of the different crops presented balanced amino acid composition compared to soybeans, which are commonly used in organic farming. Moreover, methionine contents between 7.8 and 9.1 g/kg DM were obtained in the protein products, which is more than the typical concentration found in animal feeds (5.2 g/kg DM in soybeans). This makes the organic protein product produced very promising as a feed ingredient for organic farming of monogastric animals in Europe.