To develop yeast from spruce trees, the tree fibres must be separated into lignin, cellulose and hemicellulose. The cellulose is converted to sugars by using enzyme technology. Together with rich nitrogen sources from chicken or fish hydrolysate and ammonia, these sugars are used in the fermentation media to grow yeast. The yeast is harvested, washed, centrifuged and dried, then used as a high-value protein source in diets for livestock and fish.
Foods of Norway researchers have shown that yeast produced from trees can successfully replace 40 per cent of the protein from fish meal in diets for Atlantic salmon, and up to 40 per cent of the protein from conventional protein sources in diets for piglets. Optimizing the fermentation and downstream processing conditions to reduce the production cost and to increase the yield and nutritional value of the yeast are main aspects of the research.
Foods of Norway also aims to use other microbial ingredients accumulating high levels of lipids as alternative high-quality fat sources in fish feed, read more about that work here. The NORDICFEED project will develop sustainable microbial feed ingredients from locally available waste streams , such as food waste, sugar streams from the pulp and paper industry, and animal fat co-products from the meat industry.