The yeast production process evaluated in the report is developed in Foods of Norway. The environmental impact from the production of BALI (Borregaard Advanced Lignin) sugar is assessed, as well as the production of yeast, with the use of different nitrogen sources.
The report concludes that BALI sugar accounts for the largest share of the environmental impact in the production of yeast. However, sugar also makes up most of the raw material. Ammonia and other raw materials also have an impact, although smaller. The impact of the processing of yeast stands for an almost negligible share of the climate impact.
The nitrogen source of yeast production can be either inorganic or organic. This study assesses the data for ammonia, waste and blood.
If an organic nitrogen source is used, chemicals and minerals are not required. When using offal and blood as nitrogen sources, the environmental impact for yeast is lower compared to yeast where the nitrogen source comes from ammonia. The only exception is for land occupation, were the burden is slightly higher for yeast with offal nitrogen source. How much lower depends on the value, based on economic allocation.
A possible further development of the LCA may be looking into using the biogenic CO2 emitted from the fermentation process in other industrial purposes, for example greenhouse production. In which case, the environmental impact from the upstream value chain can be allocated between the product(s) and yeast. The environmental impact of yeast will then be reduced accordingly.