# Potential Applications of Yeast Biomass Derived from Small-Scale Breweries
## 9 Conclusions and Perspectives  
For small breweries (with a production capacity of around 20 hL per batch), disposing of yeast slurry may be a considerable problem. Introducing yeast slurry to the wastewaterstream substantially increases its organic load. Taking into account that beer manufacturing generates around 750 g of COD/hL of beer, yeast disposal may increase this value by an average of 290 g of COD/hL of beer. Yeast slurry disposal into the wastewater system would also require significant dilution of the wastewater to meet parameter limits accepted by treatment plants, resulting in significant increases in water consumption (around an additional 3 hL to 6 hL of water per 1 hL of beer). Yeast biomass processing seems to be a promising alternative for yeast slurry. Fractioning processes may produce value-added products such as yeast extract, cell wall fraction, protein concentrate, or beta-glucan, which could be further used in different branches of the food or pharmaceutical industry. Appropriately designed yeast biomass fractionation procedures should result in the conversion of all cell components into commercial products. One of the possible configurations may include the following products:  
Beta-glucan fractions (for food fortification or diet supplementation);  
Mann fractions (suitable for animal fodder supplementation);  
Food-grade protein concentrates (with a reduced content of nucleotides);  
Low-mass metabolite fractions enriched with nucleotide salts derived from nucleic acid hydrolysis (suitable as a flavor enhancer). Repurposing all yeast biomass-derived products is crucial for ensuring the profitability of processing facilities. It will also substantially reduce waste generation from the process. Due to yeast biomass instability, processing should start as soon as possible. However, the equipment required for the complete processing of yeast biomass includes expensive elements such as centrifuges or high-pressure filtration systems, and their purchase in small-scale breweries would be economically unjustified. A solution to this problem may be represented by partial processing in breweries, including autolysis. Biomass suspension after yeast autolysis is more stable than yeast slurry, and the autolysis process requires much simpler equipment than the full fractioning process. A small brewery (20 hL of production capacity) would require a heated vessel with a volume of only 100 L to run autolysis. Further yeast biomass processing could be performed in specialized facilities that collect biomass from several breweries. The production profile of such facilities would be flexible since procedures utilized in the purification of different fractions of yeast biomass rely on the same equipment. The processing of yeast biomass derived from small breweries is possible only when favorable market situations emerge. This means that the price of yeast-biomass-derived products must be high enough to ensure profitability. Increasing the demand for vegetarian and functional food products may, along with developing industrial in vitro production, change the market in favor of yeast biomass processing in the near future. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app14062529/s1](https://www.mdpi.com/article/10.3390/app14062529/s1)]([https://www.mdpi.com/article/10.3390/app14062529/s1](https://www.mdpi.com/article/10.3390/app14062529/s1)). Table S1: Brewery waste stem characterization. Table S2: Exemplary waste water parametews accepted in different treatment plants in Poland. Table S3: Calculation of yeast biomass COD. Table S4: Waste stream generated in beer production process.