# Potential Applications of Yeast Biomass Derived from Small-Scale Breweries
## 4 Brewery Yeast Biomass
\begin{table}
\begin{tabular}{l c c c c} \hline  & **Yeast Biomass** & **YE, Cell Mill** & **YE, Sonication** & **YE, Autolysis** \\ \hline Proteins/peptides & 41–49 & 32.2 & 28.5 & 5.3 \\ \hline Free amino acids & 0.2–0.4 & 11.6 & 15.5 & 30.6 \\ \hline Ribonucleic acids & 1.9–7.5 & 7.5 & 7 & 5 \\ \hline Total sugars & 22–54 & 31.2 & 31.4 & 28.8 \\ \hline Lipids & 3.9 & 1 & 1.1 & 0.5 \\ \hline Ashes & 1.7–8.5 & 13.1 & 13.3 & 13.2 \\ \hline Reference & [29] & [30] & [30] & [30] \\ \hline \end{tabular}
\end{table} 
Table 2: Yeast biomass and yeast extract composition [% DW]. \begin{table}
\begin{tabular}{c c c c c} \hline
**Amino Acid** & \begin{tabular}{c} **Yeast Biomass** \\ \end{tabular} & \begin{tabular}{c} **Yeast Extract** \\ **(Total)** \\ \end{tabular} & \begin{tabular}{c} **Yeast Extract** \\ **(Free Amino** \\ **Acids)** \\ \end{tabular} & \begin{tabular}{c} **WHO Amino** \\ **Acid** \\ \end{tabular} \\ \hline Lysine & 7.13 & 7.5 & 3.2 & 4.5 \\ \hline Histidine & 2.06 & 2.4 & 1.4 & 1.5 \\ \hline Threonine & 6.16 & 4.6 & 2.7 & 2.3 \\ \hline Valine & 6.2 & 6.2 & 4.0 & 3.9 \\ \hline Leucine & 8.84 & 7.2 & 5.7 & 5.9 \\ \hline Isoleucine & 5.64 & 5.0 & 3.4 & 3 \\ \hline Phenylalanine & 5.3 & 4.6 & 3.5 & 3.8 \\ \hline Tyrosine & 4.68 & 3.5 & 2.4 & \\ \hline Typtophan & 1.1 & 1.3 & 1.0 & 0.6 \\ \hline Methionine & 2.5 & 1.6 & 1.2 & 1.6 \\ \hline Cystine & 0.34 & 1.1 & 0.5 & 0.6 \\ \hline Glutamic acid + glutamine & 13.15 & 15.8 & 5.2 & \\ \hline Aspartic acid + aspartate & 11.98 & 10.5 & 4.0 & \\ \hline Serine & 6.13 & 5.1 & 3.5 & \\ \hline Proline & 4.45 & 5.8 & 3.3 & \\ \hline Alanine & 7.07 & 7.6 & 6.0 & \\ \hline Glycine & 4.93 & 5.2 & 2.2 & \\ \hline Arginine & 4.11 & 5.1 & 3.0 & \\ \hline \multirow{3}{*}{Source material type} & \
\begin{tabular}{c} Brewery \\ yeast \\ biomass \\ \end{tabular} &
\begin{tabular}{c} Yeast extract obtained from \\ brewery yeast via lysis with \\ papain and debittering \\ \end{tabular} \\ \hline Reference & [31] & [32] & [33] \\ \hline \end{tabular}
\end{table} 
Table 3: Amino acid composition for yeast biomass and protein concentrates (g/100 g total amino acids). Yeast biomass also contains a considerable amount of water-soluble vitamins. The concentrations of individual vitamins in yeast biomass and yeast extracts are presented in Table 5. The most abundant vitamins in yeast biomass are niacin, thiamin, and pantothenic acid. The lowest concentrations are observed for biotin and cobalamin. The majority of _S. cerevisiae_ strains cannot synthesize biotin, and draw it from the medium; thus, its intracellular level is limited by the biotin availability in the culture medium [23]. Since the concentration of biotin in word is very low (0.1 mg/kg of DW), it may explain the low concentration of this vitamin in brevery yeast biomass [36].As already mentioned, after the fermentation process is finished, the yeast biomass may be collected and recycled for the production of beer from fresh word. Prolonged storage time or inappropriate storage conditions (temperature above 15 \({}^{\circ}\)C) may result in a partial degradation of biomass due to autolysis [37]. This leads to reduced cell viability and attenuation, and may also result in increased concentrations of undesired compounds in beer, such as diacetyl. It may also lead to deterioration in the quality of products derived from such biomass.