## 3 Bio-Utilization of Waste from the Agri-Food Industry during SCP Production  
Due to population growth, the demand for food increases, and as a result, the amount of agri-food waste (FW) increases. Poor waste management may contribute to the formation of toxic compounds, providing a basis for the development of pathogens or constitute generally understood environmental pollution. Waste from the agri-food industry, e.g., peels, seeds, slaughterhouse wastewater, dairy factory wastewater, and edible oil factory wastew \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & & & \\ \hline \multirow{2}{*}{**Amino Acids**} & _Candida_ & _Fusarium_ & _Saccharomyces_ & _Aspergillus_ & _Yarrowia_ & _Kluyveromyces_ \\  & _utils_[58] & _vennetatum_[50] & _cerevisiae_[59] & _oryzae_[51] & _Iipolytica_[23] & _marcianus_[60] \\ \hline Alanine & 7.59 & 2.41 & 6.89 & 2.37 & 8.00 & 3.63 \\ \hline Arginine & 4.82 & 7.12 & 4.02 & 1.99 & 4.80 & 6.03 \\ \hline Cystine & 10.16 & 2.11 & 1.24 & 0.28 & 1.10 & 1.11 \\ \hline Glycine & 3.92 & 3.50 & 5.23 & 1.72 & 4.60 & 2.67 \\ \hline Histidine & 3.78 & 7.22 & 2.78 & 0.75 & 2.60 & 2.66 \\ \hline Isoleucine & 5.28 & 1.51 & 4.63 & 1.38 & 4.40 & 6.21 \\ \hline Leucine & 6.73 & 1.90 & 8.75 & 2.46 & 6.80 & 9.57 \\ \hline Lysine & 5.81 & 2.60 & 6.73 & 2.14 & 7.00 & 8.15 \\ \hline Methionine & 1.67 & 4.21 & 3.12 & 0.57 & 1.20 & 2.48 \\ \hline Phenylalanine & 4.62 & 3.01 & 5.57 & 1.42 & 4.00 & 5.61 \\ \hline Threonine & 4.62 & 3.31 & 6.09 & 1.69 & 4.80 & 5.08 \\ \hline Valine & 6.05 & 2.91 & 5.34 & 1.72 & 5.30 & 5.30 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Amino acids composition of SCP from C. _utilis_, _F. venentum_, _S. cerevisiae_, _A. orgae_, _Y. lipolytica_, _K. marxianus_. ater, are rich in organic, bioactive compounds [61; 62]. Food producers find a number of applications for FW, using them in the production of feed, fertilizers, as a substrate for the synthesis of many chemical compounds (e.g., citric acid, xanthan gum) or as a source of dyes, enzymes, and hydrocolloids [63; 64]. One of the solutions to the increasing production of food wastes is to use it as a substrate for the production of SCP. The most commonly used waste for this purpose is waste from fruit and vegetable processing. However, it can also be liquid waste, e.g., from the dairy industry. Fruit and vegetable waste is an excellent source of bioactive compounds that are necessary for the growth of microorganisms growth. An important aspect that determines the use of waste as a compound of medium is its composition. Microorganisms choose carbohydrates as a source of carbon and energy. Potato peels, betroot pomace, and carrot pomace, rich in carbohydrates, work well as a component of the fermentation medium for the production of SCP. The second important compound for biomass production is nitrogen. It has been shown that the addition of ammonium sulfate, ammonium nitrate, or sodium nitrate to the substrate has a beneficial effect on the growth of biomass [27; 65]. In addition, among compounds that promote the production of SCP, compounds that inhibit the growth of microorganisms should be taken into account. Essential oils contained in citrus peels have proven antimicrobial properties [66], so the use of lemon, orange, or grapefruit waste may be associated with lower biomass production efficiency. The first step, after taking the industrial waste, is cleaning it with running water to remove all contaminants and pesticides (in the case of waste from the juice processing industry, Figure 2). After cleaning, the waste is dried separately at 50 \({}^{\circ}\)C for 48 h. The dried material is prepared in a grinder followed and sieved through a 80 mesh sieve [27]. The medium is prepared from a properly obtained powder (e.g., obtained from banana or potato peels) by adding a certain quantity of 10% hydrochloric acid and the heating it at 100 \({}^{\circ}\)C for an hour.