# Reuse of Spent Coffee Grounds: Alternative Applications, Challenges, and Prospects--A Review
## 8 SCGs in the Food Industry  
Both SCGs and ingredients extracted from them, such as lipids, are used in the food industry. Studies by [PERSON] et al. (2017) have shown that SCGs are a natural source of water-insoluble fiber, essential amino acids, and low glycemic index sugars, which are resistant to thermal food processing and digestion, and completely safe. SCGs added to cakes increase total dietary fiber content, antioxidant capacity after digestion, and the bioavailability of phenolic compounds (gallic acid and catechins) and amino acids. Based on tests of nutritional quality, chemical quality, microbiological safety, and sensory quality, they were found to meet consumer preferences and have high nutritional quality. In addition, they have the potential to reduce the risk of chronic diseases such as diabetes and obesity [49; 50]. SCGs can also be used to produce alcoholic beverages and spirits. SCG spirit has an organoleptic quality that is acceptable for consumption [51; 52]. SCGs can also be added to bakery products [50; 51; 53; 54]. Peptides from SCGs can be used as a health-promoting food additive ([55], Table 6). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Material** & **Application in the Food Industry** & **Procedure** & **References** \\ \hline SCGs from industrial & & & & \\ production of & & & & \\ instant coffee & & & & \\ \hline \multirow{2}{*}{Dietary fiber from SCGs} & \multirow{2}{*}{Biscuits} & \multirow{2}{*}{B} & Drying, preheat treatment (8 g SCGs + 200 mL H\({}_{2}\)O—heating & \\  & & & 80 \({}^{\circ}\)C, 1 h), and ohmic heating (275 VAC, 60 Hz, 0.31 s (as & [50] \\  & & & holding time), 90 \({}^{\circ}\)C) & \\ \hline \multirow{2}{*}{SCGs} & \multirow{2}{*}{Spirit} & Extraction by hydrothermal treatment (1 g SCGs/10 mL & \\  & & H\({}_{2}\)O, 163 \({}^{\circ}\)C, 45 min), fermentation (30 \({}^{\circ}\)C and 150 rpm) & [51] \\  & & & and distillation & \\ \hline \multirow{2}{*}{Degressed SCGs} & \multirow{2}{*}{Cookie ingredient} & \multirow{2}{*}{Supercritical CO\({}_{2}\) extraction (SCGs \(\leq\) 425 \(\upmu\)m)} & [53] \\ \hline SCGs & & & & \\ \hline \multirow{2}{*}{SCGs} & \multirow{2}{*}{Ingredient for sponge cake} & Mixture: wheat flour (98, 96, 94\%) and SCGs (2, 4, 6%) & [54] \\  & & & Acid extraction and precipitation (SCGs after 16/64\({}^{\prime\prime}\)) sieves, & \\  & & and antihypertensive effects & extraction—0.1 M HCl and 0.1 M NaCl precipitation—66\% & [55] \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Coffee oil extract \\ from SCGs \\ \end{tabular} } & \multirow{2}{*}{Coffee-flavored syrup} & Ethanol extraction & [56] \\  & & & Microwave extraction (power 71\%, pressure 827.6 kPa, time \\  & & 20 min), fermentation (30 \({}^{\circ}\)C, 150 min), and distillation & [57] \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Coffee oil extract from \\ SCGs \\ \end{tabular} } & \multirow{2}{*}{Coffee oil as a butter substitute in \\  & & & Ethanol extraction (50 g SCGs + 500 g of ethanol, \\  & & baked goods & 180 rpm, 16 h) \\ \hline \multirow{2}{*}{SCGs} & \multirow{2}{*}{Alcoholic beverages} & \multirow{2}{*}{Hydrolysis (Acid hydrolysis: 200 mM citric acid, 121 \({}^{\circ}\)C, 1 h,} \\  & & Enzymatic hydrolysis: 6% Viscozyme L 50 \({}^{\circ}\)C, 24 h) and \\ \cline{1-1}  & & yeast fermentation (20 \({}^{\circ}\)C, 14 days) & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Examples of SCG applications in the food industry. A significant issue associated with the use of SCGs in the food industry is the sanitary aspect. SCGs may contain various microbiological contaminants, such as bacteria and mold, which can pose health risks. Introducing SCGs into food production processes without proper preparation can lead to product safety issues. A practical solution to this problem could involve the use of steam disinfection combined with UV radiation. Steam disinfection eliminates microorganisms through the application of high temperatures. It is a safe solution that works quickly and effectively to remove microorganisms from SCGs.