# An Overview on Management and Valorisation of Winery Wastes
## 2 Winery Waste Composition and Source of Bio-Active Compounds
discharged by the winemaking industry [27]. Grape seeds are characterized by a high content of carbohydrates, fibre (40% \(w/w\)), lipids (16% \(w/w\)), minerals, polyphenics (7% \(w/w\)), and proteins (11% \(w/w\)) [30]. Grape stalks represent the skeleton of the grape raceme, removed before the vinicration, representing 14% by weight of the total wine solid waste [19]. The chemical composition of the stalks includes lignocellulosic materials, such as 20-30% cellulose, 3-20% hemicelluloses, and 17-26% lignin, but also 6-9% ash [28]. Stalks can also contain tannins (around 80%) associated with the lignin and more than 50% polysaccharides (the main one being glucose and xylose) [19; 31]. In terms of phenolics, grape stalks contain around 6% on a dry weight basis, the main ones being flavan-3-ols, flavonols (e.g., galactoside, glucuronide, glucoside, and rutinoside), hydroxybenzoic acids (gallic and syringic acids), and stilbenes [19; 32]. Various studies have investigated the antibacterial properties of the extracts from winemaking by-products [33; 34; 35; 36; 37; 38; 39; 40]. The phenolic compounds responsible for the antimicrobial activity from winemaking by-products are alkaloids, coumarins, flavonoids, phenolic acids, quinones, saponins, tannins, or terpenoids [24; 41]. Table 2 summarizes some studies on the antibacterial activity of winemaking by-products. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Grape Variety** & **Country** & **By-Product** & \begin{tabular}{c} **Extraction** \\ **Method** \\ \end{tabular} & \begin{tabular}{c} **Bio-Application** \\ **Gram Negative** \\ \end{tabular} & \begin{tabular}{c} **MIC Range** \\ **(mg/L)** \\ \end{tabular} & **Ref** \\ \hline Babic & & & & & & 0.08–0.42 \\ \hline Debit & & & & & & 0.02–0.25 \\ \hline Lain & & & & & 0.04–0.34 \\ \hline Merlot & Croatia & Skins & Ethanol/water (80:20) & _B. cereus_ & _C. coli_ & 0.13–0.44 \\ \hline Plavina & & & & & 0.09–0.41 \\ \hline Tmjac & & & & & 0.12–0.31 \\ \hline Vranac & & & & & 0.16–0.23 \\ \hline Arinto & & Seeds and skins & Water & _B. cereus_ & _E. coli_ & ND & [34] \\ \hline \multirow{8}{*}{[PERSON]} & & & & _B. cereus_ & & \\  & & & & _E. faecalis_ & & \\  & & Seeds & & _L. monocytogenes_ & _K. pneumoniae_ & 0.001–0.010 \\  & & & & _S. aureus_ & & \\ \cline{1-1} \cline{2-6}  & Portugal & & & _B. cereus_ & & \\  & & & & _E. faecalis_ & & \\  & & & & _L. monocytogenes_ & & \\  & & & (50:50) & _S. epidermidis_ & & \\  & & & & _S. aureus_ & & \\ \cline{1-1} \cline{2-6}  & & & & _B. cereus_ & & \\  & & & & _E. faecalis_ & & \\  & & & & _E. faecalis_ & & \\  & & & & _E. faecalis_ & & \\  & & & & _E. faecalis_ & & \\  & & & & _L. monocytogenes_ & & \\  & & & & _E. faecalis_ & & \\  & & & & _L. monocytogenes_ & & \\  & & & & _S. aureus_ & & \\ \hline Emir & & & & & _A. hydrophyla_ & & \\ \hline Hasanedde & Turkey & Defatted & \begin{tabular}{c} Acetone/water: \\ acetic acid \\ (90:9:1) \\ \end{tabular} & \
\begin{tabular}{c} _B. cereus_ \\ _E. faecalis_ \\ \end{tabular} &
\begin{tabular}{c} _E. aerogenes_ \\ _E. coli_ \\ _K. pneumoniae_ \\ _P. vulgaris_ \\ _P. aeruginosa_ \\ \end{tabular} & ND & [36] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Winery by-products as bio-active components. The scarcity of investigation concerning the antimicrobial activity of winemaking by-products and the multitude of methods to obtain them make the effort to highlight conclusions from their analyses more complicated. Winemaking by-products were found to be active against multidrug-resistant strains in various investigations [35], but also against bacteria with passive mechanisms of antibiotic exclusion (such as Clostridium or Bacillus) [26; 27; 28; 29; 30; 31; 32; 33; 38; 39]. Various studies mentioned that a broader inhibitory spectrum was found against Gram-positive bacteria [42]. It was observed that winemaking by-products were most often bactericidal [43].