## 3 Results and Discussion  
### Basic Compositional Analysis of Meat Waste  
The moisture content of meat waste used in this investigation was 45.04 \(\pm\) 1.21%. On a dry weight basis, meat waste had a protein content (proteinic substrate contained in meat waste) of 19.03 \(\pm\) 0.42%, and a lipid content (lipidic substrate contained in meat waste) of 68.91 \(\pm\) 1.14%. These results agree with those presented by [PERSON] et al. [43], who found contents of 24.6 \(\pm\) 10.3% and 69.9 \(\pm\) 13.7% for proteins and lipids, respectively, in research describing the characteristics of meat waste produced by 208 butchers.  
The results obtained for total collagen showed a content of 67.91 \(\pm\) 0.14 mg/g, representing a percentage of 35.7% of the total protein present in waste. This is coherent with the fact that collagen is the most plentiful protein in mammalians, accounting for 25% of the total body protein [44], 95% of the fibrous elements in connective tissue, and 90% of the bones [45]. It is not unexpected that the percentage of collagen obtained somewhat surpasses the typical 25% in body protein given that the bones and connective tissue in meat waste are a larger percentage than usual in the body of an animal.  
The analysis of the fatty acid profile in meat waste (Table 1) clearly showed the predominance of unsaturated fatty acids (53.36 \(\pm\) 0.33) over saturated fatty acids (46.64 \(\pm\) 0.19). Due to the lack of information in the literature on the content of fatty acid in butcher waste, a review of the literature on the fatty acid profile in different animal fats and meats was carried out. The survey showed that the fatty acid concentration changes significantly depending on whether the sample is meat or land and on the sample's origin (lamb, beef, chicken, rabbit, etc.). A range of values were established based on all these data; the outcomes are shown in Table 1. The percentages of fatty acids acquired in the current investigation were found to fall within the range established in the literature.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Fatty Acid** & \multicolumn{1}{c}{**Meat Waste**} & \multicolumn{1}{c}{**Bibliographic Values**} & **Sources** \\  & **Mean \(\pm\) SD (\%)** & **Minimum–Maximum (\%)** & **[**46**, 51**, 54**]** \\ \hline  & Saturated fatty acid & & \\ C14:0 & 4.25 \(\pm\) 0.09 & 1.70–30.20 & [46; 47; 48] \\ C15:0 & 0.27 \(\pm\) 0.03 & 0.00–0.60 & [49; 50; 51] \\ C16:0 & 25.45 \(\pm\) 0.26 & 2.28–36.89 & [46; 48; 52] \\ C17:0 & 3.48 \(\pm\) 0.10 & 0.00–3.90 & [47; 48; 53] \\ C18:0 & 12.85 \(\pm\) 0.24 & 0.40–32.73 & [46; 50; 53] \\ C20:0 & 0.34 \(\pm\) 0.02 & 0.06–4.69 & [46; 51; 54] \\ Unsaturated fatty acids & & & \\ C14:1 & 0.00 \(\pm\) 0.00 & 0.00–1.16 & [50; 51; 55] \\ C15:1 & 0.00 \(\pm\) 0.00 & 0.00–1.70 & [47; 51; 56] \\ C16:1 & 0.30 \(\pm\) 0.01 & 0.00–37.9 & [48; 55; 57] \\ C17:1 & 0.32 \(\pm\) 0.02 & 0.00–0.90 & [47; 52; 58] \\ C18:In9C + t & 24.64 \(\pm\) 0.34 & 0.84–46.29 & [46; 52; 59] \\ C20:1 & 0.00 \(\pm\) 0.00 & 0.00–2.78 & [51; 53; 58] \\ C18:2n6c + t & 10.50 \(\pm\) 0.27 & 0.49–38.28 & [46; 48; 54] \\ C20:2 & 1.76 \(\pm\) 0.05 & 0.00–2.57 & [51; 52; 60] \\ C18:3 & 3.31 \(\pm\) 0.06 & 0.03–4.71 & [46; 54; 60] \\ C20:3n3 & 4.86 \(\pm\) 0.05 & 0.07–4.82 & [47; 51; 53] \\ C20:3n6 + c21:0 & 3.88 \(\pm\) 0.08 & 0.07–4.82 & [47; 51; 53] \\ C20:4n6 & 3.78 \(\pm\) 0.07 & 0.03–6.16 & [52; 53; 61] \\ \hline \hline \end{tabular}
\end{table}
Table 1: Fatty acids profile in lipids from meat waste.