# Odor Emissions from Raw Meat of Freshly Slaughtered Cattle during Inspection
## 3 Results and Discussions  
The results of the method validation procedure (Table 3) proved that the developed method is effective for the determination and quantification of the aroma volatiles emitted by fresh-slaughtered raw meat. The average content (\(\upmu\)g/g of raw meat) of the volatile compounds released by meat at different times from slaughtering is reported in Table 4, along with their linear retention index (LRI) and odor threshold value (OTV). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multicolumn{4}{c}{**Precision**} \\ \cline{2-6}  & \multicolumn{2}{c}{**Intraday RSD\%**} & \multicolumn{2}{c}{**Interday RSD\%**} & \multicolumn{2}{c}{**Recovery (\%)**} & \multicolumn{2}{c}{**LOD (\(\upmu\)g/g)**} & \multicolumn{2}{c}{**LOQ (\(\upmu\)g/g)**} \\ \hline Toluene & 2.26 & 3.12 & 99.6 & 0.025 & 0.081 \\ Limonene & 3.41 & 4.86 & 99.7 & 0.003 & 0.010 \\
2-Methyl-3-buten-1-ol & 4.56 & 2.95 & 99.0 & 0.019 & 0.063 \\ p-Cymene & 2.27 & 4.26 & 99.3 & 0.014 & 0.046 \\ Acetoin & 4.96 & 3.71 & 99.1 & 0.038 & 0.123 \\
6-Methyl-5-hepten-2-one & 5.48 & 5.19 & 99.8 & 0.022 & 0.071 \\ Nonanal & 3.42 & 2.73 & 99.4 & 0.017 & 0.05 \\ Acetic acid & 2.38 & 4.25 & 99.3 & 0.028 & 0.094 \\ \(\gamma\)-Butyrolactone & 5.76 & 3.32 & 99.5 & 0.015 & 0.048 \\
1-Nonanol & 2.94 & 3.69 & 99.7 & 0.011 & 0.036 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Quality parameter of volatile compounds detected under the optimized HS-SPME-GC–MS method. The volatile profile of the raw meat of FSC was characterized by a small number of compounds; nine volatiles belonging to different classes of organic compounds were identified; among these, only toluene, limonene, acetoin (3-hydroxy-2-butanone), acetic acid, and \(\gamma\)-butyrolactone were quantifiable, whereas 2-methyl-3-buten-1-ol, 1-nonanol, p-cymene, and 6-methyl-5-hepten-2-one were present at trace levels. Our results cannot be compared with the literature data since they mainly refer to cooked meat and those on raw meat do not consider the volatiles emitted in the first 24 h after slaughtering, as reported above. The limited number of volatiles identified in our samples is reasonable; in fact, it is known that raw meat, characterized by a weak odor, is just a reservoir of aroma and flavor precursor compounds and the intensive meat odor and aroma are thermally derived. Regarding the identified volatiles, limonene originates directly from animal feeding, and since terpene biosynthesis occurs exclusively in the plant kingdom, its occurrence suggests the presence of green forage in the cattle diet [30; 31]. Toluene also derives directly from animal feedstuffs, as previously reported by other authors [32]. \(\gamma\)-Butyrolactone is linked to the feeding system too, but in this case, there is no direct transfer from the ingested feeds into tissue; in fact, \(\gamma\)-butyrolactone is the final product of the oxidation of the dietary fatty acids that occurs in the rumen [30; 31]. Higher lactone amounts were reported in the fat tissue of ruminants fed grain-based diets compared to grass-fed ruminants [33]. Finally, acetoin and acetic acid are associated with the activity of ruminal microorganisms since they are well-known products of rumen fermentation [34; 35]. Quantitative differences were observed in the volatile profile of the meat samples analyzed at different times after slaughtering. Specifically, significant differences were found for the amount of \(\gamma\)-butyrolactone, acetoin and acetic acid: \(\gamma\)-butyrolactone decreased during all the considered periods, acetoin decreased up to 3 h and then increased, while acetic acid remained stable for up to 3 h and then increased. OAVs were considered to evaluate the contribution of the identified compounds in developing the meat odor of FSC.