## 3 Results and Discussion
### Volatile Compounds  
Eighteen volatile \"marker compounds\" were selected to represent a number of mechanisms of formation and were quantified (ng/g cooked sample) in beef subjected to two different cooking methods. The compounds were categorized into eight groups: aldehydes, Strecker aldehydes, thiophenes, ketones, sulfides, furans, alcohols, and acids. Many aldehydes, alcohols, and ketones are formed from the thermal oxidation of fatty acids and are known for their distinctive aroma profiles, encompassing notes of butter, sweetness, florals, toastiness, or green nuances [35]. The degradation of specific amino acids--alanine, isoleucine, leucine, methionine, phenylalanine, and valine--results in the formation of Strecker aldehydes such as acetaldehyde, 2-methylbutanal, 3-methylbutanal, 3-methylbutanal, 3-(methylthio)propanal, and phenylacetaldehyde, respectively. Furthermore, 2,3-butanedione is produced through the degradation of carbohydrates [36]. The impact of the cooking method on these volatile compounds for the three distinct muscles is detailed in Table 4. Significantly lower amounts of volatile compounds were observed in the case of the roasted muscles compared to the stewed ones. No statistically significant main effects (_p_ \(\geq\) 0.05) were observed due to the type of muscle. However, there were significant cooking x muscle interactions, as illustrated in Figure 2a,b. \begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline
**Factors** & \multicolumn{3}{c}{**Cooking Method (C)**} & \multicolumn{3}{c}{**Muscle (M)**} & \multicolumn{3}{c}{**C.M**} \\ \hline  & **Stewing** & **Roasting** & **SEM** & _p-_v** & **SM \$ & **BF** & **RF** & **SEM** & _p-_v** & _p-_v** \\ \hline _n-Aldehydes_ & & & & & & & & & \\ Pentanal & 10.2 b & 1.5 a & 1.37 & \textless{}0.001 & 5.8 & 3.9 & 7.8 & 1.37 & 0.505 & \textless{}0.05 \\ Hexanal & 8.2 b & 2.7 a & 0.60 & \textless{}0.001 & 5.8 & 5.5 & 5.2 & 0.60 & 0.909 & \textless{}0.001 \\ Heptanal & 0.2 & 0.5 & 0.10 & 0.230 & 0.4 & 0.5 & 0.2 & 0.10 & 0.496 & NS \\ Octanal & 0.2 & 0.2 & 0.00 & 0.378 & 0.2 & 0.2 & 0.2 & 0.03 & 0.857 & NS \\ Nonanal & 4.6 & 3.8 & 0.02 & 0.389 & 4.0 & 4.2 & 4.4 & 0.41 & 0.941 & NS \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Means amounts of volatile marker compounds (ng/g) collected from three muscles using two different cooking methods, analyzed by ANOVA. Higher levels of the following individual volatile compounds were observed in the case of the stewing compared to the roasting: pentanal, hexanal, benzaldehyde, 2-methyl thiophene, dimethyl disulfide, dimethyl trisulfide, and 2-pentyl furan (Table 4). There were significant interactions between the muscles and cooking methods for all of these compounds. The predominant effect was an increase in the quantity of these compounds collected from the stewed beef compared with the roasted meat, with the effect most marked in SM and RF for pentanal, hexanal, and 2-pentylfuran; in SM and BF for benzaldehyde, DMDS, and DMTS; and in RF for 2-methylthiophene (Figure 2). These relatively small effects of the muscle cannot be explained by the differences in gross composition (Table 1). Differences due to cooking method will have been influenced by the MSA cooking protocols, which were designed to simulate normal practice in Australia; the stewed beef was first browned in olive oil and then stewed, while the roasted meat was trimmed of outer browned surfaces. However, the fact that the remaining eleven compounds showed no significant effects of the cooking method (Table 4) suggests that other factors are playing a part. [PERSON] et al. [37] compared the volatiles from oven-roasted brisket and boiled meat (without trimming or browning steps) and reported that, in this case, most volatiles were higher from the roasted beef. \begin{table}