## 3 Results
### Spme gc-Ms  
SPME was used for the extraction of the volatile and semi-volatile compounds found in the aging gueuze samples. A total of 41 compounds were identified using a combination of retention index and mass spectral matching against library standards. A number of these compounds have been previously identified by [PERSON] et al. [7; 12]. GC-MS was utilized to characterize all of the volatile and semi-volatile compounds found within the aging samples. A Kruskal-Wallis one-way analysis of variance was run comparing the differences between the aging samples and each total chemical group. Statistical differences (\(p<0.05\)) were observed between the aging samples of the different chemical groups with the exception of alcohols. It was not surprising to see statistically differences between thetotal groups, because, as lambic beers age, the appearance and disappearance of compounds such as esters (ethyl lactate), acids (isovalerate), and phenols (4-ethylphenol and 4-ethylguaiacol) will occur [24].  
Table 2, volatile and semi-volatile compounds identified in aging lambic beer using GC-MS, shows all of the compounds identified by GC-MS. A total of 40 compounds were identified. The volatile compounds identified came from a number of different chemical groups: esters (18), ketones (1), acids (5), alcohols (9), aldehydes (2), furans (2), monoterene alcohol (1) and phenols (2). The number of compounds identified within each aged sampled differed slight 3 months (30 compounds), 6 months (27), 9 months (28), 12 months (28), and 28 months (36).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**Age (Months)**} \\ \hline  & **LRI** & **3** & **6** & **9** & **12** & **28** \\ \hline
**Esters \({}^{*}\)** & & & & & \\ Ethyl acetate & 587 & X & X & X & X & X \\ Ethyl lactate & 821 & X & ND & ND & X & X \\ Ethyl isovalerate & 862 & ND & X & X & X & X \\ Isoamyl acetate & 884 & X & X & X & X & X \\ Amyl acetate & 917 & ND & X & X & X & ND \\ Ethyl isohexanoate & 968 & X & ND & X & X & X \\ Ethyl hexanoate & 1000 & X & X & X & X & X \\ Isoamyl lactate & 1069 & X & X & X & X & X \\ Ethyl heptanoate & 1097 & X & ND & ND & ND & X \\ Ethyl octanoate & 1198 & X & X & X & X & X \\ Ethyl phenylethanoate & 1245 & X & X & X & X & X \\ \(\beta\)-Phenethyl acetate & 1255 & X & X & X & X & X \\ Ethyl nonanoate & 1296 & X & X & X & X & X \\ Ethyl decanoate & 1395 & X & X & X & X & X \\ Isoamyl Octanoate & 1456 & X & X & ND & ND & X \\
2-methylbutyl octanoate & 1460 & X & ND & ND & ND & X \\ Ethyl undecanoate & 1494 & X & ND & X & X & X \\
**Ketones \({}^{*}\)** & & & & & \\
2-heptanone & 894 & ND & X & X & X & X \\
**Acids \({}^{*}\)** & & & & & \\ Isovaleric acid & 861 & X & ND & ND & ND & ND \\ Hexanoic acid & 1000 & X & X & ND & ND & X \\
2-ethylhexanoic acid & 1122 & ND & X & X & ND & X \\ Octanoic acid & 1180 & X & ND & ND & ND & X \\ Decanoic acid & 1366 & X & ND & ND & ND & X \\
**Alcohols** & & & & & \\ Isopentyl alcohol & 700 & X & X & X & X & X \\
2-methylbutanol & 744 & ND & X & X & X & X \\
2-Heptanol & 905 & ND & X & X & X & X \\ Heptanol & 965 & ND & ND & ND & X & X \\
2-Ethylhexanol & 1031 & X & ND & ND & ND & ND \\
2-Nonanol & 1102 & ND & X & X & X & X \\ Phenylethyl alcohol & 1112 & X & X & X & X & X \\ Nonanol & 1172 & X & ND & ND & ND & ND \\ Decanol & 1272 & X & X & X & X & X \\
**Aldehydes \({}^{*}\)** & & & & & & \\ Nonanal & 1103 & X & ND & ND & X & ND \\ Decanal & 1198 & X & X & X & X & X \\ \hline \hline \end{tabular}
\end{table}
Table 2: Volatile and semi-volatile compounds identified in aging lambic beer using GC–MS.