## 3 Results and Discussion  
This method was initially developed in the laboratory and then applied to measurements at the malting house. In the laboratory, it was determined that the SPME fiber had to be exposed for at least an hour in the kiln in order to observe peaks in the GC/MS. Exposure times of less than an hour were found to produce small peaks that could often not be discriminated from the background noise. Exposure times greater than one hour were not found to result in significant improvements, presumably as equilibrium between analyte compounds in the gas phases and retained on the SPME material had been established.  
Samples were taken during the roasting phase of a commercial malting house and measured using the developed method. Some of the identified compounds are shown in Table 2. A typical chromatogram is shown in Figure 3. Many of the compounds that were identified were aldehydes. Other oxygen containing compounds (ketones, esters, and alcohols) were identified along with alkanes and a terpene (patchoulene). Several other peaks present in the chromatograms were either identified with lower confidence (less than 90% matching value in the library search) or observed less often and, therefore, not included in Table 2. Maillard reaction products were not observed, which indicates that the malt produced in this case, a pale malt, was not roasted for sufficient time at a high enough temperature for the Maillard reaction to occur. It is worth noting that additional laboratory-based experiments (results not shown) at higher temperatures were able to identify Maillard reaction products such as 2-methylfuran, furfural, 2-ethyl-3-methylpyrazine, and 2-ethyl-3,5-dimethylpyrazine.  
\begin{table}
\begin{tabular}{l l} \hline \hline \multicolumn{2}{c}{**Steeping Cycles**} \\ \hline
**Time (h)** & **Grain Environment** \\ \hline
8 & Wet \\ \hline
14 & Dry \\ \hline
6 & Wet \\ \hline
12 & Dry \\ \hline
1 & Wet \\ \hline \multicolumn{2}{c}{**Kilning Conditions**} \\ \hline
**Time (h)** & **Temperature (\({}^{\circ}\)C)** \\ \hline
5.5 & 50 \\ \hline
41 \({}^{\ast}\) & 52 \\ \hline
3.25 & 65 \\ \hline
4.5 & 76 \\ \hline
2.25 & 85 \\ \hline \hline \multicolumn{2}{l}{\({}^{\ast}\) process stalled due to a faulty temperature probe.} \\ \end{tabular}
\end{table}
Table 1: Malting Conditions.  
Statistically significant changes in compound concentrations would require replicate measurements that were not possible given the nature of this work; however, some changes were observed over the roasting period (Figure 4). It is uncertain if these changes are due to chemical reactions or physical processes such as compound volatility. Figure 4 shows nonanal decreasing after reaching a maximum at 65 \({}^{\circ}\)C. Patchoulene also decreased after a maximum at 65 \({}^{\circ}\)C while the less volatile pentadecanal increased with an increase in temperature. The results suggest that kiln temperatures could be optimized to obtain the highest amounts of desirable compounds. The comparison headspace method identified similar compounds but failed to detect less volatile analytes (presumably due to the lower sampling temperature). It is also worth noting that some interfering compounds were observed in the headspace method that appear to originate from the septum material.  
\begin{table}
\begin{tabular}{l l} \hline \hline Alkanes & 3-methyl hexane, 4-methyl octane, 3 ethyl-5-(2-ethylbutyl) octadecane \\ \hline Aldehydes & Hexanal, heptanal, nonanal, 2-nonenal, decanal, pentadecanal \\ \hline Ketones & 2-decanone \\ \hline Alcohols & 2-decen-1-ol \\ \hline Esters & eicosanoic acid, phenylmethyl ester \\ \hline Terpenes & patchoulene \\ \hline \hline \end{tabular}
\end{table}
Table 2: Compounds commonly identified during malting.  
Figure 3: Chromatogram obtained at a kiln temperature of 65 \({}^{\circ}\)C.