## 3 Results and Discussion
### Volatile Compounds
(2014) [55] found that when cows were exposed to high levels of pasture, there was a significant influence on nonanoic acid in Montasio cheese, with this compound not detected in cheese produced from milk derived from a low pasture diet. Although not recognized to play such a significant role in odor and sensory quality of butter, toluene was significantly more abundant (\(p<0.05\)) in both FS-CLVR and FS-GRSS butter than in FS-TMR butter. Toluene is a by-product of \(\beta\)-carotene metabolism [56], demonstrating its potential as a biomarker for pasture-derived dairy products [44]. As FS-CLVR butter was rated most yellow in this study, this may also suggest higher levels of \(\beta\)-carotene and hence the abundance of toluene. The greater abundance of ethyl acetate in FS-CLVR butter is difficult to discern except that it is a product of ethanol and acetic acid. The sources of both precursors may be influenced by cow diet [45]. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Volatile** & \multirow{2}{*}{**CAS NUMBER *} & \multirow{2}{*}{**Odor Descriptors**} & \multirow{2}{*}{**RI**} & \multirow{2}{*}{**REF RI**} & \multirow{2}{*}{**FS-GRSS**} & \multirow{2}{*}{**FS-CLVR**} & \multirow{2}{*}{**FS-TMR**} \\
**Compound** & & & & & & & & & \\ \hline Aldehyde & & & & & & & & & \\ \hline Pentanal 2 & 110-62-3 & Pungent, almond like, chemical, malty, apple [22] & 731 & 733 & \(0.054\pm 0.027\) b  & 0.489 \(\pm\) 0.394 a  & 0.049 \(\pm\) 0.018 b  \\ \hline Hexanal 3 & 66-25-1 & Green, slightly fruity, lemon, herbal, grassy [22] & 836 & 839 & \(0.032\pm 0.013\) b  & 0.060 \(\pm\) 0.035 a  & 0.049 \(\pm\) 0.018 s  \\ \hline Heptanal 3 & 111-71-7 & Slightly fruity (balsam), fatty, oily [22] & 937 & 943 & \(0.020\pm 0.008\) a  & 0.035 \(\pm\) 0.027 a  & 0.010 \(\pm\) 0.004 b  \\ \hline Benzaldehyde & 100-52-7 & Bitter, almond, sweet cherry [22] & 1026 & 1028.9 & \(0.020\pm 0.012\) & \(0.019\pm 0.011\) & 0.028 \(\pm\) 0.011  \\ \hline Nonanal & 124-19-6 & Green, citrus, fatty, floral [22] & 1143 & 1150 & \(0.039\pm 0.040\) & \(0.035\pm 0.028\) & 0.024 \(\pm\) 0.017  \\ \hline Decanal 3 & 112-31-2 & Green [28] & 1246 & - & \(0.001\pm 0.001\) b  & 0.003 \(\pm\) 0.001 a  & 0.002 \(\pm\) 0.002 b  \\ \hline Ketone & & & & & & & & \\ \hline Aootone2 & 67-64-1 & Earthy, strong fruity, wood pulp, hay [22] & 529 & 533 & \(0.224\pm 0.125\) ab  & 0.216 \(\pm\) 0.052 a  & 0.124 \(\pm\) 0.027 b  \\ \hline Diacetyl & & & & & & & & \\ (2,3-b,-bantanedione 2) & 431-03-8 & Battery [50] & 628 & - & \(0.044\pm 0.015\) a  & 0.079 \(\pm\) 0.057 ab  & 0.022 \(\pm\) 0.009 b  \\ \hline
2-Butanone 2 & 78-93-3 & Battery, sour milk, etheric [22] & 635 & 639 & \(0.106\pm 0.019\) b  & 0.286 \(\pm\) 0.156 a  & 0.170 \(\pm\) 0.082 ab  \\ \hline
2-Heptanone 2 & 113-43-0 & Blue cheese, spicy, Roquefort [22] & 929 & 936 & \(0.062\pm 0.011\) & \(0.077\pm 0.034\) & 0.060 \(\pm\) 0.007  \\ \hline
2-Nonanone & 821-55-6 & Malty, fruity, hot milk, smoked cheese [22] & 1133 & 1140 & \(0.017\pm 0.003\) & \(0.037\pm 0.033\) & 0.013 \(\pm\) 0.005  \\ \hline
2-Pentanone & 107-87-9 & Orange peel, sweet, Fruity [22] & 725 & - & \(0.029\pm 0.012\) & \(0.032\pm 0.010\) & 0.031 \(\pm\) 0.014  \\ \hline Acid & & & & & & & \\ \hline Butanoic Acid 1 & 107-92-6 & Sweaty, butter, cheese, Strong, acid, fecal, & & & & & \\ \hline Hexanoic Acid 1 & 142-62-1 & Acidic, sweaty, cheessy, sharp, goats, bad breath [22] & 1045 & 1052 & \(0.023\pm 0.009\) & \(0.041\pm 0.02\) & \(0.026\pm 0.010\)  \\ \hline Nonanoic Acid 2 & 112-05-0 & Waxy, dirty and cheessy with a cultured dairy nuance * & 22.7 & - & \(0.014\pm 0.007\) b  & 0.026 \(\pm\) 0.005 a  & 0.014 \(\pm\) 0.008 b  \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Average (\(n=9\)) peak area values (\(\times 10^{6}\)) of volatile compounds identified in FS-GRSS, FS-CLVR and FS-TMR buttons.