## 3 Result and Discussion
### Physicochemical Properties
#### 3.3.3 Free Amino Acid Profile

Table 2: _Cont._ \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Compound** & \begin{tabular}{c} **Odour** \\ **Description** \\ \end{tabular} & \
\begin{tabular}{c} **Threshold in Water** \\ **(ppb) *** \\ \end{tabular} &
\begin{tabular}{c} **OAVs** \\ \end{tabular} \\ \hline \multicolumn{5}{c}{**Control**} & **Thermo-Tolerant** \\ \hline Carboxylic acid & & & \\ \hline Acetic acid & Vinegar, punggent acidic & 800 & 2.02 & 1.49 \\ \hline Propanoic acid & Vinegar, punggent, sour milk & 20,000 & \textgreater{}1 & \textgreater{}1 \\ \hline Butanoic acid & Fruity, dairy, cheesy & 240 & 19.47 & 14.69 \\ \hline Hexanoic acid & Fatty, cheesy & 3000 & 3.07 & 1.68 \\ \hline Octanoic acid & Fatty, cheesy & 3000 & 1.41 & \textgreater{}1 \\ \hline Nonanoic acid & Fatty, green & 3000 & \textgreater{}1 & \textgreater{}1 \\ \hline Dodecanoic acid & Fatty, coconut, bay oil & 10,000 & \textgreater{}1 & \textgreater{}1 \\ \hline Aldehyde & & & & \\ \hline Pentanal & Berry, nutty & 1500 & \textgreater{}1 & \textgreater{}1 \\ \hline Heptanal & Green, sweet & 3 & 50.87 & 8.88 \\ \hline
4-Heptanal, (Z)- & Cream and butter & 0.8–10 & 15.46 & 2.48 \\ \hline Nonanal & Fatty, citrus, green & 1 & 57.98 & 33.29 \\ \hline
2-Nonanal, (E)- & Fatty, green, mushroom & 0.08–0.1 & 632.25 & 156.25 \\ \hline Ketone & & & & \\ \hline
2-Butanone & Varnish-like, sweet, fruity & 50,000 & \textgreater{}1 & \textgreater{}1 \\ \hline
2-Pentanone & Fruity, acetone & 70,000 & \textgreater{}1 & \textgreater{}1 \\ \hline
2-Heptanone & Banana-like, fruity & 140–3000 & \textgreater{}1 & 14.61 \\ \hline
2-Nonanone & Fruity, cheesy, buttery & 5–200 & 19.65 & 376.31 \\ \hline
3-Octen-2-one & Mushroom, fruity & 28 & \textgreater{}1 & ND \\ \hline
2-Undecanone & Floral, rose-like, herbaceous & 14.17 & 3.87 & 15.71 \\ \hline Alcohol & & & & \\ \hline
2-Butanol & wine & 500 & \textgreater{}1 & \textgreater{}1 \\ \hline
1-Propanol & Alcoholic, punggent & 9000 & \textgreater{}1 & \textgreater{}1 \\ \hline
1-Butanol & Fruity, alcoholic & 500 & \textgreater{}1 & \textgreater{}1 \\ \hline
1-Pentanol & Alcoholic, iodoform-like & 4000 & \textgreater{}1 & \textgreater{}1 \\ \hline
2-Heptanol & Earthy oily & 3 & ND & 139.98 \\ \hline
1-Octen-3-ol & Mushroom-like & 1 & 45.45 & 19.08 \\ \hline
1-Heptanol & Earthy, oily & 3 & 39.17 & 19.43 \\ \hline
1-Octanol & pungent & 110–130 & \textgreater{}1 & 1.44 \\ \hline Ester & & & & \\ \hline Methyl butyrate & Fruity, apple, pineapple & 60–76 & \textgreater{}1 & \textgreater{}1 \\ \hline Ethyl butyrate & Pineapple-like & 1 & 51.60 & 607.84 \\ \hline Ethyl hexanoate & Fruity, apple, banana & 1 & 4.25 & 168.82 \\ \hline Ethyl hexadecanoate & Fruity, creamy, waxy & \textgreater{}2000 & \textgreater{}1 & \textgreater{}1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Odour descriptors of selected volatile compounds, relative odour activity value (OAV) and odour threshold in water identified in inoculated milk samples are shown. * Odour threshold values in water were adapted from Leffingwell & Associates’ website [28]. Odour descriptions of volatiles were adapted from [30,31].