# Volatile Profile of Nuts, Key Odorants and Analytical Methods for Quantification
## 5 Volatile Profile of Nuts after Thermal Treatments  
Processed nuts are consumed as a snack or added to confectionary and bakery products. For this purpose, heat treatments such as roasting and frying are necessary during nut processing to improve their sensory quality, digestibility, and microbiological safety. These heat treatments may significantly affect their properties and quality attributes, obtaining appreciable and desired changes in their texture, color, flavor and taste [58]. Interestingly, when nuts are thermally treated, new VOCs are formed from different reactions that are produced, others disappear, and others increase. Knowledge of the key odorants in thermal treatments of nuts can help to select the best preservation and thermal processing conditions. In this section, the most popular thermal processing methods of nuts and their influence on volatile profile are reviewed (Table 3).  
\begin{table}
\begin{tabular}{c c c} \hline
**Nut** & **Main VOCs** & **Ref.** \\ \hline \multirow{3}{*}{Almond} & 1-Hexanol, 3-methyl-1-butanol, nonanal, & [37] \\  & 2-methyl-1-propanol, 1-propanol & [38] \\  & Benzaldehyde, hexanal, 1,2-propanediol, & \\  & 1-chloro-2-propanol, 3-methyl-1-butanol, pentanal, & [38] \\  & 2-heptanone, 1-hexanol, & \\  & Hexanal, 3-methyl-1-butanol, benzaldehyde, heptanal, & [22] \\  & nonanal, 1-octanol, 2-octanone & [22] \\ \hline \multirow{3}{*}{Chestnut} & Y-terpinene, phenylaldehyde, hexanal, furfurl, & \\  & \(\alpha\)-terpinene & [57] \\ \hline \multirow{3}{*}{Hazelnut} & \(\alpha\)-tujone, \(\beta\)-tujone, 2-pentanone, acetic acid, 3-methyl-2- & [43] \\  & butanol, n-decane & \\ \hline \multirow{3}{*}{Peanut} & Hexanoic acid, 2-ethyl-1-hexanol, 1-hexanol, pentanal, & [44] \\  & hexanal, palmitic acid, & [44] \\  & 2-ethyl-5-methylpyrazine, heptanal & \\  & 2-Propanone, \(\alpha\)-pinene, benzene, & \\  & \(\alpha\)-terpinene, hexanal, d-dimonene & [29] \\  & Toluene, \(\alpha\)-lionene, \(\gamma\)-terpinene, p-cymene, nonanal, \(\beta\), & [39] \\  &pinene, hexanoic acid & \\  & 2,5-Dimethylpyrazine, nonanal, hexanal, & \\  & 2-ethyl-5-methylpyrazine, octanal, & [33] \\  & 2,5-dimethyl-3-ethylpyrazine & \\  & Hexanal, benzaldehyde, benzenoaciddehyde, & \\  & 2,5-dimethylpyrazine, 2-heptrenal, & \\  & 2-ethyl-5-methylpyrazine, trimethylpyrazine, & [26] \\  & 3-ethyl-2,5-dimethylpyrazine & \\ \hline \multirow{3}{*}{Pistachio} & 9-Octadecenoic acid, \(\alpha\)-pinene, 1-methyl-1H-pyrrole, & \\  & \(\alpha\)-terpinolene, limonene, dimethyl-2H-pyran-2-one, & [34] \\  & 2-octanel, 2-hexenal & \\  & \(\alpha\)-Pinene, \(\alpha\)-terpinolene, 1H-pyrrole, ethyl-alcohol, & \\  & limonene, hexane & \\  & \(\alpha\)-Pinene, \(\beta\)-pinene, 2-ethyl-1-hexanol, \(\alpha\)-terpineol, & [2] \\  & camphene, hexanoic acid & \\ \hline \multirow{3}{*}{Walnut} & Hexanal, hexanoic acid, 1-pentanol, 2-octanel, pentanal, & [45] \\  & 2-pentylfuran, propanoic acid & [20] \\ \cline{1-1}  & 2-Octenal, hexanoic acid, hexanal, 2-decenal, & \\ \cline{1-1}  & 1-octen-3-ol, nonanal & \\ \hline \end{tabular}
\end{table}
Table 2: Main VOCs of raw nuts.