Table 3.
Most popular thermal processing methods of nuts and main VOCs reported in the literature.
| Thermal Processing | Nut | Processing Conditions | Main VOCs | Ref. |
|---|---|---|---|---|
| Hot-air roasting | Hazelnut | 34, 18, 13 min at 130, 140 and 150 °C | 2,3-pentanedione, 2-acetyl-1-pyrroline, dimethyl sulphide, 2-furfurylthiol, 3-methylbutanal, 2-nonenal, 2-decenal, hydroxy-2,5-dimethyl-3(2H)-furanone | [59] |
| 20, 25 and 30 min at 160 °C |
2-methylpropanal, 2-methylbutanal, 3-methylbutanal, 2,5-methylpyrazine | [60] | ||
| 40 min at 140 °C | 2-methylbutanal, 3-methylbutanal, 2,5-methylpyrazine, furfuryl alcohol, 2-methylpropanal, ehtyl acetate, 2,3-pentanedione, 2-methylpyrazine, 2,5-methylpyrazine, furfural, 1-hydroxy-2-propanone | [43] | ||
| Almond | 5 min at 177 °C | Benzyl alcohol, benzaldehyde, 1-octen-3-ol, toluene, dimethylpyrazine, 1-butanol, hexanal | [61] | |
| 5–10 min at 170–190 °C |
Hexanal, 2-methyl-butanal, 2-methyl-pyrazine, 2,5-dimethyl-pyrazine, furfural | [62] | ||
| 10 min at 190 °C | 2,5-dimethyl-pyrazine, trimethylpyrazine | [48] | ||
| 33 min at 138 °C | Hexanal, benzeneacetaldehyde, 2,5-dimethyl-pyrazine, nonanal | [38] | ||
| 28 and 38 min at 138 °C | 2-methylbutanal, 3-methylbutanal, hexanal, benzaldehyde, furfural, 2-phenyl acetaldehyde | [38] | ||
| 28, 33 and 38 min at 138 °C |
2-methylbutanal, 3-methylbutanal, hexanal, benzaldehyde, furfural, 2-phenyl acetaldehyde | [63] | ||
| Chestnut | 25 min at 200 °C | Hexanal, butylacetate, ethylbenzene, 2-hydroxy-2-cyclopenten-1-one | [63] | |
| Pistachio with and without salt | 90 min at 120 °C | α-pinene, limonene, 3-carene | [64] | |
| Cashew | 3 and 9 min at 143 °C |
Methylbutanal, hexanal, acetaldehyde, heptane, ethanol, pentane, acetone | [65] | |
| Microwave roasting | Almond | 120 V for 2 min | Benzyl alcohol, methional, benzaldehyde, dimethylpyrazine, nonanal, undecane, 1-octen-3-ol, 1,4-butyrolactone | [61] |
| Pistachio | 480 or 640 W for 2, 3 and 4 min | α-pinene, limonene, nonanal | [66] | |
| Hot air-assisted radio frequency | Almond | 15 min at 120–130 °C | 2,5-dimethyl-pyrazine, toluene, hexanal and heptane | [67] |
| Deep-frying | Almond | 5 min at 135 °C | Benzyl alcohol, methional, benzaldehyde, 1-butanol, 1-octen-3-ol | [61] |
| 10–15 min at 160–200 °C | Hexanal, 2-methyl-butanal, 3-methyl-butanal, 2,5-dimethyl-pyrazine, 1-pentanol | [62] | ||
| Chestnut | 15 min at 240 °C | Hexanal, octanal, nonanal, furfural, 3-heptanone, 4-hydroxy-2-butanone | [68] |