TABLE 4.
Different compounds formed at (65°C) with PEF pre‐treatment at 5 kV/cm, 3 kV/cm and 1 kV/cm before convective drying).
| (A) Compounds | Class | Reaction pathways | Retention time (min) | Fresh grapes | Analytes (ng/g) at (65°C, 5 kV/cm) and drying time (h) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 h | 3 h | 5 h | 7 h | 9 h | 11 h | 13 h | 15 h | ||||||
| Hexanal | Aldehyde | LO | 5.72 | nd | 0.21 | 1.08 | nd | nd | nd | nd | nd | nd | nd |
| 2‐Heptanal | Aldehyde | LO, UFAO | 11.85 | nd | 0 | nd | 1.02 | nd | nd | nd | nd | nd | nd |
| Pentanal, 5‐(methylenecyclopropyl) | Aldehyde | LO | 13.48 | nd | nd | nd | nd | nd | nd | nd | 0.45 | nd | nd |
| Benzene, 1‐methyl‐3(1‐methylethyl) | Aldehyde | MR, LO, UFAO | 13.03 | nd | nd | nd | nd | nd | 0.45 | 0.25 | nd | nd | nd |
| 2(3H)‐Furanone, dihydro‐4,4‐dimethyl‐5‐(2‐oxopropyl) | Furan | MR, CR, AA, LO | 14.50 | nd | nd | nd | nd | nd | nd | nd | 1.54 | 0.97 | 1.34 |
| Furan | Furan | MR, CR | 14.50 | nd | nd | nd | nd | nd | nd | nd | nd | 1.43 | 2.98 |
| 2‐Furancarboxaldehyde (Furfural) | Furan | MR, CR, AA | 7.86 | nd | nd | nd | nd | nd | nd | 1.32 | 0.78 | 0.53 | 3.64 |
| 1‐pentanone 2‐furanyl | Furan | MR | 5.34 | nd | nd | nd | nd | nd | nd | nd | nd | 1.54 | 2.43 |
| 3‐Furaldehyde | Furan | MR, CR | 7.34 | nd | nd | nd | nd | nd | nd | 2.07 | nd | nd | 1.32 |
| (B) Compounds | Class | Reaction pathways | Retention time (min) | Fresh grapes | Drying time (h) (65°C, 3 kV/cm) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hexanal | Aldehyde | LO | 5.72 | nd | 0.51 | 1.08 | nd | nd | nd | nd | nd | nd | nd |
| 2‐Heptanal | Aldehyde | LO, UFAO | 11.85 | nd | 0 | nd | 1.02 | nd | nd | nd | nd | nd | nd |
| Benzene, 1‐methyl‐3(1 methylethyl) | Aldehyde | MR, LO, UFAO | 13.03 | nd | nd | nd | nd | nd | 0.51 | 0.15 | nd | nd | nd |
| 2(3H)‐Furanone, dihydro‐4,4‐dimethyl‐5‐(2‐oxopropyl) | Furan | MR, CR, AA, LO | 14.50 | nd | nd | nd | nd | nd | nd | nd | 0.74 | 0.82 | 0.43 |
| 2‐Furancarboxaldehyde (Furfural) | Furan | MR, CR, AA | 7.86 | nd | nd | nd | nd | nd | nd | nd | 1.23 | 0.67 | 2.41 |
| 1‐pentanone 2‐furanyl | Furan | MR | 5.34 | nd | nd | nd | nd | nd | nd | nd | nd | 0.72 | 1.38 |
| (C) Compounds | Class | Reaction pathways | Retention time (min) | Fresh grapes | Drying time (h) (65°C, 1 kV/cm) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hexanal | Aldehyde | LO | 5.72 | nd | 0.21 | 1.08 | nd | nd | nd | nd | nd | nd | nd | nd |
| 2‐Heptanal | Aldehyde | LO, UFAO | 11.85 | nd | 0 | nd | 1.02 | nd | nd | nd | nd | nd | nd | nd |
| Benzene, 1‐methyl‐3(1‐methylethyl) | Aldehyde | MR, LO, UFAO | 13.03 | nd | nd | nd | nd | nd | nd | 0.21 | 0.35 | nd | nd | nd |
| 3‐Furaldehyde | Furan | MR, CR | 7.34 | nd | nd | nd | nd | nd | nd | nd | nd | nd | 1.32 | 1.54 |
| Furan | Furan | MR, CR | 14.50 | nd | nd | nd | nd | nd | nd | nd | nd | 0.43 | 1.98 | 0.89 |
Note: All compounds measured in ng; nd = not detected at a limit of detection.
Abbreviations: 3‐DG, 3‐deoxyglucoson; AA, Amino Acid; CR, Ceramelization; LO, Lipid oxidation; MR, Maillard Reaction; UFAO, unsaturated fatty acids oxidation.