Table 2.
The changes in amounts of alkanals formed during the soybean oil heating process and food frying process a,b
| Alkanals | Treatments | 1–2 h | 1–8 h | 2–2 h | 2–8 h | 3–2 h | 3–8 h | 4–2 h | 4–8 h | 5–2 h | 5–8 h | 6–2 h | 6–8 h | 7–2 h | 7–8 h |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hexanal | Oil heating | ND | ND | ND | 0.48 ± 0.01b | 1.23 ± 0.03a | 1.25 ± 0.01b | 2.28 ± 0.04a | 1.93 ± 0.02a | 4.45 ± 0.02a | 8.54 ± 0.07a | 4.02 ± 0.01a | 4.45 ± 0.04a | 10.28 ± 0.08a | 8.10 ± 0.05a |
| WD frying | 0.70 ± 0.38b | 0.73 ± 0.22b | 0.81 ± 0.19a | 1.07 ± 0.23a | 1.03 ± 0.32a | 1.73 ± 0.13a | 1.48 ± 0.23b | 1.37 ± 0.19b | 1.30 ± 0.24b | 1.18 ± 0.11b | 1.35 ± 0.22b | 1.43 ± 0.22b | 1.61 ± 0.36b | 1.93 ± 0.20b | |
| CBM frying | ND | 1.11 ± 0.36a | 1.11 ± 0.22a | 1.11 ± 0.23a | 1.03 ± 0.32a | 0.88 ± 0.32c | 1.46 ± 0.26b | 1.28 ± 0.37b | 0.99 ± 0.35b | 1.06 ± 0.14c | 0.97 ± 0.38b | 1.10 ± 0.33b | 1.00 ± 0.20c | 0.96 ± 0.10c | |
| Heptanal | Oil heating | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | 3.89 ± 0.080a |
| WD frying | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | 0.07 ± 0.01c | |
| CBM frying | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | 1.29 ± 0.45b | |
| Nonanal | Oil heating | 2.54 ± 0.20b | 3.44 ± 0.32a | 4.21 ± 0.22a | 6.12 ± 0.27a | 5.53 ± 0.28a | 6.45 ± 0.32a | 7.06 ± 0.23a | 8.38 ± 0.31a | 9.09 ± 0.26a | 7.04 ± 0.41a | 10.20 ± 0.32a | 9.99 ± 0.28a | 8.34 ± 0.21a | 8.38 ± 0.32a |
| WD frying | 3.11 ± 0.34a | 3.56 ± 0.51a | 4.59 ± 0.42a | 4.27 ± 0.54c | 3.95 ± 0.49b | 6.02 ± 0.54a | 4.87 ± 0.65b | 5.06 ± 0.19c | 5.54 ± 0.68b | 5.05 ± 0.17b | 6.29 ± 0.54b | 6.24 ± 0.52b | 5.80 ± 0.63b | 6.52 ± 0.63b | |
| CBM frying | 1.89 ± 0.22c | 3.64 ± 0.22a | 4.30 ± 0.26a | 5.25 ± 0.28b | 5.21 ± 0.24a | 4.71 ± 0.25b | 4.61 ± 0.28b | 5.57 ± 0.24b | 5.65 ± 0.23b | 4.45 ± 0.32c | 4.66 ± 0.22c | 5.15 ± 0.34c | 5.75 ± 0.37b | 5.46 ± 0.23b | |
| Decanal | Oil heating | ND | ND | ND | ND | 0.41 ± 0.10 | 0.70 ± 0.07 | 0.63 ± 0.11 | ND | ND | ND | 1.14 ± 0.11 | 0.95 ± 0.07 | 0.87 ± 0.08 | 0.81 ± 0.06 |
a Abbreviations: WD wheat dough, CBM chicken breast meat, 1–2 h, oil sample collected at the second hour of the first day, ND not detected
b The relative contents of alkanals were express as average value ± confidence interval. The lowercase (a,b,c) behind the content represents the significant difference among the three thermal treatments (p < 0.05, n = 3)