Table 1.
Frying conditions and chemical parameters of the unheated and heated rapeseed oils with different layer heights
| Rapeseed oil samples | Frying conditions | Chemical parameters | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| OLH (cm) | TOV (mL) | TOM (g) | SOS (cm2/g) | PV* ± SD (mequiv O2/kg) | p-AV* ± SD | Totox | FFA* ± SD (%) | t (25 % TPC)* ± SD (min) | DPPH# ± SD (μmol TE/100 g) | |
| RO unheated | – | – | – | – | 0.09 ± 0.00a | 1.2 ± 0.06a | 1.4a | 0.10 ± 0.00a | – | 459.5 ± 19.6f |
| RO1 | 0.5 | 300 | 279 | 5.1 | 45.15 ± 2.34e | 235.4 ± 1.7e | 325.7e | 0.29 ± 0.01e | 71.5 ± 3.9a | 3.3 ± 0.1a |
| RO2 | 1.0 | 600 | 558 | 2.5 | 23.35 ± 0.10d | 214.2 ± 2.2d | 260.9d | 0.27 ± 0.01d | 123.2 ± 7.8b | 22.2 ± 0.9b |
| RO3 | 1.5 | 900 | 837 | 1.7 | 17.80 ± 0.36c,d | 202.6 ± 2.0c | 238.2c | 0.24 ± 0.00c | 176.5 ± 2.1c | 46.9 ± 1.2c |
| RO4 | 2.0 | 1200 | 1116 | 1.3 | 14.85 ± 0.37b,c | 190.9 ± 2.8b | 220.6b | 0.23 ± 0.01b | 212.5 ± 4.5d | 60.5 ± 1.8d |
| RO5 | 2.5 | 1500 | 1395 | 1.0 | 9.50 ± 0.65b | 192.4 ± 0.6b | 211.4b | 0.24 ± 0.01b,c | 315.1 ± 20.8e | 72.6 ± 1.9e |
Values are means ± standard deviations
Different letters (a–f) within the same column indicate significant differences between analytical parameters of the refined rapeseed oils before and after heating with different layer heights (one-way ANOVA and Duncan test, p < 0.05)
OLH oil layer height in pan, TOV total oil volume, TOM total oil mass, SOS specific oil surface, t (25 % TPC) time to achieve 25 % TPC
a n = 6 (3 × 2 heating sessions), b n = 10 (5 × 2 heating sessions); p = 0.05