The TFAs amount in the chicken fillets fried at 150, 200 and 250 °C was monitored after the first, 24th and 48th frying process (Table 4 and Supplementary Fig. 2). When frying was conducted at 150 °C and 200 °C, the trans FAs formed in the chicken fillets mainly consisted of C18:2 isomers. And the amount of trans C18:2 FAs kept relatively stable regardless of the prolong of frying time. These results suggested that the number of frying operation did not have a significant effect on the TFAs level in the fried chicken fillets at these two temperatures. In contrast, when frying at 250 °C, most of the trans 18:3 FAs and trans 18:1 FAs appeared besides the trans 18:2 FAs. These results are similar to the observation in frying oils.