3.1. Validation of lipase hydrolysis
To verify that the lipase acted only on 3-MCPD esters, three controls were used. The comparison of lipase action on 3-MCPD and lipase action on 3-MCPD esters, the comparison of lipase action on 3-MCPD esters and lipase no action on 3-MCPD esters, the comparison of pure solution of 3-MCPD, lipase action on 3-MCPD and pure solution of lipase. As seen in the chromatogram, comparison between the effect of lipase on 3-MCPD and the effect of lipase on 3-MCPD esters (Fig. 1), the peak time, mass spectrogram information and ratio in qualitative ion map of the two were similar, indicating that the same substance was finally obtained, that is, the enzymatic hydrolysis was successful.
Comparison between the effect of lipase action on 3-MCPD esters and lipase no action on 3-MCPD esters (Fig. 2). 3-MCPD is produced by the action of lipase on 3-MCPD ester, but the lipase does not act on the 3-MCPD ester does not produce the 3-MCPD, and 10.705 min is peak time of 3-MCPD esters. This indicated that the enzymatic hydrolysis was successful.
Comparison among pure solution of 3-MCPD, lipase action on 3-MCPD and pure solution of lipase (Fig. 3). The comparison of the three results shows that, the response of pure solution of 3-MCPD and lipase action on 3-MCPD is almost the same. However, the pure solution of lipase do not produce 3-MCPD peak, indicating that the lipase can not act on 3-MCPD. Therefore, 3-MCPD produced by lipase action on 3-MCPD esters is successful, and has nothing to do with the addition of 3-MCPD internal standard during the experiment.
3.2 Selection of