*2.4. Cooking Operations*

According to the cooking method of this experiment, the positive simulated livestock and poultry meat blocks of each matrix (pork, beef, lamb and chicken) were divided into three groups of 21 portions each. Before further treatment, three pieces of meat blocks were randomly selected from each group to verify the spiking homogeneity of the positive mock samples. The remaining pieces were used for boiling, deep-frying and microwave processing, respectively.

#### 2.4.1. Boiling

The boiling process was performed at 100 ◦C in a water bath (TW20, Julabo Laborthechnik GmbH, Seelbach, Germany) for 5, 10, 15, 20 and 25 min, respectively, and then it was allowed to cool naturally to room temperature (22 ± 2 ◦C) before being weighed and subsequently detected and analyzed within one day. Three parallel experiments were conducted at each time point, with the unprocessed meat blocks serving as the control group.
