## 2 Materials and Methods
### LC-MS/MS Method  
This method allowed the identification, quantification, and confirmation of the presence of ochratoxin A and aflat B1, B2, G1 and G2, by liquid chromatography coupled with mass spectrometry (LC-MS/MS) [34]. The method was applied to the olive paste matrix and involved the extraction of mycotoxins from the homogenized matrix with a mixture of methanol:water (80:20 \(v/v\)). The extract was purified with immunoaffinity columns specific for aflat (B1, B2, G1, and G2) and ochratoxin A. The purified extract was then added with the labeled analogues of each mycotoxin used as internal standards. The extract was analyzed by LC-MS/MS, a technique that simultaneously provides confirmatory analysis and quantitative determination. Quantification was performed by linear calibration. Sample preparation involved using about 5 g of olive paste, which was placed into a 50 mL conical tube and extracted in 30 mL of methanol:water solution (80:20 \(v/v\)). The mixture was stirred vigorously in a multi-tube vortex for 2 min, sonicated for 30 min in an ultrasonic bath, and centrifuged at 5000 rpm for 15 min. The supernatant was collected and purified by immunoaffinity columns specific for aflat and ochratoxin A. Specifically, aflat B1, B2, G1, and G2 were inoculated in 4 mL of supernatant; this occurred through dilution with 25 mL of phosphate buffer solution (Phosphate Buffer Saline pH 7.4) and purification with the immunoaffinity column. After the process, the mixture was washed with deionized water (20 mL) and aflat were extracted through dilution of the product in 3 mL of methanol. Then, 0.5 mL ofuate was added to 0.5 mL of solution containing the internal standards labeled for each aflatoxin (B1, B2, G1, and G2). For ochratoxin A, 5 mL of supernatant was taken and diluted in 50 mL of phosphate buffer solution (Phosphate Buffer Saline pH 7.4) and then purified with the immunoaffinity column. Next, the mixture was washed with 20 mL PBS and 10 mL of deionized water; subsequently, the mixture containing ochratoxin A was diluted with 3 mL of acetic acid and methanol solution (2:98 \(v/v\)). Then, 0.5 mL of Fluate was taken and mixed with 0.5 mL of solution containing the labeled internal standard for ochratoxin A. The instrument used to perform the analyses was the Thermo UHPLC Ultimate 3000 (ThermoFisher Scientific (Waltham, MA, USA)), equipped with an autosampler and a Thermo MS/MS Q Exactive Focus detector. The analytes were detected by injecting 10 \(\mu\)L into the liquid chromatograph coupled to the high-resolution mass spectrometer and acquiring the signal in Full Scan and parallel reaction monitoring (PRM) modes. In Full Scan, the instrument allowed for visualization of the signal of selected molecular adduct ions (H+) of mycotoxins by determining their exact mass (\(m/z\)). In PRM mode, the instrument isolated and fragmented the mycotoxin precursor ions, and the fragments were selected to be quantified. Separation was performed with a Thermo UHPLC model Ultimate 3000 consisting of a binary pump, autosampler, and column heater set at 25 \({}^{\circ}\)C. The column used was a Thermo Scientific Accucore RP-MS 100 \(\times\) 2.1 mm, 2.6 \(\mu\)m. The mobile phase was divided as follows:  
Phase A: Water with 5 mM ammonium formate, 0.1% formic acid. Phase B: Methanol with 5 mM ammonium formate, 0.1% formic acid. The gradient determination started by maintaining phase B at 5% for 1 min, then reaching a linear gradient of 95% B over 4.5 min. This phase was maintained for 3.5 min, then decreased to the original 5% B and equilibrated for another minute. The total run lasted 13 min, with an LC-MS/MS flow rate of 0.350 mL/min. For calibration, six concentration levels were prepared in methanol. Aflatoxin B1 and G1 were prepared in concentrations between 0.1 and 2.0 ng/mL (equivalent to 0.9-18 ng/g); aflatoxin B2 and G2 were prepared at concentrations between 0.025 and 0.5 ng/mL (equivalent to 0.2-4.5 ng/g); ochratoxin A was prepared at concentrations between 0.05 and 2.5 ng/mL (equivalent to 0.4-18 ng/g).