*2.2. Plant Material*

*R. coriaria* L. drupes (1 kg) were collected in Messina (38◦1331.42 N 15◦3221.7 E) in September 2020. The fresh material was immediately dried in the dark at a low temperature and then pulverized.

#### *2.3. Proximate Composition Determination*

The determination of the proximate composition was carried out according to the AOAC (Association of Official Analytical Chemist) methods [18]. In particular, the following methods were used: dry matter (method 925.10), crude ash (method 923.03), crude protein (method 990.03), crude fiber (method 962.09), starch (method 996.11), and crude fat by Soxhlet extraction (method 960.39 with some modifications). The sumac sample was analyzed in triplicate.

For the fatty acids profiling, 15 g of sample was extracted for 6 h with a Soxhlet apparatus using heptane as solvent. After the extraction, the solvent was eliminated with a rotating evaporator and stored at −18 ◦C until the chromatographic analysis. The analysis of FAMEs was performed as described by the EU Regulation n. 1833/2015 (European Commission, 2015). One μL of each extract was analyzed by a gas chromatograph (GC) (Dani Master GC1000) equipped with a split/splitless injector and a flame ionization detector (FID) (Dani Instrument, Milan, Italy). A 60 m × 0.25 mm ID 0.20 μm film thickness Supelco SLB-IL100 capillary column (Supelco, Sigma-Aldrich, St. Louis, MO, USA) was used. The chromatographic conditions used were as follows: temperature from 165 ◦C to 210 ◦C (10 min held) at 2 ◦C/min, injector and detector temperature was 250 ◦C, and helium was at a linear velocity of 30 cm/s. The injection volume was 1 μL with a split ratio of 1:100. The Clarity Chromatography Software v4.0.2 (DataApex, Prague, Czech Republic) was used for data acquisition and processing. The sample was analyzed in triplicate. FAMEs were identified by comparing the retention times of the peaks with those of the standards. The percentage of each FAMEs was calculated by comparison with the corresponding chromatogram peak area. The precision of the method was assessed in terms of RSD% analyzing five times each sample [19].

#### *2.4. Total Phenolic and Anthocyanin Content Determination*

The total phenolic content of *R. coriaria* L. was determined using the Folin–Ciocalteu method [20]. Briefly, 3 g of dried and minced sample was homogenized with 8 mL of an 80% aqueous methanol solution and placed in a vessel at −20 ◦C overnight. The sample was then centrifuged (10000 rpm for 15 min), and the supernatant was filtered with a 0.45 μM filter.

The total phenolic content absorbance measurements were registered using a Ultrospec 2100 Pro UV-VIS spectrophotometer (GE Healthcare Ltd., Chicago, IL, USA) at a wavelength of 760 nm. Absorbance values were converted to gallic acid equivalents and expressed as mg/g.

The total anthocyanins content was spectrophotometrically evaluated, as described by Landi et al. [21], in acidified methanol (0.1% HCl, *v*/*v*), and the absorbance was measured at 535 nm. Absorbance values were converted to cyanidin-3-O-glucoside equivalents and expressed as mg/g.

#### *2.5. Mineral Element Content Determination*

The determination of the mineral elements in the *Rhus coriaria* samples was carried out using an ICP-MS iCAP-Qc spectrometer (Thermo Fisher Scientific, Milan, Italy) equipped with a 27 MHz radiofrequency solid-state generator at 1550 W. A closed vessel microwave digestion system Ethos 1 (Milestone, Bergamo, Italy) was used for the sample digestion. Approximately 0.50 g of *R. coriaria* sample was digested with 7 mL of HNO3 (69% *v*/*v*) and 1 mL of H2O2 (30% *v*/*v*) in a pre-washed PTFE vessel. The sample was then cooled down at room temperature, diluted up to 25 mL with ultrapure water, and filtered with a 0.45 μm filter [19,22]. The certified reference materials were processed using the same conditions. The ICP-MS operating parameters were the incident radiofrequency power 1500 W, plasma gas flow argon (Ar) at 15 L/min, auxiliary gas flow rate (Ar) 0.9 L/min, and carrier gas flow rate (Ar) 1.10 L/min. Helium (He) was the collision cell gas (4 mL/min), and the spray chamber was set at T = 2 ◦C. The injection volume and sample introduction rate were 200 μL and 1 mL/min, respectively. A full scan mode (dwell time 0.5 s point 1) was used for spectra acquisition. All samples and the analytical blanks were analyzed in triplicate.

Data acquisition was performed using the Qtegra™ Intelligent Scientific Data Solution™ (Thermo Scientific) software. For the quantification, an external calibration procedure was used. The determination of mercury was performed using the automatic mercury analyzer DMA-80 (Milestone Srl, Bergamo, Italy). An aliquot of the sample (100 mg) was placed in a vessel, dried for 3 min at 200 ◦C, and decomposed at 650 ◦C for 2 min. The content of Hg was determined by measuring the absorbance at 253.7 nm.

#### *2.6. Preparation of Extracts*

The dried and ground fruits were extracted with different solvents obtained from Sigma-Aldrich: methanol (SM), ethanol (SE), acetone (SA), methanol and water (SMW), ethanol and water (SEW), acetone and water (SAW), and water (SW). The samples (2 g) in the respective extraction solvents (20 mL) were sonicated for 15 min, filtered with a Whatman filter, dried with a rotary evaporator (BUCHI R-210, Merck KGaA, Darmstadt, Germany), and lyophilized. The resulting dried extracts were used for further microbiological analysis.

#### *2.7. Polyphenols Profile in SM*

Amounts of 229.16 mg and 224.29 mg of sumac powder were added to 3 mL aliquots of HPLC grade MeOH. The ultrasound-assisted extraction of phenolics from each powder was performed using a Transonic 460 H ultrasonic bath (Elma Hans Schmidbauer, Singen, Germany) at room temperature operating for 15 min at 35 kHz ultrasonic frequency. Then, each sample was centrifuged (5000 rpm, 6 min) using an SL 16 centrifuge (Thermo Fisher Scientific, Waltham, MA, USA). The supernatant was recovered, and to the solid residue, another 3 mL of MeOH were added two times. The methanolic extracts were dried under reduced pressure. Samples were then added with 2 mL of MeOH, filtered, and transferred in a glass vessel. Analyses were carried out using an HPLC Alliance e2695 (Waters, Milford, MA, USA) system equipped with an autosampler, degasser, and column heater coupled with a Q-Tof Premier quadrupole time-of-flight mass spectrometer (Waters, Milford, MA, USA).

The compounds were separated using a 50 × 2.1 mm ID Hypersil GOLD HPLC column (Thermo Fisher Scientific, Waltham, MA, USA) kept at 20 ◦C. The injection volume was 5 μL. A thermostated auto sampler, kept at 4 ◦C, was used, and all samples were injected in triplicate. The HPLC eluent was a mix of 0.1% aqueous formic acid solution and 0.1% formic acid in MeOH, with a flow rate of 0.25 mL/min.

Elution started with 95% aqueous formic acid and 5% methanol formic acid, and then isocratic for 1 min. Then, in the following 14 min, the solvent became 100% MeOH, remaining isocratic for the subsequent 5 min (from min 15 to min 20). After 30 s, the eluting solvent mixture was reverted to 95% aqueous formic acid and 5% methanolic formic acid and maintained for another 30 s. Each run lasted 21 min. Every sample was injected three times. The concentration values, which are reported in Table 4, are the arithmetic mean of the values observed in each run.

For the detection of flavonoids and other phenols, the calibration curves of quercetin and gallic acid, both of HPLC purity grade, were used. The calibration curves were performed using a standard solution of quercetin in methanol (1000 ppm 10 mg/10 mL) and a standard solution of gallic acid in methanol (1000 ppm 10 mg/10 mL), respectively. Each calibration curve was obtained using 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, and 20 ppm solutions.

The following compounds were investigated: quercetin, quercetin 2O-gallate, quercetin glucuronide, quercetin-hexose malic acid, methyl-dihydroquercetin hexoside, kaempfer-

olol, myricetin-rhamnose malic acid, quercetin 3-O-hexuronide, kaempferol 3-O-glucoside, quercetin 3-O-galactoside, myricetin, myricetin 3-O-hexoside, apigenin glucoside, myrecetin O-rhamnosylglucose, phenols, gallic acid, methyl digallate, pentagalloyl-hexoside, p-coumaric acid, peonidin 3-O-hexoside isomer, and vanillic acid.

## *2.8. Antimicrobial Tests*
