Potassium chloride (kcl)

The S. aureus ATCC 33593 strain was purchased from the Korean Culture Center of Microorganisms (Seoul, Republic of Korea). The MRSA CCARM 3820 and CCARM 3879 strains were purchased from the Culture Collection of Antimicrobial Resistant Microbes (CCARM, Guri, Republic of Korea). All S. aureus strains were stored at −80 °C in 25% glycerol (catalog number: 4066–4400, Daejung Chemical & Metals Co., Ltd., Siheung, Republic of Korea). Cells were cultured using tryptic soy broth (TSB, catalog number: 211825, Becton Dickinson Korea Co., Ltd., Seoul, Republic of Korea) and tryptic soy agar (TSA) made using TSB with 1.5% agar (catalog number: 214010, Becton Dickinson Korea Co., Ltd.). Cultures were incubated at 37 °C with a shaking speed of 250 rpm. A saline solution was prepared by dissolving sodium chloride (catalog number: S0476, Samchun Chemicals Co., Ltd., Seoul, Republic of Korea) at 0.85% (w/v). Phosphate-buffered saline (PBS) was made with 8 g/L of sodium chloride, 0.2 g/L of potassium chloride (catalog number: PR-1938, Tedia Company Inc., Fairfield, OH, USA), 1.44 g/L of sodium phosphate dibasic (catalog number: 7613–4405, Daejung Chemical & Metals Co., Ltd.), and 0.245 g/L of potassium phosphate monobasic (catalog number: P1122, Samchun Chemicals Co., Ltd.). All solutions were autoclaved at 121 °C for 20 min.

To perform the 11 experiments designed by the CCRD, S. Typhimurium cells recovered from BDL samples—MS cells (Section 2.2 and Section 2.3.1)—at each incubation condition of the CCRD runs were estimated by enumerating surviving cells (Table 1). S. Typhimurium inactivation was calculated as decimal logarithm reductions between the initial inoculum and the recovered cells—Log N₀/N.
The same 11 experimental conditions were used to assess the effect of each exposure condition in the BDL matrix on subsequent SGF S. Typhimurium survival (Table 1). After each experiment, 10 g of the BDL samples were homogenized using the stomacher with 90 mL of SGF and incubated at 37 ± 1 °C for 1 h. The SGF comprised 8.3 g proteose peptone (Sigma-Aldrich, Darmstadt, Germany); 2.05 g sodium chloride; 0.6 g potassium phosphate (Sigma-Aldrich, Darmstadt, Germany) 3.5 g D-glucose (Vetec Química Fina Ltd.a, RJ, Brazil), 0.11 g calcium chloride (Vetec Química Fina Ltd.a), 0.37 g potassium chloride (Tedia Company Inc, RJ, Brazil), 0.1 g lysozyme, and 13.3 mg pepsin (Thermo Fisher Scientific, MA, USA) per liter of distilled water [23 (link),24 (link),25 (link)]. S. Typhimurium enumerations were performed by plating an aliquot of the BDL-SGF cell suspension prior and after the 1 h incubation at 37 °C. S. Typhimurium inactivation was calculated by the logarithm difference from initial and final counts Log N₀/N.