Orion 3 star benchtop ph meter

The negative logarithm of the hydrogen ion concentration in the sausages was determined using a pH meter (Orion 3-Star pH Benchtop Meter, Thermo Fisher Scientific, Waltham, MA, USA). Two measurements were made directly in the sausage samples after their preparation and after reaching ambient temperature.

The determination of TBARS in raw beef patties was assessed according to Skowyra et al. [45 (link)]. The absorbance of each sample was measured at 531 nm and the results were expressed as mg MDA/kg meat sample. The pH measurement of the beef patties was determined electrometrically every two days using an Orion 3-Star pH Benchtop Meter (Thermo Fisher Scientific, Waltham, MA, USA).

Readings of soil pH were taken to determine any changes in soil acidity caused by weeds, which might affect mango tree health, nutrient uptake, and growth. Soil slurries were made with a 3:1 deionized water to soil ratio, 4 g of distilled DI water to 2 g of wet soil, and pH readings were taken with an Orion 3 Star Benchtop pH meter (Thermo Fisher Scientific, Waltham, MA USA), following methods outlined by Miller and Kissel [45 (link)]. The ideal pH range for mango cultivation is between 4.5 and 7.5 pH, which is neutral to acidic soil, although mango trees do tolerate slightly alkaline soil [46 ].

For all measurements of physicochemical and microbial properties, Baechu kimchi broth was sampled following previous studies [32 (link),34 (link),45 (link)]. The physicochemical properties, including pH, acidity, salinity, and water activity, and the microbial properties, including the counts of total viable mesophilic bacteria and LAB, of the samples from respective experiment groups were measured as in the previous studies [32 (link),34 (link),45 (link)]. Briefly, the pH and water activity (a_w) of Baechu kimchi samples were determined using a pH meter (Orion 3-star Benchtop pH meter; Thermo Scientific, Waltham, MA, USA) and a water activity meter (AquaLab Pre; Meter Group, Inc., Pullman, WA, USA), respectively. The acidity and salinity of Baechu kimchi samples were determined according to the AOAC methods, respectively [46 ]. The counts of total viable mesophilic bacteria and LAB were determined on Plate Count Agar (PCA; Becton Dickinson, Sparks, MD, USA) and MRS agar, respectively.

A portion of the bulk soil samples was used to determine the metal composition using Total Reflection X-Ray Fluorescence (TXRF) technique. Briefly, for each sample 1 g of soil was resuspended in 1 mL of distilled water and homogenized for 2 h at room temperature. After mixing, the samples were centrifuged at 11,440 g for 10 min in a Hettich Universal 32R. The soluble fraction was recovered and measured in a Bruker S2 PICOFOX.
Soil texture (sand:silt:clay), electrical conductivity, and nitrogen levels (total N, NO₃⁻, NH₄⁺) were provided by the Laboratorio Agroanálisis UC, Facultad de. Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, according to the methods established by the Normalization and Accreditation Commission (CNA) of the Chilean Society of Soil Science⁹³ , as performed before^{62 (link)}.
For soil pH measurement, 2 g of soil were mixed with 5 mL milliQ water and homogenized during 2 h at RT (S1000 Gyrotwister) at 60 rpm. Afterwards, the soil was decanted during 2 h. The pH was measured in triplicate for each sample in a Thermo Scientific Orion 3 star benchtop pH meter.