Laquatwin ph 11

The selection of biochemical and metabolic traits for this study was based on their relevance to assessing tomato fruit quality and the impact of limited irrigation on fruit development. Fruit juice pH was chosen as it directly relates to flavor, with a lower pH often indicating enhanced acidity and improved taste. Brix (soluble solids content) is an important measure of sweetness, reflecting the concentration of soluble sugars in the fruit, which are crucial for consumer preference. Vitamin C content, a key antioxidant, was included to evaluate the nutritional benefits and shelf life of tomatoes, as increased levels are associated with enhanced fruit quality. Electrolyte leakage was assessed to gauge the integrity of fruit cells under water stress, as lower leakage indicates better cellular health and reduced damage. Lastly, metabolomic analysis provided a comprehensive view of the fruit’s biochemical composition, identifying metabolic changes such as increased sugar content, which influence flavor and quality. These traits collectively offer a detailed understanding of how limited irrigation affects both the quality and nutritional value of tomatoes, providing insights into sustainable irrigation practices for optimal fruit production.
Fruit juice pH was measured using a pH meter (LAQUAtwin-pH-11; Horiba Ltd., Kyoto, Japan). Brix was recorded using a Brix meter (Hybrid PAL-BX I ACID F5; Atago Co., Ltd., Saitama, Japan). Vitamin C (ascorbic acid mg/100 g) was measured using a reflectometer (RQflex plus; Merck, Darmstadt, Germany) and ascorbic acid strips (Reflectoquant^®; Merck). First, 1 g of pulp was mixed with 2 mL of metaphosphoric acid at 5% in a 1.5 mL Eppendorf tube; then 1 mL of the mixture was centrifuged at 25 °C and 5000 rpm for 5 min using a centrifuge (MX-307; Tomy Seiko Co., Ltd., Tokyo, Japan); finally, the test strip was immersed in the solution and placed in the reflectometer. Electrolyte leakage, indicative of fruit damage, was assessed by determining the number of electrons leaking from the fruits. Ten random fruits were selected for measuring electrolyte leakage in each treatment, treating each fruit as a replication. Fruit cuttings, made using a 1 cm diameter stainless steel cork borer, were stored in pure water in 2 mL tubes at room temperature (25 ± 1 °C) for half an hour. The electric conductivity (EC) of these fruit cuttings was measured using an electrical conductivity meter (LAQUATWIN-S070, Horiba Scientific Ltd., Kyoto, Japan) [60 (link)].
Metabolomic analysis was conducted following the method previously explained by Oliver [61 (link)] with some modifications. Ten replicated samples of individual fruits from each treatment were homogenized using pre-cooled mortars and pestles with liquid nitrogen. A hundred grams of the resulting puree was used for the extraction. Methanol (250 µL) and one zirconia bead were added to each sample and mixed well using a tissue layer (Oscillating Mill MM 400, Retsch GmbH, Haan, Germany) at 27 Hz for 2 min. After adding 250 µL of chloroform, samples were put in a thermo mixer (Eppendorf Thermomixer F2.0, Hamburg, Germany) for 3 min at 37 °C, 1200 rpm. The standard solution of 50 µL and 175 µL of ultra-pure water were subsequently added to the mixture and centrifuged (TOMY MX-307 high-speed refrigerated microcentrifuge, Tokyo, Japan) at 120 × 100 rpm for 10 min at 25 °C. The standard solution was prepared by diluting 0.2 mg of Ribitol in 1 mL of ultra-pure water. Then carefully, 80 µL of supernatant from each sample was added to the 1.5 mL of Eppendorf tube and put in a centrifugal vaporizer (EYELA CVE-200D, TOKYO RIKAKIKAI Co., Ltd., Tokyo, Japan) for 2 h with a cooling trap apparatus (EYELA UT-80, TOKYO RIKAKIKAI Co., Ltd., Tokyo, Japan). After that, samples were transferred to a freeze dryer (EYELA FDM-1000, TOKYO RIKAKIKAI Co., Ltd., Tokyo, Japan) and kept overnight. The resulting residues were dissolved in 40 µL of Methoxyamine hydrochloride solution by putting in the thermo mixer for 90 min at 37 °C followed by adding 50 µL of N-Methyl-N-trimethylsilyl tri fluoroacetamide (MSTFA) with another 30 min incubation in the thermomixer under the same condition. Then 50 µL from the extraction was used to analyze metabolomics components. The Methoxyamine hydrochloride solution was prepared by diluting 20 mg of Methoxyamine hydrochloride in 1 mL of Pyridine.
Metabolomic analysis was performed using gas chromatography–mass spectrometry (GC-MS-QP2010 plus, SHIMADZU, Tokyo, Japan). The column used was DB-5 (0.25 mm internal diameter, 30 cm length, and 1.00 µm of film thickness, Agilent Technologies Inc., Santa Clara, CA, USA). The GC conditions were as follows: The oven temperature was held for 1 min at 60 °C, raised to 320 °C at a rate of 4 °C min⁻¹, and held at 10 min, with the flow rate of Helium 1.1 mL min⁻¹. The analysis method of mass spectrometry was scan mode and conditions. The transfer line was set at 290 °C, and the ion source was kept at 200 °C. Mass spectra were recorded at a scan s⁻¹ with an m z⁻¹ 45–600 scanning range.

The pH and conductivity of vinegar samples were measured using a pH meter (LAQUAtwin-pH-11, Horiba Scientific, Kyoto, Japan) and a conductivity meter (LAQUAtwin-EC-11, Horiba Scientific, Japan), respectively. The pH buffer solutions at pH 4.01 (Model 514-4) and 7.00 (Model 514-7) were used to calibrate the pH meter, whereas the conductivity solution at 1.413 mS/cm (Model514-22) was used to calibrate the conductivity meter before use. The sugar content of vinegar samples was measured using a brix refractometer (MA871, Milwaukee Instruments, Milwaukee, WI, USA).
The acidity of vinegar samples was determined using the titrimetric method (Metrohm 665 Dosimat autotitrator, Herisau, Switzerland). A 10 g sample was weighted in a beaker, and 600 mL of distilled water was added into the beaker with two drops of phenolphthalein as indicator. The solution was titrated with 0.1 M sodium hydroxide until the solution turned stable pink. Equation (8) is used to calculate the acidity of vinegar expressed in acetic acid percentage.
$$\mathrm{Acidity} =\frac{\left(\mathrm{Titrant} \mathrm{volume} \left(\mathrm{mL}\right)\times \mathrm{NaOH} \left(\mathrm{M}\right)\times \mathrm{Molar} \mathrm{mass} \mathrm{of} \mathrm{acetic} \mathrm{acid} \left(\mathrm{g}/\mathrm{mol}\right)\right)}{\mathrm{Sample} \mathrm{weight} \left(\mathrm{mg}\right)}\times 100$$
The color of jaboticaba vinegar samples was spectrophotometrically measured at 4 different wavelengths, namely 430 nm, 520 nm, 580 nm, and 620 nm [16 ]. Citrate-phosphate or McIlvaine buffer at pH 3.0 was used to dilute vinegar samples to prevent the color change of pH-sensitive compounds. This citrate-phosphate buffer was prepared by mixing 4.11 mL of disodium hydroxyphosphate (0.2 M) and 15.89 mL of citric acid solution (0.1 M). The change of absorbance at different concentrations of vinegar samples was plotted. The slope of the linear curve is expressed as the absorption coefficient (Equation (9)).
$$\mathrm{E} =\frac{\mathrm{A}}{\mathrm{C}.\mathrm{l}}$$
where ε is the absorption coefficient, A is the absorbance, C is the sample concentration, and l is the length of the cuvette (1 cm).
The ratio of the absorbance at different wavelengths was applied to determine brown and blue indexes as presented in Equations (10) and (11). Fresh berries were also macerated in water in a ratio of 1:1 for 24 h. The solution was then harvested and used as a positive control.

6–8-wk-old mice were sacrificed, and the intestine was isolated. Approximately 2-cm pieces of ileum and colon were cut open longitudinally, and the luminal side was exposed using a pair of forceps. The luminal pH and sodium ion concentration were measured using a pH meter (LAQUAtwin pH11; Horiba) and sodium ion meter (LAQUAtwin Na-11; Horiba), respectively.
To determine fecal sodium ion concentrations, fresh feces were collected from mice in preweighed tubes and weighed and subjected to lyophilization. Double-distilled water was added to each sample (100 mg/ml), and the fecal pellets were homogenized using a Spinwin micro pestle (Tarsons). The samples were vortexed for 30 s, followed by centrifugation at 3,000 rcf for 5 min. Sodium ion in the supernatant was measured using a sodium ion meter (LAQUAtwin Na-11; Horiba) and normalized to the weight of the dry feces.