Titroline easy

Gastric acid was analyzed using the protocol as described by Waghray et al. [47 (link)]. Briefly, thawed gastric contents were centrifuged at 3000× g for 15 min at 4 °C, and the supernatant was recovered for acid titration with an automatic titrator (TitroLine easy, Schott Instruments GmbH, Germany). The supernatants were diluted 10 × with 0.9% saline solution and titrated with 0.01 N sodium hydroxide (NaOH) solution using the titrator. Each sample was analyzed in triplicate and the volume of NaOH used to titrate to a final pH of 7.4 was recorded. Gastric acidity was expressed as mEq H+/mL and calculated by the formula: ((volume of NaOH of sample − volume of NaOH of blank) × normality of the titrating solution)/sample volume) × sample dilution factor.

For the determination of the residual carbon sources, broth of strain cultures grown on HS-S was collected from three biological replicates at 48 and 96 h, respectively. Samples were centrifuged at 16,000× g for 5 min to remove cell biomass and any residual low weight molecules, as suggested by [42 (link)]. Enzymatic analysis was performed on the supernatant to estimate the concentration of residual sugars (sucrose, glucose, and fructose) using the commercial K-SUFRG enzymatic kit (Megazyme^®, Bray, Ireland), and gluconic acid using K-GATE kit (Megazyme^®, Bray, Ireland), previously suggested by [16 (link),42 (link),43 (link)]. pH and titratable acidity were measured by using an automatic titrator (Titroline^® easy, Schott, Mainz, Germany), samples were neutralized by titrating against NaOH (1 M) to pH 7.0.

pH analyses were performed with a titrator pHmeter (Titroline Easy, Schott Instruments) calibrated with two buffer solutions (pH = 4.0 and 6.87). Chemical Oxygen Demand (COD) values were measured using LCK 1414 Hach kits (5–60 mgO₂/L).
Total Organic Carbon (TOC) analyses were performed using a Shimadzu TOC-VCSN analyzer after first passing the samples through a 0.45 µm filter. UV254 absorbance and specific UV absorbance at 254 nm (SUVA₂₅₄) were used to track a relative amount of unsaturated and/or aromatic carbon of natural organic matter (NOM) [44 (link)]. SUVA₂₅₄ was determined from the ratio of UV254 absorbance to TOC value. UV254 absorbance was measured in a 1 cm quartz cuvette using a Shimadzu model UV-2401PC UV-vis spectrophotometer (Shimadzu, Japan).
Concentrations of anions and cations were measured using an ICS-1000 ion chromatograph equipped with an AERS suppressor (4 mm), an IonPac AS19 column and a DS6 conductivity detector for anions and an ICS-900 equipped with a CSRS suppressor (4 mm), an IonPac CS12A column and a DS5 conductivity detector for cations (Dionex, Thermo Scientific, Waltham, MA, USA). Samples were added automatically using a sample changer (AS40).
For the samples collected after ozonation, 200 µL of Na₂SO₃ (10 mg.L⁻¹) was added to 2 mL of sample as scavenger of the dissolved ozone.

Firmness in the 1‐MCP‐treated and control groups was measured using a handheld FT‐327 penetrometer (UC Fruit Firmness Tester, Milano, Italy) with an 8 mm diameter probe. Following the removal of a small piece of fruit skin, the firmness from three slices extracted from three different parts of the mango was recorded (means are presented in newtons [N]). The total soluble solid (TSS) content of the fruit was examined on the basis of the AOAC method (AOAC, 2000) using a handheld refractometer (ATAGO, Tokyo, Japan). Mango fruit juice was titrated with 0.1 N NaOH to pH 8.2 in order to determine the titratable acidity (TA) using an automatic titrator (TitroLine Easy, Schott, Mainz, Germany).

Fifteen fruits per treatment were sampled to assess the fruit quality. Skin color was monitored using a color meter (Minolta CR-400; Konica Minolta, Osaka, Japan), and values were reported based on the Hunter’s scale, redness (a*). Firmness was analyzed using a texture analyzer (TA Plus Lloyd Instruments Ltd., Fareham, Hampshire, UK) at a speed of 2 mm/s with a plunger head of 5 mm in diameter. The total SSC of the samples was analyzed using a digital refractometer (PAL-1; Atago Co., Ltd., Tokyo, Japan), and TA was determined by titrating 5 mL of juice from one fruit with 0.1 N NaOH until a pH of 8.2 was reached. This procedure was performed using an auto-pH titrator (Titroline Easy; SCHOTT Instruments GmbH, Mainz, Germany), and the TA was expressed in grams of citric acid per 100 g of sample juice. CI was measured as described by Park et al. [21 (link)]: 0 = no pitting, 1 = few, scattered pits, 2 = pitting covering up to 5% of the fruit surface, 3 = pitting covering 5–25% of the fruit surface, and 4 = extensive pitting covering >25% of the fruit surface. Fruit decay was expressed as the percentage of fruits showing decay symptoms. The CI index and decay rate were recorded as three replicates (three boxes of 30 fruits each) per treatment, per day.