Fiveeasy f 20 ph meter

An Agilent 1220 Infinity LC system equipped with a binary pump integrated with two-channel degasser, autosampler, temperature-controlled column compartment and diode-array detector (Agilent Technologies, Waldbronn, Germany) was used for the HPLC–UV experiments. Data acquisition and analysis were performed using an OpenLAB CDS ChemStation software. Analytes were separated on ZORBAX SB-C18 (150 × 4.6 mm, 5.0 µm) column from Agilent Technologies (Waldbronn, Germany). During the study, a Mikro 220R centrifuge with fast cool function (Hettich Zentrifugen, Tuttlingen, Germany), and a FiveEasy F-20 pH-meter (Mettler Toledo, Greifensee, Switzerland) were also used. Water was purified using a Milli-QRG system (Millipore, Vienna, Austria).

LiNO₃, H₃PW₁₂O₄₀, 1,4‐Dioxane (DO) and Dimethyl sulfoxide (DMSO) were purchased from Sigma Aldrich.
H₃PW₁₂O₄₀ was dried at 50 °C under vacuum for 24 hours in order to remove the adsorbed water.
The electrolytes used in this work are listed below:

1 M LiNO₃ in H₂O

1 M LiNO₃ in H₂O: DMSO (1 : 1 v/v)

1 M LiNO₃ in H₂O: DO (1 : 1 v/v)

1 M LiNO₃+1 mM H₃PW₁₂O₄₀ in H₂O

1 M LiNO₃+1 mM H₃PW₁₂O₄₀ in H₂O: DMSO (1 : 1 v/v)

1 M LiNO₃+1 mM H₃PW₁₂O₄₀ in H₂O: DO (1 : 1 v/v)

1 M LiNO₃+10 mM H₃PW₁₂O₄₀ in H₂O

1 M LiNO₃+10 mM H₃PW₁₂O₄₀ in H₂O: DMSO (1 : 1 v/v)

The conductivity of the electrolytes was measured with a Mettler Toledo conductometer at 23 °C. The pH was measured with a Mettler Toledo (Five Easy f20) pH meter at 23 °C.

The a_w of the pizza samples were determined at 25°C, using an Novasina Labswift Portable water activity meter (Novasina-AG, Lachen, Switzerland) as described by Michael et al. (2020) (link). The a_w and pH for baking validation study were measured during baking (dough, 0, 2, 4, 6, 8, 10, 12 min) and at 17, 22, and 27 min during ambient cooling. At each sampling point, for a_w, the samples were placed in Novasina sample cups (diameter 40 mm × Height 13 mm) with lids (Novasina-AG, Lachen, Switzerland) within 10 s of removal from the oven, and analyzed within 30 min. For pH, a 15 g of pizza sample was added to 45 ml of deionized water, and the mixture was stirred continuously until a stable pH reading was attained using a pH meter (FiveEasy F20 pH meter, Mettler-Toledo, Greifensee, Switzerland). A separate triplicate study was carried out to measure the humidity of the thermal environment inside the oven during baking using the Scorpion^® 2 Digital Humidity Sensor (Reading thermal, Sinking Spring, PA, United States). Before starting the pizza baking process, the humidity sensor enclosed in the thermal barrier was preheated to ∼65°C and placed inside the oven to record the humidity ratio (kg of moisture / kg of dry air). The humidity ratio was recorded every second during the pizza baking process.