Fiveeasy f20

The pH of each brewed coffee sample was measured with a Mettler Toledo FiveEasyTM F20 (Mettler-Toledo, Warszawa, Poland) benchtop pH/mV meter.
The method of determination of titratable acidity consists of neutralization of the organic acids present in the tested coffees in a properly prepared solution of the tested sample with 0.1 M sodium hydroxide solution until the titration point is reached [9 ]. Approximately 10 mL of the test material was measured and transferred into 150 cm³ and 200 cm³ volumetric flasks and made up to 2/3 of the flask’s capacity with distilled water. The samples were boiled in a water bath for 30 min at 100 °C. After cooling the volumetric flasks to room temperature, they were again made up to the mark with distilled water. The resulting solutions were then mixed and filtered through material strainers, and 50 cm³ of each filtrate was taken. The obtained filtrates were titrated with 0.1 M sodium hydroxide solution using a titrator. The result was calculated by converting to malic acid content.

The color was evaluated on grilled and raw burgers after 0 and 7 days of storage. The color measurement was performed on the entire surface, at 5 different locations for one burger. The analysis measurement was performed in two batches. Analysis was performed using a Minolta CR-400 chromameter with a glass cell (10 mm optical path) with the CA-A98 attachment (Konica Minolta Inc., Tokyo, Japan) and D65 illuminant (color temperature: 6500 K), as well as a standard observer (2°) in the CIE L* a* b* system. The diameter of the measuring head was 8 mm. For calibration, the white standard plate was used (L* = 98.45, a* = −0.10, b* = −0.13). In addition, the total color difference value (ΔE) was calculated according to the formula by Altmann et al. [23 (link)]. The pH was measured using a digital pH meter (FiveEasy F20, Mettler Toledo, Greifensee, Switzerland).

Instrumental color parameters were measured on the burger surface (five measurements) before and after cooking, avoiding areas with a lot of fat. A CM 700-d spectrophotometer (Minolta, Osaka, Japan) was used, and the following operating conditions were applied: illuminant D65; observation angle 10°; measuring hole 1 cm; and the specular component excluded. The color coordinates L* (lightness), a* (redness), and b* (yellowness) were obtained using the CIELab system space, and Chroma [√(a*2 + b*2)] and Hue [tan-1 (b*/a*)] were calculated.
The pH was measured directly on raw and cooked burgers at room temperature using a pH meter (Five Easy F20, Mettler Toledo, Greifensee, Switzerland) equipped with a glass electrode (XS Sensor 2-pore T DHS, Sensor Instruments, Thurmansbang, Germany), after calibration with pH 7.0 ± 0.02 and 4.0 ± 0.02 buffer solutions. The measurements were performed in three different positions of each sample.

The biomaterials included S53P4 bioactive glass (500–800 μm granules), Putty A, Putty B (Bonalive® Biomaterials Ltd.) and loose S66 powder (Table 1). The biomaterials were added to 2 mL fresh MH-II broth (without pathogens) and incubated overnight (16–18 h) on a rolling plate (IKA® roller 6 digital, IKA®-Werke GmbH & Co. KG, Staufen, Germany) at room temperature. This overnight incubation was performed to precondition the broths by the ions released from the different biomaterials. Per tested biomaterial, 11 test tubes were preconditioned of which 10 were used to for the pathogen cultures (n = 2 per bacterial strain) and 1 was used as a negative control to evaluate the pH of the broth with biomaterial, over time. The pH was measured with a Litmus red paper and a pH meter (FiveEasy F20, Mettler Toledo®, Tiel, The Netherlands); no bacteria were added to this specific test tube.

At the end of sperm incubation, 1.7 mL of sperm sample from each treatment was centrifuged at 16,300 g for 10 min at room temperature. Then, 700 μL of the supernatant was transferred into a microcentrifuge tube and incubated at 38 °C for a minimum of three minutes before reading. The ORP was measured using a micro ORP electrode with a platinum ring connected to a pH meter (Five Easy F20, Mettler-Toledo, Switzerland). The ORP of each sample was recorded after embedding the microelectrode into the solution for 3 min. After each sample analysis, the probe was calibrated into a redox buffer solution (220 mV, pH 7, Mettler-Toledo, Switzerland) for 30 s. The assay was run in duplicate per sample and expressed in millivolts (mV). The ORP levels were not normalized [55 ], because the experiments were performed at the same sperm concentration (i.e., 20 × 10⁶/mL). The ORP was evaluated only in samples submitted to induced oxidative stress (i.e., experiment IIb).

The pH and RP (mV), were measured with a digital pH meter (FiveEasy F20, Mettler Toledo^®, Greifensee, Switzerland) during the fermentation process every hour and during the storage of samples on days 0, 7, 14, 21, and 28. For the measurement of TA (°T), 10 mL of samples was mixed with 10 mL of distilled water using as an indicator 0.5% phenolphthalein and titrated with 0.1 N NaOH [37 (link)]. The measurements were made with a digital burette (ISOLAB Laborgeräte GmbH, Eschau, Germany) at the same experimental points as pH and RP during the process of fermentation and the storage time.

Water activity was determined according to ISO 18787:2017 [31 ] using the Aqualab Pawkit DE201 apparatus (METER Group, Inc., Pullman, WA, USA). The pH value was determined according to ISO 2917:1999 [32 ] using a pH-meter FiveEasy F20 with a LE438 electrode (Mettler-Toledo GmbH, Greifensee, Switzerland).