Toledo five easy ph meter

Leflunomide, teriflunomide, α-, β- and γ-cyclodextrins were purchased from Sigma-Aldrich. All other reagents (HCl, KH₂PO₄ and Na₂HPO₄⋅12H₂O) used for the preparation of the buffers were of analytical grade. The pH of buffer solutions was controlled using Mettler Toledo Five Easy pH-meter.

A macroscopic observation of pellicles was made from the time of inoculation (D0), during the next 3 days of production (D1, D2, and D3) for kombucha, and after 14 days for pure AAB cultures.
Variations of fresh pellicle weight were determined with biological triplicates that were sacrificed for each measurement. The determination of dry weight content was also made for each measurement point in triplicates using gravimetric methods after treating the samples at 102°C in an oven for 24 h.
The samples were kept frozen at −20°C and were centrifuged prior to chemical analyses (3,000 × g, 15 min, 10°C). After thawing, the pH was determined using a Mettler Toledo Five Easy pH meter coupled with a LE498 probe. Total acidity was determined by titration with 1 N NaOH and 0.2% phenolphthalein as the color indicator (OIV, 2009 ).

Sugar content was measured using Sucrose Glucose Fructose enzymatic kit from Biosentec (Portet-sur-Garonne, France). The pH values were measured with a Mettler Toledo Five Easy pH meter coupled with a LE498 probe and total acidity was determined by titration with 0.1 N NaOH (purity ≥ 98%) and 0.2% phenolphthalein as color indicator, with reagents purchased from Merck (Darmstadt, Germany).