Determination of the total acidity through titration
This method is used to determine the total titratable acids in beverages and concentrates.
Titratable acidity represents the sum of the free acids present in a beverage, with the exception of the dissolved carbon dioxide (carbonic acid). In fruit juices and the beverages prepared from them, they usually consist of malic acid, citric acid and tartaric acid.
The titration of the degassed beverage sample (freed from carbonic acid) is carried out potentiometrically using 0.25 mol/l sodium hydroxide solution either to a pH of 7.0 calculated as tartaric acid or to a pH of 8.1 calculated as citric acid.
This method describes how to determine the free carbon dioxide content of water.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
The water sample is titrated with sodium hydroxide against phenolphthalein until a pink color is sustained for 3 min:
CO2 + NaOH → NaHCO3
The method describes how to determine the free and total chlorine content using a titrimetric method with DPD.
The analysis involves a reaction with N,N-diethyl-1,4-phenylenediamine (DPD), which forms a compound possessing a red color at a pH of 6.2–6.5. The solution is titrated with an ammonium iron(II) sulfate standard solution until the red color disappears. Total chlorine is measured through the addition of potassium iodide, of which a known amount in excess of that required is added to the solution in advance.
The method describes how to determine the free chlorine and total chlorine content using a photometric method with DPD.
The analysis involves a reaction with N,N-diethyl-1,4-phenylenediamine (DPD), which forms a compound possessing a red color at a pH of 6.2–6.5. The color is measured photometrically at 510 nm. Total chlorine is measured through the addition of potassium iodide, of which a known amount in excess of that required is added to the solution in advance.
The method describes how to determine the chlorine dioxide content of water photometrically with a cuvette test.
Determination of the osmolality of beverages
Suitable for carbonated and non-carbonated beverages
Osmolality is defined as the number of particles of osmotically active substances per kilogram of a solvent (usually water). The size or type of particles is irrelevant for the osmotic pressure, only the number of particles (cations, anions, sugars, organic acids, amino acids, proteins, ethanol, etc.) is of importance. The presence of substances dissolved in an aqueous solution lowers the freezing point, as compared with pure water. The freezing point is lowered in proportion to the amount of dissolved particles or molecules. For this reason, measuring the freezing point of a solution provides a means for calculating the concentration of dissolved particles. The more dissolved particles there are in a solution, the greater the drop in freezing point.