This method describes the complexometric determination of calcium in water.
Calcium ions are bound by the disodium salt of ethylenediaminetetraacetic acid (EDTA) as water-soluble chelates (undissociated complexes). Calconcarboxylic acid serves as an indicator due to its specificity for calcium ions.
Foreign organisms in brewery yeasts are primarily obligate beer-spoilage organisms and wild yeasts. This method aims to detect wild yeasts in brewery yeast cultures.
Process samples containing yeast
Brewery yeast cultures cannot grow in the presence of more than 200 ppm copper sulphate (CuSO4) in a culture medium. The majority of wild yeasts are not inhibited by this concentration. This means that a universal yeast medium (e.g. YM) with the addition of 200 ppm CuSO4 can help detect the presence of wild yeasts in bottom- and top-fermenting brewery yeast cultures.