This method is suitable for (bottom-fermented) beer and beverages.
The fraction of phenols extracted using steam are converted to color complex using 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one (4-aminophenazone) in an alkaline medium and through oxidation with potassium ferrocyanide (III), which can be measured spectrophotometrically after extraction with chloroform (fig. 1).
Foreign organisms in industrial yeasts are primarily obligate beer-spoilage organisms (gram-positive and gram-negative anaerobes) and wild yeasts.
Brewery yeast and purchased yeast
Dark-field microscopy of the sample with subsequent enrichment.