Determination of the yeast cell concentration in stored pitching yeast, fermenting or stored beer. Descriptors: Haemocytometry, counting chamber, counting chambers (Thoma, Malassez, Bürker-Türk, Neubauer), counting area.
Instrumental determination of the yeast cell concentration in fermenting beer or pitching yeast. Descriptors: Electronic Counter, modifies the resistance between the electrodes, electrolyte.
Determination of the yeast cell concentration of stored pitching yeast, fermenting or stored beer with counts over 1 million cells per ml. A concentration step is necessary for samples containing less than 1 million cells. Descriptors: Photometric Determination, photometer, calibration curves.
It is necessary to use EBC Microbiology 3.1.1.1 or 3.1.2.2
Instrumental determination of yeast cell concentration and yeast viability in brewing yeast containing samples.
The rapid estimation of yeast fraction in a slurry. Descriptors: Centrifugation of yeast mass, alkaline treatment.
Determination of the concentration of yeast in suspension by means of its dry weight. Descriptors: Dry Weight of Yeast, centrifugation, alkaline solution.
Rapid estimation of the percentage of “viable” yeast cells by counting dead cells. The method is applicable to all samples containing yeast. Descriptors: Methylene Blue / Violet Stain, ratio between total and dead cells.
Rapid estimation of the percentage of “viable” yeast cells by counting dead cells. Descriptors: Fluorescence Stain for yeast analysis, fluoresce under UV-light, percentage of fluorescing cells.
Estimation of the percentage of viable cells capable of reproducing in a yeast sample. Descriptors: Slide culture techniques for yeast analysis, micro-colonies.
Primary differentiation of yeasts based on cell morphology. Descriptors: cell morphology of yeasts, size, shape, vegetative reproduction of the cells, examine only pure cultures.
Quantitative estimate of the proportions of the different brewing yeast strains present in a mixed culture. Descriptors: cell colony morphologie, yeast giant colonies, long-time incubation.
The method is intended for breweries that use different yeast strains in fermentation. lt may give a quantitative estimate of the proportions of the different strains present in a mixed culture depending on the strains. Descriptors: yeast morphology on WLN agar.
The laboratory storage of brewing yeast stocks cultures over a number of years. It has been demonstrated that the genetic stability and survival of brewing yeast strains are optimal after cryopreservation at ultra-low temperatures (below -139 °C) compared to other preservation methods. The cultures may be stored in plastic tubes or straws. The present method describes the preservation in polypropylene straws under liquid nitrogen or in mechanical freezers. Descriptors: yeast storage at ultra-low temperatures, cryoprotectant agent, long-term storage, cryopreservation, dehydration, osmotic imbalance, intracellular ice.
This method describes the storage of brewing yeast strains for short periods of time (up to 6 months) in the laboratory. Changes in brewing yeast genotype following maintenance of the strains by repeated subculturing have been reported to influence yeast brewing performance. Preservation of the original properties of the stored yeasts in the long term is only recommended at ultra-low temperatures. For short-term storage (up to 6 months), other methods are available that allow safe and simple management of strains in the lab. Repeated subculturing for preservation of brewing yeast should be totally avoided. Descriptors: yeast subculturing for short-term storage.
It is necessary to use EBC Microbology 3.4.1
The shipment of brewing yeast strains from a supplier laboratory to a receiving laboratory where they are to be propagated for industrial purposes. Descriptors: yeast strain transport, short-term storage, free from contaminant microorganisms.
It is necessary to use EBC Microbiology 3.4.2
Propagation of brewing yeast strains from stock cultures to obtain sufficient yeast to pitch the first propagation tank in the brewery. As the objective is to produce large numbers of yeast cells (not to produce beer), the propagation conditions are more flexible than in brewery fermentation, so general guidelines, as well as a standard protocol as a guide are provided. Descriptors: laboratory storage.
it is necessary to use EBC Microbiology 3.4.1 and 3.1
The determination of the percentage of cells in a yeast culture which are respiratory deficient (known as “petite mutants”, or simply “petites”). Descriptors: detection and enumeration of respiratory deficient mutants, deficiency in metabolism, low yield of biomass, diacetyl formation.
This technique allows the prediction and evaluation of the stability of brewing characteristics in a strain of yeast, and also permits the study of the influence of certain technological parameters on its behaviour in fermenter. It can also be used to assess the characteristics of newly isolated yeast cultures. Descriptors: yeast characterisation by fermentation in EBC Tall Tubes.
Classification of yeast isolates according to their ability to flocculate or form flocs. Descriptors: Gilliland Method, yeast analyis, aggregation of yeast cells.
Classification of yeast isolates based on their ability to flocculate or form flocs and to de-flocculate. Descriptors: Hough Method, yeast analysis, determine the flocculation characteristic, appearance of yeast suspensions.
It is necessary to use EBC Microbology 3.5.3.1
Classification of a suspension of yeast based on its rate of flocculation. Descriptors: Helm Method, sedimentation of yeast, calcium sulphate solution, yeast analysis.