Developments in Using Off-Line Radio Frequency Impedance Methods for Measuring the Viable Cell Concentration in the Brewery

Carvell, John; Austin, Glen D.; Matthee, A.; Spiegle, K. Van de; Cunningham, Shaun Cameron; Harding, C L

doi:10.1094/asbcj-58-0057

Cited by 5 publications

(5 citation statements)

References 4 publications

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“…Variation in the reading of volumes is also likely to be a source of error when using the spin method. A more recent development for biomass determination is the measurement of yeast capacitance [1,14,15]. This has the advantage of also providing yeast viability data.…”

Section: Discussionmentioning

confidence: 99%

A flow-cytometric method for determination of yeast viability and cell number in a brewery

Boyd

Gunasekera

Attfield

et al. 2003

FEMS Yeast Research

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A flow-cytometric assay, using the fluorescent dye, oxonol, for the simultaneous determination of yeast cell viability and cell number is described. The assay was optimised, and trialed at a brewery for 6 months. The flow-cytometry assay offered a substantially reduced error in viability determination, compared to methylene blue which is the industry standard for measuring viability. Further, by calculating yeast cell number at the same time, this assay provides a reliable method for determining pitching rate, allowing increased quality control of subsequent fermentations.

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Section: Discussionmentioning

confidence: 99%

A flow-cytometric method for determination of yeast viability and cell number in a brewery

Boyd

Gunasekera

Attfield

et al. 2003

FEMS Yeast Research

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

A flow-cytometric method for determination of yeast viability and cell number in a brewery

BOYD¹,

GUNASEKERA²,

Attfield³

et al. 2003

FEMS Yeast Research

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“…It is of course possible to determine the relationships between these parameters and cell number, for each strain, but not with any great precision because of the errors involved. The Aber yeast biomass monitor, the current market leader for automatic yeast quantification ( 5, 6 ) can be calibrated in units of cell number and if set up properly should give a repeatable result; however, since it is responsive only to the fraction of cells judged to be viable on the basis of possessing an intact membrane, it does not give any information on yeast physiological condition. In addition, the initial calibration cannot be more precise than the method used to quantify the yeast cell concentration in the test suspension, a figure derived from the traditional viable count based on manual counting using methylene blue.…”

Section: Quantification Of Yeast Populationsmentioning

confidence: 99%

Provocation: all yeast cells are born equal, but some grow to be more equal than others

Boulton¹

2021

J. Inst. Brew.

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Yeast is central to the brewing process and as such deserves great care and attention to ensure it is fit‐for‐purpose. It is widely accepted that assessment based on simple viability testing is useful but far too blunt an instrument to give much useful information regarding the physiological state of the live yeast cells within the population. The need to address this issue has spawned a plethora of procedures collectively termed ‘vitality tests’. The concept of yeast vitality is nebulous, and this goes some way to explain why no single test has been universally adopted. There is, however, another major flaw in the underlying assumptions of the majority of vitality tests. This is, most are based on bulk samples which ignore heterogeneities within the population of cells being examined. The asymmetric mode of proliferation of Saccharomyces yeasts means that mother and daughter cells are always unequal. Individual cells have finite lifespans, old cells die and must be replaced with new fitter progeny. We are fortunate in that budding yeasts are widely used as a model cell for studies into ageing in higher eukaryotes and as a result there is a huge and ever‐expanding body of literature devoted to this subject. This has shown that yeast populations comprise several distinct sub‐populations which respond differently to external messengers. These messengers may be generated by one sub‐set of the population and received and acted upon by another indicating a degree of cooperation designed to ensure survival of the whole. Death of individuals within populations can be as a result of the application of lethal external stresses but more usually is a programmed process in which targeted cells commit suicide in an expression of altruism for the greater good of the whole. On reflection, perhaps this is unexpected but perfectly logical behaviour for single celled organisms to adopt. Most yeast population studies have been performed using haploid laboratory strains cultivated under relatively defined conditions. The industrial scale model is, of course, far removed from this. Brewing yeast strains are very different, and the complexities of serial fermentations and associated yeast handling processes introduce added layers of complexity. Nevertheless, there is every reason to believe that similar population heterogeneities and cooperative behaviour exist within the context of brewing. The thrust of the arguments presented in this article is that we should embrace this and consider individual cells within yeast populations within a fermenter, for example, as being individual free‐living components of a multicellular organism. Further, intercellular cooperation is managed by a network of messenger molecules many of which are likely to trigger the global shifts associated in metabolic activities which accompany the reversible passage from growth to quiescence and which coincidentally are likely to be of importance in beer flavour. The purpose of this article is to argue that the majority of current yeast vitality tests are not fit...

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Developments in Using Off-Line Radio Frequency Impedance Methods for Measuring the Viable Cell Concentration in the Brewery

Cited by 5 publications

References 4 publications

A flow-cytometric method for determination of yeast viability and cell number in a brewery

A flow-cytometric method for determination of yeast viability and cell number in a brewery

A flow-cytometric method for determination of yeast viability and cell number in a brewery

Provocation: all yeast cells are born equal, but some grow to be more equal than others

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