Flow Cytometry-A New Tool for Direct Control of Fermentation Processes

Hutter, K.‐J.

doi:10.1002/j.2050-0416.2002.tb00122.x

Cited by 20 publications

(22 citation statements)

References 4 publications

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“…7,8 Therefore rapid on-line control of all parameters relevant for the termination of the fermentation process is strongly recommended. 9 Besides the formation of alcohol and the reduction of amino acids, other analytes relevant for taste, stability and further characteristics of the beer are formed during fermentation of the wort. 8 One of those analytes is diacetyl, a diketone with an intense "butter-aroma", which is formed via a potential side reaction during the enzymatic production of the amino acid valine.…”

Section: Introductionmentioning

confidence: 99%

“…9 Only a few investigations have been published providing on-line methods that can be used during fermentation, such as the determination of the growth phase of the yeast population 9 , mass spectrometry with membrane inlet (MIMS) 18 or the determination of ethanol relying on ion mobility spectrometry 10 . Because the ethanol concentration is about 50 times higher than the threshold values for the volatile diketone analytes, relevant for the termination of the fermentation process (µg/L range), the loss of ethanol when using a membrane inlet does not play an important role.…”

Section: Introductionmentioning

confidence: 99%

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Beer Fermentation Control Using Ion Mobility Spectrometry - Results of a Pilot Study

Vautz

Baumbach

Jung³

2006

Journal of the Institute of Brewing

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Beer fermentation -a time consuming part of the production process -is typically terminated based on the degradation of diacetyl and 2,3-pentanedione below the odour threshold. Presently no on-line control of both analytes is available. As a consequence, fermentation is often carried out longer than necessary, thus decreasing productivity. In this pilot study, an ion mobility spectrometer using a UV-lamp as an ionisation source and a GC column (30°C constant) for pre-separation were used for the rapid determination of both analytes from the headspace of beer wort, during and after fermentation. Samples were heated to 60°C. Results from such analyses were available after a few minutes without further sample treatment or pre-concentration. Detection limits were below the odour threshold (ng/L range in the gas phase corresponding to the µg/L range in the liquid phase). Results were validated by comparison with the brewery's standard GC-MS method. When applied on-line and in-situ, as a routine test in a brewery, it will help to ensure low levels of diacetyl and 2,3-pentanedione in the product on the one hand and will increase productivity by saving time during fermentation on the other (up to one day in large breweries and even more than one day in smaller ones) by obtaining on-line data of the relevant analytes. After optimisation of the method, further odour or taste relevant analytes could be determined simultaneously.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Beer Fermentation Control Using Ion Mobility Spectrometry - Results of a Pilot Study

Vautz

Baumbach

Jung³

2006

Journal of the Institute of Brewing

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“…Flow cytometry is becoming a standard tool in biotechnology research and has been successfully applied to analyze and optimize yeast processes (13,14,15,24,36). Cytometric measurements provide the opportunity to detect single cells.…”

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confidence: 99%

Application of a Short Intracellular pH Method to Flow Cytometry for Determining Saccharomyces cerevisiae Vitality

Weigert

Steffler

Kurz

et al. 2009

Appl Environ Microbiol

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The measurement of yeast's intracellular pH (ICP) is a proven method for determining yeast vitality. Vitality describes the condition or health of viable cells as opposed to viability, which defines living versus dead cells. In contrast to fluorescence photometric measurements, which show only average ICP values of a population, flow cytometry allows the presentation of an ICP distribution. By examining six repeated propagations with three separate growth phases (lag, exponential, and stationary), the ICP method previously established for photometry was transferred successfully to flow cytometry by using the pH-dependent fluorescent probe 5,6-carboxyfluorescein. The correlation between the two methods was good (r 2 ‫؍‬ 0.898, n ‫؍‬ 18). With both methods it is possible to track the course of growth phases. Although photometry did not yield significant differences between exponentially and stationary phases (P ‫؍‬ 0.433), ICP via flow cytometry did (P ‫؍‬ 0.012). Yeast in an exponential phase has a unimodal ICP distribution, reflective of a homogeneous population; however, yeast in a stationary phase displays a broader ICP distribution, and subpopulations could be defined by using the flow cytometry method. In conclusion, flow cytometry yielded specific evidence of the heterogeneity in vitality of a yeast population as measured via ICP. In contrast to photometry, flow cytometry increases information about the yeast population's vitality via a short measurement, which is suitable for routine analysis.Yeast plays an important role in the food industry. It is primarily used for making bread, beer, and wine, and the flavor and aromatic compounds it produces are characteristic of these fermented products. The physiological state of the yeast biomass influences the fermentation performance and thus the quality of the resulting product, e.g., of beer (1, 32). Food processors who depend on yeast health for consistent fermentations demand a method to measure yeast's physiological condition during yeast growth, that is, its vitality. The term "vitality" refers to the health of living biomass where high vitality results in a fast fermentation with minimal undesired by-products, while low vitality results in sluggish or poorly attenuating fermentation. In contrast, the term "viability" only distinguishes between dead and alive cells.

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“…Sedimentation remains the basis for most of the modern flocculation assays, but the rate at which a flocculent yeast suspension sediments is a function of the floc size, cell concentration, floc density, and the extent of agitation imposed on the yeast suspension prior to the settling period 7 . Many authors 12,13,18 have described the use of a precise, quick and reproducible fluorescent optical method, flow cytometry, for monitoring physiological changes in Saccharomyces cerevisiae. Flow cytometric measurement allows for the analysis of single yeast cells and measurement speeds of up to 3000 cells per second are possible, however recommended measurement speeds are generally lower.…”

Section: Introductionmentioning

confidence: 99%

“…Changes in the glycogen content of yeast cells, under aerobic and anaerobic conditions, were investigated in the course of this study. A rapid method for flow cytometric determination of glycogen and cell protein in yeast cells has been developed by Hutter 12,13 . The measurement of the DNA content of yeast cells was one of the first major applications of flow cytometry in brewing and is still one of the main applications of this method in this field.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of Brewing Yeast Propagation Under Aerobic and Anaerobic Conditions Employing Flow Cytometry

Novák

Basařová

Teixeira

et al. 2007

Journal of the Institute of Brewing

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The vitality and viability of industrial strains of Saccharomyces cerevisiae was monitored during pilot plant experiments simulating yeast propagation under aerobic and anaerobic conditions. Industrial wort of 12°P original gravity was used as a growth substrate for yeast propagation. The work was carried out with three widely used Czech lager yeast industrial strains: strains 2, 7 and 95. Cell cycle, cell size, granularity, glycogen content, DNA and protein content were analyzed by flow cytometry. Significantly higher specific growth rates, higher content of yeast glycogen, earlier G2 /M phase cells maximum, and faster cell protein creation was observed under aerobic conditions compared to anaerobic. Strains 7 and 95 showed losses in flocculation ability after aerobic propagation compared to anaerobic propagation. Under either aerobic or strictly anaerobic conditions, only strain 2 did not show a significant loss in flocculation ability.

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Flow Cytometry-A New Tool for Direct Control of Fermentation Processes

Cited by 20 publications

References 4 publications

Beer Fermentation Control Using Ion Mobility Spectrometry - Results of a Pilot Study

Beer Fermentation Control Using Ion Mobility Spectrometry - Results of a Pilot Study

Application of a Short Intracellular pH Method to Flow Cytometry for Determining Saccharomyces cerevisiae Vitality

Monitoring of Brewing Yeast Propagation Under Aerobic and Anaerobic Conditions Employing Flow Cytometry

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