Flocculation onset, growth phase, and genealogical age in <i>Saccharomyces cerevisiae</i>

Soares, Eduardo V.; Mota, M.

doi:10.1139/m96-073

Cited by 47 publications

(70 citation statements)

References 35 publications

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“…Mannan ligands have been reported by Soares and Mota 31 to be present during all stages of yeast growth. Mannans were also shown to be constant throughout fermentations by the strain used in this study (LCC125) 50 .…”

Section: Introductionmentioning

confidence: 91%

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation¹

Speers

Wan

Jin³

et al. 2006

Journal of the Institute of Brewing

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Industrial wort was fermented with a NewFlo phenotype ale yeast in lab-scale cylindrical fermenters. The effects of various fermentation parameters and yeast cell wall properties on yeast flocculation were studied during 120 h fermentation. The evaluation of the cell volume during the fermentation revealed a non-normal distribution (p < 0.05) at most fermentation times. Overall yeast cell size initially decreased during the first 24 h of fermentation then increased during the 24-60 h fermentation period. Cell size subsequently declined until the end of fermentation presumably due to floc settling. While yeast flocculation began after 24 h fermentation, most flocs remained in suspension until 60 h when the average turbulent shear rate caused by CO 2 evolution declined to below 8 s -1 . Both the Helm's flocculence and cell surface hydrophobicity values rapidly increased to high numbers from 24 h onward. Changes in the orthokinetic capture coefficient (␣ 0 ) value with fermentation time, measured in fermenting worts, indicated a significant increase (p < 0.001) after 24 h of fermentation. Presumably, this change was due to increases in ethanol and the decline in sugar concentration with time. Although a significant positive correlation (p < 0.05) was observed between zymolectin densities and cell surface areas, the total zymolectin level on yeast cell walls did not change significantly with fermentation time (p > 0.05). Interestingly, no significant difference existed in Helm's flocculation values of suspended and settled yeast cells (p > 0.05). The flocculation rate of LCC125 was readily inhibited by addition of glucose or maltose. Results suggest that fermentable sugar levels and shear force exert major influences on yeast flocculation during beer fermentations.

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Section: Introductionmentioning

confidence: 91%

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation¹

Speers

Wan

Jin³

et al. 2006

Journal of the Institute of Brewing

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“…Serial fermentations can select for an undesirable subpopulation enriched with elderly cells. The aged brewing yeasts show changed flocculation characteristics 5,74,86,107 and fermentation performance 15,74 . It is believed that the performance of lager strain begins to degenerate after 10 serial repitchings 39 .…”

Section: Aging Of Yeast In Continuous Culturesmentioning

confidence: 99%

A Review of Flavour Formation in Continuous Beer Fermentations*

Brányik

Vicente

Dostálek

et al. 2008

Journal of the Institute of Brewing

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The attractive prospect of a continuous beer fermentation system consists mostly of the accelerated transformation of wort into beer. Although continuous beer fermentation has been studied as a promising technology for several decades, the number of industrial applications is still limited. The major obstacle hindering the extensive industrial exploitation of this technology is the difficulty in achieving the correct balance of sensory compounds in the short time typical for continuous systems. This paper offers an integral view on the particularities of continuous systems, which may impart beer a sensorial character distinct from conventionally fermented counterparts. The main groups of flavour active compounds are discussed from the perspective of possible control strategies by means of process parameters and strain selection.

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“…Flocculation of yeast cells belonging to Flo1 phenotype is specifically inhibited by mannose and derivatives; on the other hand, NewFlo phenotype contains the majority of brewery ale strains, which flocculation is reversibly inhibited by mannose, maltose, glucose and sucrose but not by galactose (Stratford and Assinder 1991). Flo1 and NewFlo strains also display different sensitiveness to culture conditions, such as temperature (Soares et al 1994), pH (Soares et al 1994;Stratford 1996;Soares and Seynaeve 2000) and nutrients availability (Soares and Mota 1996).…”

Section: Introductionmentioning

confidence: 99%

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity

Holle

Machado

Soares

2011

Appl Microbiol Biotechnol

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Flocculation is an eco-friendly process of cell separation, which has been traditionally exploited by the brewing industry. Cell surface charge (CSC), cell surface hydrophobicity (CSH) and the presence of active flocculins, during the growth of two (NCYC 1195 and NCYC 1214) ale brewing flocculent strains, belonging to the NewFlo phenotype, were examined. Ale strains, in exponential phase of growth, were not flocculent and did not present active flocculent lectins on the cell surface; in contrast, the same strains, in stationary phase of growth, were highly flocculent (>98%) and presented a hydrophobicity of approximately three to seven times higher than in exponential phase. No relationship between growth phase, flocculation and CSC was observed. For comparative purposes, a constitutively flocculent strain (S646-1B) and its isogenic non-flocculent strain (S646-8D) were also used. The treatment of ale brewing and S646-1B strains with pronase E originated a loss of flocculation and a strong reduction of CSH; S646-1B pronase E-treated cells displayed a similar CSH as the non-treated S646-8D cells. The treatment of the S646-8D strain with protease did not reduce CSH. In conclusion, the increase of CSH observed at the onset of flocculation of ale strains is a consequence of the presence of flocculins on the yeast cell surface and not the cause of yeast flocculation. CSH and CSC play a minor role in the auto-aggregation of the ale strains since the degree of flocculation is defined, primarily, by the presence of active flocculins on the yeast cell wall.

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Flocculation onset, growth phase, and genealogical age in Saccharomyces cerevisiae

Cited by 47 publications

References 35 publications

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation¹

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation¹

A Review of Flavour Formation in Continuous Beer Fermentations*

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity

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Flocculation onset, growth phase, and genealogical age in Saccharomyces cerevisiae

Cited by 47 publications

References 35 publications

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation1

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation1

A Review of Flavour Formation in Continuous Beer Fermentations*

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity

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Product

Resources

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Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation¹

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation¹