The Determination of Glycogen in Yeasts

Quain, David E.

doi:10.1002/j.2050-0416.1981.tb04038.x

Cited by 60 publications

(12 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that this variant ferments faster and more completely under high-gravity conditions and has high crop viability at the end of the fermentation provides a significant economical benefit for the brewer. It is important to note that, while the absolute differences between the variants and the control strain may seem small to nonspe- (34). Trehalose functions not only as a storage carbohydrate but also as a stress protectant (4).…”

Section: Discussionmentioning

confidence: 99%

Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions

Blieck

Toye

Dumortier

et al. 2007

Appl Environ Microbiol

107

View full text Add to dashboard Cite

To save energy, space, and time, today's breweries make use of high-gravity brewing in which concentrated medium (wort) is fermented, resulting in a product with higher ethanol content. After fermentation, the product is diluted to obtain beer with the desired alcohol content. While economically desirable, the use of wort with an even higher sugar concentration is limited by the inability of brewer's yeast (Saccharomyces pastorianus) to efficiently ferment such concentrated medium. Here, we describe a successful strategy to obtain yeast variants with significantly improved fermentation capacity under high-gravity conditions. We isolated betterperforming variants of the industrial lager strain CMBS33 by subjecting a pool of UV-induced variants to consecutive rounds of fermentation in very-high-gravity wort (>22°Plato). Two variants (GT336 and GT344) showing faster fermentation rates and/or more-complete attenuation as well as improved viability under high ethanol conditions were identified. The variants displayed the same advantages in a pilot-scale stirred fermenter under high-gravity conditions at 11°C. Microarray analysis identified several genes whose altered expression may be responsible for the superior performance of the variants. The role of some of these candidate genes was confirmed by genetic transformation. Our study shows that proper selection conditions allow the isolation of variants of commercial brewer's yeast with superior fermentation characteristics. Moreover, it is the first study to identify genes that affect fermentation performance under high-gravity conditions. The results are of interest to the beer and bioethanol industries, where the use of more-concentrated medium is economically advantageous.Today's need to produce quality beers in a short time and in the least-expensive way has led most breweries to switch to high-gravity brewing. Traditionally, brewing worts of 12°Plato (12°P) (i.e., 12 g extract per 100 g liquid) are fermented to produce beers of 5% (vol/vol) ethanol. However, substantial cost savings can be realized by increasing the wort density (called "gravity") from 12°P to 18°P and diluting the 7.5% (vol/vol) ethanol-containing product in order to obtain beer with regular ethanol content (5%). The use of this technology increases the brewery capacity by 50% (for 18°P wort) without the need for any investments, reduces the costs in energy and labor (because liquid volumes are reduced), improves the stability of the beer, and enhances the recovery of ethanol per unit of fermentable sugar ("extract") (15, 44). However, the technology is limited by the stress resistance and fermentation performance of the brewer's lager yeast Saccharomyces pastorianus. S. cerevisiae (used for ale and wine fermentations) can cope much better with such stress conditions. Wine must typically contains up to 25% (wt/wt) sugar, but a major difference from beer production is that the yeast is only used once in wine fermentation whereas it is used multiple times in beer fermentation. In addition, wine m...

show abstract

Section: Discussionmentioning

confidence: 99%

Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions

Blieck

Toye

Dumortier

et al. 2007

Appl Environ Microbiol

107

View full text Add to dashboard Cite

show abstract

“…Glycogen was determined according to Quain 26 . Alkaliand acid-soluble glycogens were extracted from 0.1 g of wet cells pellet with 1 mL of 0.25 M sodium carbonate (100°C, 15 min) and 1 mL of 0.5 M perchloric acid (100°C, 10 min), respectively.…”

Section: =Iewx Gipp Erep]wmwmentioning

confidence: 99%

The Effects of Linoleic Acid Supplementation of Cropped Yeast on its Subsequent Fermentation Performance and Acetate Ester Synthesis

Moonjai

Verstrepen

Delvaux

et al. 2002

Journal of the Institute of Brewing

View full text Add to dashboard Cite

For beer wort fermentation the addition of unsaturated fatty acids has sometimes been suggested as an alternative to wort oxygenation. This can however negatively affect the synthesis of acetate esters and consequently beer flavour. This work investigates the effect of supplementing a cropped yeast with an unsaturated fatty acid on the fermentation performance of the pitching yeast. Cropped yeast is in a different physiological state to yeast pitched in unfermented wort. Using a synthetic medium for the fermentations, it was found that the incubation of cropped yeast with linoleic acid resulted in two important changes in the yeasts composition: (1) the ratio of unsaturated fatty acids to total fatty acids increased from 0.53 to 0.66 and (2) the ratio of trehalose to glycogen increased from 0.17 to 0.49. The performance of this yeast in subsequent fermentations was compared to unsupplemented yeast under three conditions: medium pre-aeration, de-aerated medium and de-aerated medium with newly added unsaturated fatty acid. It was found that the supplemented pitching yeast showed growth, attenuation and ethanol formation profiles similar to those obtained with unsupplemented yeast in pre-aerated medium, which simulated the normal brewing practice. Compared to fermentations with unsaturated fatty acids added to the medium, the supplemented cropped yeast did not induce a reduction in acetate ester synthesis. Results indicated that the supplementation of cropped yeast with unsaturated fatty acids could be an interesting alternative to wort oxygenation to restore the optimal membrane fluidity of the yeast.

show abstract

“…There is much evidence to suggest that the lack of membrane function in pitching yeast requires that the carbon and energy for sterol synthesis is provided by the dissimilation of endogenous glycogen reserves (Quain, 1981;Quain and Tubb, 1982). As these authors point out, glycogen may account for up to 40% of the dry weight of yeast at the end of fermentation.…”

Section: Fermentation Efficiencymentioning

confidence: 98%

4 Developments in Brewery Fermentation

1991

Biotechnology and Genetic Engineering Reviews

View full text Add to dashboard Cite

The Determination of Glycogen in Yeasts

Cited by 60 publications

References 21 publications

Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions

Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions

The Effects of Linoleic Acid Supplementation of Cropped Yeast on its Subsequent Fermentation Performance and Acetate Ester Synthesis

4 Developments in Brewery Fermentation

Contact Info

Product

Resources

About