Effect of Yeast Adaptation to Maltose Utilization on Sugar Uptake During the Fermentation of Brewer's Wort

A three-factorial experiment with a level of confidence of P < 0.05 was performed to study fermentable carbohydrate depletion and ethanol production during 144 h fermentations of lager beers produced with barley malt (BM), sorghum malt (SM), refined maize (MZ) or waxy sorghum (WXSOR) grits treated during mashing with or without amyloglucosidase (AMG). The percentage glucose, maltose and maltotriose, based on total fermentable carbohydrates for the BM wort was 20, 68 and 13% and for the SM wort 35, 48 and 17% respectively. Treatment with AMG increased wort glucose from 9.3 to 24.5 g/L wort and total fermentable sugar equivalents, expressed as g glucose /L, from 59.2 to 72.6 g/L wort. The SM worts had approximately 50% more glucose and 40% less initial maltose content respectively compared to the BM worts. The WXSOR grits produced worts and beers with similar properties to those produced from the MZ adjuncts. AMG addition led to a >2.5 fold increment in wort glucose and 23% in total fermentable carbohydrate content. Linear regression analysis determined that the consumption rate of fermentable carbohydrates during fermentation followed first order reaction kinetics. Depletion times to reach 50% of the initial concentrations of glucose, maltose and maltotriose were 49, 128 and 125 h, respectively, clearly indicating that the fermenting yeast preferred glucose. Maltose and maltotriose depletion times of the AMG treated worts were significantly faster and lower, respectively, when compared with the untreated worts. At the end of the fermentation, the BM beers contained higher ethanol levels (5.1% v/v) than the SM beers (3.9% v/v). For AMG treated beers, no significant differences in ethanol content were observed among samples mashed with BM and beers produced from SM and MZ grits. The results demonstrated that AMG could be used to increase the initial concentration of glucose and total fermentable carbohydrates thus decreasing dextrin levels, especially from sorghum mashes.

Section: Wort and Beer Productionmentioning

confidence: 99%

Effect of Amyloglucosidase on Wort Composition and Fermentable Carbohydrate Depletion in Sorghum Lager Beers

Pozo‐Insfran

Urias-Lugo

Hernández-Brenes

et al. 2004

“…In the brewing industry, maltose and maltotriose are of special importance to fermentation completion since these are the predominant sugars in wort, typically occurring at 50-60 and 15-20 g/L, respectively 13 . Their uptake and utilisation are considered major factors dictating fermentation performance by the brewing strain.…”

Section: -2863(9'8-32mentioning

confidence: 99%

Expression Patterns of Genes and Enzymes Involved in Sugar Catabolism in IndustrialSaccharomyces cerevisiaeStrains Displaying Novel Fermentation Characteristics

Meneses

Jiranek

2002

The utilisation of maltose or sucrose by a selection of nine brewing, baking or laboratory strains of Saccharomyces cerevisiae was either repressible, constitutive or absent. Overall fermentation rate showed a good correlation with maximum specific maltose transport rate (R 2 = 0.79), but a poor correlation with maximum maltase activity (R 2 = 0.34), implying that transport rather than hydrolysis of maltose was a rate-limiting step determining fermentation performance. The genetic basis for differences seen between the strains in terms of fermentation kinetics was investigated. All strains were found to possess genomic sequences detectable with probes for the MAL11 (AGT1), MAL31 permease genes and the SUC2 invertase gene, however, the loci present and the pattern of expression of these and other MAL genes varied widely. From comparisons of sugar utilisation and gene expression patterns, constitutive maltose utilisation in strain NCYC 1681 was best explained by AGT1 expression. Such expression of AGT1 was not, however, mirrored by changes in the pattern of expression of the transcriptional activator(s) (MALx3). Patterns of sucrose utilisation were poorly predicted by the kinetics of SUC2 gene expression, indicating that other SUC loci may be of greater importance.

“…During industrial fermentations, in order to select the best options out of the large diversity of available nitrogen and carbon sources, the yeast has developed molecular mechanisms of sensing and regulation, which include the induction and repression of key regulatory systems 13,16,19,20,28,31 . Sugar catabolite repression 13,31 ensures an ordered sequence of sugar utilization, and during fermentation, brewing yeast strains utilize sucrose, glucose, maltose and maltotriose in this approximate sequence, with some degree of overlap 10 . However, altered patterns of sugar utilization among brewing, wine, baking and distilling strains have been reported 4,23 .…”

Section: Introductionmentioning

confidence: 99%

Glucose and Fructose Fermentation by Wine Yeasts in Media Containing Structurally Complex Nitrogen Sources

Júnior¹,

Batistote²,

Ernandes

2008

Glucose and fructose fermentations by industrial yeasts strains are strongly affected by both the structural complexity of the nitrogen source and the availability of oxygen. In this study two Saccharomyces cerevisiae industrial wine strains were grown, under shaken and static conditions, in a media containing either a) 20% (w/v) glucose, or b) 10% (w/v) fructose and 10% (w/v) glucose or c) 20% (w/v) fructose, all supplemented with nitrogen sources varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Data suggest that a complex structured nitrogen source is not submitted to the same control mechanisms as those involved in the utilization of simpler structured nitrogen sources, and mutual interaction between carbon and nitrogen sources, including the mechanisms involved in the regulation of aerobic/anaerobic metabolism, may play an important role in defining yeast fermentation performance and the differing response to the structural complexity of the nitrogen source, with a strong impact on fermentation performance.