Uptake of Amino Acids in Bottom Fermentations

Palmqvist, U.; ÄYräpää, T.

doi:10.1002/j.2050-0416.1969.tb03199.x

Cited by 37 publications

(8 citation statements)

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“…Thus, the amount of free amino nitrogen is important to guarantee a stable fermentation process. For conventional wort (specific gravity of 1.048, 12 P), a FAN level of about 145 mg/L or more is reported to be necessary for a healthy fermentation (39)(40)(41)(42)(43)(44). The results of the current research revealed that all of the teff varieties had higher levels of FAN ( Table 2).…”

Section: Other Malt Quality Attributesmentioning

confidence: 99%

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Gebremariam¹,

Zarnkow²,

Becker³

2013

J. Inst. Brew.

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Varieties of a cereal may have a considerable influence on malting qualities owing to variations in the physicochemical properties of the grains. This research was aimed at assessing the influence of five teff varieties on malt quality attributes. The teff samples were malted using previously optimized malting conditions and mashed with the congress mashing procedure. In this research, the Kuncho teff variety was malted in a one year period after harvesting, whereas the other four varieties were malted after three years of storage. Alpha-and b-amylase, and limit dextrinase activity, were in the ranges 14-68, 10-440 and 375-1072 U/kg, respectively. Extracts ranged from 54% for Dessie to 74% for Ivory teff. Free amino nitrogen, protein content, soluble nitrogen, Kolbach index, viscosity and wort colour were in the ranges 160-364 mg/L, 8.6-13.6%, 532-1048 mg/100 g, 24-50%, 1.441-1.629 mPa s and 5.9-9.0 EBC units, respectively. High-performance liquid chromatographic analysis for individual fermentable sugars revealed that the highest value in all varieties was recorded for glucose followed by maltose. The concentration of glucose ranged from 9.49 g/L in Brown teff, to 19.42 g/L in Ivory teff, whereas maltose ranged from 2.95 g/L in Dessie teff to 16.1 g/L in Kuncho teff. All of the malt quality attributes considered in this study were markedly influenced (p < 0.05) by the type of teff cultivar. It was concluded that the use of different teff varieties yielded malts with significantly different malt quality attributes. Copyright © 2013 The Institute of Brewing & Distilling Keywords: enzyme activity; malt quality; teff IntroductionTeff (Eragrostis tef) is a tropical gluten-free cereal that originated in Ethiopia, between 4000 and 1000 BC (1). It is environmentally more flexible than most other cereals. Teff is a low-risk cereal that grows over a wider ecology and can tolerate harsh environmental conditions where most other cereals are less viable, and it shows better tolerance to many diseases and pests (2,3). Among other applications, teff is mainly used in Ethiopia and Eritrea for making injera and tela. It is also gaining popularity as a health food in the Western world, notably in the Netherlands and the USA, and its flour is becoming a preferred ingredient in gluten-free diets and sport foods (4). Since teff is a gluten-free cereal with a high nutritional value, researchers are interested in studying it for utilization in different food applications. In addition to its nutritional and agricultural benefits (2,3), it has also shown promising brewing properties (5).Malt is the major raw material used in the brewing industry. The primary quality criterion for use of cereals in the brewing industry is their potential to produce malt with diastatic power (amylase activity), which is needed to hydrolyse starch molecules and produce fermentable sugars. The brewing industry is reliant on the enzymes of malted cereals in order to ensure the efficient utilization of the raw materials. Hence, the fundamental role of the ma...

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Section: Other Malt Quality Attributesmentioning

confidence: 99%

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Gebremariam¹,

Zarnkow²,

Becker³

2013

J. Inst. Brew.

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“…However, few studies have explored the assimilation of nitrogen compounds when present as a complex mixture of ammonium and amino acids, as found in grape juice. These substrates are generally classified into four groups based on the time and the percentage of removal from the medium during industrial (brewing or wine) fermentations (7,26,27,39,40,43). Nitrogen compounds of the first group are consumed almost totally during the first hours of the fermentation; those of the second group are removed gradually throughout the process; those of the third group are only used after depletion of the compounds of the first group.…”

mentioning

confidence: 99%

Sequential Use of Nitrogen Compounds by Saccharomyces cerevisiae during Wine Fermentation: a Model Based on Kinetic and Regulation Characteristics of Nitrogen Permeases

Crépin

Nidelet

Sanchez

et al. 2012

Appl Environ Microbiol

172

194

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The efficiency of nitrogen use is a key determinant of the completion of alcoholic fermentation. We analyzed the kinetics of consumption of 18 nitrogen compounds by 14 Saccharomyces cerevisiae strains of various origins in a synthetic medium that mimicked a grape must. The kinetic profiles of total nitrogen consumption were diverse, but the order of nitrogen source consumption was similar for all strains. The nitrogen compounds could be classified into three groups, according to their order of use: prematurely consumed (Lys), early consumed (Asp, Thr, Glu, Leu, His, Met, Ile, Ser, Gln, and Phe), and late consumed (ammonium, Val, Arg, Ala, Trp, and Tyr). The initial concentrations of these compounds did not alter the order in which they were consumed, except for arginine and ammonium. Early consumed amino acids are transported by specific permeases under Ssy1p-Ptr3p-Ssy5 (SPS)-mediated control that are expressed at the beginning of consumption. Most nitrogen compounds consumed late are transported by permeases under nitrogen catabolite repression (NCR), and others (Val, Trp, and Tyr) are transported by SPS-regulated low-affinity permeases. Therefore, the kinetic characteristics of transporters, as well as SPS and NCR, are likely key factors controlling the temporal sequence of consumption of nitrogen compounds and constitute a system highly conserved in S. cerevisiae species. This work sheds new light on the mechanistic basis of the sequential use of different nitrogen compounds in complex environments.

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“…The Group A amino acids were characterized by fast absorption into the yeast cells (usually complete absorption within 20 h); Group B amino acids were more gradually absorbed into the yeast cell; Group C amino acids were slowly absorbed into the cell after a ‘lag phase’ of around 12 h, while proline, despite being the most abundant amino acid in wort, is only marginally absorbed. Other studies on the absorption of amino acids by brewing yeast in brewery conditions report similar classifications, with minor regrouping of some amino acids (such as reclassifying methionine as a Group A amino acid).…”

Section: Valine Uptakementioning

confidence: 75%

“… also observed that valine uptake was slower in Saccharomyces pastorianus than in Saccharomyces cerevisiae , suggesting that valine could be classified as a Group C amino acid for S . pastorianus fermentations [as suggested by Palmqvist and Äyräpää ].…”

Section: Valine Uptakementioning

confidence: 99%

125^thAnniversary Review: Diacetyl and its control during brewery fermentation

Krogerus

Gibson

2013

J. Inst. Brew.

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Diacetyl is a butter-tasting vicinal diketone produced as a by-product of yeast valine metabolism during fermentation. Concentration is dependent on a number of factors including rate of formation of the precursor α-acetolactate by yeast, spontaneous decarboxylation of this acetohydroxy acid to diacetyl and removal of diacetyl by yeast via the action of various reductase enzymes. Lowering concentrations of diacetyl in green beer represents an expensive and time-consuming part of the brewing process and strategies to minimize diacetyl formation or hasten its reduction have potential for improving overall efficiency of the lager brewing system. Here we review the processes that determine diacetyl levels in green beer as well as the various ways in which diacetyl levels can be controlled. The amount of diacetyl produced during fermentation can be affected by modifying process conditions, wort composition or fermentation technique, or by yeast strain development through genetic engineering or adaptive evolution. The process of diacetyl reduction by yeast is not as well understood as the process of formation, but is dependent on factors such as physiological condition, cell membrane composition, temperature and pH. The process of diacetyl removal is typically rate-limited by the reaction rate for the spontaneous decarboxylation of α-acetolactate to diacetyl. Copyright © 2013 The Institute of Brewing & Distilling Keywords: diacetyl; vicinal diketone; amino acid; beer; yeast; fermentation Diacetyl production during fermentationDiacetyl (2,3-butanedione) and 2,3-pentanedione are vicinal diketones (VDK) formed during beer fermentation as byproducts of amino acid synthesis (valine and isoleucine, respectively) in Saccharomyces yeast, and these can have a significant effect on the flavour and aroma of beer. Diacetyl is known for its butter-or butterscotch-like flavour, with a flavour threshold usually reported as around 0.1-0.2 ppm in lager and 0.1-0.4 ppm in ales (1,2), although flavour thresholds as low as 17 ppb (3) and 14-61 ppb (4) have been reported. It has also been suggested that the flavour threshold of diacetyl varies with taster's geographical background, ethnicity and diet (5). The compound 2,3-pentanedione has a similar flavour to diacetyl, although often described as more toffee-like, but with a higher flavour threshold of around 0.9-1.0 ppm (1,2). VDKs are most easily detectable in lighter beers, where the flavour is not masked by malt and hop flavours. The presence of VDKs above their flavour threshold in beer is generally regarded as a defect, since their flavour is undesirable in many beer styles and it can also indicate microbial contamination, for example, by Lactobacillus spp., Pediococcus spp. or Pantoea agglomerans (6-8). Nevertheless, diacetyl at detectable concentrations is acceptable in some beer styles, such as Bohemian Pilsner and some English ales. Martineau et al. (9) found diacetyl concentrations ranging from 0.002 to 0.1 ppm (average concentration of 0.046 ppm) during the analysis of 11 comm...

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Uptake of Amino Acids in Bottom Fermentations

Cited by 37 publications

References 10 publications

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Sequential Use of Nitrogen Compounds by Saccharomyces cerevisiae during Wine Fermentation: a Model Based on Kinetic and Regulation Characteristics of Nitrogen Permeases

125^thAnniversary Review: Diacetyl and its control during brewery fermentation

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Uptake of Amino Acids in Bottom Fermentations

Cited by 37 publications

References 10 publications

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Sequential Use of Nitrogen Compounds by Saccharomyces cerevisiae during Wine Fermentation: a Model Based on Kinetic and Regulation Characteristics of Nitrogen Permeases

125thAnniversary Review: Diacetyl and its control during brewery fermentation

Contact Info

Product

Resources

About

125^thAnniversary Review: Diacetyl and its control during brewery fermentation