CZ307574B6 - The yeast strain of Saccharomyces cerevisiae CCM 8822 and its use in beer production - Google Patents

Abstract

The invention relates to the yeast strain ofCCM 8822 isolated from spontaneous fermentation of grape must, which aerobically and anaerobically processes sucrose, raffinose, maltose, lactate and glucose, aerobically treats galactose, anaerobically treats trehalose and glycerol and hydrolyzes esculin and which forms ellipsoid to spherical cells with sizes of 6 to 8 μm x 4 to 6 μm that do not create mycelium.  The invention further relates to the production of beer in which the main fermentation of the wort is carried out by the yeast strain of CCM 8822.

Description

Saccharomyces cerevisiae strain CCM 8822 and its use in beer production

Field of technology

The invention relates to a novel strain of the yeast Saccharomyces cerevisiae CCM 8822.

The invention further relates to the use of this yeast strain in the production of beer.

Prior art

Beer production consists in the controlled fermentation of sugars contained in wort by brewer's yeast. Brewer's yeasts are cultural yeasts of several species and genera: Saccharomyces pastorianus is used for the production of bottom-fermented beers, Saccharomyces cerevisiae is used for the production of top-fermented beers, and Brettanomyces or Torulaspora are produced for the production of special beers (see eg T. Kochláňová et al .: "Yeasts nonSaccharomyces and their importance in the brewing industry. Part I - Brettanomyces (Dekkera)" and "Yeasts wn-Saccharomyces and their importance in the brewing industry. Part II", both Kvasný Průmysl 62/2016 (7 -8)). In its operation, brewer's yeast converts carbohydrates into ethanol, carbon dioxide and the energy needed to multiply the yeast, as well as about two thousand other substances, especially higher alcohols, esters, aldehydes, etc., which affect the resulting sensory properties of the finished beer. The overall ratio of all these higher alcohols and esters is very important for the overall sensory impression, as the individual compounds are very often below the threshold concentration of sensory perception. It is generally known, for example, that strains of the upper yeast Saccharomyces cerevisiae produce a larger amount and a wider range of sensory active substances than strains of the lower yeast Saccharomyces pastorianus (see, for example, Lodolo et al .: The yeast Saccharomyces cerevisiae - the main character in beer brewing. FEMS Yeast Res 8 (7): 1018-36, 2008), and the fact that the “lighter” taste of bottom-fermented beers is caused, in addition to the lower main fermentation temperature, by altered expression of genes responsible for ester production in Saccharomyces pastorianus (see eg Procopio et al .: "Function and regulation of yeast genes involved in higher alcohol and ester metabolism during beverage fermentation", European Food Research and Technology 233 (5): 721729, November 2011).

The production of wine then consists in the fermentation of carbohydrates present in grape must by wine yeasts. During this fermentation, carbohydrates are converted into ethanol and carbon dioxide and the energy needed to multiply the yeast. Wine yeast is more resistant to alcohol than brewer's yeast. They enter the must either from the surface of the berries (spontaneous fermentation) or by adding a pure culture of noble yeasts (pure fermentation). Cultural wine yeasts belong to the species Saccharomyces cerevisiae and Saccharomyces bayanus.

The essence of the invention

The invention relates to a new strain of the yeast Saccharomyces cerevisiae CCM 8822, which has been isolated from the spontaneous fermentation of grape must. For further use, it was prepared by selection and re-inoculation on wort agar with tetracycline. The cultivation was then performed aerobically in a microbiological incubator at 26 ° C for 3 to 5 days. After increasing the yeast culture on the agar surface, this culture was transferred with a sterilized inoculum loop to a new petri dish with agar and inoculated with a so-called cross-smear, in which the yeast concentration on the agar was diluted. This procedure was repeated until the yeast culture grew into visibly separated colonies. Subsequent isolation of the yeast strain Saccharomyces cerevisiae CCM 8822 was then performed by inoculating a selected colony onto a petri dish containing wort agar.

- 1 CZ 307574 B6

The strain thus isolated was then characterized by biochemical assays and polymerase chain reaction (PCR).

The yeast strain Saccharomyces cerevisiae CCM 8822 produces ellipsoidal to spherical cells measuring 6 to 8 μm x 4 to 6 μm, which do not form a mycelium and rarely form a pseudomycelium.

Appearance and consistency of colonies - the paint is pasty, creamy, light brown, smooth, glossy. The nature of the increase in a liquid medium - in liquids it forms sediment, butterflies never form.

The Saccharomyces cerevisiae strain CCM 8822 uses both aerobically (oxidizes) and anaerobically (fermented) sucrose, raffinose, maltose, lactate and glucose. It uses galactose aerobically. It uses trehalose and glycerol anaerobically. Hydro skis esculin.

The yeast strain Saccharomyces cerevisiae CCM 8822 has some advantageous properties for use in the preparation of beer compared to the brewer's yeast Saccharomyces cerevisiae and Saccharomyces pastorianus. In particular, it is the production of only a minimal amount of diacetyl, which gives the finished beer a taste of butter and is considered undesirable in higher concentrations. The optimum temperature for beer production using this strain is in the range of 18 to 22 ° C, where the yeast produces the optimal amount of sensory active substances; however, this strain can also be used for fermentation at temperatures of 12 to 16 ° C, and even at these temperatures it is characterized by a high fermentation rate.

The strain of the yeast Saccharomyces cerevisiae CCM 8822 according to the invention is deposited in the collection of microorganisms of the Research Institute of Brewing and Malting, under the code RIBM (Research Institute of Brewing and Malting) under number RIBM 193 and in the Czech Collection of Microorganisms in Brno under number CCM 8822.

Examples of embodiments of the invention

Example 1: Preparation of the yeast strain Saccharomyces cerevisiae CCM 8822 for laboratory fermentation tests

In the preparation of the yeast strain Saccharomyces cerevisiae CCM 8822 for practical use - eg for its further testing or for beer production, a pure culture of this strain, used by isolation from spontaneous fermentation of grape must (see above), was used and which until stored in a refrigerator at 2 ± 1 ° C.

The culture of the yeast strain Saccharomyces cerevisiae CCM 8822 was inoculated on slant wort agar in tubes closed with a cotton plug. A portion of the biomass from the formed yeast growth was then sterile transferred to 10 ml of 10% sterile wort with a loop, followed by cultivation at 25 ° C for 2 days. The upper fermented layer was then discarded, and the yeast sediment was transferred to 50 ml of 10% sterile wort, followed by culturing at 20 ° C for 2 days. Subsequently, this strain was propagated by transferring it to an ever-increasing volume in a ratio of approximately 1: 4. The yeast sediment was first transferred to 250 ml of 10% sterile wort, where propagation was carried out at 17 ± 1 ° C for 5 days, then the formed yeast sediment was transferred. to 1000 ml of 10% wort, where cultivation was carried out at 17 ± 1 ° C for 3 days.

The Saccharomyces cerevisiae strain CCM 8822 prepared in this way can be used directly for laboratory fermentation tests or for beer production. If necessary, it is previously washed with water (repeated sedimentation and washing) to remove the culture medium.

-2EN 307574 B6

Example 2: Preparation of beer using the yeast strain Saccharomyces cerevisiae CCM 8822

Centrifuged yeast concentrate of Saccharomyces cerevisiae CCM 8822 prepared as described in Example 1 was added to wort with an original extract of about 12% (but beer can be prepared from wort with a different extract by the same procedure). Subsequent fermentation was performed in a sterilized plastic vessel at 21 ° C ± 1 ° C for 5 days.

During the fermentation, the course of cell proliferation and sedimentation was monitored by counting the cells by microscopic technique using a Burker chamber. In addition, extract loss, fermentation, alcohol concentration and pH change were further measured. The measured values are given in Table 1.

Table 1

Measured parameter 0h 24 h 48 h 72 h 96 h 120 h Alcohol (% vol.) 0 1.96 3.95 3.96 3.97 3.97 Apparent fermentation (%) 0 31.75 64.82 65.46 66.50 66.64 Apparent extract (% by weight) 11.87 7.83 4.02 3.82 3.78 3.74 pH 5.74 4.34 4.08 4.12 4.18 4.20 Number of cells (mil / ml) 30.8 77.35 120 59.5 46.2 34.5

After fermentation, the beer thus prepared was transferred to lager containers and stored at a temperature of 2 ± 1 ° C in a lager cellar. After 6 weeks of aging, its pH, fermentation, extract, alcohol content, diacetyl, pentanedione, acetaldehyde and dimethyl sulfide (DMS) concentrations were measured, and the measured values are shown in Table 2.

As can be seen, Saccharomyces cerevisiae strain CCM 8822 produces only low concentrations of diacetyl compared to conventional brewer's yeast, which is responsible for the undesirable buttery taste of beer.

Table 2

Measured parameter Value Apparent extract (% wt.) 3.72 Real extract (% by weight) 5.18 Alcohol (% vol.) 4.00 Apparent fermentation (%) 66.9 Diacetyl (mg / l) 0.011 Pentandione (mg / 1) <0.005 Acetaldehyde (mg / l) 40.75 DMS (pg / l) 19

In addition, the content of higher alcohols and esters in this beer was also measured, which significantly contributes to the sensory profile of the finished beverage. Table 3 lists selected higher alcohols and esters and the ratio of total higher alcohols to esters (A / E ratio). The value of this ratio then indicates that the yeast Saccharomyces cerevisiae CCM 8822 behaves

-3GB 307574 B6 similar to upper brewer's yeast, but produces higher amounts of betaphenyl alcohol than most of their strains (usual values are up to 4) and at the same time very low amounts of diacetyl and pentanedione. This is very advantageous from the point of view of beer production technology, since it is not necessary to include a long delay in the decomposition of diacetyl in the production process.

Table 3

Monitored substance Content ethyl formate (mg / l) 0.04 ethyl acetate (mg / l) 9.52 propyl acetate (mg / l) 0.06 isobutyl acetate (mg / l) 0.103 ethyl butyrate (mg / l) 0.157 propanol (mg / l) 24.25 isobutanol (mg / l) 11.39 isoamyl acetate (mg / l) 0.8 2 and 3-methyl-butanol (mg / l) 45.24 ethyl capronate (mg / l) 0.154 ethyl caprylate (mg / l) 0.174 ethyl hexanol (mg / l) 0.012 furfuryl alcohol (mg / l) 0.054 phenylethyl acetate (mg / l) 0.314 β-phenyl alcohol (mg / l) 16.99 sum of alcohols (mg / 1) 97.94 sum of esters (mg / l) 11.39 A / E ratio 8.60

In addition, the production of phenolic substances responsible for the medicinal or clove aroma of beer was also analyzed. The values obtained are shown in Table 4.

Table 4

Monitored substance Content 4-vinylguaiacol (mg / 1) 0.654 Tyrosol (mg / l) 9.99

Furthermore, sensory evaluation of beer was also performed by a tasting commission. The drink prepared using the yeast Saccharomyces cerevisiae CCM 8822 did not show any sensory defects, it was pleasantly saturated, with a pleasant aroma of coriander and cloves and the taste resembled top-fermented beer. The bitterness was evaluated as slightly adhering. The overall subjective impression was evaluated as above average.

Claims (2)

PATENT CLAIMS 1. A strain of the yeast Saccharomyces cerevisiae deposited with the Czech Collection of Microorganisms under number 8822 isolated from spontaneous fermentation of grape must, which aerobically and anaerobically processes sucrose, raffinose, maltose, lactate and glucose, aerobically processes galactose, anaerobolys and trees and which produces ellipsoidal to spherical cells measuring 6 to 8 μm x 4 to 6 μm that do not form a mycelium. -4GB 307574 B6 Process for the production of beer, characterized in that the main fermentation of the wort is carried out by the yeast strain Saccharomyces cerevisiae CCM 8822 according to claim 1.