SK279586B6 - Method of continuous wort fermentation during the beer production - Google Patents

Abstract

The wort is continuously fermented with the beer yeast, preferably with yeast that are in an immobilized form in calcium pectate gel during the temperature ranging from 0 to 35 degrees Celsius, pH from 3.0 to 7.0, in the gas-lift reactor using a carrier gas, e.g. carbon dioxide or nitrogen.

Description

Technical field

The invention relates to a process for the continuous fermentation of wort in the production of beer by free and immobilized yeast in a gas-lift reactor environment.

BACKGROUND OF THE INVENTION

Beer is one of the oldest drinks. An important factor that affects its quality are not only the basic raw materials, but also the way of fermentation (in the classical way the main fermentation takes place in open vats and fermentation in a closed tank at moderate overpressure, in semi-continuous fermentation in so-called semispilke). fermentation with elimination of lag phase and in single-phase fermentation the main fermentation and fermentation takes place in the same tank) and the fermentation conditions - sawing, temperature. Since beer production is time-consuming and energy consuming (during the main fermentation and post-fermentation it is necessary to cool the beer, which is extremely energy intensive especially in the summer months), the aim is to reduce the fermentation time as much as possible. Most efforts are directed to continualization and thus to acceleration of the wort fermentation process while preserving the taste and analytical parameters of beer. The beginnings of continuous fermentation of beer date back to 1954, when Wellhover began to produce beer in a flow-through manner (Wellhover, H.J .: Brauwelt, 94, 624-626 (1954)). Yeast concentration has a great influence on the acceleration of fermentation in a continuous process - at a higher concentration the fermentation is faster. However, at a higher yeast concentration, the possibility of regulating the flow of the substrate through the reactor is limited, since as the flow increases, the biomass of the yeast is washed out. To eliminate this deficiency, the immobilization of yeast (Masschelein, C.A. et al: Crit. Rev. Biotechnol. 14, 155-177 (1994)) results.

The yeast can be immobilized in various materials, so-called. carriers, the most common carrier being calcium alginate gel (Yamakchi, Y. et al, J. Ferment.Bioeng., 78 (6), 443-9 (1994)). Continuous fermentation of wort is known (Suzuki, A. et al, WO 9109110) as well as fermentation (Aivasidis, A. et al, EP 0508343) using immobilized yeast, furthermore the use of immobilized yeast for the production of non-alcoholic beer (Aivasidis, A. et al., EP 0508344; Back, W. et al., EP 0601362). The disadvantage is that the alginate gel is relatively costly and less stable in solutions where a constant level of calcium ion is not ensured.

An important role besides the method of immobilization of yeast resp. The design and environment of the reactor also play a role in the yeast immobilization carrier to ensure maximum contact of the liquid and solid phase in the bioreactor. Said methods of fermentation and post-fermentation are most often carried out in the liquid medium of reactors with fixed anchored immobilized cells or in reactors with a fluidized layer of immobilized cells. A disadvantage of these liquid medium reactors is that they accumulate carbon dioxide, which is produced during fermentation, and can cause cavitation.

It is an object of the present invention to provide a method of fermenting wort in the production of beer that would make continuous fermentation more efficient and reduce costs without adversely affecting the quality of the final product - beer.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method of fermenting wort in beer production according to the invention by continuously fermenting the wort with beer yeast at a temperature of 0 to 35 ° C and a pH of 3.0 to 7.0. The essence of the invention is that the continuous fermentation is carried out in a gas-lift reactor environment using a carrier gas.

It has been found to be advantageous if the carrier gas is carbon dioxide or nitrogen.

It has further been found to be advantageous if the brewer's yeast is immobilized in a calcium pectate gel.

Ethanol producing yeasts can be used as microorganisms, with Saccharomyces breeding strains being preferred. In the culture medium, the pH is maintained spontaneously during fermentation, without treatment of the medium. Fermentation takes place without aeration.

Non-toxic carriers are used to mobilize the nutrients to ensure good transfer of the nutrients to the immobilized yeast and transport of the yeast metabolites from the carrier to the medium. Calcium pectate gel, as a natural material, meets the above conditions and is sufficiently stable and resistant to the metabolites produced by fermentation. The pectin from which calcium pectate is prepared is widely used as a raw material in the food industry. In calcium pectate, it is possible to bind the yeast at a sufficiently high concentration of cells to ferment the wort. Yeast immobilized in a calcium pectate gel is active and viable for several months.

By applying the yeast immobilized according to the invention, it is possible to increase the substrate flow rate even above the Dj value. It is possible to ferment the wort used for classical fermentation of beer, as well as other aqueous media containing fermentable carbohydrates.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Fermentation with free yeast

The culture medium is fed into the tubular reactor from the bottom of the column, and the product is discharged into the top tank. When fermenting wort containing reducing sugars 100 g / l, pH 6.5 and Saccharomyces uvarum cell concentration W-96 1.10? in ml, different stroke times were tested at intervals of 22 to 30 hours. In the case of 70% fermentation (residence time 30 h), yeast sedimentation (the strain has excellent sedimentation properties) and the concentration of fermenting yeast in the reactor decreases by 80%. At a retention time of 22 hours, the yeast concentration decreases only by 47%, but the fermentation is less efficient (55% fermentation).

Example 2

Fermentation with immobilized yeast

In the application of immobilized yeast, the procedure is analogous to Example 1, except that yeast immobilized in calcium alginate is used for fermentation. A) A method for preparing a biocatalyst.

distilled water such that the concentration of cells in yeast milk is 10-fold higher than that required in the carrier gel.

Prepare a suspension of 2.5% sodium alginate, 10% yeast milk and water. From these components, a viscous composition is obtained which by dropping into a 0.1 M CaCl2 solution provides beads with immobilized yeast. In contrast to free yeast (example 1), there is no yeast sedimentation here, at a holding time of 18 hours, 75% wort fermentation with a carbohydrate concentration of 100 g / l is achieved, but during fermentation carbon dioxide accumulates in the fermenter and dead areas are created where no bioconversion (fermentation) takes place.

Example 3

The culture medium is fed from the bottom of the column, the product drains from above into the container. Different retention times at intervals of 15 h to 28 h were tested for wort fermentation containing 100 g / l of reducing sugars and pH 6.5 and Saccharomyces uvarum W-96 10 µm cell concentration. At a holding time of 18 h, an overflow of 75% is achieved. With shorter retention time, biomass is already washed out. This fermentation is a perfectly stirred reactor and there is no sedimentation at the bottom of the reactor.

At the top of the column there is a discharge of the resulting gas, which is connected to a foam separator and to a variable speed compressor. The compressor returns the gas to the bottom of the inner tube of the reactor. In the center of the inner tube is a tube through which the carrier gas is fed to the bottom of the column. With the carrier gas flow rate, the liquid flow rate in the fermenter is controlled.

Example 4

Example 4 is carried out as Example 3, except that the following fermentation parameters were achieved in a wort fermentation with a reducing carbohydrate content of 50 g / l and using nitrogen as carrier gas at a holding time of 14 h:

pH 3.0 7.0 temperature (° C) 0.5 35 0.5 35 degree of fermentation (%) 73 61 67 56

The following fermentation process parameters were achieved when the wort fermented with a reducing carbohydrate content of 140 g / l and using nitrogen as the carrier gas at a holding time of 18 h:

pH 3.0 7.0 temperature (° C) 0.5 35 0.5 35 degree of fermentation (%} 69 58 62 52

Example 5

The procedure is analogous to Example 3, except that yeast immobilized in calcium alginate is used in the fermentation.

a) The method of preparation of the biocatalyst is the same as in Example 2a.

b) The fermentation is carried out as in Example 3. In the fermentation of the wort with a reducing carbohydrate content of 100 g / l and a pH of 6.5, different residence times were tested in the interval from 15 h to 28 h. At a holding time of 15 h, an over-flow of 75% was achieved. The decrease in specific substrate consumption rate over 70 days was 11%. Since the fermentation in the gas-lift reactor environment is mixed in the fermenter spaces, the carbon dioxide produced during fermentation does not accumulate and does not create dead spaces. At the same time, carbon dioxide is used as a carrier gas.

Example 6

Example 6 is carried out as Example 5, except that

(a) instead of sodium alginate, pectate is used; a salt of pectic acid, prepared by catalytic de-esterification of apple pectin. In contrast to alginate, a 5% pectate solution, e.g. potassium.

(b) in the wort fermentation with a reducing carbohydrate content of 100 g / l and a pH of 6,5 different retention times were tested at intervals of 15 h to 28 h. At a holding time of 12.5 h, unlike Example 3, an overflow of 75% was achieved. The decrease in specific substrate consumption rate over 70 days was 8%.

Example 7

Example 7 is performed as example 5, except that

a) instead of pectate; pectic acid salts prepared by catalytic de-esterification of apple pectin are used pectate, i. a salt of pectic acid, prepared by catalytic de-esterification of citrus pectin. In contrast to Example 4, a 6% pectate solution, e.g. potassium.

(b) in the wort fermentation with a reducing carbohydrate content of 100 g / l and a pH of 6,5 different retention times were tested at intervals of 15 h to 28 h. At a residence time of 12.7 h, unlike Example 4, a flow rate of 75% was achieved. The decrease in specific substrate consumption rate over 70 days was 9%.

Claims (3)

A process for the continuous fermentation of wort in beer yeast production at a temperature of 0 to 35 ° C and a pH of from 3.0 to 7.0, characterized in that the continuous fermentation by brewing yeast is carried out in a gas-lift reactor environment using carrier gas. Continuous fermentation process according to claim 1, characterized in that the carrier gas is carbon dioxide or nitrogen. Continuous fermentation process according to claims 1 and 2, characterized in that the brewer's yeast is immobilized in a calcium pectate gel.