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    • 专利摘要:

    公开号:BE1020484A5
    申请号:E201200851
    申请日:2012-12-18
    公开日:2013-11-05
    发明作者:Michel Moortgat；Hedwig Neven
    申请人:Duvel Moortgat Nv；
    IPC主号:
    专利说明:

    IMPROVED METHOD FOR HARVESTING Yeast Technical field
    The invention relates to the harvesting of yeast. More specifically, the invention relates on the one hand to a device for harvesting yeast and on the other hand to a method therefor.
    Background One of the most essential ingredients for brewing beer is beer yeast. Most breweries have their own yeast strains, specifically for one or more beers.
    For a yeast to be a suitable beer yeast, it must meet a number of conditions, including: good vitality of the yeast cells; strong adaptability in a new environment; efficient sugar conversion; good resistance to high alcohol concentration; must give the desired taste and aroma products and preserve the brewing properties so that the yeast can be recovered.
    The main yeasts used in the brewery are Saccharomyces carlsbergensis and Saccharomyces cerevisiae. They both belong to the Saccharomycetaceae family and the Saccharomycetoideae subfamily. This subfamily is characterized by the occurrence of spores in an ascus and by reproduction through budding. The genus Saccharomyces, abbreviated to S., is mainly characterized by the merger of an alcoholic fermentation. It is generally believed that S. carlsbergensis was created by crossing the varieties cerevisiae and bayanus. An important distinction between both yeasts is based on whether the yeast rises or sinks during fermentation. Yeast that sinks is called 'low' yeast, yeast that rises 'high' yeast. S. carlsbergensis is a low yeast, S. cerevisiae a high one.
    Characteristics of importance for the brewer include the distinction between high and low yeasts. The distinction between high or low yeasts and therefore high or low fermentation is based, as previously stated, on the rise or sagging of the yeast during fermentation. High yeasts have the property to immediately consume glucose through the
    Cancer cycle while low yeasts do not. Further differences between high and low yeasts are their needs for growth factors and nitrogen compounds. They also show differences in the production of volatile compounds.
    A low yeast can only be reused 5 to 6 times because this yeast is no longer pure due to coagulation with other particles. High yeast does not have this problem and can be reused much more often. The viability of the yeast is the limiting factor here.
    Yeast viability is expressed as
    Where% dead cells is determined as follows:
    With D the number of dead cells and L the number of living cells.
    To ferment, glucose must be converted to pyruvate (see Figures 2 and 3). After glycolysis, yeast can ferment pyruvate under anaerobic conditions or ferment into mainly alcohol and CO2. This process, the actual fermentation process, is therefore also called alcoholic fermentation. In addition to alcohol and carbonic acid, various by-products are formed during alcoholic fermentation. These by-products make up only 3% of the total of formed substances, but still have a major influence on the taste and aroma of beer. The most important by-products are: acetic acid, lactic acid, higher alcohols, esters and diacetyl. The sugar content gradually decreases during fermentation. At the end of the fermentation, approximately 20% of the sugars remain. These are the so-called unfermentable sugars. If fermentable sugars are no longer present, the term "fermented beer" is used.
    Other biochemical reactions relate to sugar consumption and N-metabolism.
    About 2/3 of all sugars present in wort are fermentable. The sugar composition is as follows: Monosaccharides (glucose 10%, fructose 0.5%); Disaccharides (maltose 65 to 75%, sucrose 2%); Trisaccharides (maltotriose 14 to 20%). The monosaccharides and sucrose are used first. Then maltose and finally maltotriosis. Glucose permease is required for glucose uptake. In the glycolysis, glucose is transformed into pyruvate (see figure 3). This pyruvate is converted by the yeast into either acetaldehyde (anaerobic) or acetyl coenzyme A (aerobic). Acetyl-CoA can be incorporated into the Krebs cycle (see figure 2). In this Krebs cycle, CO2 is produced and reduced coenzymes are formed which connect to the respiratory chain. The acetaldehyde is reduced to ethanol.
    Amino acids and peptides are essential for yeast growth and give the beer a certain fullness and are converted by the yeast into volatile compounds. These flavor compounds are partly responsible for the organoleptic characteristics of the beer.
    Yeast growth is influenced by temperature, pressure, dissolved oxygen, the content of fatty acids, assimilable nitrogen compounds, vitamins, minerals and sugars. Suitable nitrogen sources for yeasts include ammonium, amino acids and peptides. Proteins on their own cannot be assimilated by yeasts.
    During the brewing process, yeast is added to the wort after the wort cooling. This yeast comes from a breeding or propagation, or recovered from a previous fermentation. Starting from a relatively low number of yeast cells, the purpose of a propagation is to obtain a very high number. These yeast cells can then be used during fermentation or main fermentation to ferment the sugar in the wort to alcohol and CO2. It is not the intention to form ethanol during propagation. To obtain a strong multiplication of yeast cells, yeast needs sufficient oxygen and nutrients. Moreover, the propagation must take place at optimum temperature and pH.
    During propagation or cultivation of yeast, large quantities of yeast of known origin are produced in the shortest possible time with the main purpose of being used for fermentation. The known origin means that the cultivated yeast is of the desired specific strain, specific to the brewery. Propagation includes various steps. In a first step, part of the yeast stem cells are grown on a laboratory scale in contact with nutrients, usually a small amount of sterile wort and aeration. After this, the yeast is cultivated in successive fermentations, with the yeast mass increasing each time. When the desired yeast weight is reached, the yeast cells are transferred to the propagation tank. Sterile wort is added gradually to the yeast in the propagator.
    EP 0 647 708 describes a device and method for harvesting yeast according to the prior art. During fermentation, high yeast will rise in the propagation tank with CO2 bubbles. In current propagation tanks, high yeast is harvested through an overflow. This allows continuous harvesting, but the harvested yeast is of poorer quality. An additional disadvantage of such an arrangement is that it is difficult to clean, so that there is a continuous risk of infection. Because the sterility of these installations is not optimally guaranteed, the harvested high yeast can be reused less often.
    For the harvesting of low yeast, the settled low yeast is drained in the existing plants below. Due to the presence of impurities, the quality of this low yeast is suboptimal.
    The present invention aims at least partially to eliminate the disadvantages of the current installations and to optimize the quality of the harvested yeasts so that the yeasts can also be reused more. Reusing yeast also implies an economic advantage for the brewer.
    Summary
    The present invention provides a method for harvesting yeast according to claim 1. The method according to the present invention makes it possible to harvest high-quality yeast. This can be used in brewing beers through high fermentation.
    In a second aspect, the present invention provides a device for harvesting yeast according to claim 11.
    In a third aspect, the invention relates to a beer according to claim 10 and the use of the harvested yeast according to claim 9.
    Detailed description
    The present invention describes a method for harvesting yeast, preferably beer yeast. This method makes it possible to harvest high-quality yeast that can then be used in fermentation processes for brewing beer.
    In particular, the method comprises the following steps: - propagating yeast in the presence of wort in a closed propagation tank; - building up the pressure in the propagation tank; and - transporting the high yeast in the propagation tank to a communicating tank.
    By the term "yeast" is meant a single-celled eukaryote belonging to the fungi. Examples of genera of yeasts are Brettanomyces, Candida, Citeromyces, Cyniclomyces, Debaryomyces, Issatchenkia, Kazakhstania, Kluyveromyces, Komagataella, Kuraishia, Lachancea, Lodderomyces, Nakaseomyces, Pachysolen, Pichia, Saccharomyces, Spathasporisya tetysaporazy, Tetrasisporazy, Tetrasisporazy, Tetris Zygotorulaspora. Among the genus Saccharomyces are examples of species: S. bayanus, S. boulardii, S. bulderi, S. cariocanus, S. cariocus, S. cerevisiae, S. Chevalieri, S. dairenensis, S. ellipsoideus, S. eubayanus, S exiguus, S. florentinus, S. Kluyveri, S. Martiniae, S. Monacensis, S. norbensis, S. paradoxus, S. pastorianus, S. spencerorum, S. turicensis, S. unisporus, S. uvarum, S. zonatus .
    Of these, mainly S. cerevisiae and S. carlbergensis are used for brewing beer, so-called "beer yeast".
    In particular, the harvested yeast will be "high yeast". By the term "high yeast" is meant in the present invention yeast that floats on the wort during propagation and fermentation.
    Propagation of yeast on an industrial scale preferably takes place in a propagation tank that provides suitable environmental factors for the yeast propagation. This means, among other things, that a suitable culture medium is provided for the yeast cells. This nutrient medium will preferably be wort. Sterile wort is preferably used to avoid contamination. Furthermore, the wort will preferably have a high density. The density of the wort is a measure of dissolved compounds such as sugars and proteins. Because yeast requires a lot of nutrients, it is necessary to work with a sufficiently high root density. In particular, the wort density will be at least 120 g / l.
    Furthermore, the supply of oxygen must also be provided to optimize the propagation. Moreover, too little aeration in propagation can act as a brake on later fermentation. To obtain sufficient oxygen, the wort and yeast suspension must be well aerated. At atmospheric pressure, and use of air, a maximum concentration of 8ppm of oxygen can be obtained. Sometimes it is necessary to achieve a higher concentration, up to 15ppm. To achieve these concentrations, the suspension is aerated under pressure or pure oxygen is used to "aerate". To prevent microbial infections, the air supplied must be applied through a filter.
    Both the propagation temperature and the pH are also essential. Preferably, the temperature in the propagation tank will be between 22 ° C and 32 ° C. Yeast growth is optimal at an acid pH. In a preferred form, the pH in the tank will be between 4 and 6.
    During the propagation, the yeast cells will produce CO2. Since the propagation in the present invention takes place in a closed system, CO2 production will give rise to a pressure rise in the propagation tank. In particular, when a certain limit pressure is exceeded in the propagation tank, the supernatant high yeast will be transported to a communicating tank. The transport is preferably initiated at a limit pressure between 0.2 and 0.5 bar.
    The transported yeast is preferably collected and stored under refrigerated conditions. Preferably, the temperature of the harvested yeast will be between 0 ° C and 5 ° C. When sufficient yeast of good quality and viability has been harvested, it is further transported to the fermentation tanks for fermentation into beer. Accordingly, the present invention also describes the use of the harvested yeast for brewing beer.
    In a further aspect, the present invention describes a device for harvesting yeast, preferably harvesting high yeast. In particular, such a device will comprise a propagation tank and a storage tank for yeast, both of which are in communication with each other through an overflow, preferably a fixed overflow.
    By the term "fixed overflow" is meant an overflow comprising an inlet and an outlet where the position of the inlet does not change. This is in contrast to a floating inlet where the position of the inlet changes over time.
    The overflow will in particular be provided with a non-return valve, such as a pressure relief valve, which closes the overflow under atmospheric pressure. In particular, the non-return valve will open at an overpressure in the propagation tank between 0.2 and 0.5 bar.
    The propagation tank according to the present device is a closed system. Consequently, as already mentioned, with propagation of the yeast, the pressure in the tank will rise due to the CO2 produced by the yeast cells. The high yeast rises in the propagation tank and reaches the fixed height of the inlet. When the limit pressure is exceeded by the CO2 produced, the high yeast is introduced into the inlet and passed through the overflow. The high yeast is collected when leaving the outlet of the overflow in the yeast storage tank. The latter preferably has a capacity between 5 and 50 hectoliters.
    When adding yeast to wort in the propagation tank, after about 48-60 hours high yeast will reach the overflow where the yeast has the desired viability. High yeast can be harvested until the height of the wort containing the high yeast falls below the position of the inlet. Over time, high yeast can rise again up to the level of the inlet, whereby high yeast can be harvested again. This ensures a discontinuous harvesting process, in which only high yeast with a sufficiently high quality is harvested. The quality of high yeast can be described by the viability of the yeast.
    In a preferred form of a device according to the invention the overflow is provided on the upright wall of the propagation tank, more preferably on the upper half of the upright wall, closest to the top of the propagation tank. The position of the overflow is preferably fixed and is determined by the height of the rising high yeast. This placement of the overflow has the consequence that only high-quality yeast can flow through the overflow. Another consequence is that the high yeast will flow through the overflow discontinuously. The overflow has an inlet on the inside of the propagation tank and runs through the wall of the propagation tank, with an outlet on the outside of the propagation tank. Due to the large hydrophobic zones in the cell wall of the high yeasts, they rise under the influence of rising CO2 bubbles. When the high yeast reaches the height of the inlet of the overflow and with a slight overpressure, the non-return valve opens and the yeast flows out through the overflow.
    Because the overflow has a fixed position, as opposed to a floating arrangement, it is easy to clean, so that infections can be better avoided in the propagation tank.
    Types of infections that can occur are: other yeasts, such as wild yeasts such as Pichia, Candida, Brettanomyces; fungi and bacteria. Among the gram-positive bacteria, lactic acid bacteria can occur, such as pediococci or Streptococci. Common gram-negative bacteria include Enterobacteriaceae such as Klebsiella, Aerobacter or Hafnia. Other potentially occurring gram-negative bacteria are Zymomonas, Megasphera or Pectinatus. Each of these bacteria has an influence on the taste and / or visual appearance of beer.
    The propagation tank is also provided with a gas outlet, preferably placed at the top of the propagation tank. In particular, the gas outlet can be closed, preferably by means of a valve. The gas outlet is particularly suitable for the evacuation of produced CO2 from the propagation tank. In the active state this gas outlet will be closed so that the pressure can be built up in the tank and consequently yeast can be harvested by means of the overflow. However, when sufficient yeast has been harvested, or when harvesting is not desirable (for example, with low quality yeast), the gas outlet can be opened. The CO2 produced will be discharged continuously and, consequently, no pressure increase will occur in the propagation tank. This ensures that the limit pressure will never be exceeded, so that the non-return valve of the overflow remains closed and no transport of yeast will take place. The CO2 discharged can be recovered separately or released into the environment.
    In a preferred form of a device according to the invention, the propagation tank is a closed tank with a volume comprised between 200 and 8000 hl with a useful volume of more than 90% for low fermentation and more than 60% for high fermentation. Preferably, the propagation tank has a double wall and the propagation tank is cooled.
    The propagation tank is preferably made from an alloy comprising chromium and nickel, in another embodiment, molybdenum is also added to the alloy.
    In a preferred form of a device according to the invention, the propagation tank is a cylindroconic tank (CCT) with an upper cylindrical part and a lower conical part.
    In one embodiment, the propagation tank can also be provided with a closable opening at the bottom. The latter can be used for harvesting low yeast, if this is desirable. The normal CO2 evacuation valve is hereby opened, so that the non-return valve remains closed and no yeast is recovered.
    Figure 1 outlines an embodiment of a device according to the present invention. Propagation tank 1 is hereby connected to a storage tank for yeast 2 by means of an overflow 3. The overflow 3 is herein provided with a non-return valve 4, wherein the non-return valve will open at a specific pressure. Hereby the supernatant high yeast 8 will be discharged from the propagation tank 1 to the storage tank 2. The propagation tank 1 is further also provided with a gas outlet 6. This gas outlet is preferably closable by means of a valve 5. At the bottom the propagation tank 1 can be provided from a closable opening 7, through which low yeast can be discharged.
    In a final aspect, the invention relates to a beer brewed with yeast harvested according to a method according to the invention.
    In an embodiment according to the invention, the beer is brewed with high yeast, harvested according to a method according to the present invention. Examples of such beer are: Maredsous®, Duvel®, La Chouffe®.
    权利要求:
    Claims (17)
    [1]
    Method for harvesting yeast, preferably beer yeast, comprising: - propagating yeast in the presence of wort in a closed propagation tank; - building up pressure in the propagation tank and; - transporting the high yeast in the propagation tank to a communicating tank, characterized in that the transport of the yeast is initiated at an overpressure in the propagation tank between 0.2 and 0.5 bar.
    [2]
    Method according to claim 1, characterized in that the propagation of the yeast occurs at a temperature between 22 and 32 ° C.
    [3]
    Method according to claim 1 or 2, characterized in that the wort used contains a density of at least 120 g / l.
    [4]
    Method according to one of claims 1 to 3, characterized in that propagation takes place at a pH between 4 and 6.
    [5]
    A method according to any one of claims 1 to 4, characterized in that the harvested yeast is stored in a cooled place at a temperature between 0 ° C and 5 ° C.
    [6]
    Method according to one of claims 1 to 5, characterized in that the pressure in the propagation tank is built up by CO2 production of the yeast.
    [7]
    Method according to any of claims 1 to 6, characterized in that the transported yeast is high yeast.
    [8]
    Method according to one of claims 1 to 7, characterized in that the harvested yeast is beer yeast, preferably Saccharomyces cerevisiae.
    [9]
    Use of a yeast harvested according to the method of any of claims 1 to 8 for brewing beer.
    [10]
    Beer brewed through a yeast harvested according to the method of any one of claims 1 to 8.
    [11]
    A device for harvesting yeast, comprising a propagation tank (1) and a storage tank for yeast (2), in communication with each other by means of an overflow (3) provided with a non-return valve (4), characterized in that the non-return valve (3) ) opens at an overpressure in the propagation tank (1) between 0.2 and 0.5 bar.
    [12]
    Device according to claim 11, characterized in that the propagation tank (1) is further provided with a closable gas outlet (6).
    [13]
    Device according to claim 12, characterized in that the gas outlet can be closed by means of a valve (5).
    [14]
    Device according to one of claims 11 to 13, characterized in that the propagation tank (1) has a closable opening (7) in the underside.
    [15]
    Device according to one of claims 11 to 14, characterized in that the propagation tank (1) is a cylindroconic tank.
    [16]
    Device according to one of claims 11 to 15, characterized in that the overflow is provided at the top of the propagation tank (1), preferably on the upright wall of the propagation tank (1).
    [17]
    Device according to one of claims 11 to 16, characterized in that the propagation tank (1) has a capacity between 200 and 8000 hectoliters. Device according to one of claims 11 to 17, characterized in that the storage tank for yeast (2) has a capacity between 5 and 50 hectoliters.
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    同族专利:
    公开号 | 公开日
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    GB191221491A|1912-09-21|1913-08-14|Walther Scott|Method or Process of Assisting Fermentation and Apparatus therefor.|
    GB346361A|1928-12-18|1931-04-07|Alfred Braun|Improvements in or relating to producing yeast|
    GB1087307A|1965-05-31|1967-10-18|Inst Die Gaerungs Und Getraenk|Process and apparatus for the continuous fermentation and maturing of beer|
    DE8516347U1|1985-06-04|1986-04-03|Ludwig Edel GmbH & Co, 7988 Wangen|Fermentation tank|CN109370929A|2018-12-05|2019-02-22|北京工商大学|A kind of application of S. cervisiae in wine brewing|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    BE201100744|2011-12-21|
    BE201100744|2011-12-21|
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