Device and process for return of the aromatics in the fermentation broth

Abstract

The device and method for returning aromatics to the fermentation broth solves the technical problem of the loss of aromatics during fermentation process if fermentation is carried out at temperatures that are ideal for yeast operation in such a way that the temperature of the fermentation broth is maintained at 15°C to 30°C or a temperature that is ideal for the development of yeasts. At the same time, C02 is formed, and aromatics in form of vapors. This gas mixture is fed to the condenser, where the aromatics are condensed while C02 continues on. The condensed aromatics are returned to the fermentation broth by use of device according to the invention.

Description

DEVICE AND METHOD FOR RETURNING AROMATICS TO FERMENTATION BROTH Field of technology winemaking; fermentation; fermentation technology Technical problem The technical problem solved by the present invention is the loss of aromatics during fermentation of the fermentation broth in the winemaking process, when fermentation is carried out at temperatures that are ideal for the activity of yeasts. State of the art FR2307037 describes a gas scrubber comprising a refrigerated condenser, preferably in the form of a vertical tube-and-shell exchanger, with ethylene glycol refrigerant at -50°C circulating in the shell. The condenser has a funnel below the tubes which collects the condensate and returns it to a container. FR2459280 describes a device for recovering the vapours contained in the carbon dioxide produced in fermentation vessels, in particular those used in the production of wine. The installation is of the type in which the vapours are separated from the carbon dioxide in a condenser and the condensate is then returned to the fermentation vessel. The installation shown shows a plurality of fermentation vessels, where the vapours and gases are led to a common gas collector and then to a condenser where the carbon dioxide is separated from the condensed vapours. The condensate is then returned to each of the fermentation vessels, this taking place in sequence, with a complex opening and closing of valves. In chemical terms, condensers are used primarily in the field of distillation (brandy, whiskey, cognac), which condense distillation vapors released at high temperatures. temperatures, and in winemaking, the condensation of aromatics has so far been mainly linked to the binding of aromatic substances in absorption solutions, which are returned to the process after use. In this way, the absorption of aromatic components is possible, but at the same time it also involves additional dilution of the fermentation broth, since due to continuous saturation, the absorption liquid must often be replaced and returned to the process. The aforementioned process represents an artificial intervention in wine production and is therefore undesirable in the technology of producing premium wines. Top-quality wines are produced using fermentation temperatures in the range of 10 to 15°C, as the evaporation of aromatics is lower than at higher temperatures. In the technology of producing premium wines, various esters are represented - aromatic components of yeast metabolism, which enrich the wine bouquet and thus enrich the aroma and quality of the wine (Eustace R., Thornton RJ 1987. Selective hybridization of wine yeasts for higher yields of aromats and glycerol. Can. J. Microbiol. 33: 112-117). Increased production of aromatics in wine also has a beneficial effect on the sensory perceptions of wine (Pretorius IS, Van der Westhuizen TJ 1991. The impact of yeast genetics and recombinant DNA technology on the wine industry. A review. S. Afr. J. Enol. Vitic. 12: 3-31). Among the parameters that promote the growth of metabolic quality and components that give fullness to wine, the character of the selected yeast strain and mixing with the flow of exhaust gases are also included (Radler F., Schiitz H. 1982. Production of various strains of Saccharomyces. Am. J. Enol. Vitic., Vol. 33, No. 1: 36-40). Research results have shown that with a gradual increase in temperature, the content of metabolites in the resulting wine slowly increases (Ough CS, Fong D., Amerine MA 1972. Determination and some factors affecting. Amer. J. Enol. Vitic. 23: 1-5; Gardner N., Rodrigue N:, Champagne CP 1993. Combined effect of sulfites, temperature and agitation time on production of aromates in grape juice by Saccharomyces cerevisiae. Applied and Environmental Microbiology. 59:2022-2028). Description of the new solution The device and process for returning aromatics to the fermentation broth solves the above-described technical problem by allowing the fermentation broth temperature to be 15°C to 22°C, or the temperature that is ideal for yeast development. This produces CO2 and aromatic vapors. The gas mixture is led to a condenser, where the aromatics are condensed, and the CO2 continues its journey. The condensed aromatics are returned to the fermentation broth. Wine production by fermenting grape juice into wine takes place in winemaking technology in fermentors (i.e. the vessel in which fermentation takes place), preferably with a volume of 1,000 to 100,000 liters. The fermentation process is initially an endothermic process that requires temperature stimulation at its start, and in its continuation in the exponential or turbulent growth phase requires heat removal, which also accelerates fermentation. In this phase, the fermentation reaction or glucose conversion produces ethanol and carbon dioxide, which is released from fermentation. Upon leaving the fermentation tanks in the turbulent fermentation phase, the carbon dioxide is moistened up to 100% with water vapor in which the aromatics that give the wine its fullness of smell and taste are dissolved. The resulting gas mixture removes aromatic substances, which for the purposes of this application are also called aromatics, from the fermentation broth, usually into the environment of the cellar, and thus the evaporation of aromatic substances from the wine being produced.As a result, the potential of the resulting wine is weakened, which is primarily evident in the fullness of the aroma and taste. The problem of evaporation of aromatic substances is now solved in winemaking by lowering the boiling temperature and thus in a less turbulent fermentation process, typically the fermentation process takes place in the temperature range between 12 and 16°C. In the case of a change in the technological fermentation process by raising the boiling temperature from 12-16°C to 16-22°C (possibly 16-30°C) in the device and process according to the invention, optimal yeast metabolism is enabled. In the changed technological process, the yeast produces maximum aromatic products, as a result the reaction is more turbulent and thus the aromas are removed from the boiling vessel by removing saturated CO2, with the device and process according to the invention the aromatics are returned to the fermenter. The process of fermenting grape juice into wine depends on the winemaker's individual desires for distinct characteristics (smell, taste, etc.) and his production technology, as well as the process depending on the grape variety and yeast species. Traditionally, fermentation temperatures are kept within a certain range to limit the violent nature of the reaction. The process according to the invention comprises the following steps: obtaining a fermentation broth comprising yeast for processing into wine; temperature regulation of the fermentation broth to a temperature between 16°C and 30°C; condensation of exhaust gases - mixtures of CO2 and aromatics; passing said mixture into a condenser; cooling said mixture in a condenser and condensing the aromatics; returning the aromatics to the fermentation broth. The method according to the invention is further characterized in that it comprises the following steps: - preparation of wine yeast suspension; - preparation of wine must; - adding a suspension of wine yeast to the prepared wine must; - further fermentation of the mixture thus obtained. The step of preparing wine must according to the invention comprises: - preparation of wine must in a fermenter at a temperature between 15°C and 30°C, preferably at around 18°C - in a specific embodiment, for smaller fermentors, said wine must is mixed with a mixer, preferably at 20 - 80 rpm, even more preferably around 50 rpm, while simultaneously blowing the surface of the liquid with nitrogen gas, preferably at a flow rate of 0.3 - 1.2 1 / min, even more preferably 0.5 1 / min for 10-30 min, preferably 20 min. The fermentation step of the mixture thus obtained according to this invention thus comprises: - fermenting said mixture of said wine must and said wine yeast suspension for a period of up to 360 hours, preferably up to 240 hours, with stirring said mixture with a stirrer, preferably at 20 - 80 rpm, even more preferably around 50 rpm while simultaneously purging the surface of the liquid with nitrogen gas, preferably at a flow rate of 0.3 - 1.2 1 / min The described process differs significantly from that described in FR2307037 and FR2459280, in particular in that it limits the temperature to a temperature that is optimal for yeast development, as well as in the design of the condenser, which is separate from the condenser with a tube bundle and jacket and with an integrated non-return valve, and finally in that it precisely determines the process parameters. The device according to the invention is a condenser in the form of a container, preferably of oval shape, which acts as a condenser, which is preferably placed on top of the fermenter. In an embodiment, the device has a condensing surface, preferably in the form of a tubular coil, even more preferably ribbed. On the condensing surface, aromatic vapors condense from the gas mixture, which are then returned to the fermentation broth. The condensing surface is cooled by a medium with a temperature lower than the temperature of the CO2 and vapor mixture, preferably between -5°C and 10°C. The device according to the invention can further be equipped with a check valve, which after the end of the intensive gas release prevents the ingress of gases from the environment into the fermenter. According to the embodiment, the check valve is a flap, preferably spring-loaded, which automatically opens when there is excess pressure in the fermenter and allows the passage of the gas mixture into the condenser, and closes again in a substantially gas-tight manner when the pressure difference between the fermenter and the environment or the condenser decreases. The essence of the invention is presented in more detail below with the help of drawings, which form an integral part of this application, and comprise: Figure 1 shows a device according to the invention, i.e. a condenser (1), comprising a housing (8), a flow of an inlet mixture of CO2 and aromatics (2), a non-return valve, preferably in the form of a swing flap (3), tubes of a coil through which the refrigerant flows (4), a flow of an exiting gas, comprising in particular the remaining CO2 (5), cooling fins (6). Figure 2 shows the device according to the invention, i.e. the condenser (1) in cross-section, namely the housing (8), the tubes of the coil through which the coolant flows (4), and the cooling fins (6). Figure 3 shows the device according to the invention, i.e. the condenser (1) in cross-section, namely the housing (8), the tubes of the coil through which the coolant flows (4), and the cooling fins (6). Sketch 4 shows the condenser (1), the fermenter (7). The device according to the invention is a condenser comprising a housing (1) in which there is a coil of tubing through which the coolant flows through the tubes (4). The device according to the invention may optionally also have cooling fins (6), or it may have only cooling fins (6) without a coil of tubing (4), in which case the coolant flows inside the cooling fins (6) A mixture of gases, namely saturated moist CO2 and aromatics, the products of fermentation in the fermentation broth, rises from the fermentor (7) in the direction of flow of the incoming mixture of CO2 and aromatics (2) into the condenser (1). The mixture rises through a tube coil, which is cooled by a cooler, and in a substantially cross-flow manner covers the tubes (4) of the tube coil and / or covers the cooling fins (6). In this process, condensation of the aromatics contained in the circulating mixture occurs. The liquid aromatics flow back into the fermentor, while the remaining gas, which mainly comprises CO2, flows through a non-return valve, preferably in the form of a swing flap (3), preferably with a spring that resists the opening of the flap, in the direction of flow of the outgoing gas, which mainly comprises the remaining CO2 (5), either for further processing or to the surroundings. Implementation examples and experiments The process is described in more detail below with examples and experimental results, with the first and third experiments describing the process without using the device according to the invention, and the second and fourth experiments describing the process with using the device according to the invention. The essential difference between the two processes is immediately apparent to the expert. According to the implementation example, the procedure is carried out as follows: a) We use Laško Riesling must from Ljutomerško-Ormoške Gorice, which has not been previously sulphured or filtered. Before the start of fermentation, the concentration of reducing sugars is 110 g / 1 glucose and 105 g / 1 fructose, pH 3.15 and the content of organic acids is 8.0 g 1 _1 Fermaid E (Danstar Ferment AG) is used as a bioactivator at a rate of 30 g per 100 l of must. b) prepare 10 liters of wine must of the Laško Riesling variety, the temperature of which is maintained in the fermentor at a temperature of 15 - 30° C, preferably at 18° C and mixed with a paddle Rushton mixer with a mixing intensity of 20 -80 rpm, preferably 50 rpm, while blowing the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 -1.2 1 / min, preferably 0.5 1 / min for 10-30 min, preferably 20 min. c) to the must thus conditioned, an inoculum of 0.1-0.5 g / l, preferably 0.3 g / l, of wine yeast Saccharomyces cerevisiae (Fermicru, AR2Val de Loire, France), revitalized and heat-treated according to paragraph a) is added and again this temperature is essentially maintained for 60 minutes at 18 °C, to the wine must conditioned at a temperature of 15 - 30 °C, preferably at 18 °C, optionally for 45 minutes to 75 minutes, preferably around 60 minutes d) the further fermentation process is conducted for up to 240 hours at a temperature of 15 - 30° C, preferably at 18° C and stirred with a paddle Rushton stirrer with a stirring intensity of 20 - 80 rpm, preferably 50 rpm, while purging the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 -1.2 1 / min, preferably 0.5 1 / min. e) As process control instrumentation, we use redox and pH electrodes (Mettler Toledo) and an electrode for measuring the partial pressure of carbon dioxide (Mettler Toledo), which allows process control in the absence of oxygen. First attempt Prepare 10 liters of Sauvignon blanc blanc wine must, which is maintained at a temperature of 15 - 22° C, preferably 18° C, and mixed with a paddle Rushton mixer with a mixing intensity of 20 - 80 rpm, preferably 50 rpm, while blowing the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min from 10 - 30 min, preferably 20 min. The must must not have been previously sulphured. To the thus conditioned must, an inoculum of 0.1-0.5 g / 1, preferably 0.3 g / 1, of wine yeast Saccharomyces cerevisiae (Uvaferm SLO) revitalized in wine must of the Sauvignon blanc blanc variety is added, at a temperature of 15 - 22° C, preferably at 18 °C, optionally for 45 minutes to 75 minutes, preferably around 60 minutes, The further fermentation process is conducted at a temperature of 15 - 22° C, preferably at 18° C and stirred with a paddle Rushton stirrer with a stirring intensity of 20 - 80 rpm, preferably 50 rpm, while purging the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min for 10 - 30 min, preferably 20 min, until the end of fermentation, which is completed after 200 hours. This experiment is performed without the device according to the invention. As process control instrumentation, we use redox and pH electrodes (Mettler Toledo) and an electrode for measuring the partial pressure of carbon dioxide (Mettler Toledo), which allows process control in the absence of oxygen. In the described case, 2.64 mg / 1 of total methoxypyrazines and thiols were measured in the wine. Prepare 10 liters of Sauvignon blanc blanc wine must, which is maintained at a temperature of 15 - 30° C, preferably 18° C, and mixed with a paddle Rushton mixer with a mixing intensity of 20 - 80 rpm, preferably 50 rpm, while blowing the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min from 10 - 30 min, preferably 20 min. The must must not have been previously sulphured. To the thus conditioned must, an inoculum of 0.1-0.5 g / 1, preferably 0.3 g / 1, of wine yeast Saccharomyces cerevisiae (Uvaferm SLO) revitalized in wine must of the Sauvignon blanc blanc variety is added, at a temperature of 15 - 30° C, preferably at 18 °C, optionally for 45 minutes to 75 minutes, preferably around 60 minutes, The further fermentation process is conducted at a temperature of 15 - 30° C, preferably at 18° C and stirred with a paddle Rushton stirrer with a stirring intensity of 20 - 80 rpm, preferably 50 rpm, while purging the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min for 10-30 min, preferably 20 min, until the end of fermentation, which is completed after 200 hours. This experiment is carried out using a device according to the invention, which is permanently connected to the lid of the fermentor, and connected to the fermentor in such a way that gases flow from the fermentor into the device according to the invention through a non-return valve according to the invention. The temperature of the coolant in the condenser is between 4°C and 10°C, preferably around 6°C. As process control instrumentation, we use redox and pH electrodes (Mettler Toledo) and an electrode for measuring the partial pressure of carbon dioxide (Mettler Toledo), which allows process control in the absence of oxygen. In the described case, 7.73 mg / l of methoxypyrazines and thiols were measured in the wine. Prepare 10 liters of Sauvignon blanc wine must, maintain it at a temperature of 15 - 22° C, preferably 18° C, and mix it with a paddle-type Rushton mixer with a mixing intensity of 20 - 80 rpm, preferably 50 rpm, while blowing the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min from 10-30 min, preferably 20 min. The must has not been previously sulphured. To the thus conditioned must, an inoculum of 0.1-0.5 g / l, preferably 0.3 g / l, of wine yeast Saccharomyces cerevisiae (Uvaferm SLO) revitalized in Sauvignon blanc wine must is added, at a temperature of 18 - 28° C, preferably at 24 ° C, optionally for 45 minutes to 75 minutes, preferably around 60 minutes, The further fermentation process is conducted for up to 4 hours at a temperature of 18 - 28° C, preferably at 24° C and stirred with a paddle Rushton stirrer with a stirring intensity of 20 - 80 rpm, preferably 50 rpm, while purging the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min for 10 -30 min, preferably 20 min. After 4 hours, increase the fermentation temperature from 24° C to a temperature of 28-36° C, preferably to 34° C, and maintain the fermentation process at this temperature until the end of fermentation, which is completed after 200 hours. This experiment is performed without using the device according to the invention. As process control instrumentation, we use redox and pH electrodes (Mettler Toledo) and an electrode for measuring the partial pressure of oxygen (Mettler Toledo), which allows process control in the absence of oxygen. In the described case, 2.94 mg / 1 of total methoxypyrazines and thiols were measured in the wine. Prepare 10 liters of Sauvignon blanc wine must, maintain it at a temperature of 15 - 30° C, preferably 18° C, and mix it with a paddle-type Rushton mixer with a mixing intensity of 20 - 80 rpm, preferably 50 rpm, while blowing the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min from 10 - 30 min, preferably 20 min. The must has not been previously sulphured. To the thus conditioned must, an inoculum of 0.1-0.5 g / l, preferably 0.3 g / l, of wine yeast Saccharomyces cerevisiae (Uvaferm SLO) revitalized in Sauvignon blanc wine must is added, at a temperature of 18 - 28° C, preferably at 24 ° C, optionally for 45 minutes to 75 minutes, preferably around 60 minutes, The further fermentation process is conducted for up to 4 hours at a temperature of 18 - 28° C, preferably at 24° C and stirred with a paddle Rushton stirrer with a stirring intensity of 20 - 80 rpm, preferably 50 rpm, while purging the surface above the liquid substrate with gaseous nitrogen at a flow rate of 0.3 - 1.2 1 / min, preferably 0.5 1 / min for 10 -30 min, preferably 20 min. After 4 hours, increase the fermentation temperature from 24° C to a temperature of 28-36° C, preferably to 34° C, and maintain the fermentation process at this temperature until the end of fermentation, which is completed after 200 hours. In the described experiment, we use a device according to the invention, which is essentially connected to the lid of the fermenter during the entire fermentation. In doing so, we use a non-return valve according to the invention, the temperature of the cooling liquid in the reflux condenser is from 1 - 6° C, preferably 3° C. As process control instrumentation, we use redox and pH electrodes (Mettler Toledo) and an electrode for measuring the partial pressure of carbon dioxide (Mettler Toledo), which allows process control in the absence of oxygen. In the described case, 9.88 mg / 1 of total methoxypyrazines and thiols were measured in the wine.

Claims

PATENT APPLICATIONS 1. A process for returning aromatics to a fermentation broth, characterized in that it comprises the following steps: obtaining a fermentation broth comprising yeast for processing into wine; temperature regulation of the fermentation broth to a temperature between 16°C and 30°C; collecting a mixture of CO2 and aromatics; passing said mixture into a condenser; cooling said mixture in a condenser and condensing the aromatics; returning the aromatics to the fermentation broth.

2. A process for returning aromatics to a fermentation broth according to claim 1, wherein the process further comprises the following steps: preparation of wine yeast suspension; preparation of wine must; adding a suspension of wine yeasts to the prepared wine must; further fermentation of the mixture thus obtained.

3. A process for returning aromatics to a fermentation broth according to any one of the preceding claims, wherein the step of preparing the wine must further comprises: preparing the wine must in a fermenter at a temperature between 15°C and 30°C, preferably at about 18°C.

4. A process for returning aromatics to a fermentation broth according to any one of the preceding claims, wherein said wine must is stirred with a stirrer, preferably at 20 - 80 rpm, even more preferably around 50 rpm, while simultaneously purging the surface of the liquid with nitrogen gas, preferably at a flow rate of 0.3 - 1.2 1 / min, even more preferably 0.5 1 / min for 10 - 30 min, preferably 20 min.

5. A process for returning aromatics to a fermentation broth according to any one of the preceding claims, wherein the step of adding a suspension of wine yeasts to the prepared wine must further comprises: adding to said wine must an inoculum of said suspension of wine yeast in a proportion of 0.1 to 0.5 g / 1, preferably about 0.3 g / 1 maintaining the temperature of the mixture thus obtained at a temperature between 15°C and 30°C, preferably at about 18°C, optionally for a period of 45 minutes to 75 minutes, preferably about 60 minutes; 6. A process for returning aromatics to a fermentation broth according to any one of the preceding claims, wherein the step of fermenting the mixture thus obtained further comprises: fermentation of said mixture of said wine must and said wine yeast suspension for a period of up to 360 hours, preferably up to 240 hours, while stirring said mixture with a stirrer, preferably at 20 - 80 rpm, even more preferably at about 50 rpm, while simultaneously purging the surface of the liquid with nitrogen gas, preferably at a flow rate of 0.3 -1.2 1 / min 7. A device for returning aromatics to a fermentation broth, characterized in that the process according to any one of the preceding claims takes place therein.

8. A device for returning aromatics to the fermentation broth according to claim 7, wherein the device comprises a non-return valve (3), preferably in the form of a flap with a spring resisting the opening of the flap, to prevent gases from entering the fermenter in a direction opposite to the outgoing mixture of CO2 and aromatics during the boiling of the fermentation broth.

9. Apparatus for returning aromatics to a fermentation broth according to claim 7 or claim 8, wherein the apparatus comprises a condenser (1) comprising a housing (8), a non-return valve, preferably in the form of a swing flap (3), cooling means selected from the group comprising coil tubes through which the coolant (4) flows, cooling fins (6), coil tubes (4) and cooling fins (6).