Patent Application
20240191162
The invention relates to a method and device for continuous (“on-line”, i.e., real-time) monitoring and automatic control of temperature of the process of alcoholic fermentation of grape must or of other sugary liquids using acoustic emission techniques in a fermentation tank, for the purpose of obtaining an improved automated control of temperature and of aeration-oxygenation in alcoholic fermentation.
Wine can only be obtained by means of alcoholic fermentation of grape must, this being the most important step in wine-making. In alcoholic fermentation (an anaerobic process), sugar from must is converted by means of anaerobic fermentation yeasts (e.g., Saccharomyces cerevisiae, which are capable of performing complete fermentation in the absence of oxygen; however, oxygen is a key parameter in the process of fermentation since yeasts need it during their growth stage) into alcohol (fundamentally ethanol) and carbon dioxide (CO2), and a large amount of thermal energy is also given off. As it is in a liquid medium, CO2 is generated in the form of bubbles which move up towards the surface. The release of the CO2 is usually turbulent and causes the sensation of boiling, hence the name “fermentation”, from the Latin expression fervere.
The present invention proposes a novel method and device for the continuous monitoring of the kinetics of alcoholic fermentation by means of measuring the acoustic emission originating with the formation, movement (up towards the surface), and collision of CO2 bubbles for the purpose of implementing in said process an improved, continuous, and automated control of temperature and of aeration or oxygenation.
The invention belongs to the field for producing wine, beer, and alcoholic beverages (distilleries), and more specifically to a method and device for improved and automated control of temperature, and of aeration or oxygenation, of alcoholic fermentation for the wine-growing field.
Fermentation refers to the phase of the wine-making process in which must is transformed into wine. In the case of wine, the yeasts responsible for wine-making are single-celled (microscopic) fungi which are naturally found in grape skins (generally in a layer in the form of a fine white powder covering the skin of the grapes and referred to as bloom).
To curb the appearance of undesirable bacteria and other fermentation-limiting organisms, the must is sometimes sterilized with sulfur dioxide (SO2) before the process of fermentation. One of the reasons is to inhibit beforehand the work of lactic acid bacteria while there is sugar in the must, preventing at that time the “souring” of the wine.
Alcoholic fermentation
The making of wine comprises a first fermentation called alcoholic fermentation, in which sugars in grape must are transformed into alcohol. It is a turbulent process due to the production of a significant bubbling for a period of ten to fifteen days. The process is carried out in stainless steel bioreactors or fermentation tanks where, as a result of the action of the different yeasts, the sugars are converted to ethyl alcohol (during the first few days of spontaneous fermentation, a series of species of yeast is produced until Saccharomyces cerevisiae wins out over the others due to the presence of ethyl alcohol, thereby being responsible for ending the process). Said bubbling favors the solid parts of the grapes (skins) rising up to the surface of the vat, forming a floating layer in the upper part thereof called the “cap”. In the production of red wines, this cap imparts to the must an enormous quantity of substances contained in the skins (tannins, anthocyanins and flavonoids) as a result of which red wine acquires its characteristic reddish color and aromas. To favor the extraction of said substances existing in the skins and the mixing thereof with the must that is being fermented, it is necessary to break, soak, move, and, if it is even possible, submerge said cap, preventing it from becoming solid, and the method most widely used by wineries is the method known as “pumping over”, which consists of moving the must from the lower part of the vat to the upper part, an operation that is performed several times a day (pumping over is furthermore necessary in the yeast multiplication stage since it aerates the must, but it does cause a loss of aromas). During the natural process of fermentation, it is possible to soften and guarantee an optimal quality of the wine, since alcohol acts as a barrier against possible substances that could negatively influence and damage the properties of the wine. Oxygen, acidity, as well as the presence of different substances, can trigger major impediments in the process of fermentation by hindering the work of the yeasts. For this reason, during alcoholic fermentation, a meticulous control of the different variables that affect the development of the process and impede the correct evolution of the yeasts must be carried out. Alcoholic fermentation is carried out with systems for the automatic control of temperature.
Once the first fermentation is finished, where all the sugar present in the grapes has been transformed and the SO2 has been combined with other molecules, the next step is a second fermentation called malolactic fermentation, which can develop spontaneously. Malolactic fermentation of wine consists of the transformation of malic acid into lactic acid. Malic acid is found naturally in grapes and, by transforming it into lactic acid, a decrease in the total acidity of the wine is generated. This type of fermentation is generally carried out in red wines. This is because in white and rosé wines, it would cause a loss of acidity and freshness (two of the most important characteristics in wines of this type) because they are young wines. It is carried out in barrels, in stainless steel and concrete tanks (which have greater temperature stability in the optimal range of malolactic fermentation, i.e., from 19 to 23° C.). In general, malolactic fermentation is carried out without systems for the automatic control of temperature.
Acoustic emission (AE), as it is currently known, is the propagation of mechanical waves in a solid caused by breakage or fracture of the material. When a material breaks, the material emits energy in the form of transient elastic waves that propagate through the material and can be detected by means of different types of sensors, such as piezoelectric sensors. The properties of AE can be a frequency of 10 kHz to 1 MHz and with an amplitude of the order of nm. AE is the kind of phenomenon that generates transient elastic waves by the rapid release of energy from localized sources, or transient waves generated in this way. Conventional sources of AE are deformation processes related to defects such as crack generation and propagation, material deformations, detachment of the aggregate from the matrix, contractions or expansions due to setting or temperature variations, etc. AE originates from the stress field created within the material. Therefore, if there are no variations in the stress field, AE does not occur.
Tracking the kinetics of alcoholic fermentation is done by controlling the fermentation temperature and measuring the amount of residual sugar and ethanol formed in the fermenting must; but the measurement of the density or the amount of CO2 released are more practical tracking parameters to follow its evolution in order to immediately detect any disturbances occurring in the fermentation (Ribéreau-Gayon et al., 2006a).
Fermentation temperature is one of the most important factors involved in the development of alcoholic fermentation. It is measured automatically and continuously by means of specific temperature sensors (Flanzy, 2003; Ribéreau-Gayon et al., 2006a; Hidalgo, 2011). The temperature range (minimum-maximum in the fermentation tank) is 20-32° C. for red wine and 18-20° C. for white wine. In order for the biological reactor to function correctly, it must not exceed any of the aforementioned limit values. Below the minimum temperature, microbial kinetics are inhibited. Yeast reproduction is too slow and the fermenter does not “startup”. Above 32° C., in addition to reducing the cellular activity of the microorganisms, there can be serious organoleptic deviations. In other words, the cap is susceptible to being affected by undesirable thermophilic bacteria, transmitting unpleasant odors to the wine.
However, the measurement of the rest of the parameters in each of the fermentation tanks of the winery is of great difficulty or involves tedious techniques that are impractical for tracking alcoholic fermentation in a winery (Cenzano et al., 2003; Ribéreau-Gayon et al., 2006a; OIV, 2015a). Therefore, conventional supervision of the kinetics of alcoholic fermentation has been carried out by manually measuring once or twice a day the density (graduated mustimeter, densimeter, or hydrometer), this being an approximate measurement of the main components of the fermented must; as fermentation progresses, the consumption of sugars causes a decrease in density, which is accentuated by the subsequent formation of ethanol (Ribéreau-Gayon et al. 2006a). This measurement does not require any conversion for its interpretation; it only needs a correction according to the temperature of the sample during its measurement. The representation of density values versus time allows the winemaker to evaluate fermentation kinetics. Fermentation is complete when the density is between 0.990 and 0.995 g/mL depending on the final ethanol content and the amount of extracted constituents.
One of the most common methods to estimate the alcoholic strength of a wine is through its density; winemakers measure the density of the must before fermentation, and once the yeast has done its job, they measure again. The first result is called original gravity (OG) and the second result is called final gravity (FG). The number that results from subtracting the original gravity from the final gravity shows the amount of CO2 that escaped from the fermentation tank. This amount is multiplied by the grams of ethyl alcohol gained per gram of CO2 which is a constant 1.05 grams, and the result is the weight of alcohol in the fermenter, which is referred to as the mass of alcohol in solution. Once the results of these measurements are available, the alcohol by volume (ABV) percentage is calculated, being obtained by dividing the mass of alcohol in solution by the final gravity.
The completion of alcoholic fermentation is verified chemically by measuring the concentration of sugars using the Clinitest method, the content of which should be less than 2-3 g/L in dry or still wines (Ribéreau-Gayon et al., 2006a; Hidalgo, 2011).
An upward increase in the probable alcoholic strength due to the effects of climate change can be seen in today's wine industry. Excess sugars in the must result in increased problems in fermentation management, while the increase in the final alcoholic strength leads to problems in marketing these wines. The main metabolic pathways that give rise to CO2 production are respiration (no alcohol is produced) and fermentation (Morales, et al., 2015).
In non-patent literature, a laboratory-level improvement in conventional alcoholic fermentation is known that aims to reduce the alcoholic strength of wine by means of ventilated fermentations with mixtures of air and nitrogen, allowing the yeast to perform respiration by providing the necessary oxygen during the first stages of the process (hours), such that a part of the sugars in the must undergoes respiration instead of fermentation; subsequently, the oxygen supply must be stopped in order to continue with the conventional process of fermentation; an excess presence of oxygen causes a reduced quality of the wine. On the contrary, there are no known devices and methods in fermentation tanks (real industrial-scale bioreactors) for oxygenation or aeration to allow yeasts to perform respiration (Gonzalez et al., 2013).
In the closest prior art patent literature, different types of devices and methods which allow the oxygenation or aeration of wine can be found. Within this type are, among others, the invention patent entitled “Method for fermenting must, and fermentation vat” (ES2396676B1, 25.02.2013), which proposes a method and a device for introducing a mixture of CO2 gas and external air in a fermentation vat, said mixture being ejected into the must below the layer of skins, generating bubbles formed by CO2 gas and air which, in their upward movement towards the surface, cause the breakage and movement of said layer of skins. In no case is respiration described since the sole purpose is to carry out fermentation.
In non-patent literature, one of the most widely studied improvements in the wine-growing field for the purpose of obtaining a higher quality in wine is the control of continuous alcoholic fermentation using to that end the control system theory; the problem from the viewpoint of systems engineering is highly non-linear and oscillatory, because microorganisms, e.g., Saccharomyces cerevisiae, Zymomonas mobilis, are involved in the process, and they exhibit behavior with high kinetic complexities. Reference problems (benchmarks) for processes of continuous fermentation using models with two state variables: biomass and substrate, and growth rate equations coupling both variables, are known to be used; said models thereby have high non-linearities. The complex dynamics of the fermentation tanks or bioreactors are also investigated for the design of different stabilizing, non-linear control techniques for relatively simple processes of continuous fermentation, using for this purpose linear methods as a reference for non-linear methods. The control of bioreactors has been studied by many investigators, including those schemes based on adaptable control, optimal control and control using artificial intelligence (AI) techniques. However, investigations in this field are still in a latent state and an automatic method for optimized control which can be implemented in fermentation tanks (real industrial-scale bioreactors) with a high performance is not available in the current state of the art (Onder et al., 1998; Sing and Xiao, 1998; Aguilar et al., 2001; Hodge and Nazmul, 2002). As a result, most industrial wineries today only perform automatic control of the temperature during the process of fermentation through cooled liquid circulated through the external jacket of the alcoholic fermentation tank.
In the closest prior art patent literature, different types of devices and methods for the monitoring (measuring the temperature, measuring the level, measuring/calculating the density or some other variable) and continuous automated control (control of the temperature or some other variable, control of pumping over, etc.) of a process of alcoholic fermentation can be found.
Devices and methods based on the direct measurement of the fermentation temperature and the estimate by means of calculating the sugar and alcohol content from the indirect measurement of the density of the fermenting matter are known. This type includes, among many others, the patent document entitled “Process for monitoring and regulation of a fermentation process” (EP1270716A1, 02.01.2003), which proposes a device for the continuous monitoring and control of fermentation comprising a temperature sensor (thermal resistor) and a differential pressure sensor (piezoresistor) measuring at two different heights in the fermentation tank; the density at a certain temperature is calculated from the pressure differences measured at the measurement points; regulation of the temperature of the fermenting matter can furthermore be performed in the fermentation tank by means of the opening/closing of the passage of a cooled liquid going through a cooling plate located inside the tank.
Devices and methods which are based on the continuous direct measurement of alcohol in the fermenting matter are known. This type includes, among many others, the patent document entitled “Ethanol sensor for computerized fermentation control” (CA2011297A1, 01.09.1991), which proposes an ethanol sensor controlled by diffusion; the computer can automatically control the temperature and other process parameters for the fermenting matter.
Devices and methods that measure or determine the amount of CO2 exiting the fermentation tank are also known. This type includes, among many others, the invention patent document entitled “Automatic fermentation provided with a control system” (ES2330242T3, 11.10.2006), which proposes a method of supervising a process of fermentation in a fermentation tank, where the amount of gas exiting said fermentation tank is determined and the temperature of the exiting gas is measured right above a plug arranged in the tap hole of the fermentation tank, in the plug of the fermentation tank, or at the end of the side of the fermenting matter of a fermentation airlock which is located in the tap hole. This type also includes the invention patent document entitled “System for tracking alcoholic fermentation” (ES2241457B1, 16.10.2005), which proposes a method for the tracking and control of alcoholic fermentation characterized by the continuous measurement of the weight loss of the fermenting matter due to the release of CO2.
During alcoholic fermentation, the fermentation mass (two phases can be distinguished inside the alcoholic fermentation tank: a liquid phase made up of the fermenting must and a solid phase known as “cap” (made up of the skin of the grape) gradually gains in alcoholic strength as the following fundamental parameters are modified:
When the fermentation ends (after around 10-14 days), the primary wine is transferred from the alcoholic fermentation tank to the malolactic fermentation tank for malolactic fermentation to take place, but the cap is not. The cap is transferred to the pneumatic press, from which a second-class wine will be obtained.
The automated method that is most widely used to perform the automated tracking of alcoholic fermentation consists of calculating the density of the liquid (which decreases due to the effect of the loss of mass due to the release of CO2), by measuring the pressure and temperature difference at two points at different heights (the lower part and upper part of the cylindrical base body of the fermentation tank); it should be taken into account that most control systems for controlling alcoholic fermentation try to maintain the fermentation temperature at a value or within a range pre-established by the wine expert. Methods of measuring the amount of CO2 given off by calculating, or in some cases by measuring, the weight loss of the fermenting matter, or in other cases by measuring the gas generated in real time by means of flowmeters, are also used.
The most advanced automated tracking systems try to detect the fermentation speed (g CO2/l/h) and, therefore, the activity of the yeasts, this being a parameter that is as important as the temperature; to that end, they measure the amount, by weight or by volume, of CO2 that is produced per unit of time for the purpose of controlling the fermentation temperature (Ribéreau-Gayon et al., 2006a). The speed of alcoholic fermentation is proportional to the speed of generation of CO2 (Perret et al., 1995).
Another approach consists of creating a model of the process of alcoholic fermentation. Different calculations relating to the time, temperature, and alcohol, and the concentrations of sugar are used to predict the fermentation behavior, particularly the risk of the fermentation being stopped (Bovée et al., 1990)
Finally, these rules of the control system must be adapted to the particular needs of each fermentation tank in terms of quantifiable data and according to the experience of the wine expert. A highly advanced, automated control system that seeks to optimize alcoholic fermentation in wine-making would have to use artificial intelligence in order to take into account the actual experience of the wine expert (Grenier et al., 1990).
The devices and methods known in the prior art have a technical or problematic limitation in closed vat fermentation tanks, in which red wines are made without the need for pumping over (by means of injecting the CO2 released during the alcoholic fermentation and aeration of the process of fermentation by means of controlled oxygenation), which is fundamentally focused on the following aspects:
The method and device for continuous monitoring and improved automatic control of temperature, and of aeration-oxygenation, of the process of alcoholic fermentation (AF) in wine by means of acoustic emission techniques, proposed by the invention, is preferably, though in a non-limiting manner, applied in self-emptying closed-vat alcoholic fermentation tanks (batch-type biological reactor) or any other fermentation tank in the current state of the art (preferably made of food-grade stainless steel with European Conformity (CE) or other similar international standards) in which red wines are made (also valid for rosé and white wines) without the need for (mechanical) pumping over and which allow the measurement of the released CO2 flow, and which generally consist of three parts: an upper part referred to as a torispherical head, having high resistance to manometric pressure; a cylindrical base body and a lower part referred to as toriconical end, which is based on the ease of collecting the “cap”, or any other form of fermentation tank in the current state of the art.
No modification of an existing fermentation tank is required for the implementation of the system of tracking and control of AF claimed by the invention, i.e., the invention is intended to be applied both in new tanks and in existing tanks.
The present invention solves in a fully satisfactory manner the drawbacks set forth above in each and every one the different aspects discussed, where the technical advantage provided by the invention which provides a method and means for being able to carry out the method using acoustic emission techniques is that it allows an improved estimate (without the need to use empirical approaches) of the typical parameters of AF from the following on-line measurements taken in the fermentation tank (by means of automated measurement sensors): pressure and temperature at two points of the fermentation must, pressure and temperature of the released CO2, acoustic emission of CO2 in dissolution and released CO2 flow, which allow knowing the fermentation kinetics very accurately for the purpose of carrying out a control of the optimal fermentation temperature, as well as a control of the optimal aeration or oxygenation, by means of acoustic emission techniques.
The invention proposes, with respect to and controls of temperature of AF, of aeration or oxygenation known in the state of the art, measuring the acoustic emission of CO2 in dissolution and in a released CO2 flow which allows knowing at an early time the evolution of fermentation kinetics (speed) as it is proportional to the CO2 generation speed, implementing an optimal control of temperature, aeration or oxygenation by means of acoustic emission techniques which have been found to achieve, for a maximum generated CO2 speed of 0.81 g of CO2/l/h, a reduction of 16.25%*(3.25% per degree of hysteresis) in the duration of fermentation with respect to the mean of isothermal controls of temperature in red wine (22° C.-26° C.), simultaneously obtaining an increase in wine quality of 5-10%* in the total polyphenol index (TPI) which causes a qualitative leap in terms of organoleptic parameters (proven in tasting sessions by means of sensory analysis).
(*) Results obtained by UNIVERSIDAD DE LA RIOJA during the 2018 and 2019 grape harvests. A campaign of in situ measurements in the must obtained in six conventional red wine fermentation tanks and in six tanks with the system claimed in the present invention was carried out in each grape harvest.
To complement the description and for the purpose of helping to better understand the features of the invention, a set of illustrative and non-limiting figures as well as a glossary with the references used in the figures along with a description of each reference are attached as an integral part of said description.
A preferred embodiment of the invention, from among different possible alternatives, is described in detail by means of listing the components of the embodiment, as well as their functional relationship based on references to the figures, which have been included, in an illustrative and non-limiting manner, according to the principles of the claims. Reference is made to the figures, where necessary, in order to better understand what is shown therein.
Once the bunches of grape are destemmed (with the stem removed), the dense must (pulp or mesocarp, seeds, skins, and bloom) coming from the red grape, although it can also be rosé or even white, is sent to the self-emptying fermentation tank (0) provided with a device for continuous monitoring and improved automatic control of temperature, and of aeration-oxygenation, of the process of alcoholic fermentation in wine by means of acoustic emission techniques (D1), in order to proceed with alcoholic fermentation.
The invention proposes, with respect to and controls of temperature of AF, of aeration or oxygenation known in the state of the art, measuring the acoustic emission of CO2 in dissolution and in a released CO2 flow which allows knowing at an early time the evolution of fermentation kinetics (speed) as it is proportional to the CO2 generation speed, implementing an optimal control of temperature, aeration or oxygenation by means of acoustic emission techniques which have been found to achieve, for a maximum generated CO2 speed of 0.81 g of CO2/l/h, a reduction of 16.25%*(3.25% per degree of hysteresis) in the duration of fermentation with respect to the mean of isothermal controls of temperature in red wine (22° C.-26° C.), simultaneously obtaining an increase in wine quality of 5-10%* in the total polyphenol index (TPI) which causes a qualitative leap in terms of organoleptic parameters (proven in tasting sessions by means of sensory analysis).
(*) Results obtained by UNIVERSIDAD DE LA RIOJA during the 2018 and 2019 grape harvests. A campaign of in situ measurements in the must obtained in six conventional red wine fermentation tanks and in six tanks with the system claimed in the present invention was carried out in each grape harvest.
Therefore, the invention seeks to perform continuous tracking of alcoholic fermentation in wine by means of acoustic emission techniques using the following subsystems comprised in the invention: —an instrumentation subsystem (1); —an acoustic emission instrumentation subsystem (2); —a gas processing and storage subsystem for the gases of air, CO2, N2 or O2 (3); and—a control subsystem (4).
The invention proposes a device for continuous monitoring and improved automatic control of temperature of the process of alcoholic fermentation in wine by means of acoustic emission techniques (D1), of the type of devices that incorporate means for tracking and controlling alcoholic fermentation in a self-emptying fermentation tank (0), and is characterized in that the means for tracking and controlling comprise:
A set of sensors arranged in the self-emptying fermentation tank (0) in the torispherical head, these sensors being:
A set of sensors arranged in the self-emptying fermentation tank (0) in the upper cylindrical body, these sensors being:
A set of sensors arranged in the self-emptying fermentation tank (0) in the lower cylindrical body, these sensors being:
Therefore, calculation of the density (D) of the fermentation must is performed based on measurements given by pressure sensors (13, 15). Since the tank is closed, the CO2 released in the upper part thereof causes a pressure in the fermentation must which causes a calculation error of the density (D) of the fermentation must; this is due to the fact that Pascal's principle which states that “pressure applied to a point of a static incompressible fluid confined in a container is transmitted entirely to all the points of the fluid” is not complied with given that the fermentation must contains a fraction of CO2 in dissolution, which is a compressible gas; error elimination is carried out based on the measurement given by the pressure sensor (10) which measures the pressure (P) of CO2 or other gases. To that end, the invention proposes performing an initial calibration before starting alcoholic fermentation which consists of performing a first measurement by means of the three pressure sensors (13, 15, and 10) when there is still no CO2 dissolved in the fermentation must (error-free measurement) and a second measurement by injecting CO2 (measurement with error), opening the injection control valve (35) of the gas processing and storage subsystem (3) until the pressure sensor (10) indicates the same CO2 pressure as the working pressure marked by the inerting control valve (32); the error produced in the pressure sensors (13, 15) (error=measurement with error−error-free measurement) is obtained with both measurements. In general, the pressure of the inerting control valve (32) is fixed for each type of tank, so calibration only needs to be performed once.
In this case, ultrasound signals are not processed, rather the vibro-acoustic emission (below the ultrasonic frequency range) generated by the carbon dioxide gas resulting from respiration and alcoholic fermentation is captured. The effects of temperature on the alcoholic fermentation range do not significantly affect measurements.
The subsystem (3) further contains in a preferred embodiment a plurality of valves, these valves being:
The subsystem (3) further contains in a preferred embodiment a plurality of tanks, these tanks being:
The subsystem (3) further contains in a preferred embodiment a compressor (315) with a design pressure of 10 bar according to ISO 8573-1 standard, class 0, in terms of the quality of air suitable for the food industry; and an N2 generator (318); being an N2 generator for inerting the fermentation tank (0).
In a preferred embodiment, the inerting control valve (32) will allow pressurizing in a range of minimum 5 mbar and maximum 40 mbar for large tanks (0) and minimum 5 mbar and maximum 120 mbar for other tanks (0).
A method for continuous monitoring and improved automatic control of temperature of the process of alcoholic fermentation in wine by means of acoustic emission techniques (P1) using a system (D1) for the implementation thereof is described in detail by means of listing the steps to be executed according to the indicated order.
In order to improve understanding and clarity, the operation of each step and sub-step is graphically described by means of Graphs of Control by Steps and Transitions (GRAFCET) and Piping and Instrumentation Diagrams (P&IDs), mentioning in each of them the corresponding figure in each case, avoiding textual description as it is less clear. The P&IDs show the active element in grey and passage through the pipes in black. In the GRAFCET: in selected steps “a-f”, the equations of transition of each sub-step, as well as the actuators activated in each of them, are indicated; in steps that are likely to work simultaneously, i.e., steps “g, h, i”, the equations of transition of each sub-step, as well as the actuators activated and deactivated in each of them, are indicated. The invention proposes a method for continuous monitoring and improved automatic control of temperature of the process of alcoholic fermentation in wine by means of acoustic emission techniques (PI) using a system (D1) for the implementation thereof, of the type of methods which interact with means for tracking and controlling alcoholic fermentation in a self-emptying fermentation tank (0), comprising a method module implemented in a PLC program (P0), installed in a PLC (401) which incorporates means for communicating with an HMI device (402); wherein if the hardware (HW) of the PLC (401) is correct (OK), a start block is cyclically executed (
STEP “a” (P10): Providing, in a Controlled Manner, by Means of Acoustic Emission Techniques, a Fermentation Tank (0, D1) with a Gas Mixture (Air+CO2), Allowing Yeasts to Perform Respiration Exclusively.
The passage of air to the fermentation tank (0, D1) is allowed or prevented to perform aeration or oxygenation by means of an aeration or oxygenation control valve (111), and the passage of CO2 to said fermentation tank (0, D1) is allowed or prevented by means of an injection control valve (35).
In this step “a” (P10), it is proposed that the yeast (naturally present or artificially inoculated) mainly performs, by means of the supply of gas (air and CO2), respiration controlled by means of acoustic emission techniques in a fermentation tank (0) in which a device (D1) object of the invention has been implemented.
In this optional step “a” (P10), the object is to reduce the probable alcoholic strength of the wine, causing the yeast to perform respiration by providing it with the required air (of which the yeast will use oxygen), such that a part of the sugars in the must undergoes respiration instead of fermentation. Subsequently, the air supply must be stopped in order to continue with the conventional process of fermentation, since an excess presence of oxygen causes a reduced quality of the wine (Gonzalez et al., 2013).
The chemical equation (symbolic description) of the chemical reaction of respiration is as follows:
C6H12O6(glucose/fructose)+6·O2→6·H2O(water)+6·CO2+Q(kJ) RESPIRATION
With the following stoichiometry:
The CO2 (gas) generated during respiration remains in dissolution until it is released once the fermentation must (liquid) becomes saturated, whereas the water (liquid) remains in dissolution (three times as much CO2 is produced in respiration compared to fermentation).
The CO2 is suctioned for subsequent injection into the fermentation must for the purpose of achieving homogenization, avoiding the performance of pumping over.
During an exhaustive experimentation campaign, it has been found that, in a preferred embodiment, the maximum aeration conditions which maintain the quality of the wine since the level of dissolved oxygen is kept close to zero from the start and the levels of acetic acid at the end of the process are similar to those obtained in an anaerobic process of alcoholic fermentation (0.3 g/I) are:
Lower aeration conditions may arise maintaining the quality of the wine, but with an ethanol reduction of less than 2% (v/v).
STEP “a” (P10) comprises a prior routine sub-step, STEP “a.0” (P100), of refilling the air tank (317) which is implemented, by way of illustration, in a preferred embodiment of the invention, for the purpose of refilling the air tank (317) within operating limits according to the pressure thereof (
STEP “a” (P10) of respiration with air is characterized in that it comprises at least the following sub-steps (
The following can be selected simultaneously along with STEP “a” (P10):
STEP “b” (P20): Providing, in a Controlled Manner, by Means of Acoustic Emission Techniques, a Fermentation Tank (0, D1) with a Qas Mixture (O2+CO2), Allowing Yeasts to Perform Respiration Exclusively.
The passage of O2 to the fermentation tank (0, D1) is allowed or prevented to perform aeration or oxygenation by means of an aeration or oxygenation control valve (111), and the passage of CO2 to said fermentation tank (0, D1) is allowed or prevented by means of an injection control valve (35).
In this STEP “b” (P20), it is proposed that the yeast (naturally present or artificially inoculated) mainly performs, by means of the supply of gas (O2 and CO2), respiration controlled by means of acoustic emission techniques in a fermentation tank (0) in which a device (D1) object of the invention has been implemented.
STEP “b” is similar to STEP “a” but with the difference that a gas mixture containing O2 instead of air is provided.
During an exhaustive experimentation campaign, it has been found that, in a preferred embodiment, the maximum oxygenation conditions which maintain the quality of the wine since the level of dissolved oxygen is kept close to zero from the start and the levels of acetic acid at the end of the process are similar to those obtained in an anaerobic process of alcoholic fermentation (0.3 g/l) are:
Lower oxygenation conditions can arise maintaining the quality of the wine, but with an ethanol reduction of less than 2% (v/v).
STEP “b” (P20) of respiration with O2 is characterized in that it comprises at least the following sub-steps (
The following can be selected simultaneously along with STEP “b” (P20):
The passage of air to the fermentation tank (0, D1) is allowed or prevented to perform aeration or oxygenation by means of an aeration or oxygenation control valve (111), and the passage of CO2 to said fermentation tank (0, D1) is allowed or prevented by means of an injection control valve (35).
In this STEP “c” (P30), it is proposed that the yeast (naturally present or artificially inoculated) mainly performs, by means of the supply of gas (CO2 and air), alcoholic fermentation monitored and controlled by means of acoustic emission techniques in a fermentation tank (0) in which a device (D1) object of the invention has been implemented.
The chemical equation (symbolic description) of the chemical reaction of alcoholic fermentation is as follows:
C6H12O6(glucose/fructose)→2·C2H5OH(ethanol)+2·CO2+Q(kJ) FERMENTATION
With the following stoichiometry:
The CO2 (gas) generated during alcoholic fermentation remains in dissolution until it is released once the fermentation must (liquid) becomes saturated, whereas ethanol (liquid) remains in dissolution, although a small fraction of ethanol is lost through evaporation.
The CO2 is suctioned for subsequent injection into the fermentation must for the purpose of achieving homogenization, avoiding the performance of pumping over.
The aeration in this STEP “c” allows the yeast to also perform respiration for the purpose of facilitating its growth and reproduction by providing it with the required air (of which the yeast will use oxygen), such that a part of the sugars in the must undergoes respiration instead of fermentation. STEP “c” differs from STEP “a” in that in STEP “a” respiration is performed continuously for some time, whereas in this STEP “c” respiration can be performed discontinuously or continuously together with fermentation, producing wines with more color that is fixed by the oxygen from aeration, in addition to achieving a greater disassociation of tannins and anthocyanins.
The maximum aeration conditions which maintain the quality of the wine since the level of dissolved oxygen is kept close to zero from the start and the levels of acetic acid at the end of the process are similar to those obtained in an anaerobic process of alcoholic fermentation (0.3 g/l) are the same as those found during the experimentation campaign described in STEP “a”, these conditions being:
Lower aeration conditions can arise maintaining the quality of the wine, but with an ethanol reduction of less than 2% (v/v).
This step comprises a prior routine sub-step, STEP “a.0” (P100), of refilling the air tank (317) which is implemented, by way of illustration, in a preferred embodiment of the invention, for the purpose of refilling the air tank (317) within operating limits according to the pressure thereof (
STEP “c” (P30) of alcoholic fermentation plus aeration is characterized in that it comprises at least the following sub-steps (
The following can be selected simultaneously along with STEP “c” (P30):
The passage of O2 to the fermentation tank (0, D1) is allowed or prevented to perform aeration or oxygenation by means of an aeration or oxygenation control valve (111), and the passage of CO2 to said fermentation tank (0, D1) is allowed or prevented by means of an injection control valve (35).
In this STEP “d” (P40), it is proposed that the yeast (naturally present or artificially inoculated) mainly performs, by means of the supply of gas (CO2 and O2), alcoholic fermentation monitored and controlled by means of acoustic emission techniques in a fermentation tank (0) in which a device (D1) object of the invention has been implemented.
STEP “d” is similar to STEP “c” but with the difference that a gas mixture containing O2 instead of air is provided.
The oxygenation of this STEP “d” allows the yeast to also perform respiration for the purpose of facilitating its growth and reproduction by providing it with the required oxygen, such that a part of the sugars in the must undergoes respiration instead of fermentation. STEP “d” differs from STEP “b” in that in STEP “b” respiration is performed continuously for some time, whereas in this STEP “d” respiration can be performed discontinuously or continuously together with fermentation, producing, like in the preceding step, wines with more color that is fixed by the oxygen from oxygenation, in addition to achieving a greater disassociation of tannins and anthocyanins.
The maximum oxygenation conditions which maintain the quality of the wine since the level of dissolved oxygen is kept close to zero from the start and the levels of acetic acid at the end of the process are similar to those obtained in an anaerobic process of alcoholic fermentation (0.3 g/I) are the same as those found during the experimentation campaign described in STEP “b”, these conditions being:
Lower oxygenation conditions may arise maintaining the quality of the wine, but with an ethanol reduction of less than 2% (v/v).
STEP “d” (P40) of alcoholic fermentation plus oxygenation is characterized in that it comprises at least the following sub-steps (
The following can be selected simultaneously along with STEP “d” (P40):
A routine step which is implemented, by way of illustration, in a preferred embodiment of the invention (
STEP “f” (P60): Performina a Normal Stop in the Control of a Fermentation Tank (0. D1).
A routine step which is implemented, by way of illustration, in a preferred embodiment of the invention (
STEP “g” (P70): Monitoring and Controlling the Temperature in a Fermentation Tank (0, D1) by Means of Acoustic Emission Techniques.
Since alcoholic fermentation is an exothermic reaction, the heat generated during the process of fermentation must be removed in order to maintain the optimal temperature. To that end, a cooling system of any of the state of the art is used which, by means of a cooling control valve (113), allows or prevents the passage of the liquid coolant to the jackets (05) of the fermentation tank (0, D1).
One of the parameters having the most influence on the evolution of the process of alcoholic fermentation is temperature which, in addition to an optimum temperature, contributes to obtaining wine with the typical characteristics of its denomination. In general, wines prepared at low temperature are more aromatic and better valued in the organoleptic analysis but, on the other hand, their fermentation can be incomplete.
The acoustic emission (ACO2) caused by the CO2 generated during respiration and alcoholic fermentation is measured and the acoustic emission speed (dACO2/dt) is calculated for the early detection of the fermentation speed (g of CO2/l/h) (amount, by weight or by volume, of CO2 produced per unit of time), and therefore the activity of the yeasts.
In a preferred embodiment, the analog signal of the omnidirectional hydrophone sensor (20) is collected in the slave panel (41), being sent to the main control panel (40) and reaching the programmable logic controller (401) where it is internally converted to a digitalized signal, first being processed in a calibration module (P101) of the program (P0) to obtain the basic amplitude, frequency, and spectral descriptors thereof by applying fast Fourier transform (FFT); with the correct frequency range, the digitalized signal passes to the filtration module (P102) where a digital filter is applied to the signal to discriminate frequencies not related with the process of fermentation, finally obtaining the real-time value of the acoustic emission (ACO2).
According to another configuration for obtaining acoustic emission (ACO2), noise from aeration, oxygenation, CO2 injection recirculation of cooling water through the jackets, and any other desired noise is eliminated; to that end, before the start of alcoholic fermentation the acoustic emission of aeration (AAera), of oxygenation (AO2), of CO2 injection (AICO2), of cooling (AR), and of any other desired noise (AO) is recorded, then, noise is eliminated from the acoustic emission measured in the fermentation must (AMF) by means of the following equation:
ACO2=AMF−AAera−AO2−AICO2−AR−AO
since the PLC program (P0), installed in the PLC (401), has at all times the state of the aeration, oxygenation, CO2 injection, and cooling sub-steps so that in the case where one or more of them are activated, the corresponding noise from the active sub-steps can be subtracted by means of the preceding equation; that which is indicated above is performed if a noise emitting source is detected for the purpose of obtaining only the acoustic emission (ACO2) caused by the CO2 generated during respiration and alcoholic fermentation.
When the acoustic emission speed (dACO2/dt), i.e., CO2 production, exceeds a previously established limit ((ACO2)setpoint), taking into account a preestablished hysteresis value (Δ(ACO2)), the cooling control valve (113) is opened to keep the temperature within compatible winemaking limits to stabilize alcoholic fermentation, as shown in the following simple conditional logic equation (
When the acoustic emission speed (dACO2/dt), i.e. production of CO2, is below a previously established limit ((ACO2)setpoint), taking into account a preestablished hysteresis value (Δ(ACO2)), the cooling control valve (113) is closed allowing the temperature to rise to within compatible winemaking limits in order to reactivate alcoholic fermentation, as shown in the following simple conditional logic equation (
This set of indicated operations allows an optimum alcoholic fermentation kinetics (speed), as well as a quicker completion of fermentation.
STEP “h” (P80): Monitoring and Controlling the Aeration or Oxygenation of a Fermentation Tank (0, D1) by Means of Acoustic Emission Techniques.
The passage of air or oxygen to the fermentation tank (0, D1) is allowed or prevented to perform aeration or oxygenation by means of an aeration or oxygenation control valve (111).
The acoustic emission (ACO2) caused by the CO2 generated during respiration and alcoholic fermentation is measured and the acoustic emission speed (dACO2/dt) is calculated for the early detection of the fermentation speed (g of CO2/l/h), and therefore the activity of the yeasts.
In a preferred embodiment, the analog signal of the omnidirectional hydrophone sensor (20) is collected in the slave panel (41), being sent to the main control panel (40) and reaching the programmable logic controller (401) where it is internally converted to a digitalized signal, first being processed in a calibration module (P101) of the program (P0) to obtain the basic amplitude, frequency, and spectral descriptors thereof by applying fast Fourier transform (FFT); with the correct frequency range, the digitalized signal passes to the filtration module (P102) where a digital filter is applied to the signal to discriminate frequencies not related with the process of fermentation, finally obtaining the real-time value of the acoustic emission (ACO2).
According to another configuration for obtaining acoustic emission (ACO2), noise from aeration, oxygenation, CO2 injection recirculation of cooling water through the jackets, and of any other desired noise is eliminated; to that end, before the start of alcoholic fermentation the acoustic emission of aeration (AAera), of oxygenation (AO2), of CO2 injection (AICO2), of cooling (AR), and any other desired noise (AO) is recorded, then, noise is eliminated from the acoustic emission measured in the fermentation must (AMF) by means of the following equation:
ACO2=AMF−AAera−AO2−AICO2−AR−AO
since the PLC program (P0), installed in the PLC (401), has at all times the state of the aeration, oxygenation, CO2 injection, and cooling sub-steps so that in the case where one or more of them are activated, the corresponding noise from the active sub-steps can be subtracted by means of the preceding equation; that which is indicated above is performed if a noise emitting source is detected for the purpose of obtaining only the acoustic emission (ACO2) caused by the CO2 generated during respiration and alcoholic fermentation.
When the acoustic emission speed (dACO2/dt), i.e., CO2 production, is below a previously established limit ((ACO2)setpoint), taking into account a preestablished hysteresis value (Δ(ACO2)), the aeration or oxygenation control valve (111) is opened in order to reactivate the activity of the yeasts, as shown in the following simple conditional logic equation (
When the acoustic emission speed (dACO2/dt), i.e., CO2 production, exceeds a previously established limit ((ACO2)setpoint), taking into account a preestablished hysteresis value (Δ(ACO2)), the aeration or oxygenation control valve (111) is closed in order to deactivate the excessive activity of the yeasts, as shown in the following simple conditional logic equation (
This operation allows aeration or oxygenation metering to be optimized, as required, until the accumulated flow (f18), measured by the aeration or oxygenation flowmeter sensor (18), reaches the setpoint value (fsetpoint), obtaining an increase in wine quality in the Total Polyphenol Index (TPI) which causes a qualitative leap in terms of organoleptic parameters.
STEP “i” (P90): Performing an Emergency Stop in the Control of a Fermentation Tank (0, D1).
A routine step which is implemented, by way of illustration, in a preferred embodiment of the invention (
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/ES2021/070247 | 4/14/2021 | WO |
