RU2401014C1 - Method to control process of drying raw smoked and raw dried meat and fish products in convective installation of chamber type - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: invention is based on principle of drying high-moisture food products, which is carried out at permanent speed of moisture release - evaporation from surface of product, at the same time temperature of moisture evaporation from surface of product remains at the permanent level, provided that value of relative humidity of air in working chamber of installation reduces in process of drying. Temperature of water evaporation from surface of product is measured with the help of sensitive thermoelectric sensor.

EFFECT: improved monitoring and control of raw smoked and raw dried fish and meat products drying process.

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Description

The invention relates to the technology of food products, more specifically to resource-saving technologies for the production of high-quality biologically safe food products and environmentally friendly food production; as well as to technological equipment of the meat and fish industry, more specifically to machines and devices, processes of refrigeration and cryogenic equipment, air conditioning systems, and can be used in the food industry.

A known method of controlling the drying process of smoked and dried sausages, according to which the drying of sausages is carried out at a temperature of 10-12 ° C and a decreasing relative humidity (90-70%). Management of variable temperature and humidity modes of drying (ripening) of sausages is implemented according to a special program recorded in the memory of the microprocessor control unit [Some features of the production of raw smoked sausages in the conditions of sausage shops of low power. Fatyanov E.V., Aleinikov A.K., Bogachev B.V., Kamenetsky M.L., Pykhtin V.V. // “Food. Ecology. Man ”: Materials of the third international scientific and technical conference. M .: MGUPB, 1999, p.110], [Fatyanov E.V., Aleinikov A.K. Temperature and humidity treatment of meat products. // “Food. Ecology. Man ”: Materials of the international scientific and technical conference. M .: MGUPB, 1995, p.108].

The above analogue does not take into account differences in raw meat in chemical composition, moisture state, directivity and duration of autolysis.

The closest in technical essence and the achieved result is a method of controlling the drying process of raw smoked and dry-cured sausages, according to which the drying of sausages is based on the assessment of moisture loss or mass of the product during dehydration in real time [Shazzo RI Study of the processes of drying smoked sausages in order to develop technical means to create optimal conditions. Abstract. dis. Cand. tech. Sciences - M .: MTIMMP, 1981]. The drying process of sausages is controlled by the method of periodic weighing using spring or electronic scales, additionally equipped with a discharge mechanism for the sample of the drying object under study.

This method has a delayed response to changes in the physicochemical properties of the meat system of the product during drying-ripening.

As a result of these shortcomings, the likelihood of lowering the quality of products, increasing the time and energy spent on the drying process increases, and the complexity of developing a drying regime for new non-standard types of meat and fish products increases.

The present invention solves the problem of improving the control and management of the drying process of raw smoked and dry-cured fish and meat products, including sausages, by estimating the temperature of evaporation of water from the surface of the product using a sensitive thermoelectric sensor.

The problem is solved in a method of controlling the drying process of raw smoked and dry-cured meat and fish products, which includes two stages in which the mode according to the value of relative humidity and the duration of the 1st stage of drying of the product is determined from the condition of the minimum temperature of evaporation of moisture from the surface of the drying object, which is measured by a sensitive thermoelectric sensor and determine its minimum value in the time interval using an electronic differentiating device, which corresponds to the maximum possible rate of moisture evaporation at the current moment or time interval of the drying process, and support it using the control unit, while the process is carried out in a pulsed mode blowing air through the drying object, consisting of pulses and pauses, each lasting 15-60 minutes, depending from the average mass and type of product using a time relay of the control unit, and the maximum possible drying rate of the product is periodically evaluated at the beginning of each active phase of the air exchange cycle and the corresponding this cycle, the maximum rate of moisture evaporation and the minimum temperature of moisture evaporation from the surface of the drying object, the determination of which is carried out by gradually increasing the intensity of cooling and drying the air in the working chamber of the drying unit by controlling the amount of heat transfer and mass transfer between the air cooler, drying agent and the surface of the dried product with using the control unit, refrigeration unit and fans; air blow pulses, in turn, alternate in reverse mode, the process is carried out until the start of the increase in the temperature of moisture evaporation from the surface of the drying object, which occurred regardless of the intensity of dehydration of the drying agent in the working chamber with an air cooler, which in turn signals the completion of the 1st stage of drying product the mode according to the value of relative humidity at the 2nd stage of product drying is set at the same level, or according to a decreasing stepwise algorithm.

The basis of the invention is the principle of the 1st stage of drying high-moisture food products, which is carried out at a constant rate of release (evaporation) of moisture from the surface of the product, while the temperature of evaporation of moisture from the surface of the product remains at a constant level, but provided that the value of relative humidity air (HF) in the working chamber is reduced during drying [Ginzburg A.S. Fundamentals of the theory and technique of drying food products. - M .: Food industry, 1973. - S. 179-184]. As a sensitive thermoelectric sensor, an electrical resistance thermometer based on a platinum winding of a needle or other compact design, or a semiconductor sensor or a needle thermocouple should be used.

The proposed method for controlling the drying process of raw smoked and dry-cured meat and fish products differs from similar industrial drying technologies by the presence of the following features:

1. Monitoring the drying process and adjusting the relative humidity (RH) according to a stepwise or gradually decreasing algorithm depending on the current processing time in a convection-type drying chamber-type installation according to the temperature of moisture evaporation from the surface of the drying object, with its value and the rate of moisture evaporation from the surface of the object drying there is an inverse correlation. The temperature of evaporation of moisture from the surface of the drying object is measured using an additionally installed sensitive thermoelectric sensor. The signal from the thermoelectric sensor is transmitted to a temperature meter-controller with an electronic signal differentiation device built into the control unit (or connected with it), and then to the actuators of the air conditioning system in the working chamber of the dryer. Depending on the kinetics of the temperature of evaporation of water from the surface of the product, the intensity of air dehydration in the working chamber of the dryer is controlled by various methods using the listed elements of the control system. For example, a method of regulating the supply of refrigerant to the evaporator of an air cooler or changing the temperature of the refrigerant or regulating the intensity of heat and mass transfer (moisture exchange) between the air cooler and the circulating air inside the working chamber of the drying unit. As a result, it is possible to more accurately control the dehydration process of meat and fish products than when using the program unit for controlling the drying mode of the product (i.e., RHV value) using a conventional temperature controller (and RHV) meter, additionally equipped with a signal differentiation device from a sensitive thermoelectric sensor, a certain stage of the processing process. Here, the principle of self-regulation of the drying mode is implemented according to a decreasing stepwise (or linear) algorithm for changing the SIR in the working chamber of the drying installation. This technological solution is especially important for drying uncooked and dry-cured sausages. The regime according to the RH value and the duration of the 1st stage of drying the product (phase of constant drying speed) are determined from the condition of the minimum temperature of evaporation of moisture from the surface of the product, corresponding to the maximum possible intensity of moisture evaporation at the current moment (interval) of the process using a differentiating electronic device. This device is built into the temperature meter-controller circuit and processes the signal from a sensitive thermoelectric sensor.

- скорость сушки продукта (интенсивность испарения влаги с поверхности объекта сушки), кг воды/час на 1 кг сухого вещества;

- максимальная скорость сушки продукта (интенсивность испарения влаги с поверхности объекта сушки) в текущем интервале времени процесса сушки, кг воды/ час на 1 кг сухого вещества; t_i ^исп - текущая температура испарения влаги с поверхности продукта, °С; t_возд - температура воздуха в рабочей камере сушильной установки, °С; t_min - минимальная температура испарения влаги с поверхности продукта в текущем интервале времени процесса сушки, °С.2. The method of measuring (detecting) the maximum possible rate of moisture evaporation from the surface of the processed product by determining the minimum temperature of moisture evaporation from the surface of the dried object at the current time (interval) of the time of the 1st stage of drying. The method is based on the use of a pulsed mode of internal air circulation in the working chamber with the workpiece and cyclic lowering of the SIR value by lowering the temperature of the air cooler of the drying unit and (or) increasing the intensity of heat and mass transfer (moisture exchange) between the air cooler and the circulating air inside the drying chamber installation, as shown in the drawing, where a is the curve of the drying speed, that is, the rate of evaporation of moisture from the surface of the product; b - curve of the temperature of evaporation of moisture from the surface of the product; φ _i - the current value of the relative humidity in the working chamber of the drying installation,%; φ _equal - the equilibrium value of the relative humidity above the product surface at the beginning of the current interval (active phase) of the drying process,%; f _optim - the optimal value of the relative humidity in the working chamber of the drying installation to ensure maximum evaporation of moisture from the surface of the product,%; f _hardening - the value of relative humidity, at which there is a "hardening" of the surface of the product and the cessation of drying,%;

- the drying rate of the product (the rate of evaporation of moisture from the surface of the drying object), kg of water / hour per 1 kg of dry matter;

- the maximum drying rate of the product (the rate of moisture evaporation from the surface of the drying object) in the current time interval of the drying process, kg of water / hour per 1 kg of dry matter; t _i ^isp is the current temperature of evaporation of moisture from the surface of the product, ° C; t _air - air temperature in the working chamber of the drying installation, ° C; t _min - the minimum temperature of evaporation of moisture from the surface of the product in the current time interval of the drying process, ° C.

3. The mode according to the value of relative air humidity at the 2nd stage of drying of the product (the stage of falling drying speed) is set at one fixed level, depending on the required (required) final value of water activity in the center of the product, or is regulated in a known manner.

The pulse air blowing mode of the product consists of pulses and pauses, each lasting from several minutes to several hours, depending on the type of product and the average weight of the sample of the processed product. Pulses of air blowing, in turn, alternate in reverse mode. This is done by controlling the operation of the fans and the refrigeration unit using a time relay integrated in the control unit. So for meat and fish products, the duration of pulses and pauses is 15-60 minutes, depending on the average weight and type of product.

Throughout the entire 1st stage of drying a food product, provided that the working chamber of the drying unit is fully loaded, the air drying rate of the air conditioning system inside the working chamber is established from the condition of the maximum rate of moisture evaporation from the surface of the drying object at the initial moment of the current drying interval, the moisture evaporation temperature from the surface of the product is accordingly minimal.

The maximum possible speed of the 1st stage of product drying is periodically evaluated during the pulse mode of blowing off the drying object at the beginning of the active phase of the air exchange cycle, and the maximum moisture evaporation rate corresponding to this cycle and, accordingly, the minimum temperature of moisture evaporation from the surface of the workpiece are set. This operation is carried out by gradually increasing the intensity of cooling and drying the air in the working chamber of the drying unit by regulating the amount of heat transfer and mass transfer between the air cooler, drying agent and the surface of the dried product using an air cooler, fans and a time relay of the control unit. After establishing the necessary intensity of air drying in the working chamber of the drying unit, further, the temperature of evaporation of moisture from the surface of the product is either constant or decreases during drying-ripening of the product. An increase in the temperature of moisture evaporation from the surface of the drying object, regardless of the intensity of air dehydration in the working chamber by the air conditioning system, signals the completion of the 1st stage of drying the product and, accordingly, the beginning of the 2nd stage of drying. The SIR value at the 2nd stage of product drying is set at one fixed level, which depends on the required (required) final value of the water activity in the product center, or is regulated in a known manner, or SIR is set at one technologically standard level, or according to a decreasing stepwise algorithm.

Thus, the mode of self-regulation of the current value of organic matter during the drying of raw smoked and dry-cured meat and fish products by the temperature of evaporation of moisture from the surface of the processed product allows for a better quality drying process with less time and energy. He also exempts from the need to draw up an individual drying program in the development of new technologies, including recipes, food products. In addition, this invention allows to simplify the control procedure of the drying unit both in industrial production and in laboratory work. This is very convenient for scientific and technological research.

The proposed method for controlling the drying process of raw smoked and dry-cured meat and fish products using a convection drying apparatus is carried out in practice as follows.

The processed product (drying object) is loaded into the working chamber of the drying unit, on one of the samples of which a sensitive thermoelectric sensor of a needle structure is fixed, the chamber door is hermetically closed. A drying unit together with a refrigerating machine, a control unit and a temperature measuring instrument-regulator of the surface of the drying object are connected to the power supply. On the electronic controller of the control unit, the temperature of the drying process, regulated by the technology of the particular workpiece, is set, and the SIR value in the working chamber is set to 100% or the equilibrium SIR value relative to the surface of the product. During the entire 1st stage of drying the product, the air velocity is set equal to 0.5-1.0 m / s for meat products [A.S. No. 741624 of the USSR]. And for fish products its value is: dried - 1.5-2.2 m / s (or 0.5-3.0 m / s for capelin), dried - 60-90 cm / min (in some cases from 0 , 13 to 2.0 m / s), cold smoked during drying - from 0.5-1.0 to 1.5-2.0 m / s. Using the control unit, the SIR value in the drying chamber of the drying unit is gradually reduced until the temperature of evaporation of moisture from the surface of the drying object becomes minimal. This value is maintained with the help of the control unit and the meter-controller of the temperature of the surface of the drying object during one cycle of fans for internal air circulation. One cycle consists of pulses and pauses, the duration of which for most meat and fish products is 15-60 minutes, depending on the average weight and type of product. At the beginning of subsequent fan cycles, the operation to determine the minimum value of the temperature of evaporation of moisture from the surface of the drying object is repeated. This algorithm is carried out until the determination of the minimum surface temperature of the product becomes impossible, which signals the completion of the stage of constant drying speed of the workpiece (1st stage of drying) and the beginning of the stage of decreasing drying speed (2nd stage of drying).

To carry out the last stage of drying a food product (drying) on the electronic controller of the control unit, set the temperature and the SIR value of the drying process, regulated by the technology of the particular product being processed.

The mode according to the value of the OVV inside the drying chamber at the 2nd stage of drying of smoked and dry-cured meat products is regulated by one of two known methods:

1. Setting the SIR value at one fixed technologically standard level (traditional drying technology), namely φ _i = 76 ± 2%;

2. Using a step-by-step algorithm with a uniform decrease in time of the SIR value, the initial value of which depends on the equilibrium SIR value above the product surface at the end of the 1st stage of drying (according to the advanced drying technologies as applied to the proposed method for controlling the drying process). Namely, they are set, for example, by the initial value of relative humidity:

φ _beg. = φ _{equal to over. 1st Art. sushi} -5, %;

where φ is _{equal to over. 1st Art. sushi} - the equilibrium value of the relative humidity above the surface of the product after the 1st stage of drying,%.

The final SIR value is set, for example, at the level of 82-75% or 86% depending on the technological features of the processed product. The reduction of the SIR value is carried out uniformly (linearly) during the stage of drying by the method of program control.

The author of the present invention proposes a technique for carrying out the 2nd stage of drying (drying) of raw smoked and dry-cured meat products in relation to the described method of controlling the drying process, according to which the regime according to the value of the SIR inside the drying chamber is set at one fixed level depending on the required (required) final value water activity in the center of the product:

φ _dos. = a _{w con.} × 100-5,%,

where a _{w con.} - the required final value of the activity of water in the center of the product.

For example, a _{w con.} = 0.88, then φ _dos . = 0.88 × 100-5 = 83,%.

Draining should be carried out until a _wi = a _{w con.} ± 0.005,

where a _wi is the current value of the activity of water in the center of the product.

And for fish products, the value of the OVV of the drying agent is:

- dried - 40-50%; in the case of applying a pulsating (intermittent) regime of blowing the product with air in practice, it is recommended in the active phase of the process in the first 20-24 hours of drying 50-60%, the rest of the time 40-60%, with a passive phase of the process - 60-80%;

- dried - 50-55%;

- cold smoked during drying - 40-60%.

During the entire 2nd stage of drying the product, the air velocity in the working chamber for meat products is set equal to 0.1-0.2 m / s (i.e. 2 × (0.05-0.1), m / s). And for fish products, its value is left unchanged, as was established at the 1st stage of drying. The completion of the drying process of the processed product can be determined by the density (hardness) of the structure, the yield of the finished product (by the final mass) or the value of the activity of water in the center of the product, regulated by the technology of the particular processed product. Be sure to control the value of the mass fraction of moisture in the finished product, which should correspond to the normative value for each type of product.

The technical result.

The application of the above-described method for controlling the drying process of uncooked smoked and dry-cured meat and fish products in a convective chamber-type installation (depending on the autolytic maturation direction and chemical composition of the feedstock) provides:

- preventing the formation of excessive drying of the surface layer of the product ("hardening"), significantly slowing down the drying speed of the product, including with the exception of the complex laborious procedure for developing a step mode of soft drying for a particular type of product and its implementation in practice;

- a decrease in the gradient of the mass fraction of moisture ΔW _{surface-center} , which characterizes the quality of drying of the product in comparison with the traditional method (technology and technique) of drying;

- the possibility of increasing the yield of finished products and reducing the drying time by reducing the gradient of the mass fraction of moisture along the cross section of the processed product.

And the proposed method (technique) for drying meat products provides:

- obtaining products with a given value of water activity and a guaranteed level of safety;

- a significant simplification of the mode of drying the product.

This method of controlling the drying process of products in a convective chamber-type installation was developed at the Problem Research Laboratory of Electrophysical Methods of Food Processing (PNILEFMOPP) of Moscow State University of Applied Biotechnology as applied to fermented meat products in order to conduct experimental workings out of experimental products. Samples of meat products of good quality were obtained, evenly dried, without signs of "hardening" of the product surface, without the presence and growth of mold while shortening the drying time. The proposed method for controlling the drying process of raw smoked and dry-cured meat and fish products can be implemented both in typical industrial and laboratory climatic chambers or convection drying installations, or using specially designed technological equipment. In the future, it is possible to create technological equipment with a significant simplification of the circuit and structural elements, and thereby significantly reduce its cost. This method of controlling the drying process is especially effective for uncooked smoked and dry-cured sausages.

Claims (1)

A method of controlling the drying process of raw smoked and dried meat and fish products, which includes two stages, in which the mode according to the value of relative humidity and the duration of the 1st stage of drying of the product is determined from the condition of the minimum temperature of evaporation of moisture from the surface of the drying object, which is measured by sensitive thermoelectric sensor and determine its minimum value in the time interval using an electronic differentiating device, which corresponds to the maximum possible intensity moisture evaporation at the current moment or time interval of the drying process, and support it using the control unit, while the process is carried out in a pulsed mode blowing air through the drying object, consisting of pulses and pauses, each lasting 15-60 minutes, depending on the average weight and type of product using the time relay of the control unit, and the maximum possible drying rate of the product is periodically evaluated at the beginning of each active phase of the air exchange cycle and the maximum intensity corresponding to this cycle is set moisture evaporation rate and the minimum temperature of moisture evaporation from the surface of the drying object, which is determined by gradually increasing the intensity of cooling and air drying in the working chamber of the drying unit by controlling the amount of heat transfer and mass transfer between the air cooler, drying agent and the surface of the dried product using the control unit refrigeration unit and fans; air blow pulses, in turn, alternate in reverse mode, the process is carried out until the start of the increase in the temperature of moisture evaporation from the surface of the drying object, which occurred regardless of the intensity of dehydration of the drying agent in the working chamber with an air cooler, which, in turn, signals completion 1 stage of drying the product; the mode according to the value of relative humidity at the 2nd stage of product drying is set at the same level or according to a decreasing stepwise algorithm.

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