RU2743212C1 - Method of creating infrared medium for preparation of products, device for implementation thereof and source of infrared radiation used in device (embodiments) - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: group of inventions relates to food industry, in particular, to processing and preparation of food products under influence of infrared (IR) radiation. Solution is aimed at creation of an infrared medium in the food preparation device, which is universal for preparation of any food products without loss of nutritive value with minimum sufficient heat and power action. Temperature of the heating elements and the optical characteristics of the infrared radiation sources are selected such that the set of maxima of radiation spectra affecting the product corresponds to the set of spectral absorption bands of the nutrients entering the prepared product. Infrared radiation with wave length 3–10 mcm is used. IR-radiation sources also perform the function of reflection of infrared radiation and its direction into the product preparation zone. Radiation sources are flat or convex-concave and arranged in pairs opposite each other on both sides of the prepared product with possibility of changing mutual position. Infrared radiation source comprises a heating element in contact with a plate made from a material which is transparent for infrared radiation in the said range and a second plate located on the other side of the heating element relative to the first plate. Second plate is made from material having the same or less transparency for infrared radiation than first plate. Both plates are flat or convex-concave with the same radius of curvature.

EFFECT: using the group of inventions enables higher quality of food products treatment.

6 cl, 5 dwg

Description

The group of inventions relates to contact and non-contact methods and devices for processing and cooking food products under the influence of infrared (IR) radiation and can be used in household and industrial equipment for the production of finished products and semi-finished products, heating products or maintaining them at the required temperature, sterilization, proofing the dough, etc.

The most common devices for treating food products by exposure to infrared radiation, in which a heating element located inside a quartz tube or a tubular heating element, or plates with electrically conductive elements applied to them, is used as a radiation source.

Also known are devices that use flat sources of infrared radiation. An example is a device for preparing food products according to European patent No. 2906020 (IPC A47J 37/06; Н05В 6/64; Н05В 6/80, prior 10.02.2014). The device contains two sources of infrared radiation above and below the location of the product being prepared. Each source contains a resistive heating element in contact with a ceramic plate. When heated, the plates become sources of infrared radiation. The lower plate is made of a material that is opaque to infrared radiation, and the upper one is made of transparent or partially transparent. Thus, the lower heating plate serves as both a conductive and a radiation source of heat, however, it is difficult to control the physical parameters of infrared radiation with this design of the furnace. Judging by the fact that the device also uses a microwave source, there is not enough infrared radiation to cook the product.

Closest to the proposed method and device for cooking products are a method and device for cooking using an infrared radiation source according to US application No. 200829503 (IPC А21В 1/22, F24C 7/04, F27D 11/00, prior 10.02.2004). The device that implements the method contains two main sources of IR radiation located above and below in relation to the preparation zone of the product, additional radiation sources and several reflectors of IR radiation that form certain radiation patterns. Cylindrical elements are used as sources of infrared radiation. The upper main source generates IR waves in the range of 1.63-1.7 microns, and the lower one in the range of 2-2.2 microns. Reflectors and chamber walls shift the emission spectrum towards increasing wavelength. The environment formed in the device, in which there is radiation with spectra in the indicated ranges and reflected radiation with altered spectra, helps to reduce the cooking time. Due to the absorption of infrared radiation by the cells inside the food, cooking takes place simultaneously inside and outside, regardless of the ambient temperature. The disadvantage of this method and device is that the specified radiation spectrum does not allow high-quality preparation of products with different optical characteristics and consistency. In addition, with the described furnace design, it is impossible to predict the spectral characteristics of the infrared medium inside the furnace. Cylindrical sources of infrared radiation do not allow creating an energetically uniform environment with insignificant gradients. Also, reflective elements form streams with certain radiation patterns, which requires precise positioning of the product at the point of intersection. These reasons do not allow you to get a consistent culinary result. The main range of radiation lies outside the absorption band of important nutrients such as saturated and unsaturated lipids, proteins and sugars. This necessitates prolonged heat exposure and their degradation as a result.

The closest to the proposed source of IR radiation is the source used in a film oven with electric heating according to the application of China No. 102183051 (IPC F24C 7/04, prior. 06.04.2011). The source is an IR-transparent glass-ceramic plate with a resistive film applied to it, to which wires for power supply are connected. Such a heating system generates an infrared stream that does not contain reflected radiation, and is intended only for heating dishes on the stove.

Over the past decades, the nutritional value of food products has significantly decreased (SN Udintsev. TP Zhilyakova "Modern methods of increasing the nutritional value of agricultural products." Bulletin of the Tomsk State University. Biology. 2012, No. 2 (18). P. 81 -91). With traditional heat treatment, when the main methods of heat transfer are convection and conduction, there is an additional decrease in their nutritional value. As a result of overheating of the outer layers of the product, organic nutrients are destroyed, and inorganic nutrients are removed with moisture as a result of dehydration of the product. In order for the body to receive the required amount of nutrients, a person is forced to consume more foods, which leads to obesity. Excessive impact on nutrients leads to a decrease in the nutritional value of the product as a whole, therefore, it is important to create methods for preparing products in which their beneficial properties are maximally preserved. It is necessary to create an environment for cooking, in which each of the types of nutrients receives the minimum sufficient energy impact, which, on the one hand, is optimal in terms of the preservation of their beneficial properties, and on the other hand, it is necessary enough in terms of achieving the culinary result in general. It is known that food systems are complex mixtures of various biochemical molecules, biological polymers, inorganic salts and water. The infrared spectra of such mixtures arise from mechanical vibrations of molecules or individual molecular aggregates in a very complex phenomenon of mutual overlap.

The technical problem is to create a universal IR environment inside the device that minimally affects any kind of nutrients, with the possibility of operational control of its physical characteristics. The minimum sufficient measure of thermal effect on the nutrient composition can be achieved by simultaneous uniform IR exposure of the product from all directions. Thanks to this, all parts of the product will reach readiness at the same time, avoiding overheating of individual parts that are not located in front of the source. It is also necessary to develop a broadband IR source that allows such an environment. Each food product has a complex nutritional composition. Each of the nutrients has a specific infrared absorption band. The impact on the product in this particular range determines the greatest effect of preserving useful properties. In a universal environment, for each nutrient and, accordingly, for each product, an optimal effect should be provided that contributes to the best preservation of the nutritional value of the product as a whole. The uniformity of the environment will make it possible to obtain the necessary effect on the nutrient composition with minimal heat and power impact.

To create such an IR environment, it is proposed to use radiation with a wavelength of 3-10 μm in a method for preparing products in which more than one source of IR radiation with broadband spectral characteristics of IR radiation is used. The temperature of the heating elements and the optical characteristics of the sources of infrared radiation must be selected in such a way that the set of maxima of the radiation spectra affecting the product corresponds to the set of spectral absorption bands of the nutrients included in the prepared product. The intensity of the total radiation of the sources should be as low as possible to bring the product to readiness. Sources of infrared radiation must be positioned so that the total flux of infrared radiation directed to the product is evenly distributed throughout the entire cooking zone.

Amino acids, polypeptides and proteins exhibit 2 intense absorption bands located in the range from 3 to 4 and from 6 to 9 μm. On the other hand, lipids show significant absorption across the entire infrared spectrum with 3 stronger absorption bands located at 3-4, 6 and 9-10 µm, while carbohydrates have 2 strong absorption bands in the 3 and 7-10 µm region. Thus, by creating an IR environment with broadband spectral characteristics, the problem of such an effect on the product is solved, in which each type of nutrient receives a minimum sufficient energy effect, which, on the one hand, is optimal in terms of the preservation of their beneficial properties, and on the other hand, it is necessary enough in relation to the achievement of the culinary result in general. Until now, when creating devices for IR-processing of products, it was not taken into account that different nutrients have different absorption spectra. The task was not set to preserve the maximum preservation of the useful properties of the product. We used radiation of a narrow spectrum with a further uncontrolled process of its change using reflectors.

The cooking device contains several infrared radiation sources, and the infrared radiation sources also perform the function of reflecting infrared radiation and directing it to the product preparation area. Their number, optical characteristics of the material, location (mutual and in relation to the prepared product) and shape are chosen so that the spectrum of IR radiation of each source directed to the preparation zone corresponds to the spectral absorption bands of the nutrients included in the product, and its intensity is minimal sufficient to bring the product to readiness. That is, the combined radiation from all sources creates an additive IR environment that is optimal for its preparation. The radiation sources are flat or convex-concave and are located in pairs opposite each other on both sides of the product being prepared with the possibility of changing the distance between them.

The source of infrared radiation, which can be used in the proposed device, contains a heating element, a plate made of a material transparent to infrared radiation and a plate located on the other side of the heating element with respect to the first plate parallel to it, made of a material having a lower transparency for infrared radiation than the first plate, and both plates are flat or convex-concave with the same surface curvature radius (the distance between the plates should be the same over the entire area). The heating element must be of such a design that it is possible for the IR radiation reflected from the second plate to pass towards the first plate and the cooking zone, i.e. there must be infrared-permeable gaps between the individual parts of the heating element.

The first plate can also be partially transparent to infrared radiation. In this case, it serves as an optical filter to obtain the IR spectrum with the desired characteristics.

In contrast to the device according to European patent No. 2906020, the proposed radiation sources make it possible to form IR radiation more evenly distributed over the cooking zone.

Part of the radiation from the heating element, passing through the first plate, enters the product placement area. Another part of the radiation, directed in the opposite direction, is reflected from the second plate and, also passing through the first plate, enters the product placement area and is added to the original radiation. In addition, the first plate is heated by the heating element and from the temperature in the product placement area and also emits IR waves to the product placement area. The plates in the IR source have several purposes. So, the first plate 2 has a structural purpose, forming a wall (edge), limiting the inner area of preparation of the product, it can serve as an infrared radiation filter, itself a radiation source when it is heated, and can also serve as a bearing surface when a heating element is located on it, as is the case with a thin or thick film resistance heating element. The second plate 3 can also have a limiting function, only external with respect to the cooking area and be a reflective element of IR radiation emanating from the heating element and the first plate 2 and not entering the cooking area. In turn, these types of radiation are also reflected from various structural elements. This process happens many times. Thus, in the area of product placement, infrared radiation from various structural elements is added. An opportunity is created to provide the necessary degree of impact on the product.

To increase the energy saving properties of the device, a heat insulating gap can be created between the heating element and the second plate. An infrared-permeable thermal insulation material can be additionally placed in the gap, which minimizes the thermal effect on the outer wall of the structure.

The technical result of the proposed solution will be the creation of an infrared environment in the device that is universal for the preparation of any food products without loss of nutritional value (preservation of the nutrient composition) with a minimum sufficient thermal energy impact (reduction of exposure time and reduction of local overheating).

The practical consequence of this result is a reduction in energy consumption and an increase in productivity and equipment durability.

FIG. 1 is a schematic sectional view of the arrangement of the plates of the IR radiation source. 1a - flat plates; 1b - convex-concave plates.

FIG. 2 shows an embodiment of an IR radiation source, where a resistive heating element is applied to the IR transparent first plate uniformly over its effective area, and the second plate is an IR reflecting element.

FIG. 3 depicts an embodiment of an infrared radiation source in which a gap exists between the heating element and the second plate, which can be air or filled with insulating material.

FIG. 4 shows the arrangement of flat sources of infrared radiation in a cube-shaped cooking device in section.

FIG. 5 shows a structure similar to that shown in FIG. 4, composed of convex-concave infrared sources.

During the implementation of the method, infrared radiation penetrates deep into the product. The depth of penetration depends on the wavelength and structure of the product. Therefore, the radiation, which is a wide spectrum of simultaneously emitted waves of different lengths, affects, respectively, different areas within the product. Conditions are created for cooking the product both outside and in volume. It has been experimentally established that it is precisely when exposed to radiation of the spectrum from 3 to 10 μm that it penetrates uniformly into the depth of the product and further initiates the mechanisms of heat and mass transfer, which are practically independent of convection processes. Most food products have a heterogeneous structure and, accordingly, heterogeneous optical characteristics, while the permeability of products of various structures for a narrow spectrum is hardly predictable. A wide spectrum of radiated wavelengths simultaneously affecting the product compensates for the inhomogeneity of the product structure with respect to heat and mass transfer processes. When the limits of this spectrum were exceeded, the indicators of the preservation of the nutrient composition deteriorated, for example, a decrease in the content of vitamins and some amino acids.

Equally important is the possibility of a minimally sufficient heat and power selective effect on the nutrients of the product, taking into account their absorptive properties. Infrared waves, which, when generated, are emitted in the direction opposite to the product placement zone, can be directed at it by means of reflection. As a result of the additivity of the study, a more intense IR environment is obtained from all elements of the device, providing the necessary degree of impact on the product.

In case of technological necessity, it is also possible to additionally influence the product with heat generated by the IR source in the air in the area of the product placement (convection) or in direct contact with the source (conduction). Thus, the product is exposed to complex effects.

In the simplest version, the IR source (Fig. 1) contains a heating element 1, a first plate 2, which is an IR emitting surface, and a second plate 3, which reflects radiation from the first plate and at the same time generates its own IR radiation its spectrum. The heating element 1 is also the source of infrared radiation with the shortest wavelength in this system. Plate 2, depending on the optical properties of the material from which it is made, can partially or completely transmit IR radiation from the heating element and, under the action of the heating element 1, form its own spectrum of IR radiation in the required range. That is, it must be made of a material that is transparent or partially transparent to infrared radiation. Plate 3 serves as a reflector of radiation from the heating element 1 and plate 2 and, under the influence of the heating element 1, forms its own spectrum of IR radiation in the required range. For this, plate 3 must be made of a material having a lower IR transparency than the first plate 2. Thus, three elements of the IR radiation source form a wide spectrum of radiation in the range from 3 to 10 μm with the ability to accentuate radiation in the range determined by the nutrient composition of the product. Plates 2 and 3 can be flat (Fig. 1a) or convex-concave (Fig. 1b).

Both hydrocarbon fuel and resistive heating can be used to generate infrared radiation. The heating elements can be of any design so as to ensure the generation of infrared radiation with the required radiation spectra. In addition, the structure must provide the possibility of passing infrared radiation reflected from the second plate towards the first plate and the cooking zone, i.e. there must be infrared-permeable gaps between the individual parts of the heating element. For example, individual portions of the heating element can be uniformly interlaced with IR-permeable gaps.

In one embodiment (Fig. 2), the heating element 1 is electrically conductive sections of resistive material on the surface of the plate 2. The second plate 3 is located behind them with respect to the product placement area. The best results were observed if the parts of the heating element were evenly spaced relative to the working part of the first plate.

The heating element can also be applied to the first plate by any known method using thick film or thin film technology. As indicated above, the areas with the applied layer should alternate with the areas that are transparent to infrared radiation in order to allow the reflected infrared radiation from the second plate 3 to pass towards the first plate 2.

Regulating the supply of hydrocarbon fuel or the power supply of the heating elements and the control of the temperature of the plates and the temperature in the cooking zone can be carried out by known methods.

To improve the energy-saving properties of the device, a heat-insulating gap can be created between the heating element 1 and the second plate 3. In the gap, an IR-permeable heat-insulating layer of heat-insulating material 4 (Fig. 3) can be additionally placed, which minimizes the thermal effect on the outer wall of the structure.

The device for cooking food contains several IR radiation sources consisting of a heating element 1, a first plate 2 and a second plate 3 (Figs. 4 and 5). Their number, location and shape are selected in such a way as to ensure the required degree of influence of infrared radiation on the product, which is determined by the optical properties of the nutrient composition of the product. The main method of delivering thermal energy to a product is electromagnetic radiation. The measure of this energetic effect for solving the set tasks must correspond to the ability to absorb one or another predominant nutrient composition of the product (proteins or carbohydrates, for example). Therefore, since each of the sources contributes to the total energy supply, and additive factors increase it, it is necessary to choose the number of sources and regulate the distance from the sources to the product, taking into account the main nutrient composition.

In a practical way, it was found that the ambient temperature in the cooking zone plays a secondary role in comparison with the energy effect of infrared radiation, and the spectral characteristics themselves and their operational management, on the contrary, are of decisive importance in achieving the preservation of nutritional value and culinary results. Operational control means the degree of heating and the frequency of power supply to the heating element, as well as the choice of the distance from the IR emitters to the product with its change if necessary, as well as the change in the volume of the working area inside the device, that is, the distance between pairs of IR emitters. In some cases, in order to avoid convectional overheating of the product, in which intense losses in the nutrient composition occur, it is advisable to produce forced removal of hot air.

Changing the distance between IR sources, i.e. a decrease in the internal volume of the proposed device led to a decrease in energy consumption by up to 40%.

In order to use the additive effect in conjunction with multiple reflections, infrared light sources must be placed opposite each other, forming pairs. Moreover, each IR source reflects radiation from opposite IR sources. This process happens many times. Thus, in the area of product placement, the radiation is added up.

There can be several pairs of infrared radiation sources. The optimal embodiment of the device is the formation by three pairs of flat sources of a closed space in the form of a cube or parallelepiped (Fig. 4), but there can be more pairs. The sources can also have a convex-concave shape (Fig. 5).

IR radiation sources can serve as structural parts of the equipment frame (walls, doors, under and roof, shelves).

The best embodiment of the invention is a device with three pairs of glass-ceramic infrared emitters, forming a cube-shaped structure. In this device, upon reaching, in order to obtain a wide spectrum of radiation from 3.7 microns to 9 microns, the temperature of the heating element at 600 ° C and plate 2, facing the inside of the device, at 500 ° C, a forced air vent was made to maintain the temperature of the air environment to 60 °.

A piece of meat weighing 1000 g was placed in the device. It was finished in 30 minutes. to a core temperature of 78 ° C (ready temperature). Core temperature was monitored with a cooking thermometer.

Bread weighing 700 grams, located in the proposed device, was cooked at an ambient temperature of 150 ° C for 17 minutes, i.e. 2 times faster than cooking in a household oven or industrial oven.

A fish carcass weighing 760 g is brought to a cooked temperature of 73 ° C in 10 minutes.

In some technological processes (for example, processing of a homogeneous product, in particular, baking bread or sterilizing milk), a limited IR environment is required. In this case, the first plate 2 must be made of a material that is partially transparent to infrared radiation, i.e. having optical characteristics corresponding to the required bandwidth of infrared radiation.

Possible embodiments of the invention are described herein. However, specialists in this field in the described designs can be made changes and additions related to solving specific problems that do not go beyond the scope of the claims.

The time for cooking products using devices of the proposed design was reduced by up to 50% compared to traditional methods. For example, making bread from 600 g of dough in the apparatus shown in FIG. 4, took 15 minutes. at a standard of 40 min.

It turned out to be possible to achieve the readiness of the product to the required condition at temperatures lower than conventional ones. For example, the preparation of a meat steak in the same device took place at a temperature in the product placement area of less than 50 ° C.

Shorter cooking times and lower temperatures reduce energy consumption and increase productivity and longevity.

Weight loss was significantly less than with traditional cooking methods (in bakery products - up to 6% of the weight of raw materials, in meat - up to 5%, in fish - up to 6%). There was practically no vaporization during cooking. The cooked product was soft and juicy. If desired, the product can be cooked with or without crust. The proposed technology allows you to maximally preserve the nutritional composition of products, which cannot be done with conventional heat treatment methods.

The number of operations required for cooking is reduced. So, for the preparation of frozen meat, it is not required to preheat it to room temperature. When roasting meat, you do not need to roast it at a higher temperature first. Requirements for the qualifications of personnel are being reduced.

Claims (6)

1. A method of preparation of products in which more than one source of infrared radiation with broadband spectral characteristics is used, characterized in that infrared radiation is used in the wavelength range of 3-10 μm, the location and shape of the sources are chosen so that the total flux of infrared radiation directed on the product, was evenly distributed throughout the entire cooking zone, the temperature of the heating elements and the optical characteristics of the infrared radiation sources are selected so that the set of maxima of the radiation spectra of the sources corresponds to the set of spectral absorption bands of the nutrients included in the prepared product, and the intensity of the total radiation is minimally sufficient to bring product until cooked. 2. A device for preparing products containing more than one source of infrared radiation, characterized in that the radiation sources are also reflectors of radiation, the number of sources, the optical characteristics of the materials from which they are made, the location and shape are chosen so that the set of infrared radiation spectra from of all sources directed to the cooking zone of the product corresponded to the spectral absorption bands of the nutrients included in the product, and its intensity was minimally sufficient to bring the product to readiness, and the sources are flat or convex-concave and are located in pairs opposite each other on both sides of the prepared product with the ability to change the distance between them. 3. An infrared radiation source containing a heating element and a plate made of a material transparent to infrared radiation, characterized in that it further comprises a plate located on the other side of the heating element with respect to the first plate parallel to it, made of a material having a lower transparency for infrared radiation than the first plate, where both plates are flat or convex-concave with the same surface curvature radius, and the heating element is designed to allow reflected radiation from the second plate to pass towards the first plate. 4. An infrared light source as claimed in claim 3, wherein a gap exists between the heating element and the second plate for a thermal insulation function. 5. An infrared radiation source comprising a heating element and a plate made of a material partially transparent to infrared radiation, characterized in that it further comprises a plate located on the other side of the heating element with respect to the first plate parallel to it, made of a material having a smaller transparency to infrared radiation than the first plate, where both plates are flat or convex-concave with the same surface curvature radius, and the heating element is designed to allow reflected radiation from the second plate to pass towards the first plate. 6. An infrared light source as claimed in claim 5, wherein a gap exists between the heating element and the second plate for a thermal insulation function.

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