Equipment for thermal processing of food products. Classification of thermal equipment of catering establishments - test. Boilers and dishwashers
According to their technological purpose, heating appliances are divided into cooking (cooking boilers, steam ovens, electric cookers, coffee makers), frying and baking (frying, bakery and confectionery cabinets, frying pans, deep fryers, grills), multifunctional (stoves, microwaves, combi steamers), water heating units (water heaters and boilers) and devices for keeping prepared food hot - devices for dispensing lines (bain-marines, thermal display cases and cabinets, thermoses, thermal containers).
Depending on the type of energy carrier, everything thermal devices For Catering are divided into two main groups: electric and gas. For operation in “field” conditions, firing equipment is produced that runs on solid fuel - wood, coal, shale, etc.
In electric thermal devices, the main element is an electric heater, in which electrical energy is converted into thermal or electromagnetic field energy. The main advantages of electrical energy include: the simplicity and compactness of converters of electrical energy into heat, the simplicity and reliability of controlling electrothermal devices, the ability to quickly and accurately account for electricity consumption, good sanitary and hygienic conditions in production, and the relatively high efficiency of the devices.
Gas heating devices use natural, artificial or liquefied gas as an energy carrier. The advantages of gas appliances include good sanitary and hygienic indicators, the ability to automatically regulate thermal conditions and a high efficiency factor. The disadvantages include the ability of flammable gases to form an explosive mixture with air, which requires special operating conditions.
According to the heating method, contact ones are distinguished thermal devices and devices that are surface heat exchangers with direct and indirect heating.
Thermal devices, in which the product is processed directly on the heating surface, are called conductive. Frying surfaces and grills operating on this principle are increasingly called contact surfaces.
According to the work cycle structure thermal devices, used in public catering, are divided into periodic and continuous devices.
According to geometric shape thermal devices are divided into non-sectional modulated (having different dimensions and cylindrical shape, which does not allow such equipment to be installed in line with other devices without gaps) and sectional modulated rectangular shape, the design of which is based on a single size - a module (such equipment is designed for installation in a line, where the determining size is depth, for example, thermal electric lines 700 from the Italian company Magepo and 900 from the Slovenian company KOGAST).
All thermal devices Regardless of the technological purpose and design solution, they consist of the following main parts: working chamber (surface), heat-generating device, apparatus body, thermal insulation, casing, base, instrumentation, automatic control devices and fittings.
The working chamber is designed for heat treatment food products. Its shape and dimensions depend on the technological purpose of the apparatus (reservoir of a digester, deep fryer bath, combi oven chamber, heating surface of a contact grill or frying pan). It can be mobile or immobile.
Thermal insulation reduces heat loss from the device in environment and is made in the form of layers of special materials on the outer surface of the working chamber.
The casing is used to protect the insulation from the effects of air moisture and destruction and gives the device an aesthetic appearance. The base serves to mount the device body and is most often made in the form of a casting made of cast iron, duralumin or plastic of various shapes.
Instrumentation and automatic control devices, as well as fittings, are used to turn on, turn off, control the operation of the device, regulate the thermal regime and safe operation of the devices.
Classification of thermal equipment of catering enterprises
Thermal equipment of public catering establishments can be classified as follows:
1) on organizational and technical grounds; 2) by functional or technological purpose; 3) by design features; 4) by the method of heat exchange; 5) by type of heat sources and coolants; 6) on changes in process parameters over time; 7) by degree of specialization.
According to organizational and technical characteristics There are thermal devices of continuous or periodic action and combined ones.
In continuous appliances, food is cooked in a continuous cycle, i.e. loading of raw materials, preparation of the product and its unloading occur simultaneously.
The successful development of public catering equipment can be carried out only if continuous action devices are developed and widely implemented, since they can dramatically increase labor productivity, reduce production space, and improve working conditions for service personnel. Continuous machines are easy to automate.
In batch machines, loading of raw materials, cooking and unloading of the finished product are separated in time. As a rule, the longest process is the cooking process.
These devices are more difficult to automate and their maintenance requires significant labor costs.
Combined-action devices include those in which some of the processes are carried out periodically, and some occur continuously.
By functional or technological purpose Heat devices can be divided into: devices for cooking (in boiling liquid or steam), for frying or baking (on a heated surface, in a hot air environment, in a large amount of edible fat, in the field infrared radiation etc.), as well as devices for implementing combined thermal culinary processes - stewing, baking, poaching, blanching, etc.
Based on their functional (technological) purpose, they distinguish a group of thermal equipment designed for defrosting and warming up (warming) food, as well as for maintaining a constant temperature of finished culinary products.
By degree of specialization devices are divided into single-purpose (specialized) (for example, frying or cooking, on which only one of these processes can be carried out), highly specialized and multi-purpose (universal). The first include devices for implementing one process, but for all kinds of food products. Universal devices are designed to carry out any thermal processing of food associated with its heating during processing.
By design features (according to characteristics) devices are divided into the following groups: sectional and non-sectional, modulated and non-modulated. Of course, sectional and modulated type devices, consisting of separate sections and modules, are more progressive. This allows, by assembling several sections, to obtain a thermal apparatus of the required performance.
Special modular equipment allows you to reduce when installing it by 12-20 % production area. This equipment is easier to operate and maintain.
By heat transfer method Three main groups of devices can be distinguished, operating on the principles of convection, radiation and thermal conductivity. However, in virtually all thermal apparatus these methods of heat transfer coexist, but manifest themselves to varying degrees. Sometimes, when classified according to this criterion, devices are divided into surface devices, devices that directly influence the heat source on the product, and devices in which the heated medium is mixed with the heat source.
In devices of the first type, there is necessarily an interface between the heat source and the heated object. For example, the product is in the boiler, and the heat source is outside it, i.e. the boiler wall serves as such a surface.
The vast majority of heating devices used in public catering are surface-based. As an example of devices in which there is direct contact between the heat source and the heated object, steam cookers can be cited.
Finally, an example of devices of the third type are water heaters, in which heating steam is introduced into the water it heats.
By type of heat sources and coolant There are electrical, steam and fire (solid-liquid-gas fuel) apparatuses.
By type of coolant There are devices that use water, various organic and inorganic liquids, molten metals, steam, air, etc.
According to the method of changing the parameters of processes occurring in devices in time , classify devices in which processes occur in steady-state (stationary) and unsteady (non-stationary) modes.
In the first case, the change in parameters, for example temperature, at any point does not depend on time.
In an unsteady process, the temperature at any point depends not only on the coordinates characterizing its location in space, but also on time.
For the vast majority of heating devices used in public catering, the most characteristic processes are those occurring in a non-stationary mode. Stationary processes in their present form are realized in continuously operating devices.
2. REQUIREMENTS FOR HEATING EQUIPMENTS IN PUBLIC CATERING ENTERPRISES
The basic requirements for heating equipment of public catering establishments are common to most heating devices. These are technological, operational, energy, structural, environmental and economic requirements. A special place is occupied by requirements related to labor protection of service personnel.
Technological requirements . The apparatus must provide the ability to prepare a product of excellent quality, characterized by high nutritional value and safe for consumption.
An indispensable technological requirement is to ensure such heat treatment in which the loss of raw materials and the product itself is minimal. In addition, the device must ensure the preparation of the product in the shortest possible period of time.
Operational Requirements . The devices must be convenient and easy to maintain. During the cooking process, it must be possible to control the basic parameters and regulate the process depending on the technological modes. An important operational requirement is the accessibility of all components of the device for washing and sanitizing, as well as preventive inspection and routine repairs.
The most important operational requirement is the complete safety of personnel servicing the equipment.
Energy requirements . They are multifaceted and cover a number of related conditions. Appliances must operate in energy-saving modes (i.e., with minimal consumption of electricity, fuel, steam and any other sources of heat and coolants), must be provided with devices or devices that regulate the amount of energy supplied depending on the requirements of technological modes at different stages of food preparation .
The main characteristic of the energy intensity of the process implemented in thermal apparatus is the specific energy consumption (per unit of production):
where Esp is specific energy consumption, J/kg; Ez - total energy consumption for the operation of the device during the entire production cycle (bringing the device to operating mode, operation of the device in operating mode), J; P - quantity of product, expressed in units of mass, volume or portions.
In order to save energy consumption, devices must have thermal insulation, which significantly reduces heat loss to the environment.
Design requirements . They combine all other requirements for thermal equipment. When designing, food preparation technology and operating conditions of the equipment are taken into account, taking into account the labor protection of operating personnel. When designing machines and devices, it is necessary to strive for their minimum energy intensity.
One of these requirements is to ensure low material consumption (i.e., the mass of metals and other structural materials that are necessary for the manufacture of thermal devices should be as minimal as possible). To characterize the material consumption of devices, you can use its specific indicator:
where m ud.p - specific material consumption of equipment for the product, kg/kg (or kg per 1 serving, or kg/m 3); M- total weight of equipment, kg, P - quantity of products.
The specific material consumption of devices can also be related to their volume:
where m beats V is the specific metal consumption of the apparatus, related to the volume of the apparatus, kg/m 3 ; V - apparatus volume, m3.
The design of thermal devices should include the use of standardized units and parts that are easily replaceable and accessible for repair. The optimal design is one consisting of sections or modules.
The design requirements also include the conditions for transporting equipment and their installation. Devices that have large dimensions that do not correspond to the dimensions of conventional vehicles must be collapsible. Installation of equipment should not be difficult.
When designing thermal devices, it is necessary to take into account that their components and elements that have direct contact with the product must be made of metals and materials that do not have any harmful effects on the product, operating personnel and the environment. Design requirements include reliability, durability and maintainability of devices, which determines their reliability in operation.
Under reliability understand the ability of the device to operate without disrupting its performance both as a whole and its parts.
Durability represents the property of a device to maintain high performance until a limiting state in which the use of the device is impossible. It is characterized by operating time (duration of operation) and resource (service life) incorporated during design.
Environmental requirements . During operation, heating equipment should not emit harmful substances into the atmosphere or sewerage system that are hazardous to human health, animal life and plant life.
This means that gases, coal, firewood, and petroleum products that have a high degree of combustion and, therefore, produce smoke waste to a minimum extent and do not contain harmful substances that pollute the environment should be used as fuel. When washing equipment, the washing liquids should not contain harmful substances from the surfaces of the devices, i.e. they should be made from materials that are insoluble in water and washing solutions, which go into the sewer without additional cleaning.
Economic requirements. Their essence is that the equipment should be cheap and quickly pay for itself. Economic requirements synthesize virtually all of the above discussed.
Requirements related to labor protection. It is quite obvious that all heating equipment operated in public catering establishments must ensure complete safety for service personnel.
Thermal devices must be equipped with various blocking, signaling and other devices that are automatically activated when situations dangerous to people occur.
Requirements for automation systems of thermal equipment. Automation involves the creation of systems of machines and devices in which the main processes are carried out with minimal physical labor.
Automation in public catering has the main goals: facilitating human labor, ensuring his safety, improving product quality, reducing its consumption, and reducing energy costs.
Currently, automation systems are divided into the following three main types: automatic control, automatic protection and automatic control.
Scientific and technological progress of modern production Food Industry made big changes in the methods of thermal processing of culinary products of public catering establishments. Along with traditional surface (conductive) cooking methods, they are widely used volumetric methods heat treatment of products.
Volumetric heating methods are based on the interaction of the product with an electromagnetic field. Electromagnetic energy from the radiation generator, turning into heat, penetrates the mass of the product to a considerable depth and, in a very short period of time, ensures its heating to a ready-made state.
Superficial methods The preparation of food products according to technological purpose is classified into cooking, frying, frying and baking, hot water and auxiliary. Cooking equipment includes:
digester boilers, the technological medium of which is water or broth at a temperature of 100°C;
autoclaves in which heat treatment is carried out with steam at a temperature of 135 ... 140 ° C;
steam cookers in which the technological process of cooking is carried out with steam at a temperature of 105 ... 107 ° C;
vacuum devices, the working medium of which is heating steam at a temperature of 140 ... 150 ° C.
The group of frying equipment includes:
frying pans in which the frying operation is carried out in small quantity fat at a temperature of 180 ... 190°C;
deep fryers, in which the frying process takes place in fat at a temperature of 160 ... 190 ° C;
ovens (grills, kebab ovens) that carry out the process of cooking food in hot air at a temperature of 150 ... 300 ° C.
Frying and baking equipment includes: ovens, frying and baking cabinets, in which the technological medium is hot air at a temperature of 150 ... 300 ° C;
steam fryers, the working medium of which is a mixture of hot air and superheated steam at a temperature of 150 ... 300 ° C.
Water heating equipment is represented by boilers and water heaters.
Auxiliary equipment includes food warmers, heating cabinets and racks, thermostats, equipment for food transportation.
Volumetric methods of heat treatment of products are carried out: in microwave cabinets of periodic and continuous operation; ultra-high-frequency method provides a high heating rate of products;
IR devices; infrared heating is based on the intense absorption of infrared radiation by free water in products;
EC heating devices; electric contact heating is based on the thermal energy released by current for a certain time when it passes through a product that has a certain active (ohmic) electrical resistance;
induction heating installations; induction heating food products, especially with high humidity, occurs when they are placed in an external alternating magnetic field, in which, according to the law electromagnetic induction Eddy currents (Foucault currents) arise, the lines of which are closed in the thickness of the product, electromagnetic energy is dissipated in its volume, causing heating.
The main advantage of microwaves is the speed of heating food products.
However, this heating method also has disadvantages - the absence of a crust on the surface of the product and, as a rule, the natural color of the raw material.
Positive indicators IR heating results in uniform browning color and thickness.
However, this method has disadvantages:
not all products can be subjected to IR heating;
at high density the flow of infrared radiation may “burn” the product.
EC heating is used as independent species processing, and in combination with other methods. In particular, it is successfully used in the bakery industry for heating the dough mass when baking bread, in the production of sausages, and when blanching meat products.
The induction heating method has not yet received widespread in catering establishments, but it has significant economic potential for successful use in the future.
Considering that surface and volumetric methods of thermal processing of food products, along with advantages, also have disadvantages, it is advisable to use them in combination in the production of public catering.
1. Classification of thermal shop equipment
The equipment of thermal shops is divided into three groups: main, additional and auxiliary.
Basics equipment is used to perform operations heat treatment and turns on the ovens, heating installations, cooling devices (quenching tanks, hardening machines, cold treatment equipment, etc.). The classification of the main equipment of thermal shops is shown in Fig. 1.1.
Rice. 1.1. Classification of the main equipment of thermal shops
TO additional equipment includes equipment for straightening and cleaning parts (straightening presses, pickling baths, sandblasting and shot blasting machines, washing machines, etc.). The classification of additional equipment for thermal shops is shown in Fig. 1.2.
Figure 1.2. Classification of additional equipment for thermal shops
Auxiliary equipment includes installations for the preparation of carburizer and controlled atmospheres, devices for cooling quenching liquids, sanitary equipment, overhead and slewing cranes, monorails with electric hoists, roller tables, conveyors, conveyors, etc. The classification of auxiliary equipment of thermal shops is shown in Fig. 1.3.
Figure 1.3. Classification of auxiliary equipment of thermal shops
Furnaces and heating installations are classified according to their technological purpose, the type of thermal energy, the method and degree of mechanization, and the use of various heating media.
By technological purpose Furnaces and heating devices are divided depending on the operations for which they are intended: annealing, hardening, tempering, carburization, etc.
By type of fuel or thermal energy used furnaces and heating devices operate on liquid, gaseous fuels and electricity.
By method and degree of mechanization ovens are divided into pusher, conveyor, rotary, drum and others. These ovens may have devices for manual loading and unloading of products, for automatic unloading, etc.
By use of different heating media furnaces and heating devices are classified into furnaces with controlled atmospheres (neutral, carburizing), bath furnaces with molten salts and metals.
2. Basic equipment for heating materials and products
2.1. Furnace indexing
First letter The index indicates the type of heating. The letter adopted for electric ovens is WITH(resistance heating), for fuel stoves - letter T(thermal flame) or letter N(heating flame).
Second letter The furnace index indicates the main design feature of the furnace. The following basic notations are accepted: N– furnace with a fixed hearth; D– oven with a retractable hearth; Sh– shaft (round); L– tunnel; G– bell-shaped; E– elevator (furnace with a lifting hearth); T– push;
TO– oven with conveyor hearth; E– oven with overhead conveyor; R– furnace with a roller hearth; YU– furnace with walking hearth; AND– furnace with pulsating hearth; B– drum; A– carousel (with a rotating hearth or vault);
I- pit stove; SCH– slot furnace; U– methodical (blacksmithing).
B (bath) – the second letter of the index for bath furnaces and electrode-salt baths.
Third letter The furnace index indicates the nature of the environment in the workspace. For electric resistance furnaces, the following atmosphere designations are accepted: ABOUT– oxidative; Z– protective; IN– vacuum; N– hydrogen; A– nitrogen.
Third letter index for bathtub furnaces is indicated by: M- oil; G– molten metal, salt or alkali, and for fuel furnaces – indicates the nature of the environment in the working space: ABOUT– oxidative (that is, conventional oven); Z– artificial (protective, non-oxidizing, for cementation, etc.).
Fourth letter The index indicates individual characteristic features of the furnace. The following notations are accepted: A– the furnace is included in the unit, that is, it can be aggregated with a quenching tank and other equipment; IN– vertical arrangement of the furnace (in furnaces round section) or vertical movement of products (in mechanized ovens); AND– grooved under the stove; TO– well furnace (batch operation) or ring hearth (in rotary hearth furnaces); T– plate hearth (in furnaces with a rotating hearth); M– the furnace is mechanized; N– continuous furnace (drum); P– batch furnace (drum).
The numbers following the hyphenated letters indicate the dimensions (in decimeters) of the furnace working space (or the dimensions of the muffle, retort).
For ovens with rectangular cross-section working chamber, the first number indicates the width of the hearth, the second – the length of the hearth, the third – the height of the chamber (or the loading window, if the height of the window is less than the height of the oven chamber).
For circular furnaces (shaft, well, etc.), the first number indicates the diameter of the chamber, the second – the length of the chamber.
For rotary hearth kilns, the first digit indicates external diameter hearth, the second is the inner diameter of the hearth, the third is the width of the hearth.
The numbers indicating the dimensions of the hearth chamber, window and retort are separated by dots.
The maximum oven temperature (in hundreds of degrees Celsius) is given in the denominator (through a slash).
For fuel stoves, next to the number indicating the temperature of the stove, a letter indicating the type of fuel is placed separated by a hyphen: G– natural or other gas; M– fuel oil or other liquid fuel, for example, furnace index.
SKZ-12.70.01/7 reads as follows: electric furnace, with a conveyor hearth, with a protective atmosphere, hearth width 12 dm, hearth length 70 dm, chamber height 1 dm, maximum temperature 700 °C.
The stove index TTZA-8.72.8.5/9.5-G is read as follows: fuel stove, pusher, with a protective atmosphere, aggregated, hearth width 8 dm, hearth length 72 dm, chamber height 8.5 dm, maximum temperature 950 °C, gas fuel.
Basics of Cooking Foods
Classification of thermal devices and their structure
Heat sources and coolants
Heat generating devices
Cooking thermal equipment
Frying heat devices
Operation of thermal equipment
1. Basics of thermal processing of food products
Heat treatment changes the structural-mechanical, physico-chemical and organoleptic properties of the product, which determine the degree of culinary readiness. Heating causes changes in proteins, fats, carbohydrates, vitamins and minerals in the product.
The main methods of thermal processing of food products are boiling and frying, used both as independent processes and in various combinations. Each technique has several varieties (steam cooking, deep frying, etc.). To implement these techniques in thermal equipment, use various ways heating products: surface, volumetric, combined. With all methods of heating food products, external heat exchange is accompanied by mass transfer, as a result of which part of the moisture in the food passes into the external environment. When cooking products in liquid media, some of the dry substances are also lost along with moisture.
Almost all food products are capillary-porous bodies, in the capillaries of which liquid is held by surface tension forces. When foods are heated, this liquid begins to migrate (move) from heated layers to colder ones.
When frying food, moisture from the surface layers partially evaporates and partially moves deeper to colder areas, which leads to the formation of a dry crust in which thermal decomposition of organic substances occurs (at temperatures above 100 ° C). The faster the surface heats up, the more intense the transfer of heat and moisture occurs and the faster a surface crust forms.
Surface heating of the product is carried out by thermal conductivity and convection when heat is supplied to the center of the product through its outer surface. In this case, heating the central part of the product and bringing it to culinary readiness occurs mainly due to thermal conductivity.
The intensity of heat transfer depends on the geometric shape, size and physical parameters the product being processed, the mode of movement (product and environment), temperature and physical parameters of the heating medium. The duration of the cooking process during surface heating is due to the low thermal conductivity of most food products.
The volumetric method of supplying heat to the processed product is implemented in devices with infrared (IR), microwave, electric contact (EC) and induction heating.
Infrared radiation is converted into heat in the volume of the processed product without direct contact between the IR energy source (generator) and the product itself. The carriers of IR energy are electromagnetic oscillations of an alternating electromagnetic field that arise in the product.
Infrared energy in the processed product is formed during the transition of electrons from one energy level to another, as well as during the vibrational and rotational movements of atoms and molecules. Electron transitions and the movement of atoms and molecules occur at any temperature, but as it increases, the intensity of IR radiation increases.
Microwave heating of food products is carried out by converting the energy of an alternating electromagnetic field of ultrahigh frequency into thermal energy, generated throughout the entire volume of the product. The microwave field is capable of penetrating into the processed product to a significant depth and carrying out its volumetric heating regardless of thermal conductivity, i.e. Suitable for products with different humidity levels. High speed and high heating efficiency make it one of the most efficient ways to cook food.
Microwave heating is called dielectric heating due to the fact that most food products are poor conductors. electricity(dielectrics). Its other names - microwave, volumetric - emphasize the short wavelength of the electromagnetic field and the essence of the heat treatment of the product occurring throughout the entire volume.
The effect of heating food products in a microwave field is associated with their dielectric properties, which are determined by the behavior of bound charges in such a field. The displacement of bound charges under the influence of an external electric field is called polarization. The greatest energy consumption of an external electric field is associated with dipole polarization, which arises as a result of the influence of an electromagnetic field on polar molecules that have their own dipole moment. An example of a polar molecule is a water molecule. In the absence of an external field, the dipole moments of molecules have arbitrary directions. IN electric field Polar molecules are acted upon by forces that tend to rotate them so that the dipole moments of the molecules coincide. The polarization of a dielectric consists in the fact that its dipoles are set in the direction of the electric field.
Electric contact heating provides a rapid increase in the temperature of the product throughout the entire volume to the required value in 15-60 s by passing an electric current through it. The method is used in the food industry for heating dough pieces when baking bread and when blanching meat products. Products subject to heating are located between electrical contacts. Gaps between the surface of the product and the contacts may cause surface burns.
Induction heating is used in modern induction household stoves and in catering establishments. Induction heating of conductive materials, which includes most metals for cookware, occurs when they are placed in an external alternating magnetic field created by an inductor. An inductor installed under the stove floor creates eddy currents that close in the volume of the cookware. The product is processed in a special metal stovetop container, which heats up almost instantly due to the directed action of the electromagnetic field. At the same time, heat loss to the environment is reduced to a minimum, which reduces energy costs for cooking compared to conventional electric stove by 40%. In such heating devices, the slab flooring is usually made of ceramic materials and remains practically cold during heat treatment.
Combined methods of heating food products are sequential or parallel heating of products using several of the known methods in order to reduce heat treatment time, improve the quality of the final product and the efficiency of the technological process. Thus, combined heat treatment of products in a microwave field and infrared rays makes it possible to realize the advantages of both heating methods and obtain products with a crispy crispy crust.
