The term “extraction” (extraction), used so far, incorrectly characterizes the nature of the tooth extraction operation. As you know, the teeth are firmly connected to the jaw bone with periodontal fibers, and with the gum through fibrous tufts. Extraction of the tooth becomes possible only after dislocating the tooth, tearing the periodontal and gum fibers holding it and disrupting the connection of the tooth with the alveoli and gum. Thus, the main technique determining the effectiveness of this operation is dislocation of the tooth; only after this is its extraction.

The tooth extraction operation is performed with special tools: forceps and elevators (elevators). In addition, there is also a method of tooth extraction by gouging and cutting.

Before starting the operation, the doctor should carefully examine the tooth to be removed in order to outline an intervention plan and select the appropriate tools. Hard and soft deposits must be removed from the teeth. The latter should be done at least on the teeth to be removed and on the teeth adjacent to it, so that when moving under the gum of the forceps cheeks, these infected deposits should not be pushed into the wound and surrounding soft tissues.

The position of the doctor and the patient. Of great importance for the successful operation of tooth extraction is the correct position of the doctor and patient, as well as the use of the left hand by the doctor.

To remove the upper teeth, the patient is seated in a chair with his head slightly thrown back so that the entire upper dentition is clearly visible. The chair is raised depending on the growth of the doctor and the patient so that the tooth to be removed was at the level of the shoulder joint of the doctor. The doctor becomes to the right and front of the patient.

To remove the lower teeth, the chair does not need to be lifted. The patient is seated in such a way that the head is in a straight or slightly inclined anterior position, and the lower jaw is at the level of the elbow joint of the doctor’s dropped arm. When removing teeth on the right half of the lower jaw, the doctor becomes to the right and somewhat posterior to the patient (Fig. 24), and when removing teeth of the left half - to the left and somewhat in front of the patient (Fig. 25). If tooth extraction is performed while the patient is lying down, the assistant must slightly raise the patient’s head when removing the lower teeth. Care must be taken to ensure that the dislocated tooth, especially when working with elevators, does not slip out and does not fall into the respiratory tract of the patient.

Fig. 24. Tooth extraction on the right half of the lower jaw.


Fig. 25. Tooth extraction on the left half of the lower jaw.
Fig. 26. The position of the doctor when removing a tooth in the upper jaw.

The position of the free left hand when removing teeth on the upper jaw is as follows: the upper lip is moved with one of the fingers of the left hand, index or large, and the other finger is placed on the palatal surface of the alveolar bone in the region of the extracted tooth (Fig. 26).

When removing teeth on the lower jaw on the right, the doctor covers the patient’s head with his left hand; with the index finger of the left hand pulls the lip or cheek and fixes this finger on the alveolar process in the transitional fold; with a thumb pushes the tongue and covers the alveolar process from the lingual side; the remaining fingers are located outside and fix the jaw. When removing the left lower teeth, the doctor stands to the left and somewhat in front of the patient; the index finger pushes the lip or cheek near the tooth to be removed, the middle finger is located on the lingual side. Other fingers are outside.

If the doctor, while removing the teeth on the left side of the lower jaw, stands to the right and front of the patient, then his freedom of movement is constrained and the surgical field is darkened. When teeth are removed with elevators, the position of the left hand is the same as with forceps.

Proper use of the free left hand allows you to clearly view the surgical field, protects the soft tissues (lip, tongue, bottom of the oral cavity, etc.) from injury by forceps or elevators, makes it possible to fix the alveolar process during surgery, and finally allows you to fix the lower jaw , which facilitates tooth extraction and prevents the possibility of dislocation of the lower jaw.

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Introduction

In the process of storing food raw materials or finished products, their damage is possible, associated with the vital activity of microorganisms. As a result, new, more simple in composition substances appear that have an unpleasant taste and smell, some of them are poisonous. This spoilage can be slowed down, slowed down significantly, but it is impossible to completely avoid.

Many products, even with a short shelf life, often deteriorate (meat, fish, milk, most vegetables, berries and fruits, etc.). You can protect them from spoilage and increase the shelf life by canning.

Preservation is the processing of food products to increase their shelf life.

The task of preserving products is to stop the activity of microorganisms and prevent unwanted changes in products.

It is necessary to preserve exclusively fresh raw materials. There are many canning methods. The choice of one or another of them depends on the type and properties of the raw materials, as well as the purpose of the finished product, however, in all cases it is necessary not only to preserve the raw materials or finished products, but also to obtain a product of high nutritional value.

Canning history

When a man was still a gatherer and a hunter and literally “barely making ends meet,” he did not need canned food. Their long storage was not required, since nature provided him with constant sources of food. With the beginning of the Neolithic revolution (about 10 thousand years ago), when a person began to switch to a sedentary lifestyle, gathering and hunting were replaced by cultivation of the land and the domestication of wild animals. The man began to make food supplies, like a squirrel or a hamster, protecting them from relatives and bad weather. The transition to food supplies also led to a change in its structure, a violation of traditional (physiological) norms. At the same time, the organoleptic properties of the products changed significantly.

The first methods of conservation were drying and salting. Food stored in this way had corresponding deficiencies. For example, a 14th-century Parisian merchant advised his customers to prepare dried cod, which had been stored for 12 years, to soak it overnight in water and then beat it back with a sledgehammer until it softens. Reading historical documents on the nutrition of the population of temperate climatic zones in winter or on the diet of seafarers, we see that this food consisted entirely or mainly of canned foods. The diet was dominated by grain and flour, dried, dried and salted meat or fish. In many countries, bread was baked only two or three times a year. Then it was dried and used for months soaked, in the form of gruel. The uniformity of such food is obvious. Almost nothing was known about the influence of canning methods on the components of food products. Often there were diseases.

Over time, the list of preservatives used has been replenished with alcohol, smoke, sulfuric acid, acetic, lactic and some other organic acids. These substances have been used for two millennia.

Shifts in food preservation appear with the beginning of industrialization. The consumer is becoming more demanding, he is no longer satisfied with the quality of food stored using preservatives known at that time - they change the structure and properties of food products too much.

Advances in chemistry began to be applied in canning. Theories began to arise that justify the technology of this process. Examining smoke, Reichenbach found an oily substance in the products of dry distillation of wood, which he called creosote because of its ability to preserve meat. He announced his discovery in enthusiastic tones, although at the same time he established that this substance poses a health hazard. The use of creosote was limited by its unpleasant odor. However, in one book on food chemistry, published in 1848, creosote was described in detail as another preservative along with salt (the use of which was correctly called indirect drying), drying, heating, lactic fermentation, sugar, alcohol, vinegar, and smoke.

Only a hundred years ago, efforts began to not only “somehow” preserve food products, but also to protect the unstable constituent parts contained in them from destruction, as well as preserve their nutritional and taste properties. At first, substances such as hydrofluoric acid, fluorides, chlorates, etc., were included in the list of food preservatives. Proposals to add such “chemicals” to food products were not associated with immoral motives (self-interest or the desire to mislead). Most likely, they were caused by ignorance of the possible harmful consequences of their use, because toxicological studies have not yet been conducted. It was believed that the addition of those small quantities of substances that are necessary for preservation can hardly be harmful to health. Therefore, at first, the choice of preservatives was not particularly ceremonial. The proposal made about a hundred years ago to add salicylic and boric acids to the list of food preservatives was progressive, although today both of these preservatives no longer meet the safety requirements.

The word "Conservation" comes from the Latin word conserve, which means "Preservation." The scientific foundations of modern conservation methods were given back in the 19th century, when in addition to the visible culprits of decomposition of products, such as mold and fungi, invisible forms of microorganisms, bacteria and yeast were discovered. This discovery was made by the famous French chemist Louis Pasteur (1822 - 1895), who studied in detail primarily yeast and pathogenic microbes and at the same time laid the scientific basis for killing their spores. In honor of him was called "Pasteurization" a method of partial sterilization of substances, especially liquid, with elevated temperature

At the end of the XIX century, formic acid was used as a preservative, and at the beginning of the XX century - benzoic acid, which is still used on a large scale. Since at first benzoic acid (and salicylic acid) was treated with caution, ranking them as compounds of the aromatic series, and considering them to be carcinogenic, searches were made for its substitutes. They turned out to be chlorobenzoic acid and hydroxybenzoic acid esters. In the late 1930s, propionic acid salts began to be used as preservatives, and after World War II, sorbic acid and its salts were used. The wide distribution of sorbic acid is largely a consequence of the new approach to the toxicological evaluation of food additives in general and preservatives in particular that arose in the 1950s. This is an unsaturated fatty acid, it has been studied better than all other commonly used preservatives, and the safety of its use does not raise the slightest doubt.

In the last 15-20 years, there has been a strong desire for the consumption of fresh food. In this regard, the industry is trying to shorten the path from producer to consumer. In developed countries, cooling is widely used to preserve fresh food (even during transport).

Current trends in the development of food preservation methods suggest that in the near future “sparing” methods of chemical preservation will be applied. This should be understood as the use of substances that can be obtained from plants or microorganisms exhibiting antimicrobial properties. Non-experts consider such substances less suspicious, because they are natural compounds.

It is noteworthy that in publications directed against food additives, preservatives are least criticized, as critics know that in certain cases the use of preservatives protects the health of consumers. Thus, it is undoubted that chemical preservation of food products will retain its significance in the future.

Microbiological spoilage

Food products tend to deteriorate quickly. Therefore, you have to use them immediately or, if this is not possible, take measures to preserve them, i.e. canning.

Physical, chemical, biochemical and microbiological processes that negatively affect its quality can occur in a food product.

Microbiological spoilage of food products occurs in the presence of certain conditions necessary for the flow of biological processes:

The presence of pathogens damage. Microbiological spoilage of a food product is impossible if microorganisms are absent on its surface or inside it.

* Availability of nutrients available to microorganisms. If there are none, then microorganisms cannot develop.

* The presence of temperature, water activity, oxygen concentration, redox potential, and concentration of hydrogen ions (pH) favorable for the life of microorganisms. If these conditions are unfavorable, microorganisms will either not develop, or their development will be slowed down.

* A sufficiently long storage time of the food product. If a food product is used before the unwanted growth of microorganisms begins, measures against microbiological spoilage are unnecessary.

Microbiological spoilage can only be said when, as a result of the activity of microorganisms, the quality of the food product deteriorates.

By spoiling a food product is understood only an undesirable change in its quality. It follows that not every microbiological change is spoilage. For example, fermenting grape juice with yeast is not a spoilage if the goal is to get wine, and is if you want to keep grape juice unchanged. Vinegar can be formed during undesirable souring of wine, and can be deliberately obtained from wine using the same acetic acid bacteria; in the first case, corruption is evident, while in the second it is not. Recall also that microorganisms are necessary to obtain such well-known food products as bread, yogurt, etc. Sometimes the answer to the question of whether to evaluate the microbiological change in a food product as a deterioration in its quality or not depends on the depth and direction of this change. For example, the process of ripening cheese can smoothly go into its spoilage, and it is often impossible to accurately determine the transitional moment. Such uncertainty can have legal consequences, since in many countries there are bans on the supply of damaged products to trade.

food preservation

Canning

Canning   - This is the processing of food products to increase their shelf life. Conservation is understood as a set of measures against various types of damage. In a narrower sense, conservation refers to actions against microbiological damage.

Preservation aims to create conditions under which the development of microorganisms and the activity of enzymes causing food spoilage are impossible. A prerequisite for canning is the preservation of the nutritional value of the product, its quality and safety.

The quality of food products is one of the most important factors in the effective economic activity of any enterprise

With the development of civilization, life habits and needs of people have changed, they have a desire to enjoy delicacies and exotic products from distant countries. Many “branded” food products are produced, the safety of which is particularly high. In all these cases, one cannot do without using appropriate conservation techniques, i.e. without canning.

Although canning (at least in developed countries) has reached a high level, still an astounding amount of food is lost as a result of spoilage. According to some estimates, more than 20% of manufactured products do not reach the consumer’s table, but go to rodents, insects and microorganisms. In less developed countries, these losses are much greater.

If earlier food was canned solely for economic reasons, then recently the toxicological aspect has been added. For example, in the 60s, it was discovered that many molds form toxins that can enter food. If you limit the growth of molds, for example, using preservatives, then the formation of toxins is reduced. Therefore, from the point of view of disease prevention, the use of unconditionally non-toxic preservatives is less risky than refusing them.

Biological principles

Based on the biological principles developed by prof. I.Ya. Nikitsky, canning methods can be divided into four groups:

· Bios principle - maintaining life processes and using the natural immunity of living organisms (slaughtering livestock, poultry, keeping live fish, storage of fruits and vegetables)

· The principle of suspended animation - suppression of the vital activity of microorganisms and enzymatic processes of the products themselves as a result of: the creation of modified and regulated gas environments for storing fresh fruits and vegetables, fish - drug addiction; the use of lower temperatures above cryoscopic (cooling) - psychoanabiosis; creating high osmotic pressure in the product (canning with salt, sugar) - osmoanabiosis; removal of excess moisture from the product (drying) - xeroanabiosis;

· The principle of coenanabiosis - a change in the microflora of the product as a result of various external influences (ripening, souring, fermentation);

· The principle of abiosis - the cessation of the activity of microorganisms, enzymatic processes as a result of the action of high temperatures (thermobiosis), the use of antiseptics and other chemicals (chymabiosis);

Canning methods

Depending on the technological nature of the conservation methods are divided into physical, physico-chemical, chemical, biochemical, combined.

The choice and application of food preservation methods is determined by their influence on the feedstock and the quality of the resulting canned product. All methods of conservation are reduced to the destruction of microbes and the destruction of enzymes or to the creation of adverse conditions for their activity.

Physical methods of canning products

Physical methods are based on the use of high and low temperatures, ultrasound, ultraviolet and infrared rays, ionizing radiation, etc.

Conservation at low temperatures consists in suppressing the vital activity of microorganisms, reducing the activity of enzymes, and slowing down biochemical processes.

Groceries are a favorable environment for the development of microorganisms. Depending on the relation to temperature, microorganisms are divided into: thermophilic, developing at 50-70 ° С; mesophilic - at 20-40 ° С; psychrophilic - from +10 to -8 "C. Thermophiles include spore forms of microorganisms, the spores of which are particularly resistant, as a result of which they can tolerate sterilization. Mesophiles include many putrefactive bacteria that cause spoilage of food products at positive temperatures, as well as all pathogenic and toxigenic forms of bacteria Cooling and freezing include preservation at low temperatures.

Cooling - refrigeration of products and raw materials at a temperature close to cryoscopic, i.e., to the freezing temperature of the cell fluid, which is due to the composition and concentration of dry substances. Different food items have different cryoscopic temperatures. So, for meat it ranges from 0 to 4 ° C, for fish - from -1 to 5 ° C; for milk and dairy products - from 0 to 8 ° С; for potatoes - from 2 to 4 ° C; for apples - from 1 to -1 ° C.

Food cooling has one common goal - lowering their temperature to a predetermined final temperature, at which biochemical processes and the development of microorganisms are delayed. Storage at low positive temperatures ensures the preservation of food products in good condition for a sufficiently long time. So, meat, fish, poultry can be stored for one to two weeks, eggs - for several months, and some fruits and vegetables - until the new crop.

The most common industrial cooling methods that are carried out by heat transfer by convection, radiation, heat transfer during phase transformation. Cooling medium is air moving at different speeds. As a rule, cooling is carried out in refrigerators equipped with a device for distributing chilled air.

For cooling methods, which are based on convective and radiative heat transfer, low losses of moisture during cooling are characteristic of the product. This is the cooling of products in liquid media, as well as packaged in impervious shells. In a liquid medium, cool fish, poultry, some vegetables; in casings and packaging - sausages, semi-finished products, culinary, confectionery, etc.

Cooling is the best way to preserve the nutritional value and organoleptic properties of the product, but it does not provide a long shelf life. So, chilled milk and dairy products last 36-72 hours, meat - 15-20 days, fish - from 2 to 15 days. At the same time, some fruits and vegetables last up to 5-10 months.

Freezing   - this is the process of lowering the temperature of food products below the cryoscopic by 10-30 ° C, accompanied by the transition to the ice of the water contained in them. Freezing provides higher storage stability compared to refrigeration; many frozen foods can be stored for up to a year.

The lower the temperature (from -30 to -35 ° C), the faster the freezing speed, while small ice crystals are formed in the cells and in the intercellular space of the tissue and the tissues are not damaged. During slow freezing, large ice crystals form inside the cell, which damage it, and during thawing, cell juice is lost.

Microorganisms, depending on the reaction to negative temperatures, are divided into sensitive, moderately stable and insensitive. Vegetative cells of molds and yeasts are especially sensitive to freezing temperatures. Gram-negative bacteria belonging to the genera Psendomonas, Achromobaeter and Salmonella easily die. Gram-positive microorganisms and spore-forming bacteria are resistant to low temperatures.

The quality of a frozen product is determined by many factors: the condition of the product itself, the presence of biologically active substances, the method, the speed of freezing, the presence of its packaging and packaging material, etc.

Food products are frozen in various types of freezers (chamber, contact, tunnel, etc.). High efficiency is achieved when freezing small or crushed products in bulk on cooling surfaces or in a "fluidized" layer - by fluidization method. This ensures a high speed of cold air supplied under pressure, which washes suspended products from all sides.

Superfast refers to freezing in boiling coolants (liquid nitrogen, freon, etc.).

High temperature conservation is carried out to destroy microflora and inactivate enzymes in food products. These methods include pasteurization and sterilization.

Pasteurization   carried out at a temperature below 100 ° C. At the same time, spores of microorganisms remain. Pasteurization is distinguished short (at 85-95 ° C for 0.5-1 min) and long (at a temperature of 65 ° C for 25-30 min). Pasteurization is mainly used for processing products with high acidity (milk, juices, fruit drinks, beer). When the pH value is below 4.2, the thermal stability of many microorganisms decreases.

Sterilization - This is the heating of food products at temperatures above 100 ° C. In this microflora is completely destroyed. Sterilization is used in the production of canned food in sealed metal or glass containers. The sterilization mode is determined by the type of product, time and temperature. The sterilization regime of canned food with low acidity should be more stringent than canned food with high acidity. Lactic acid has a more inhibitory effect on microorganisms than citric acid, and citric acid has a more inhibitory effect than acetic acid. The presence of fat reduces the sterilizing effect.

Sterilization is usually carried out at a temperature of 100-120 ° C for 60-120 minutes (meat products), 40-120 minutes (fish), 25-60 minutes (vegetables), 10-20 minutes (condensed milk) with steam, water, air, steam-air mixture using a variety of equipment (rotational, static, continuous, etc.).

During sterilization, the nutritional value of the product decreases, its taste as a result of hydrolysis of proteins, fats, carbohydrates, the destruction of vitamins, certain amino acids and pigments.

The use of high-temperature short-term sterilization with a simultaneous reduction in the duration of the process is promising. Basically, this treatment is used for meat and dairy products at a temperature of 120-125? C for 35-45 minutes in a rotary mode. When sterilizing canned food with ultra-high and industrial frequency currents, the contents of the can quickly and evenly warm up throughout the volume, the duration of the process is reduced by 5-7 times. This is also a promising way. Microwave sterilization at a temperature of 130 ° C ensures the preservation of amino acids to a greater extent, higher protein digestibility and organoleptic properties of the product. Such processing is based on the interaction of electromagnetic fields with an oscillation frequency of 1 billion Hz and higher with dipole molecules of various substances, primarily water. Flame sterilization reduces the heat treatment time by 4-5 times compared to autoclaving. The cans are heated by rotating them in the burner flame at a speed of 0.75 s -1 for 10 minutes.

In connection with the introduction of the modern “wow in box” food packaging system, aseptic canning was widely used. The classic version of aseptic canning of goods in the wow in box system consists of three stages: sterilization of the product at a temperature of 130-150 ° C with subsequent cooling; sterilization of containers by radiation treatment; packaging a sterile product in a sterile container under aseptic conditions. Such processing is universal and is used for liquid and viscous products (milk, juices, wines, pasta, etc.).

Preservation by ionizing radiation   called cold sterilization, or pasteurization, since the sterilizing effect is achieved without increasing the temperature. For processing food products use b-, b-radiation, x-ray radiation, a stream of accelerated electrons. Ionizing radiation is based on the ionization of microorganisms, as a result of which they die. The conservation of ionizing radiation includes radiation sterilization (radaptation) of long-term storage products and radarization with pasteurizing doses.

Irradiation of products is carried out in inert gases, in vacuum, using antioxidants, at low temperatures.

A significant drawback of the ionizing treatment of products is a change in the chemical composition and organoleptic properties. In industry, this method is used to process containers, packaging, and premises.

Ultrasonic preservation   (more than 20 kHz). Ultrasonic waves have high mechanical energy, propagate in solid, liquid, gaseous media, cause a number of physical, chemical and biological phenomena: inactivation of enzymes, vitamins, toxins, destruction of unicellular and multicellular organisms. Therefore, this method is used for pasteurization of milk, in the fermentation and non-alcoholic industries, for the sterilization of canned food.

Ultraviolet radiation   (UVL). This is irradiation with rays with a wavelength of 60-400 nm. The death of microflora is due to the adsorption of UVL by nucleic acids and nucleoproteins, which causes their denaturation. Pathogenic microorganisms and putrefactive bacteria are especially sensitive to UVL. Pigment bacteria, yeast and their spores are more resistant to UVL. The use of UVL is limited due to low penetration (0.1 mm). Therefore, UVL is used for surface treatment of meat carcasses, large fish, sausages, as well as for the disinfection of containers, equipment, refrigerator chambers and storage facilities.

Using filtering filters. The essence of this method is the mechanical separation of the product from the causative agents of damage using filters with microscopic pores, i.e., the ultrafiltration process. This method allows you to maximize preserve the nutritional value and organoleptic properties of the goods and is used for processing milk, beer, juice, wine and other liquid products.

Physico-chemical methods of canning products

Physico-chemical methods of canning include drying, canning with salt, sugar.

Drying   - This is a heat and mass transfer process, as a result of which the product is dehydrated. Humidity of most food products is 40-90%, which leads to a limited shelf life. The ability of products to long-term storage is largely determined by the activity of water, which has thermodynamic significance.

When drying wet porous materials, which are the majority of food products, the wetting and capillary moisture, which evaporates from the surface of the material and from the capillaries, is primarily removed. This is free moisture, the evaporation of which obeys the laws of evaporation of a liquid from a free surface. Then, the adsorption moisture evaporates, which requires more energy to be removed. The evaporation of osmotic moisture occurs throughout the drying process, since the evaporation of all types of moisture increases the osmotic pressure. The evaporation of moisture from the product is completed upon reaching equilibrium between the processes, desorption (drying) and sorption (absorption) of moisture by the product.

During the drying process, the mass and volume of the product are reduced, which helps to save packaging, storage space and vehicles, as well as to increase the energy value of the product compared to the feedstock. Dried foods have a long shelf life. Nevertheless, during drying, a number of undesirable changes take place: oxidation of lipids and vitamins, deterioration of taste and aromatic properties

Currently, the food industry uses various drying methods.

At convective drying   (heated air) moisture is removed by air at a temperature of 80-120? C in drying plants. In this way, dried fruits, vegetables, yeast, etc.

Spray drying It is used for dehydration of liquid products that are sprayed in a drying chamber, where air with a temperature of 140-150? C is supplied. The duration of the product in the chamber is 5-30 s, while proteins and vitamins are completely preserved. Spray drying is used in the production of dry dairy products, egg white, fruit and vegetable powders, etc.

Conductive (contact) drying   carried out by direct contact of the wet product with a heated surface. The disadvantage of this method is that upon contact with a heated surface, protein denaturation occurs.

One of the varieties of the conductive method is freeze drying, which is based on the removal of moisture from frozen products by sublimation (sublimation) of water, i.e., the direct transition of ice into steam, bypassing the liquid phase, in a deep vacuum. At the first stage, the product quickly freezes to a temperature of no higher than -17 ° C for 15-20 minutes with the removal of 10-15% ice. In the second stage, the products are dehydrated as a result of heating the plates on which they are located. In this case, the product loses up to 80% moisture. The duration of the sublimation process is 10-20 hours. At the third stage, thermal vacuum drying occurs, as a result of which adsorption-bound moisture is removed within 3-4 hours to a residual moisture content of 3-6%.

When freeze-drying, the chemical composition, nutritional value, organoleptic properties of the product are maximally preserved, and the shelf life of the product can be increased up to 3 years. Freeze-drying is used to dehydrate products of plant and animal origin.

Radiation dryingit is based on the transfer of heat from an energy source through electromagnetic waves through a medium transparent to thermal radiation. Irradiation as an industrial method of processing food raw materials is used in more than 20 countries. The advantage of radiation treatment is the suppression of the vital activity of many types of putrefactive microflora and pests at relatively low doses.

The optimization of the heat treatment of the product involves the use of infrared rays   (ICL). A feature of the processing of the ICL product is the creation of a high humidity gradient due to the rapid decrease in the moisture content of the surface layers. The use of ceramic materials as ICL converters is promising.

Preservation with table salt and sugar. The method is based on an increase in the concentration of solids in the product with an increase in osmotic pressure, which leads to plasmolysis, cells and the death of microorganisms. The necessary effect is achieved with a sugar concentration of 60-65%. Salt in a concentration of 10-20% has a similar effect.

Chemical methods of canning products

For canning, they also use various chemicals approved by the health authorities - ethyl alcohol, acetic, sulfur, sorbic, benzoic, boric acids with antimicrobial effects.

Ethanol Preservation   It is used in the production of fruit juices, semi-finished products. At a concentration of ethyl alcohol of 12-16%, development is inhibited, and at 18%, the vital activity of microflora is suppressed. Alcoholic juices (25-30%) are used in the production of alcoholic beverages.

Pickling   - an increase in the acidity of the medium with the addition of acetic acid, which at a concentration of 1.2-1.8% inhibits the activity of microorganisms, primarily putrefactive. Usually pickling is combined with other methods of preservation: pickling, salting, pasteurization. Pickle fruits, vegetables, mushrooms, fish, etc.

Preservation by acids (antiseptics).   Antiseptics are called chemicals that have a detrimental effect on microorganisms. Penetrating into living cells, these substances interact with protoplasmic proteins, while paralyzing vital functions, which leads to the death of microorganisms.

Preservation of products with sulphurous acid, its salts, sulphurous anhydride is called sulfation.   Sulfuric acid inhibits the activity of molds and bacteria; more resistant yeast. This acid is used for preserving fruits, berries, vegetables, their semi-finished products. The residual content of sulfur dioxide in dried fruits and vegetables should not exceed 0.01-0.06%; in fruit puree -0.2; in juices -0.12-0.15%.

Benzoic acid (C6H5COOH) and its sodium salt at a concentration of 0.05-0.1% at pH 2.5-3 inhibit the action of yeast and mold; bacteria are more resistant. The amount of benzoic acid in the product should not exceed 70-100 mg / 100 g. Used for preserving fruits and vegetables, fish products.

Sorbic acid (С6Н802) and its salts are strong antiseptics and are used for preserving juices, purees, marinades, and other products with a low pH value. This acid and sorbates suppress the vital activity of yeast and mold, but do not affect bacteria. The amount of these substances is not the same for different products: from 0.05% - in soft drinks to 0.5% - in semi-smoked sausages.

Preservation with antibiotics.   Like antiseptics, antibiotics have a bactericidal effect. Antibiotics used in the food industry should be easily inactivated by heat treatment of the product. Currently used: biomycin (chlortetracycline), acting on mucus-forming microorganisms, is used to process meat and fish, as well as ice to cool fish; nystatin, acting on yeast and fungi that cause moldy meat; nisin, which inhibits the growth of staphylococci, streptococci, clostridia and other pathogenic microorganisms, is used in the production of canned and dairy and fruit and vegetable.

Gas canning. The essence of the method is to change the ratio of oxygen and carbon dioxide, as a result of which the vital activity and development of microorganisms are suppressed, and the enzymatic processes in the products themselves are slowed down. Inhibition of mold development occurs at a CO2 concentration of about 20%; at 40-50% CO2, their growth almost stops. Bacteria are more resistant to CO2. The use of gaseous media in combination with the refrigeration processing of food products is more efficient, and the shelf life is increased by 2-3 times.

Distinguish between regulated and modified gas environments. Gas canning is widely used for fruits, vegetables, fish, meat, poultry, and sausages.

Ozonation   - This is the treatment of products and premises with ozone, which has a disinfecting and deodorizing effect. As a strong oxidizing agent, ozone stops the development of bacteria, molds, and their spores both on the surface of the product and in the air. For the processing of food products (meat, sausages, cheeses), the ozone concentration should not exceed 10 mg / m 3. When ozonizing refrigeration chambers, containers and equipment, the ozone concentration should be high - 25-40 mg / m 3 for 12-48 hours, which reduces infection by 90%.

Biochemical methods of canning products

These methods include the preservation of products with lactic acid and ethyl alcohol, which are formed as a result of lactic acid and alcoholic fermentation.

Fermentation is a metabolic anaerobic process in which ATP is regenerated, and the cleavage products of the organic substrate serve both as a donor and an acceptor of hydrogen. According to L. Pasteur, fermentation is life without air.

The fermentation of fruits and vegetables is based on lactic acid fermentation. The term “pickling” is usually used in relation to cabbage, “salted” - to cucumbers and tomatoes, “soaked” - to apples and berries.

Under the influence of lactic acid bacteria, carbohydrates are converted to lactic acid, which gives a specific taste to the finished product. Lactic acid at a concentration of 0.5% inhibits the development of many microorganisms. Upon reaching its concentration of 1-2%, the effect of lactic bacteria ceases. Alcoholic fermentation proceeds simultaneously with lactic acid. The concentration of ethyl alcohol in sauerkraut and pickles reaches 0.5-0.7%, in soaked apples - 0.8-1.8%.

When salting and pickling, table salt is used in an amount of 2-3%, which causes plasmolysis of plant cells, stimulating the fermentation process, and also inhibits oil and other bacteria.

Ethyl alcohol is formed as a result of alcoholic fermentation during the fermentation of carbohydrates by yeast. Alcoholic fermentation is used in the production of wine. In grape and fruit wort, carbohydrates are available for fermentation, that is, they contain glucose and fructose, which are fermented without prior hydrolysis by yeast. When the alcohol content in alcoholic beverages is 10-20%, the development of microorganisms is suppressed, and at higher concentrations of alcohol they die.

Combined Food Preservation Methods

When combined methods use the preservative effect of several factors.

Smoking   - This is a method of preserving a salted semi-finished product with incomplete combustion of wood contained in smoke or smoke preparations. Smoking is used to obtain meat smoked meats, processed fish, sausages and other products.

In the formation of consumer properties of smoked products, the most important role belongs to three groups of organic compounds: phenols, carbonyl compounds and organic acids. Phenolic compounds (guaiacol, methyl guaiacol, eugenol, etc.) contribute to the formation of the taste and aroma of smoked meats. Carbonyl compounds (formaldehyde, furfural, glycolaldehyde, methylglyoxal) partly enhance the smoked flavor and form the color of the product. The mechanism of color formation is represented by a number of non-enzymatic reactions similar to the Maillard reaction (melanoidinogenesis). Volatile acids play an auxiliary role, contributing to the formation of taste and aromatic properties of the product in combination with phenols and carbonyl compounds. The preserving effect is determined by phenols and furfural.

Aldehydes and alcohols have an aseptic effect, contribute to the death of surface microflora.

In the process of processing, in addition to substances that give the effect of smoked products, undesirable chemicals with carcinogenic properties pass into the product. Such substances include semi-cyclic aromatic hydrocarbons (PAHs) and nitrosamines (HA). PAHs are formed in smoke from the thermally generated methylene radicals and accumulate on the surface of the product when smoked. The concentration of PAHs in smoked products is from 1 to 58 μg / kg. The level of benzpyrene in smoked fish products is higher than in meat products. The concentration of benzpyrene in hot smoked fish is especially high. In addition to benzpyrene, 18 PAHs were found in smoked products.

Free formaldehyde has a carcinogenic effect, the permissible content of which in foods is 50 mg / kg.

Smoking methods are divided according to the following factors:

smoking temperature: cold (not higher than 40 ° C), semi-hot (50-80 ° C), hot (80-180 ° C); method of using wood decomposition products: smoke, smokeless (wet) and mixed.

During smoke smoking, the semi-finished product is impregnated with substances released during incomplete combustion of wood, which are in an aerosol state (smoke). Smokeless smoking is carried out by dry wood distillation products in the form of solutions (smoke liquid). Mixed smoking is a combination of smoke and smokeless methods, that is, the sequential processing of the semi-finished product by the decomposition products of wood in liquid or gaseous states; conditions for the deposition of products of incomplete combustion of wood on the surface of semi-finished products and their penetration deep into: natural (without the use of special techniques) and artificial (using high-frequency currents, infrared rays, electric smoking), combined (a combination of natural and artificial smoking). Electric smoking (at a temperature not exceeding 100 ° C) is based on the deposition of products of incomplete combustion of wood in an electric field of high voltage direct current. Electric smoking is used to obtain smoked meat, hot and cold smoked fish, sausages, etc.

Drying   - This is a method of combined exposure to sodium chloride and drying the product to partially remove moisture, sufficient to suppress microflora. Mostly dried meat and fish products. Sun-dried products along with many others belong to products with intermediate humidity, as they are in a state of equilibrium with a relative humidity of 60-85%. Humidity of such products is 15-40%. They are well preserved without additional heat treatment, have a soft consistency and are suitable for direct consumption.

Concentration   - It is used in the manufacture of condensed milk canned goods, concentrated juices, tomato products. This method consists in concentrating solids by partially removing moisture. In addition, the addition of sugar, pasteurization or sterilization have a preservative effect, due to which concentrated food products are stored at a temperature of 0-15 ° C for up to a year or more.

Condoms - is a method of manufacturing a special type of canned food - condoms. The latter are an unsterilized product placed in a sealed tin container (jar). The preservative effect in preserves is achieved due to the combined combined effect with other preservative factors - salting, pickling, the action of spices herbs, etc. Thus, condoms are related to combined preservation products. Preserves are products with a limited shelf life and quick sale. Storage of condoms should be carried out under conditions of slight cooling (6-8 °).

Preservatives

Preservatives are substances that increase the shelf life of products.

Modern living conditions dictate the need to use a number of chemical compounds that can effectively prevent the development of microbial flora - mainly bacteria, mold, yeast, among which there can be both pathogenic and non-pathogenic species.

Under preservatives   understand substances that increase the shelf life of food products and protect them from spoilage caused by microorganisms.

Chemical preservatives should provide long-term storage of products without exerting any negative effect on its organoleptic properties, nutritional value and consumer health. The effectiveness of the preservative depends on its concentration, pH, the qualitative composition of the microflora. None of the known preservatives is universal for all food products. Each preservative has its own spectrum of action.

Vitamin C. The antimicrobial effect of preservatives is enhanced in the presence of ascorbic acid. Preservatives can have a bactericidal (destroy, kill microorganisms) or bacteriostatic (stop, slow down the growth and reproduction of microorganisms) effect.

One of the main signs of hygienic regulation of chemical preservatives is their use in concentrations that are minimal to achieve a technological effect.

The use of antimicrobial substances in lower doses can contribute to the multiplication of microorganisms. This must be taken into account when developing sanitary rules and norms for food additives and their practical application.

Sulfur compounds. Common sulfur preservatives include sulfur compounds such as anhydrous sodium sulfite (Na2S03) or its hydrated form (Na2S03 7H20), sodium metabisulfate (thiosulfate) acid (Na2S203), or sodium hydrosulfite (NaHS03). They are highly soluble in water and emit sulfur dioxide (S03), which determines their antimicrobial effect. Sulfur anhydride and its excreting substances inhibit mainly the growth of molds, yeast and aerobic bacteria. In an acidic environment, this effect is enhanced. To a lesser extent, sulfur compounds affect the anaerobic microflora. Sulfur anhydride has a high reducing ability, as it is easily oxidized. Due to these properties, sulfur compounds are potent inhibitors of dehydrogenases, protecting potatoes, vegetables and fruits from non-enzymatic browning. Sulfur dioxide is relatively easy to leave the product when heated or prolonged contact with air. However, it is able to destroy thiamine and biotin and enhance the oxidative decomposition of tocopherol (vitamin E). Sulfur compounds are not suitable for the preservation of food products that are the source of these vitamins.

Once in the human body, sulfites are converted to sulfates, which are well excreted in urine and feces. However, a high concentration of sulfur compounds, for example, a single oral administration of 4 g of sodium sulfite, can cause toxic effects. The acceptable daily intake (PSP) level of sulfur dioxide determined by the FAO / WHO OKEPD is 0.7 mg per 1 kg of human body weight. Daily intake of sulfonated foods may result in exceeding the allowable daily dose. So, with one glass of juice, about 1.2 mg of sulfur dioxide is introduced into the human body, 200 g of marmalade, marshmallows or marshmallows - 4 mg, 200 ml of wine - 40 ... 80 mg.

Sorbic acid. It has a mainly fungicidal effect due to its ability to inhibit dehydrogenases and does not inhibit the growth of lactic acid flora, therefore it is usually used in combination with other preservatives, mainly with sulfur dioxide, benzoic acid, sodium nitrite. Sorbic acid salts are widely used.

The antimicrobial properties of sorbic acid are little dependent on the pH value; therefore, it is widely used in the preservation of fruit, vegetables, eggs, flour products, meat, fish products, margarine, cheeses, and wine.

Sorbic acid is a low-toxic substance, in the human body it is easily metabolized with the formation of acetic and b-hydroxybutyric acids.

Benzoic acid. The antimicrobial effect of benzoic acid (C7H602) and its salts - benzoates (C7H505Na and others) is based on the ability to suppress the activity of enzymes. In particular, during the inhibition of catalase and peroxidase, hydrogen peroxide accumulates, inhibiting the activity of the microbial cell. Benzoic acid can block succinate dehydrogenase and lipase - enzymes that break down fats and starch. It inhibits the growth of yeast and bacteria of ferric acid fermentation, has a weak effect on bacteria of acetic fermentation and very little on lactic acid flora and mold.

N-hydroxybenzoic acid and its esters (methyl, ethyl, n-propyl,) are also used as preservatives. However, their preservative properties are less pronounced, a negative effect on the organoleptic properties of the product is possible.

Benzoic acid practically does not accumulate in the human body. It is part of some fruits and berries as a natural compound; esters of n-hydroxybenzoic acid - as part of plant alkaloids and pigments. In small concentrations, benzoic acid forms hippuric acid with glycol and is completely excreted in the urine. In high concentrations, the manifestation of toxic properties of benzoic acid is possible. The permissible daily dose is 5 mg per 1 kg of human body weight.

Boric acid. Boric acid (H3BO3) and borates have the ability to accumulate in the human body, mainly in the brain and nerve tissues, showing high toxicity. They reduce tissue oxygen consumption, ammonia synthesis, and adrenaline oxidation. In this regard, in our country, these substances are not used.

Hydrogen peroxide. In a number of countries, hydrogen peroxide (Н2О2) is used to preserve milk intended for the manufacture of cheese. In the finished product, it should be absent. Catalase of milk breaks it down.

In our country, hydrogen peroxide is used to bleach slaughter blood. Additionally, catalase is added to remove hydrogen peroxide residues. Catalase is used in the manufacture of roots for various semi-finished products.

Hexamethylenetetramine, or urotropine, hexalin. The active principle of these compounds is formaldehyde (CH2O). In our country, hexamine (C6H12N4) is allowed for the preservation of salmon caviar and the cultivation of uterine yeast cultures. Its content in granular caviar is 100 mg per 1 kg of product. Hexalin content is not allowed in prepared yeast.

The permissible daily dose established by WHO is not more than 0.15 mg per 1 kg of human body weight.

Hexamethylenetetramine is used abroad for preserving sausage casings and cold marinades for fish products.

Diphenyl, biphenyl. Cyclic compounds, sparingly soluble in water, have strong fungicidal properties that inhibit the development of mold and other fungi.

The substance is used to extend the shelf life of citrus fruits by immersing them for a short time in a 0.5 ... 2% solution or by soaking brown paper with this solution. In our country, these preservatives are not used, however, the sale of imported citrus fruits using this preservative is allowed.

The considered compounds have a moderate degree of toxicity. When ingested, about 60% of diphenyls are excreted from it.

The permissible daily dose according to WHO recommendations is 0.05 for diphenyl per 1 kg of human body weight. Different countries allow different levels of residual biphenyls in citrus fruits - 20 ... 110 mg per 1 kg of human body weight. It is recommended to thoroughly wash the citrus fruits and soak their peels, if they are used in food.

In the Russian Federation, organic acids (formic, propionic, salicylic, etc.) are used only for the conservation of roughage of farm animals.

Formic acid. In its organic structure, formic acid (HCOOH) is a fatty acid and has a strong antimicrobial effect. In small quantities, formic acid is found in plant and animal organisms.

At high concentrations, it has a toxic effect, it has the ability to precipitate pectins in food products, therefore, in general, it is limitedly used as a preservative.

In our country, salts of formic acid - formates are used as salt substitutes in the diet.

For formic acid and its salts, the DSD should not exceed 0.5 mg per 1 kg of human body weight.

Propionic acid. Like formic, propionic acid (C2H5COOH) is widespread in living nature, being an intermediate in the Krebs cycle, which provides the biological oxidation of proteins, fats and carbohydrates.

In the USA, propionic acid is used as a preservative in the production of bakery and confectionery products, preventing their mold. In a number of European countries, it is added to flour.

Salts of propionic acid, in particular sodium propionate, are low toxic. The daily dose of the latter in the amount of 6 g does not cause any negative effects, and therefore it is not established by the WHO OKEPD.

Salicylic acid. The substance is traditionally used in the home canning of tomatoes and fruit compotes. In the UK, salicylic acid salts - salicylates - are used to preserve beer. The highest antimicrobial properties of salicylic acid are manifested in an acidic environment.

At present, the toxicity of salicylic acid and its salts has been established; therefore, the use of salicylic acid in Russia as a dietary supplement is prohibited.

Diethyl ether of pyrocarbonic acid. It can inhibit the growth of yeast, lactic acid bacteria and, to a lesser extent, mold, and in some countries it is used for canning drinks. The substance has a fruit odor. At a concentration of more than 150 mg of the substance per 1 kg of the product, the taste of drinks deteriorates and its toxic properties are manifested.

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Canning -this is the processing of food products to increase their shelf life.

Based on the biological principles developed by prof. I.Ya. Nikitsky, canning methods can be divided into four groups:

· The principle of biosis - the maintenance of life processes and the use of the natural immunity of living organisms (slaughtering livestock, poultry, keeping live fish, storage of fruits and vegetables;

· Principle of suspended animation - suppression of the vital activity of microorganisms and enzymatic processes of the products themselves as a result of: the creation of modified and regulated gas environments for storing fresh fruits and vegetables, fish - drug addiction; the use of lower temperatures above cryoscopic (cooling) - psychoanabiosis; creating high osmotic pressure in the product (canning with salt, sugar) - osmoanabiosis; removal of excess moisture from the product (drying) - xeroanabiosis;

· Principle of coenanabiosis - a change in the microflora of the product as a result of various external influences (ripening, souring, fermentation);

The principle of abiosis - cessation of the activity of microorganisms, enzymatic processes as a result of the action of high temperatures (thermal abiosis), the use of antiseptics and other chemicals (chemical biosis);

Depending on the technological nature of the conservation methods are divided into physical, physico-chemical, chemical, biochemical, combined.

Physical methods

Low temperature preservation -this method includes cooling and freezing.

Cooling is a common canning method. It is widely used to preserve fresh fruits, vegetables, meat, fish and dairy products, eggs. Food products with this method of canning are cooled to temperatures close to 0 ° C. Cooling preserves the nutritional value and organoleptic properties of the goods, but does not ensure the long-term preservation of products (for example, sour cream - up to 72 hours, curd products - up to 36 hours; pasteurized milk - up to 36 hours). This method is used when transporting goods over short distances, subject to rapid implementation in the distribution network.

Freezing - this is a canning method in which the temperature of the products drops to -8 ° C or lower. Freezing promotes long-term preservation of food. Shelf life of frozen foods is measured in months and even years. The lower the temperature, the faster the freezing speed and the higher the quality of the products. Quick freezing reduces product weight loss. During slow freezing, large crystals of ice are formed inside the cell, which damage it and during thawing, cell juice is lost.

Frozen foods are inferior in quality to chilled ones, as long-term storage changes their nutritional and taste value, as well as possible loss of nutrients during defrosting.

High temperature preservation   carried out to destroy microflora and inactivation of enzymes in food products. This method includes pasteurization and sterilization.

Pasteurization is carried out at a temperature below 100 ° C. With this heating, microorganisms die, but their spores remain. Therefore, although pasteurization lengthens the shelf life of goods, it does not guarantee their full safety. Kvass, milk, beer, fish caviar are pasteurized. During pasteurization, the nutritional value of the product changes little; vitamins and some other biologically active substances are only partially destroyed.

Sterilization -   more effective method of conservation than pasteurization. Sterilization is carried out at a temperature above 100 ° C for a certain time (from a few seconds - instant sterilization, up to 1 hour) depending on the type of product.

This method is widely used for the preparation of various types of canned food (meat, fish, dairy, vegetable), milk. During sterilization, not only microorganisms die, but also their spores, which lengthens the shelf life of products (up to several years - canned food). However, during sterilization, the nutritional value of the product decreases, its taste changes.

Preservation by ionizing radiation   called cold sterilization or pasteurization, since the sterilizing effect is achieved without increasing the temperature. For processing food products use b-, b-radiation, x-ray radiation, a stream of accelerated electrons. Ionizing radiation is based on the ionization of microorganisms, as a result of which they die. The conservation of ionizing radiation includes radiation sterilization (radaptation) of long-term storage products and radarization with pasteurizing doses. Irradiation of products is carried out in inert gases, vacuum, using oxidizing agents, at low temperatures. The disadvantage of this method is a change in the chemical composition and organoleptic properties. In industry, this method is used to process containers, packaging, and premises.

Ultrasonic preservation(more than 20kHz). This method is used for pasteurization of milk, in the fermentation and non-alcoholic industries, for the sterilization of canned food.

Ultraviolet radiation   (UVL). This is irradiation with rays with a wavelength of 60-400 nm. UVL is especially fatal for pathogenic microorganisms and putrefactive bacteria. Therefore, UVL is used for surface treatment of meat carcasses, large fish, sausages, as well as for the disinfection of containers, equipment, refrigerator chambers and storage facilities.

Use of supporting filters.The essence of this method in the mechanical separation of the product from the causative agents of damage using filters with microscopic pores, i.e. ultrafiltration process. This method allows you to maximize preserve the nutritional value and organoleptic properties of the goods and is used for processing milk, beer, juice, wine and other liquid products.

Physicochemical Methods

Drying (dehydration). This oldest preservation method is based on the removal of moisture from products, as a result of which microorganisms are not able to develop. Dried milk, dairy products, fish, fruits, vegetables, mushrooms. When drying, products significantly lose weight, which facilitates their transportation and storage, increases the energy value of the product compared to the feedstock. Dried foods have a long shelf life. But when drying, there are a number of undesirable changes: the oxidation of lipids and vitamins, the deterioration of taste and aroma properties. Drying can be natural (in the sun and in the shade) and artificial (thermal, sublimation, microwave). Thermal drying is carried out in dryers using air heated to a temperature of 60-200 ° C.

Conductive (contact drying) is the contact of the product with the hot surface of the drums (drying of milk, mashed potatoes).

Freeze-drying is a type of conductive method, based on the removal of moisture from frozen products by sublimation (sublimation) of water, i.e. direct transition of ice to steam, bypassing the liquid phase, in a deep vacuum.

When freeze-drying, the chemical composition, nutritional value, organoleptic properties of the product are maximally preserved, and the shelf life of the product can be increased up to 3 years. Freeze-drying is used to dehydrate products of plant and animal origin.

Radiation drying is based on the transfer of heat from an energy source through electromagnetic waves through a medium transparent to thermal radiation. The advantage of radiation treatment is the suppression of the vital activity of many types of putrefactive microflora and pests at relatively low doses.

Canning with salt and sugar.The method is based on an increase in the concentration of solids in the product, which leads to plasmolysis of cells and the death of microorganisms. The necessary effect is achieved with a sugar concentration of 60-65%. Salt in a concentration of 10-20% has a similar effect. Commodity management and organization of food trade: Textbook / Ed. A.M. Novikova, T.S. Golubkina. M. - ProfOborIzdat. - 2001. - p. 44. Sugar preservation is usually combined with boiling, pasteurization or sterilization, which leads to the destruction of vitamins, aromatic and other substances.

With salting, the nutritional value of the product decreases, since under the influence of salt, cell juice flows out, forming a brine. When salting some species of fish, they mature, resulting in food products with high taste properties. A feature of the salt and sugar canning method is that it significantly changes the properties of the raw materials and as a result a product with new consumer properties is formed.

Chemical methods

Ethanol Preservationit is used in the production of fruit juices, semi-finished products. At a concentration of ethyl alcohol of 12-16%, development is inhibited, and at 18%, the vital activity of microflora is suppressed.

Pickling-increasing the acidity of the medium with the addition of acetic acid, which at a concentration of 1.2-1.8% inhibits the activity of microorganisms, primarily putrefactive. Pickle fruits, vegetables, mushrooms, fish.

Preservation by acids (antiseptics) -using sulfuric acid, benzoic acid, sorbic acid (C 6 H 8 O 2).

Preservation of products with sulfuric acid, its salts is called sulfation. Sulfuric acid inhibits the activity of molds and bacteria; more resistant yeast. that acid is used for preserving fruits, berries, vegetables, their semi-finished products.

Benzoic acid (C 6 H 5 COOH) inhibits the action of yeast and mold, bacteria are more resistant. Used for canning fruits and vegetables, fish products.

Sorbic acid (C 6 H 8 O 2) and its salts are used for preserving juices, mashed potatoes, marinades. These substances suppress the vital activity of yeast and mold, but do not affect bacteria. Sorbic acid in a concentration of 0.1% inhibits the action of microorganisms more than benzoic and sulfur, without changing the organoleptic properties of the product; in small doses, it is harmless to humans. Timofeeva V.A. Commodity research of food products. - Rostov n / a: Publishing house "Phoenix". - 2002. -

Preservation of antibiotics.Like antiseptics, antibiotics have a bactericidal effect. Currently using: biomycin   (used for processing meat and fish; nystatin   acting on yeast and fungi causing moldiness of meat; lowlands,   growth retardant staphylococci, streptococci and other pathogenic microorganisms, are used in the production of canned and dairy and fruit and vegetable.

Gassing.The essence of the method is to change the ratio of oxygen and carbon dioxide, as a result of which the vital activity and the development of microorganisms are suppressed. The use of gaseous media in combination with refrigeration processing of food products is effective, and the shelf life is increased by a factor of 2-3. Used for preserving vegetables, fish, meat, poultry, sausages.

Biochemical methods   Fermentation - this is a metabolic anaerobic process in which ATP is regenerated, and the cleavage products of the organic substrate serve both as a donor and an acceptor of hydrogen. The fermentation of fruits and vegetables is based on lactic acid fermentation. The term "pickling" is usually used in relation to cabbage, "salted" - to cucumbers and tomatoes; "Soaked" - to apples, watermelons and berries. Alcoholic fermentation is used in the production of wine.

Combined methods.

Smoking - this is a method of preserving salted semi-finished products with incomplete combustion of wood contained in smoke or smoke preparations. This method combines the preservative effect of smoke, salt, heat or drying. Separate smoke substances and salt improve the taste of the product and give it the smell of smoking. Smoking is cold (at a temperature of 18-40 ° C) and hot (60-120 ° C). Smoke using smoke liquid is widely used. Its advantage is that smoking times are reduced and it is possible to exclude carcinogenic substances harmful to the human body from the smoking product.

Drying - it is preservation by the simultaneous action of salt and drying. Drying is used to preserve fish, sometimes meat. The action of salt and a small amount of moisture inhibit the development of microorganisms. At low temperatures, jerky foods last up to several months.

Concentration - used in the manufacture of condensed milk canned foods, concentrated juices, tomato products. This method consists in concentrating solids by partially removing moisture. In addition, the addition of sugar, pasteurization or sterilization have a preservative effect, due to which concentrated food products are stored at a temperature of 0-15 ° C for up to a year or more.

Food preservation is used to extend their shelf life, which is of particular importance for perishable products. For food preservation, various methods are used - physical, chemical and biological. Of the physical methods, canning is most widely used by means of low (cooling, freezing) and high (sterilization, pasteurization) temperatures.

During cooling, the product is stored at a temperature of 0 to + 4 °. Under such conditions, the activity of oxidative processes decreases in products and the development of pathogenic and saprophytic microflora ceases. However, chilled products continue to change, so their shelf life is limited to 10-20 days.

In cases where it is necessary to preserve the product for a longer period, freeze is used. For this, a temperature of about 20 ° is used. Freezing almost does not change the initial properties of the products and guarantees their high quality.

High temperature preservation is carried out by sterilization, pasteurization, drying.

During sterilization, the complete destruction of all forms of bacteria occurs. This is achieved by autoclaving at a temperature of 100-120 ° and an exposure of 30 minutes. Canned food after sterilization can be stored from 1 year to 1 5 years.

Pasteurization involves the destruction of vegetative forms of microorganisms. For this, a temperature of 63 ° is often used for 30 minutes (prolonged pasteurization).

For short-term pasteurization, a relatively high temperature is used - 85-90 °, but the exposure time is limited to 30 s - 1 min. Short-term pasteurization is used in the manufacture of fruit juices and milk in large enterprises where it is necessary to ensure the continuity of the pasteurization process. After pasteurization, the product almost does not change its original properties and vitamins are stored in it.

Drying - dehydration of food products in a stream of hot air or in direct contact with a heated surface. When humidity is less than 15%, the reproduction of bacteria stops.

Drying - dehydration of products by drying in the sun. When dried, vitamin C is completely destroyed, and carotene is partially destroyed.

Preservation of table salt. When the content in the preservative medium of 9-10% of sodium chloride is delayed the growth of bacteria due to dehydration. In addition, salt reduces the amount of oxygen in the medium, thereby inhibiting the development of aerobes. With salting, some of the vitamins are destroyed, and some are transferred to brine.

Sugar preservation. With a sugar content of 70%, a high osmotic pressure is created in the product, which inhibits the development of microorganisms. Sugar preservation by simply mixing the product with sugar without heating preserves its original properties (taste, aroma) and vitamins.

Pickling preservation. When pickling products with food acids (acetic, citric), the reaction shifts to the acidic side, which leads to inhibition of microflora development. Salt and spices also contribute to this. To preserve vegetables, fermentation is often used. When fermentation is influenced by the microflora found in vegetables and fruits (lactic acid microflora), sugar is converted into lactic acid, which inhibits the growth and development of putrefactive bacteria. Salt added during pickling also inhibits the development of microorganisms.

Smoked canning. When smoking, three factors act: dehydration, increased concentration of salt and antiseptic substances contained in the smoke. Smoking can be cold and hot. Cold smoking is carried out at a temperature of 25-30 ° for 3-7 days. After smoking, the product acquires a specific taste and smell. Hot smoking is carried out at a temperature of 120-140 ° for several hours. This method canned fish most often. After hot smoking, the fish is unstable during storage, therefore, in the distribution network, its shelf life is limited to 72 hours at a temperature not exceeding 8 °.

Preservation by ionizing radiation. Currently, in different countries, a method of preserving food products by processing them with ionizing radiation of radioactive isotopes is being developed. This method is economical, but when irradiated with large doses, the organoleptic properties of the products change: they acquire extraneous tastes and smells. When food is irradiated, amino acids and vitamins are almost not destroyed.

Canning   - a method of preserving food products (making canned food), consists in the technical processing of food products to inhibit the activity of microorganisms spoiling products. As well as some other ways to increase the shelf life of food products.

In a broad sense, by canning is meant any process that significantly lengthens the safety of products in a form suitable for human consumption. The main objective of canning is to reduce the level of water activity to a minimum level, which deprives harmful microorganisms of the living environment for further development and damage to the product.

20. Up to half of all restaurant business expenses are procurement costs   food products. The restaurant manager must ensure strict control over this process.

The following parameters are important:

• determination of standards of technical characteristics of purchased food products (product specifics);
• installation of tools and procedures for monitoring theft and loss of products (for example, the tool is an accounting computer program, and the procedure is a detailed instruction on accounting for the movement of material assets and periodic inventories),
• rationing the quantity of each of the products, which should always be available;
• certainty in who is responsible for the procurement - both for the selection of the supplier and for compliance with the procurement procedure.
• appointment of those responsible for acceptance (receipt), storage in a warehouse and delivery of food products to work

Restaurant business experts note that different restaurants use different procurement process procedures, but all of them can lead to three enlarged business procedures.

Personal hygiene of catering workers. A uniform.

Personal hygiene is a set of sanitary rules that catering workers must observe. Compliance with personal hygiene is important in preventing contamination of food by microbes that can cause contagious diseases and food poisoning. Personal hygiene of employees increases the culture of customer service and serves as an important indicator of the overall culture of public catering enterprises.

Keeping the body clean is an important hygienic requirement, therefore, all employees of a catering company, especially cooks and confectioners, need to keep their bodies clean. It is recommended to take a shower every day before work using soap and a washcloth. And immediately before work, wash your hands to the elbow. Keeping your hands clean is of particular importance to catering workers who constantly come into contact with food during cooking.

The appearance of the hands of catering workers must meet the following requirements: short-cut nails, clean subungual space. Do not wear watches or jewelry. The contents of the oral cavity, catering workers, is also of great hygienic importance, since the mouth usually contains a large number of microbes. It is necessary to brush your teeth daily. In colds, you can’t start work without a doctor’s opinion.

Sanitary clothing protects food products from contamination that may get into them from the body and personal clothing of workers during cooking.

The set of sanitary clothing of the cook and pastry chef includes: jacket or bathrobe, cap or scarf, apron, towel, trousers or skirt, special shoes.

Sanitary clothing is made of white cotton, easily washable fabric.

When wearing sanitary clothing, the following rules must be observed: do not put foreign objects in your clothing pockets; do not use pins and needles to fasten bathrobes; take off clothes before leaving the production room; keep it separate from outerwear.

The sanitary regime of the catering service obliges employees to monitor the cleanliness of the workplace, equipment, inventory and utensils.

Catering workers must undergo a medical examination.

Methods and approaches to the quality of products and restaurant service.

The quality of products (goods or services) is the most important indicator of the enterprise. Improving the quality of products to a large extent determines the survival of the enterprise in the market, the pace of scientific and technological progress, the growth of production efficiency, the saving of all types of resources used in the enterprise. The increase in the quality of manufactured products is a characteristic tendency of the work of leading world companies. Enterprises in the field of social and cultural services and tourism are no exception. It is far from a secret that over the past decade the number of service organizations has increased significantly, employment in this area has increased, the range of services offered has expanded, competition has intensified.

Modern quality management of restaurant services and services consists of the following parameters:

Service management is a holistic integrated management model that serves as the basis for making effective management decisions in the field of creating and implementing services, both in a separate area and in the complex as a whole;

Service management, which is focused on the client of the restaurant and his needs;

Labor cooperation, which is a collective work aimed at a common result, partnership and functional cooperation;

Restaurant product quality management is an integral part of service management;

Personnel management, whose functions include retraining, advanced training, staff development of all restaurant divisions.

Methods of canning.

Preservation is the processing of food products for long-term preservation of their good quality in various ways that ensure the suppression and termination of biochemical processes that occur in products under the action of enzymes. Canning allows you to eliminate the seasonality in the consumption of perishable products, expand the range of goods and increase the degree of their readiness for consumption. In addition, the use of some canning methods allows to obtain products with other properties, i.e. essentially other goods.

Distinguish between physical, physico-chemical, biochemical and chemical methods of conservation.

Physical methods include canning using low and high temperatures, filtering, radiant energy, ultrasound, ionizing treatment.

Physico-chemical methods - this is the preservation of products with salt, sugar and drying.

Preserving factors are an increase in osmotic pressure (i.e. pressure caused by solute molecules) and a decrease in water activity. An increase in the osmotic pressure is achieved by adding sodium chloride or sugar to the product or by concentrating the dissolved substances of the product itself by drying it. At high osmotic pressure, water activity decreases, plasmolysis (dehydration) of microbial cells occurs, and enzymes are inactivated. The preservative effect of sodium chloride is also due to the fact that active sodium cations and chlorine anions are attached at the site of peptide bonds of protein molecules, as a result of which the product proteins become inaccessible for the nutrition of microorganisms.

Chemical methods. Chemical methods include the following methods:

1. Preservation with ethyl alcohol (based on the destructive effect of alcohol on microorganisms). At concentrations of 12–16%, ethyl alcohol slows down the development of microflora, and at 18% it completely inhibits it. Ethyl alcohol is used as a preservative in the production of semi-finished fruit and berry juices, and determines the long-term storage of wine and other alcoholic beverages.

2. Marinating (based on the suppression of the vital activity of microorganisms by acetic acid, which, like lactic acid, increases the active acidity of the medium). Acetic acid in an amount of from 0.6 to 1.2% is added when pickling fruits, vegetables, fish, mushrooms. A small concentration of acid cannot fully protect the product from spoilage during storage. Therefore, fruits and vegetables pickled with a small amount of acetic acid are subjected to pasteurization or sterilization, pickling fish is combined with salting. A higher concentration of acetic acid affects the taste of the product and is not harmful to the human body.

24. Methods for determining quality.

There are the following methods for determining the quality of goods:

Organoleptic;

Laboratory;

Expert;

Measuring;

Registration, sociological.

Organoleptic method - quality is established using the senses (vision, hearing, smell, touch, taste) in appearance, color, and consistency.

The appearance of the goods is determined by inspection, making up the overall visual impression.

Color set in daylight:

by standards (roasted coffee);

on a color scale (tea);

according to special prescriptions (wine).

Taste and smell are the most important indicators of product quality. There are 4 types of taste: sweet, salty, sour, bitter. Various substances can affect the taste, causing a sharp, burning, tart aftertaste. Foreign taste can change the quality of the product.

The laboratory method of quality assessment requires special equipment, tools, it is more complex and lengthy, but accurate and objective. The laboratories conduct physical, chemical, physico-chemical, biochemical, microbiological studies of the quality of products.

Expert method. The decision on the quality of products is made by experts.

The expert group includes highly qualified specialists in this product - scientists, technologists, product experts, etc.

Measuring method. With this method, numerical values \u200b\u200bof product quality indicators are determined on the basis of technical measuring instruments. The results of this method are objective and expressed in specific units. But this method requires special equipment, chemicals, specially trained workers.

Registration method. Quality is determined by counting the number of certain events, items, and also based on observations.

Sociological method. Quality indicators are determined based on the collection and analysis of consumer opinions. At specially organized consumer conferences, sales exhibitions, tastings, consumers fill out questionnaires, which are then processed.

Comprehensive studies of the quality of goods are possible with a combination of organoleptic and laboratory methods. The quality of the goods by the laboratory method is determined by the average sample.

The average sample is a sample by which you can judge the quality of the entire batch of goods.

To get an average sample, they usually take a small amount of goods from different places (bottom, top, from the middle).

With a large number of items in the consignment, an average sample is taken from at least 10% of all places. With a small batch of goods, a sample is taken from each packaging place. Liquid and bulk goods should be mixed well before sampling. The accuracy of determining the quality of the entire batch of goods largely depends on the correctness of taking an average sample.