The use of sugars in food preparation technology. From cooking to culinary chemistry
Lecture number 1. Introduction
Plan:
1. Subject and objectives of the course
2.Folk cuisine and modernity
3.Professional cooking
1. - a technical discipline that studies the rational preparation of culinary products in conditions of mass production.
The purpose of the discipline is the acquisition by students of theoretical knowledge about the technological processes of processing raw materials, preparing, designing and dispensing culinary products, assessing their quality and safety.
The subject of the discipline are: the technology of production of semi-finished products and finished products at public catering establishments; physico-chemical and biochemical processes occurring in products during their culinary processing; requirements for the quality of culinary products; ways to control technological processes.
Course objectives:
Ensuring the quality and safety of culinary products;
Production of culinary products balanced in terms of the main nutritional factors (amino acid, fat, mineral, vitamin compositions, etc.)
Ensuring good digestion of food by giving it the necessary aroma, taste, appearance;
Reducing waste and loss of nutrients in the culinary processing of products;
use of low-waste and waste-free technologies;
maximum mechanization and automation of production processes, reducing the cost of manual labor, energy, materials.
Interdisciplinary connections with other disciplines. The basis for studying the discipline is the knowledge acquired by students in the study of general education and a number of related general technical and special disciplines.
During the processing of products and the production of finished products, a number of chemical processes occur: hydrolysis of disaccharides, caramelization of sugars, oxidation of fats, etc. Most culinary processes are colloidal: coagulation of proteins (when meat, fish, eggs are heated) , obtaining stable emulsions (many sauces), obtaining foam (whipping cream, proteins, etc.), aging jellies (staling baked goods, cereals, separating liquids from kissels, jelly), adsorption (clarification of broths).
Knowledge of chemistry is necessary to manage numerous processes in food preparation and to control the quality of raw materials and finished products.
Data on the composition and consumer properties of products that a student receives when studying the course of food production allow the technologist to correctly solve the problem of rational use of raw materials and serve as important criteria for substantiating and organizing technological processes.
Recommendations of nutritional physiology are necessary for the organization of rational nutrition. They take into account the needs for irreplaceable nutritional factors of various contingents of the population, provide an opportunity for differentiated use of products. Academician I. P. Pavlov said that physiological data put forward a new point of view regarding the comparative value of nutrients. It is not enough to know how many proteins, fats, carbohydrates and other substances are contained in food. It is practically important to compare different forms of cooking the same food (boiled and fried meat, hard-boiled and soft-boiled eggs, raw and boiled milk, etc.).
The most important indicator of food quality is its safety for the consumer. Knowledge and observance of the rules of food hygiene and sanitation ensure the manufacture of sanitary-friendly products and allow the establishment of a strict sanitary regime at catering establishments.
The processing of raw materials, the preparation of culinary products are associated with the operation of complex mechanical, thermal and refrigeration equipment, which requires the knowledge of the technologist obtained in the cycle of technical disciplines.
The discipline "Cooking Technology" is directly related to such disciplines as the economics of public catering and the organization of production and service. The study of these disciplines is an indispensable condition for the proper organization of production and increasing its economic efficiency, rational use of the material and technical base and labor resources, and reducing the cost of production. Catering specialists constantly communicate with consumers, and the organization of service depends on their general culture, knowledge of psychology, and ethics.
Public catering enterprises receive from food industry enterprises not only raw materials, but also semi-finished products of varying degrees of readiness. Food industry enterprises have workshops for the production of culinary products suitable for direct consumption: chips, ready-made sauces (mayonnaise, ketchup, etc.), soup concentrates .. meat, fish, vegetable culinary products from - deli, frozen meals, etc. Acquaintance with the technologies used in the food industry, with special types of equipment will improve technological processes in catering establishments.
The technology of cooking is based on the traditions of folk cuisine, the experience of past professional chefs, as well as the achievements of nutrition science.
2. From generation to generation, people passed on the experience of cooking. They carefully kept all the traditions associated with food, realizing that food is the basis of life, health and well-being.
Even in ancient Greece, the cult of Asclepius arose, a mythical healer who received the name Aesculapius in Rome. His Gigea was considered the patroness of the science of health, and "their faithful assistant was the cook Kulina. She became the patroness of the culinary arts, called" cooking "(from Latin culina - kitchen).
The cuisine of each "people, traditions and customs associated with food is one of the most important parts of its material culture. Folk cuisine is original and reflects the history of the people, its national tastes, character.
The main features of folk cuisine were formed under the influence of natural conditions and the characteristics of the economic structure. So, in the diet of the peoples of the North, venison and the meat of marine animals prevailed; among the peoples of Central Asia - rice and lamb dishes; among Moldovans - from corn, etc.
Folk cuisine was formed in accordance with the living conditions and the level of development of culinary techniques. Among the peoples who led a nomadic lifestyle in the past, dishes cooked in hanging cauldrons still prevail, among the peoples of the Caucasus - fried on skewers, in Russian cuisine _ dishes cooked in a Russian oven (meat fried in a large piece, stews, dishes baked in frying pans, etc.).
The religious views of the people are reflected in the folk cuisine: Muslims do not eat pork; many Buddhists are vegetarians and some do not eat beef; Judaists divide food into kosher and tref (permitted and unlawful); all dishes of Orthodox Christians are divided into lenten and quick.
Public catering professionals should carefully treat national traditions and customs, reflecting them in the range of dishes, cooking methods, table decoration and table setting. You can not mechanically transfer the methods of cooking and culinary products at home to catering establishments.
The task of technologists is to creatively develop and improve the traditions of folk cuisine in relation to modern conditions, the level of development of technology, new types of food raw materials and the features of mass production of culinary products.
3 .Even in primitive society, there was a division of labor among members of the family, clan and tribe. Most often, men were engaged in obtaining food, and women were engaged in its preparation. So it was in Russian peasant families. Prepared food in living quarters. For this, a place was allotted at the Russian stove (upechye, kut). Already in Ancient Russia, professional cooks appeared in princely courts, in the homes of rich people and in monasteries. At the same time, cookhouses appeared in residential buildings, and then in courtyards and gardens. The word "kitchen" was borrowed from the German language only in the era of Peter 1. In the Moscow Kremlin already in the XV-XVI centuries. there was a whole food supply system: a bread palace with numerous bakeries; the aft palace, which was in charge of the cookhouses; a hearty palace that was in charge of preparing drinks. Numerous highly qualified cooks, henchmen (assistant cooks), and apprentice cooks worked in the palaces.
The development of professional cooking is associated with the emergence of out-of-home catering enterprises. They originated in ancient Russia. Initially, these were taverns (from the Slavic root "fodder"), in which travelers could find shelter and food.
Then there were roadside taverns (from Latin tract - path, stream) - hotels with a dining room and a kitchen. In the XVII century. taverns opened in cities, and in the 19th century. taverns without hotels became widespread.
At the same time, along with taverns in large cities of Russia, restaurants began to appear (from the French. Restoration - restoration).
In taverns and restaurants, professional cooking was developed, which was based on folk cuisine. Professional chefs developed and improved the national cuisine, enriching it by borrowing the best achievements of European culinary specialists.
At these out-of-home catering establishments, food preparation was not regulated by any regulatory documents. Everything depended on the skill and intuition of the cook. This is the fundamental difference between the old establishments of the tavern industry and modern catering establishments, which include restaurants, bars, cafes, snack bars, canteens.
Lecture No. 2. Theoretical foundations of catering technology.
Plan:
1.Basic concepts.
2.Technological cycle of production of culinary products.
3.Technological principles for the production of culinary products.
1. To ensure mutual understanding between the developers of culinary products, their producers and consumers, the development of regulatory documentation, the certification of public catering establishments, GOST R 50647-94 "Public catering. Terms and definitions" was developed. According to this GOST, below are a number of concepts used in writing the textbook.
Raw material - initial products intended for further processing.
Semifinished (culinary semi-finished product) - a food product or a combination of products that has passed one or more stages of culinary processing without bringing to readiness.
Semi-finished product of a high degree of readiness - a culinary semi-finished product, from which, as a result of the minimum necessary technological operations, a dish or a culinary product is obtained.
culinary product - a food product or a combination of products brought to culinary readiness.
Flour culinary product - a culinary product of a given form from dough, in most cases with minced meat (pies, kulebyaki, belyashi, donuts, pizza).
Confectionery - a dough product of a given shape, with a high content of sugar and fat (cakes, cakes, muffins, cookies, waffles). Dish- a food product or a combination of products and semi-finished products brought to culinary readiness, portioned and decorated.
Culinary products - a set of dishes, culinary products and culinary semi-finished products.
Culinary cooking (or readiness) - a set of given physico-chemical, structural-mechanical, organoleptic indicators of the quality of a dish and a culinary product that determine their suitability for eating.
Culinary processing - impact on food products in order to impart properties to them, due to which they become suitable for further processing and (or) consumption.
Mechanical Cooking - culinary processing of food products by mechanical means for the purpose of making dishes, culinary products, semi-finished products.
Thermal Cooking - culinary processing of food products, which consists in heating them in order to bring them to a predetermined degree of readiness.
^ Waste from cooking - food and technical residues formed in the process of mechanical culinary processing.
Losses during cooking- reduction in the mass of food products in the process of production of culinary products.
Recipe (culinary products) - a standardized list of raw materials, products, semi-finished products for the production of a specified amount of culinary products.
2. One of the main tasks of technologists is the production of competitive culinary products of high quality.
Quality public catering products -- a set of consumer properties of food that determine its suitability to meet the needs of the population in good nutrition.
The combination of useful properties of culinary products is characterized by nutritional value, organoleptic indicators, digestibility, safety.
The nutritional value - this is a complex property that combines energy, biological, physiological value, as well as digestibility, safety.
The energy value characterized by the amount of energy released from food substances in the process of their biological oxidation.
Biological value - is determined mainly by the quality of food proteins - digestibility and the degree of balance of the amino acid composition.
. Physiological value - due to the presence of substances that have an active effect on the human body (beet saponins, coffee and tea caffeine, etc.).
Organoleptic indicators - (appearance, color, texture, smell, taste) characterize a person's subjective attitude to food and are determined using the senses.
Digestibility - the degree of use of food components by the human body.
Safety is the absence of an unacceptable risk associated with the possibility of harm to human health (life). If the permissible level of safety indicators is exceeded, culinary products are transferred to the category of dangerous. Dangerous products must be destroyed.
There are the following types of safety of culinary products: chemical, sanitary and hygienic, radiation.
Chemical safety - the absence of an unacceptable risk that can be caused by toxic substances to the life, health of consumers. Substances that affect the chemical safety of culinary products are divided into the following groups: toxic elements (heavy metal salts); mycotoxins, nitrates and nitrites, pesticides, antibiotics; hormonal drugs; prohibited food additives and dyes.
Sanitary and hygienic safety - the absence of unacceptable risk that may arise from microbiological and biological contamination of culinary products caused by bacteria and fungi. At the same time, toxic substances accumulate in the products (mycotoxins during molding, toxins of botulinum, salmonella, staphylococcus, E. coli, etc.), which cause poisoning of varying severity.
Radiation zone safety - the absence of an unacceptable risk that can be inflicted on the life and health of consumers by radioactive substances or their ionizing radiation.
The quality of culinary products is formed during the entire technological cycle of production. Its main stages are:
marketing;
product design and development;
planning and development of the technological process;
logistics;
production of products;
quality control (verification);
packaging, transportation, storage;
implementation;
recycling.
In the process of marketing research, market demand must be accurately determined, for example, what type of enterprise should be opened, what will be the range of culinary products in it, approximate quantities of it, etc. The marketing function also includes feedback from consumers. All information Relating to product quality, should be analyzed and brought to the attention of the manufacturer.
Product design and development include the preparation of menus, the development of recipes for new or branded dishes, the preparation of regulatory (technical and technological maps, specifications - TU, enterprise standards - STP) and technological (technological maps, technological instructions) documentation.
Process design and development . On the basis of the developed regulatory and technological documentation, technological schemes for the preparation of individual dishes are compiled, the sequence of operations is determined, and the production process is developed.
Culinary products in the enterprise as a whole. The need for raw materials, equipment, inventory, utensils is determined.
Material and technical supply . Raw materials, products, semi-finished products used in the technological process of production become part of the manufactured products, directly affect the quality and must comply with hygienic requirements for the quality and safety of food raw materials and food products (SanPiN 2.3.2-96). Equipment, inventory, utensils must also comply with sanitary and hygienic requirements and have hygienic certificates or certificates of conformity.
Production of products consists of three stages: 1) processing of raw materials and preparation of semi-finished products (for enterprises working on raw materials); 2) cooking and culinary products; 3) preparation of dishes for sale (portioning, decoration). All three stages have an impact on the formation of the quality of the finished product and must be carried out in accordance with the requirements of technological standards and sanitary rules.
Quality control - verification of the compliance of the quality indicators of culinary products with the established requirements, this is one of the most important stages of the technological cycle of production. Quality control is conditionally divided into three types: preliminary (input), operational (production), output (acceptance).
Preliminary is the control of incoming raw materials and semi-finished products.
Operational control is carried out in the course of the technological process: from raw materials and (or) semi-finished products accepted by the quality to the release of finished products. It includes verification:
Organization of the technological process (sequence of operations, compliance with temperature, duration of heat treatment, etc.) and individual workplaces;
The equipment and condition of the equipment, its compliance with the parameters of the technological process;
Hygienic parameters of production (temperature at the workplace, ventilation, illumination of workplaces, noise level, etc.);
Availability of regulatory and technological documents in the workplace, knowledge of their performers;
Availability of measuring equipment, its serviceability and timeliness of verification;
Ensuring the yield and quality of semi-finished products and finished products in accordance with established requirements.
Output (acceptance) control - checking the quality of finished products. At the enterprise, food is graded, laboratory control is carried out for the completeness of the investment of raw materials, safety, etc.
The quality of culinary products, its safety is controlled by organoleptic, physico-chemical and microbiological indicators. The manufacturer is obliged to ensure constant technological control of production, state supervision and control bodies in the prescribed manner - selective control.
Organoleptic evaluation the quality of semi-finished products is carried out in appearance, color, smell; culinary products and dishes - in appearance, color, smell, texture, taste.
Physical and chemical indicators characterize the nutritional value of culinary products, its component composition, compliance with the recipe. The list of normalized indicators (mass fraction of fat, sugar, salt, moisture or solids, total acidity, alkalinity, toxicity of elements, etc.) is established for each group of culinary products.
microbiological indicators culinary products are characterized by compliance with technological and sanitary requirements during their production, transportation, storage and sale.
Packing, transportation, storage . The purpose of this stage is to maintain the achieved level of quality. Culinary products delivered from procurement enterprises to pre-cooking enterprises and sold to consumers outside public catering enterprises are packed in transport containers. Semi-finished products, culinary products, dishes (chilled and frozen), which the consumer buys directly from the manufacturer, in the culinary departments and order desks, are packed in consumer packaging.
Containers and packaging materials in the process of storage, transportation and sale have a significant impact on maintaining the quality of culinary products. Therefore, the following requirements are imposed on packaging: safety, compatibility, reliability, economic efficiency, etc.
Culinary products are transported in accordance with the sanitary rules for the transportation of perishable products. Particularly perishable products are transported in refrigerated or isothermal vehicles. Each car must have a health certificate. The conditions and terms of storage of such products are regulated by sanitary rules (SanPiN 42-123-4117-86).
^ Sales of culinary products . Culinary products must be prepared in such batches that can be sold within strictly defined sanitary rules. When selling hot soups and drinks must have a temperature of at least 75 0 С, sauces and main courses - not lower than 65 0 С, cold soups and drinks - not higher than 14 0 С. later than 3 hours after their manufacture. Salads, vinaigrettes, gastronomic products, other cold appetizers and drinks should be displayed in portioned form on refrigerated showcases, which should be replenished with products as they are sold.
Dishes, culinary products left over from the previous day are not allowed to be sold: salads, vinaigrettes, jellies, jellied dishes and other especially perishable cold dishes; milk, cold, sweet soups, puree soups; portioned boiled meat for soups, pancakes with meat and cottage cheese, minced meat, poultry, fish products; mustache; omelets; mashed potatoes, pasta; com-pots and drinks of own production.
Each batch of culinary products sold outside the hall of a public catering establishment must have a quality certificate. The shelf life specified in the certificate is the shelf life of culinary products and includes the time spent by the product at the manufacturer (from the end of the technological process), the time of transportation, storage and sale.
In the production and sale of culinary products, personnel are obliged to observe the rules of personal hygiene, periodically undergo a medical examination in accordance with the current rules.
^ Recycling , obtained during the mechanical processing of raw materials, food residues, culinary products with violated sales deadlines is the final stage of the technological cycle. Non-food waste can be sent for industrial processing, for example, bones of large and small livestock. Food waste is partly used at the enterprise itself (for example, fish heads, fins, scales are used to cook broths, early beet tops are used to make soups, etc.), and partly sent to feed livestock. Leftover food, as well as products with violated terms of sale, are used for fattening livestock or destroyed. Sending them to specialized enterprises for the destruction of waste is controlled by representatives of the sanitary and epidemiological supervision.
3.Principle security. The change in the form of ownership, the provision of greater independence to public catering enterprises, the lack of regular control over their work by higher organizations led to the fact that this principle has become one of the most important. Physico-chemical and microbiological indicators that affect the safety of culinary products are provided for in all types of regulatory documentation. The development of each new type of dish, culinary, confectionery product should be accompanied by the establishment of safety indicators.
^ The principle of interchangeability. Supply conditions, seasonality in the receipt of products often necessitate the replacement of some products with others (for example, fresh vegetables - dried, tomatoes - tomato puree, margarine - vegetable oil, natural milk _ dry). The replacement is permissible if the quality of the dish, culinary, confectionery product does not deteriorate, and it is unacceptable if the culinary product acquires a different taste, structural and mechanical properties, and the nutritional value decreases. The replacement of some products by others is carried out taking into account the interchangeability coefficient established by regulatory documents.
^ The principle of compatibility. It is associated with the principle of interchangeability and often "with the principle of safety. So, for many, milk is incompatible with sour foods, cucumbers (both fresh and salted), fish. Spinach, sorrel, rhubarb are incompatible with sour-milk products, not only because taste, they reduce the absorption of calcium.
The incompatibility of products depends on individual characteristics, habits, national tastes. For example, for most Europeans, the combination of garlic with fish is unacceptable, and in Jewish cuisine, fish with garlic is one of the most common dishes. There are no direct sanitary bans on certain combinations of products.
^ The principle of balance. A person's daily diet should cover the body's need for energy and vital substances (nutrients): proteins, fats, carbohydrates, vitamins, minerals, dietary fiber. All these substances in the diet must be balanced, that is, they must be contained in certain quantities and ratios. There are no products that are completely balanced in composition: one has a high energy value, the other: - low; one contains a lot of proteins, the other contains few proteins, but a large amount of carbohydrates, etc. One of the advantages of cooking technology is the possibility of obtaining a balanced composition of culinary products through rational selection of raw materials, development of recipes and technological processes. So, boiled cabbage (cauliflower, white) contains little fat, its energy value is low. But if the cabbage is served with cracker, Polish or Dutch sauce, the fat content in the dish increases, its energy value increases by 2-3 times. Meat and fish dishes contain a lot of protein, but few carbohydrates, dietary fiber, alkaline minerals, vitamin C. The nutritional value of meat and fish is supplemented by vegetable side dishes.
^ The principle of rational use of raw materials and waste. It provides for the best use of consumer properties of raw materials. So, you should use large-sized semi-finished meat products in accordance with their culinary purpose (for frying, boiling, stewing, etc.); some types of fish (bream, carp, vobla, etc.) are recommended to be fried rather than boiled; young potatoes are best served boiled rather than used for mashed potatoes, soups, etc.
^ The principle of reducing the loss of nutrients and the mass of finished products. This principle requires compliance with the modes of thermal cooking (temperature, duration of heating). So, when laying vegetables in boiling water, the loss of soluble substances, and primarily mineral ones, is reduced by 20-30%. Frying them in devices with infrared heating or on a well-heated frying surface helps to reduce the loss of meat and poultry mass.
^ The principle of reducing cooking time.
The methods of intensification of technological processes known in culinary practice, as a rule, simultaneously contribute to improving the quality of the finished product. They include: preliminary loosening of the structure of products by soaking dry products (mushrooms, legumes, cereals, dried fruits, etc.), mechanical action (beating and loosening meat, grinding it in a meat grinder), chemical and biochemical influences (pickling and enzymatic processing of meat), etc.; intensification of heat exchange by increasing the contact surface with the heating medium (grinding products, cutting them in such a way that the heating area is the largest), increasing the temperature of the coolant; use of electrophysical methods of heat treatment of products (IR heating, microwave heating).
^ The principle of the best use of equipment.
In accordance with this principle, machines and devices, with the necessary productivity, must have low energy intensity, stable mode, be convenient and safe in operation, maintainable. The principle is successfully used, for example, in highly specialized enterprises (doughnut, patty).
^ The principle of the best use of energy. This principle means a reasonable reduction in the energy consumption of culinary products. The energy intensity of products can be characterized using the energy intensity coefficient, which is defined as the ratio of the cost of energy consumed in production to the cost of production. Energy intensity can be reduced by using modern less energy-intensive equipment, a reasonable reduction in energy-intensive methods of processing products, timely power cuts (use of stored heat), and strict adherence to technological regimes.
In the overall assessment of the technological process, water consumption, labor and other costs should also be taken into account.
Control questions.
Lecture number 3. Methods of culinary processing of food products.
Plan:
1. Classification of cooking methods.
2.Mechanical processing methods.
3. Hydromechanical processing methods.
4. Mass transfer processing methods.
1. The variety of raw materials and products used in culinary practice, an extensive range of culinary products determine the numerous processing methods.
The methods of culinary processing of raw materials and semi-finished products depend on:
The amount of waste; so, during mechanical processing of potatoes, the amount of waste is 20-40%, and during chemical processing - 10-12%;
The amount of nutrient loss; for example, when boiling potatoes with steam, soluble substances are lost 2.5 times less than when boiling in water;
Mass loss; so, when boiling potatoes, the mass decreases by 8%, and when deep-fried, by 50%;
The taste of the dish (boiled and fried meat);
digestibility of finished products; Thus, dishes from boiled and stewed foods are digested, as a rule, faster and easier than from fried foods.
The choice of cooking method largely depends on the properties of the product. So, some parts of the beef carcass reach culinary readiness only when cooked, while others reach up to a hundred: just fry. Using various methods of cooking, the technologist can obtain culinary products with desired properties and the appropriate quality.
Methods for processing raw materials and products are classified:
By stages of the technological process of production
Culinary products;
By the nature of the active principle.
According to the stages of the technological process, there are methods:
Used in the processing of raw materials in order to obtain semi-finished products;
Used at the stage of thermal culinary processing of semi-finished products in order to obtain finished products;
Used at the stage of sale of finished products. By the nature of the active principle, the methods of processing raw materials and products are divided into:
mechanical;
hydromechanical;
mass transfer;
thermal;
electrophysical.
sorting. Products are sorted by size or culinary purpose. This allows you to significantly reduce the amount of waste during further mechanical cleaning. In large enterprises, sorting machines are used for this purpose.
Of great importance is the separation of products according to culinary use: sorting through tomatoes, separate whole dense specimens for making salads, crumpled ones for sauces and soups; parts of the carcasses are divided into those suitable for frying, boiling, stewing, etc.
When sorting, products of inadequate quality and mechanical impurities are removed.
Screening. Sift flour, cereals. In this case, fractional separation is used: first, larger impurities are removed, and then smaller ones. For this, sieves with holes of various sizes are used. There are metal sieves with stamped holes, wire sieves made of round metal wire, as well as hair, silk, and nylon. In addition to manual sieves, enterprises use mechanically driven sifters for flour.
Mixing. In the manufacture of many dishes and culinary products, it is necessary to combine various products and obtain a homogeneous mixture FROM them. For this purpose, mixing is used. So, mixing minced meat, stale bread soaked in milk or water, pepper, salt get minced meat.
For mixing, special machines are used - meat mixers, dough mixers, etc. Small amounts of products are mixed manually with special spatulas, oars and other devices. The quality of finished products largely depends on thorough mixing.
cleaning- Purpose of cleaning. is the removal of inedible or damaged parts of the product (peel of vegetables, fish scales, shells of crustaceans, etc.). It is produced manually or with the help of special machines (potato peelers, peeling machines, etc.). For manual cleaning, knives, scrapers, graters and other devices are used.
Grinding. The process of mechanical division of the processed product into parts for the purpose of its better technological use is called grinding. Depending on the type of raw material and its structural and mechanical properties, two grinding methods are mainly used: crushing and cutting.
Crushing is subjected to products with low moisture content (coffee beans, some spices, crackers), cutting - products with high moisture content (vegetables, fruits, meat, fish, etc.).
Bones), use saws.
Pressing. Pressing products is used mainly to separate them into two fractions: liquid (juices) and dense (pulp, pulp). In the process of pressing, the cellular structure of the product is destroyed, as a result of which juice is released.
Pressing is also used to give a certain shape to plastic materials (dough, creams, etc.).
Molding. This method of machining is used to give the product a certain shape. Poultry carcasses are molded for greater compactness, cutlets and meatballs, pies and pies, blanks for cookies, etc. This process is carried out manually or using machines: cutlet molding machines, automatic machines for making pancakes, dumplings, dumplings, etc. .
Dosing. To obtain culinary products of the appropriate quality, it is necessary to strictly follow the established recipes. For this purpose, products are dosed by weight or volume. Dishes, drinks, confectionery products are released to visitors of catering establishments in a certain amount - in portions (portioning),
The mass or volume of which is called "yield". Dosing is carried out manually using measuring equipment, scales, as well as special machines and devices (dough dividers, dispensers, etc.).
Breading. This is a mechanical culinary treatment, which consists in applying a breading (flour, crumbs, sliced wheat bread, etc.) to the surface of a semi-finished product. As a result of breading, the leakage of juice and evaporation of water during frying is reduced, and the finished culinary product has a beautiful golden crust.
Stuffing. This mechanical cooking consists in filling specially prepared products with minced meat.
forcing. Mechanical cooking, in the process of which vegetables or other products specified in the recipe are introduced into special cuts in pieces of meat, poultry, game or fish carcasses.
Loosening. Mechanical culinary processing of products, which consists in the partial destruction of the structure of the connective tissue of products of animal origin to speed up the process of thermal processing.
3 . The hydromechanical effect on products consists in removing contaminants from the surface and reducing microbial contamination, as well as in soaking certain types of products (legumes, cereals) in order to intensify heat treatment processes, in soaking salted products, in separating mixtures consisting of parts of different specific gravity and others
^ Washing and soaking . Almost all products entering the p.o.p. are washed. Washing meat with warm water using a shower brush can reduce the contamination of its surface by 80-90%. Washing vegetables allows you to rationally use waste, extends the life of potato peelers
Root and tuber crops are washed mechanically in washing machines, as well as manually in baths with running water. Meat carcasses, half carcasses are washed with the help of gushing brushes. The effectiveness of washing devices depends on the speed of water movement.
Soaking food before cooking (for example, cereals, legumes, dry fruits and vegetables) allows you to speed up the process of bringing them to readiness.
Flotation. Flotation is used to separate mixtures consisting of particles of different specific gravity. An inhomogeneous mixture is immersed in a liquid, while the lighter particles float, and the heavier ones sink. For example, to separate stones, potatoes are immersed in a 20% solution of table salt before cleaning, where the tubers float up and the stones sink. When cereals are immersed in water (during washing), light impurities float up, and the grains sink to the bottom of the dish.
^ Precipitation, filtration . As a result of a number of technological processes, suspensions are obtained - mixtures of two (or more) "substances, of which one (solid) is distributed in the other (liquid) in the form of particles of various dispersions, which are in a suspended state. Suspensions include, for example, starch milk obtained in the production of starch, or fruit juice containing pulp particles of various sizes and shapes.Filtration and precipitation are used to separate suspensions into liquid and solid parts.
precipitation- the process of separating solid particles of suspensions under the action of gravity. At the end of the precipitation, the clarified liquid is separated from the precipitate.
Filtration e - the process of separating suspensions by passing them through a porous partition (fabric, sieve, etc.), capable of retaining suspended particles and passing the filtrate. In this way, it is possible to almost completely free the liquid from suspended particles.
emulsification. Emulsification is used to obtain some culinary products. During emulsification, one liquid (dispersed phase) is broken into small drops in another liquid (dispersed medium). To do this, two immiscible liquids (oil and water) are combined and they are quickly stirred, while the interface between the liquids increases significantly. Surface tension forces act in the surface layer and therefore individual droplets tend to grow larger, as a result of which the free energy decreases. This leads to the destruction of the emulsion. Emulsifiers are used to stabilize the emulsion. These are substances that either reduce surface tension or form protective films around the droplets of crushed liquid (oil). There are two types of emulsifiers: powdered and molecular.
Powdered emulsifiers are thin powders of mustard, ground pepper and other products that create a protective layer at the interface between two liquids and prevent droplets from sticking together. Powdered emulsifiers are used to obtain low-stability emulsions (dressings in vegetable oil). ,/
Molecular emulsifiers (stabilizers) are substances whose molecules consist of two parts: long hydrocarbon chains that have an affinity for fat and polar groups that have an affinity for water. Molecules are located on the interface between two liquids so that hydrocarbon chains are directed towards the fatty phase, and polar radicals are directed towards the water phase. Thus, a strong protective film is formed on the surface of the emulsion droplets. These emulsifiers (substances found in egg yolks, etc.) are used in the preparation of stable emulsions, such as mayonnaise and hollandaise sauces.
Foaming(whipping). This is a mechanical culinary treatment, which consists in intensive mixing of one or more products in order to obtain a lush or foamy mass.
Foaming, like emulsification, is associated with an increase in surface area. The interface is the boundary of two different phases: gas and liquid. In foams, gas bubbles are separated by the thinnest liquid films that form a film frame. The stability of the foams depends on the strength of this frame. Foams are characterized by two indicators: multiplicity and durability.
The brevity is the ratio of the volume of the foam to the liquid phase.
Persistence is the half-life of the foam during storage.
3 . Mass transfer methods are characterized by the transfer (transition) of one or more substances from one phase to another. For example, when drying food, water turns into steam. The basis of a variety of mass transfer processing methods is the difference in concentrations, therefore they are often called diffusion methods.
In culinary practice, mass transfer processing methods such as dissolution, extraction, drying, and thickening are used.
Dissolution- the transition of the solid phase to the liquid. In culinary practice, salt and sugar solutions of various concentrations are often prepared.
Extraction (extraction) - selective extraction of a substance from a liquid or solid porous body with a liquid. In culinary practice, extraction takes place when salted fish, beef kidneys, a number of mushrooms are soaked before cooking, etc.
Drying, thickening is the removal of moisture from solid plastic and liquid products by evaporation. In culinary practice, this occurs when drying croutons, home-made noodles, when boiling tomato puree, concentrated broth (fume), thickening cream, etc.
Chemical, biochemical, microbiological processing methods.
The purpose of these cooking methods is to impart certain properties to culinary products through the action of chemical reagents, enzymes, and microorganisms.
Sulfitation- chemical cooking of peeled potatoes with sulfur dioxide or solutions of sulfurous acid salts in order to prevent browning.
Pickling- chemical culinary treatment, which consists in keeping products in solutions of food acids in order to give finished products a specific taste, aroma and texture.
^ Fixation of fish semi-finished products - keeping them in a chilled saline solution to reduce the loss of juice during storage and transportation.
Chemical leavening of dough- the use of sodium bicarbonate, ammonium carbonate and special baking powders to give the dough a finely porous structure.
^ Alcoholic and lactic acid fermentation cause yeast and lactic acid bacteria in the manufacture of yeast dough, kvass, etc.
Meat fermentation- the use of proteolytic enzymes (hydrolyzing protein), softening the connective tissue of meat during its heating. This allows you to expand the range of dishes by using parts of the carcass that are not intended for frying.
Enzyme preparations acting on the protein-carbohydrate complex are widely used in the preparation of dough products. With their help, you can prepare different types of dough from the same batch of flour.
Control questions.
Lecture No. 4 Heat treatment of products.
Plan.
1. The value of heat treatment and the classification of methods.
2.Basic methods of heat treatment.
3. Auxiliary and combined methods of heat treatment.
← + Ctrl + →
The main chemical processes that occur during the thermal culinary processing of products
The nature of the processes occurring during the heat treatment of plant and animal products differs significantly.
A distinctive feature of plant products is their high content of carbohydrates - over 70% of dry matter. The vast majority of plant products used in human nutrition are parts of plants containing living parenchymal cells. They contain substances of interest in nutrition - mono- and oligosaccharides and starch. These cells have a primary envelope consisting of low molecular weight cellulose and low molecular weight fractions of hemicelluloses, a distinctive feature of which is the predominance of the p-1,4 bond between the structural units (this is important, since this particular bond is not destroyed by human digestive enzymes). In the middle plate and intercellular spaces are pectin substances. They are based on galacturonic acid residues interconnected by a-1,4-bonds (this bond is also not destroyed by human digestive enzymes). However, the degree of their polymerization, depending on the phase of development of a living cell, can vary greatly: from 20 to 200 or more residues. With an increase in the degree of polymerization, the solubility of pectin substances and water decreases and the mechanical strength increases. So washed "protopectin", which is associated with the mechanical hardness of fruits, berries and vegetables, is actually a high molecular weight pectin, which forms a "secondary" structure due to the binding of water, which, due to the special properties of the "bound" "ode", gives mechanical strength to plant products. At the same time, all plants contain active pectinesterases and somewhat less active polygalacturonases, which in a certain period of plant life are activated and begin to destroy the secondary structure of pectin with the formation of low molecular weight pectins and water. In this case, the softening of the product occurs (this enzymatic process can also occur during storage). Since the primary wall is easily permeable, and there are no secondary, and even more so tertiary, walls in living cells, the low molecular weight pectin and water formed under the action of non-political enzymes partially pass into the protoplasm of cells.
When cooking under pressure, when the temperature rises against the usual one by 2-3 C, the duration of cooking is reduced by about 1.5 times. Small pieces are heated (up to 70-80 CC in the entire volume) faster than large ones, but at the same time, the extraction of water-soluble substances increases. Therefore, the grinding cannot be very strong. Practice has established the optimal size of the product and the duration of cooking.
Cooking products with the skin on (for example, potatoes in the skin, beets and carrots in the skin) does not affect the duration, but leads to a noticeable decrease in nutrient losses, since the dense surface layer (epidermis, periderm) prevents extraction. Steam cooking also reduces nutrient loss compared to water cooking, since only the most superficial layers are affected by extraction.
During frying, there is mainly a thermal decomposition of the "secondary" structure of pectins with the formation of soluble pectins and water. Starch grains and low molecular weight pectin begin to react with water, and they partially go into a gel state. However, if the evaporation of water from the product during frying is sufficiently intense, then the gel dries out and the product becomes solid again - its mechanical strength increases several times. To reduce water evaporation, frying is carried out in the presence of fat, which, enveloping the product, reduces the surface temperature and the rate of moisture evaporation. With frequent stirring, a crust is formed, which also delays evaporation, and the product becomes juicier.
You can generally fry in a layer of fat (“deep-fried”). In fact, this is not frying, but cooking in fat. At the same time, the temperature of the medium is higher than during conventional cooking and softening occurs faster. There are few fat-soluble substances in plant foods, so the loss of nutrients during deep-frying is negligible, with the exception, of course, of the vitamins that break down during this.
In conclusion, about the heat treatment of plant products containing a small amount of pectin, but a lot of starch (cereals, legumes). Their processing consists mainly in starch gelatinization at elevated temperatures and in the presence of external water. Therefore, only cooking is applied to them. Water absorption by gelatinizing starch reaches 100-200%,
In products of animal origin, proteins are the most valuable in nutritional and culinary terms (it is more correct to say not “protein”, but “proteins”, that is, there are many individual proteins that differ in composition and properties).
The mechanical strength of meat products is due to a certain rigidity of the “tertiary” structure of proteins. Connective tissue proteins (collagen and elastin) have the highest rigidity. One of the main, but not the only factor that determines the rigidity of the "tertiary" structure of most proteins of animal origin (with the exception of eggs, caviar) is the presence of water in them (in the form of "strongly bound", "hydrated", etc., which are not considered here) . In meat products, water in the “tertiary structure is associated mainly with muscle fibers and not with connective tissue. The content of connective tissue proteins depends on the nature of the raw material, the age of the animals, and a number of other conditions.
In this case, the mechanical strength of meat products noticeably decreases. Temperature coagulation of proteins, depending on nature, starts at 60 ° C, and for most 70 ° C. When cooking and frying meat, the temperature inside the product, depending on the type of meat and the size of the cous k. -95 °C. However, frying meat with a large amount of connective tissues is not recommended, since the water released when the “tertiary” structure of muscle proteins is destroyed may not be enough for gelatinization (besides, part of the water evaporates). Such "wiry" meat is best boiled or stewed. Since the gelation of connective tissue proteins is facilitated by an acid reaction of the environment, it is desirable to soak the meat in acidic solutions (in vinegar, in dry wine) or stew in the presence of vegetables containing organic acids (for example, tomatoes), or with tomato paste - in these cases, the tissues soften significantly faster. Mechanical destruction of connective tissues gives the same effect.
In traditional frying of meat products, despite the fact that fat is added, rather intensive evaporation of water is observed; the product with prolonged frying simply dries out and becomes more solid again. To reduce this undesirable process, it is recommended to first fry a piece of meat from different sides until a partially waterproof crust forms (which also gives a pleasant specific taste) or bread it in flour or ground breadcrumbs. As a result, the humidity does not drop as sharply and the meat is more tender.
Losses of nutrients during cooking occur due to the partial rendering of fat and the extraction of a number of extractive components from tissues (nitrogen and nitrogen-free substances, minerals and vitamins). During frying, losses occur as a result of the rendering of a large amount of fat, the partial release of juice, and the thermal destruction of vitamins.
Oddly enough, at first glance, water losses occur not only during frying, but also during cooking, in water, and they reach noticeable values (compared to plant products) - an average of 30 to 50% depending on the type of meat. These losses occur due to the destruction of the "tertiary" structure of muscle proteins during their coagulation. At the same time, the "secondary" structure is no longer capable of holding a large amount of water, which is released together with water-soluble substances into the external water.
Pressure cooking, by raising the temperature, accelerates gelatinization and thus reduces the time to obtain the finished product.
You will get some ideas about the amount of losses of the main nutrients with various methods of thermal cooking by reading the table. 23.
If we summarize what has been said about the heat treatment of food products, we can draw the following conclusions.
The most rational heat treatments from the point of view of preserving valuable nutrients are: for vegetable products - cooking without draining the broth and cooking in the peel; for animals - stewing, baking, using meat in the form of cutlets, especially steam ones.
With any heat treatment, the destruction of vitamins, especially vitamin C, occurs most intensively.
What practical advice can be given to a housewife for choosing a method of heat treatment, which is better - boil, fry or stew?
It seems that for the preparation of everyday food it is necessary to use the most rational methods of heat treatment. At the same time, greens, fresh vegetables and cabbage are often served for appetizers and side dishes in order to compensate for the losses of vitamins that occur during heat treatment. Rational methods of heat treatment are also very useful for those who need dietary nutrition: the products do not contain mechanical irritants of the gastrointestinal tract (fried kidney). At the same time, it would be wrong to completely refuse the taste of their fried products for adults, practically healthy people. But it is better to postpone cooking until Sundays and holidays. Such a variety in nutrition can be justified.
← + Ctrl + →
Basics of home cookinghome cooking technology
METHODOLOGICAL MATERIAL ON THE TOPIC:
«CHEMICAL BASES
HOME COOKING»
We will try to make some generalizations
identify general patterns of changes in the chemical composition of products
during culinary treatments.
The main chemical processes taking place
during heat cooking
About 80% of food products undergo heat treatment, with
which increases digestibility, softens the products.
Exposure to heat leads to the destruction of harmful microorganisms, and
this ensures the sanitary and hygienic safety of products, in the first place
line of animal origin.
Various types of heat treatment allow you to diversify the taste
products. But the heat treatment of products is not without drawbacks:
it destroys vitamins and some biologically active substances,
valuable for the body proteins, fats, minerals. In this way,
the task of rational food preparation is to
the goal was achieved with minimal loss of useful properties of the product.
Herbal products.
The vast majority of herbal products used in
human nutrition are parts of plants with living cells in which
contains mono, oligosaccharides and starch. Heat treatment
vegetable products containing a significant amount of pectins,
aimed at partial release of water. This process starts at
temperature above 60°C and then accelerates approximately twice for every
10°C rise in temperature. As a result, in the finished product
mechanical strength decreases by more than 10 times. It should be noted,
that the mechanical strength of plant products depends on the content
they have water in them. The less water in the product, the greater its strength at
other equal conditions.
During cooking, the cells are saturated with water. Although the starch remains
in the plasma of the cell, and pectin - in the intercellular space, extraction
starch and pectin comes not only from the surface of the destroyed
cells, but also from the inner layers. At the same time, during cooking, it is extracted
a number of water-soluble substances (sugars, amino acids, organic acids,
minerals and vitamins) from product layers in contact with
water.
Steam cooking reduces the loss of substances compared to boiling in water,
since extraction comes only from the most superficial layers.
During frying, mainly thermal decomposition of the structure occurs.
pectins and water. Starch grains and low molecular weight pectin begin
react with water and partially turn into a foamy state.
However, if the evaporation of water from the product during frying occurs
intensely enough, the gel dries up and the product becomes solid again.
Its mechanical strength increases several times.
Heat treatment of herbal products,
containing
a small amount of pectin, but a lot of starch, accompanied
starch gelatinization and usually consists in boiling in water.
The absorption of water by gelatinizing starch reaches 100-120%.
Products of animal origin.
In products of animal origin, the most valuable in food and
culinary relation is protein.
The mechanical strength of meat products is due to a certain
rigidity of the tertiary structure of proteins. have the highest rigidity
connective tissue proteins. One of the factors causing
rigidity of the tertiary structure of most animal proteins
origin is the presence of water in them. Water in meat products
in the tertiary structure of the protein is associated mainly with muscle proteins,
not with connective tissue proteins.
Heat treatment of animal products consists in partial
destruction of connective tissue and muscle proteins. Destruction
occurs due to water involved in the formation of the tertiary structure
muscle proteins and released during their thermal coagulation.
During heat treatment, the released water is introduced into the secondary
structure of proteins, destroying and bringing connective tissue proteins into
gelatinous state. Mechanical strength of meat products
while significantly decreasing.
Change in the nutritional value of products
during heat treatment
In plant foods, most of the nutrients are lost during
frying: on average 5% protein and 10% fat. Great loss of carbohydrates (10–20
%) and minerals (up to 20%) as a result of juice leakage and
crust formation. Losses during cooking are highly dependent on the method
heat treatment. If cooking is done without draining (boiling soups,
kissels, compotes), the loss of almost all nutrients is minimal: 2-5%
proteins, fats, carbohydrates and minerals. When cooking most
vegetables, pasta, where plum is produced, loss with broth
proteins, fats, vitamins, minerals increases by 2-3 times and
approaching heat loss.
The greatest loss of important nutrients in the process of thermal
processing of animal products are observed during cooking: proteins - 10%,
fats - 25%, minerals and vitamins of group B - 30%, A - 50%,
C - 70% (due to the transition to the broth and partial decay). When frying meat
loss of minerals and vitamins is approximately 1.5 times less than
when cooking, protein - the same, and fat - a little more. Minimum loss -
15% proteins, fats and minerals, 15-30% vitamins -
observed during stewing and baking.
The loss of proteins in animal products is higher than in vegetable products, since
the absolute content of protein in the latter is usually quite low, and it,
obviously more strongly connected. The same can be said about fats. Losses
minerals in animal products twice as much as in
vegetable. As for vitamins, their main losses are explained
not by alteration or removal during boiling or frying, but by destruction due to
high temperature.
Send your good work in the knowledge base is simple. Use the form below
Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.
Hosted at http://www.allbest.ru/
Ministry of Education and Science of the Russian Federation
Kuban State Technological University
Department of Technology and Catering
Examination No. 1 in the discipline:
Physical and chemical foundations of catering technology
Completed by: 3rd year student
Shevelev Oleg Gennadievich
Specialty: 260800
Reviewer: Severina Natalya Aleksandrovna
Krasnodar 2013
Introduction
1. Destruction of proteins
1.1 The essence of the destruction process
3. Carotenoids and chlorophylls
List of sources used
Introduction
At present, the main principle of the production of public catering products is the creation of dishes and products that have a high nutritional value and meet modern requirements of sanitary and hygienic standards.
The scientific and theoretical substantiation of technological processes for the production of public catering products was first given by the Technological Department of the Institute of Nutrition of the Russian Academy of Medical Sciences. The first experimental and theoretical studies in this area were carried out in 1935 - 1960. In subsequent years, technological science deepened and expanded thanks to the contribution of many scientists, both in our country and abroad.
Food raw materials and food products are complex multicomponent biological systems that undergo irreversible changes at different stages of the technological process of production at public catering enterprises. The main changes occur during the mechanical, hydromechanical processing of raw materials and products, as well as during the heat treatment of semi-finished products and the preparation of ready-made food.
Physical and chemical processes occurring in food systems during the culinary processing of raw materials of plant and animal origin, the impact of these processes on the nutritional value and safety of products, changes in the structural and mechanical characteristics of raw materials and semi-finished products, as well as other issues will be discussed in this course.
The study and understanding of the physical and chemical processes that occur during the production of products are a prerequisite for creating high-quality products, as they allow you to enhance the positive and minimize the negative impact of cooking on the quality of finished products.
1. Destruction of proteins
protein cooking oil vegetable
1.1 The essence of the protein degradation process
During heat treatment of products, changes in proteins are not limited to their denaturation. To bring the product to full readiness, it is necessary to heat it at temperatures close to 100? C, more or less for a long time. Under these conditions, proteins undergo further changes associated with the destruction of their macromolecules. This leads to the destruction of the protein molecule. Destruction is a change in the composition of protein molecules during prolonged exposure. Destruction is characterized by rupture of peptide bonds and depolymerization of polypeptide chains and the formation of soluble and volatile compounds that determine the taste and smell of products.
There are mechanical, enzymatic and thermal degradation.
An example of the mechanical destruction of a protein is the whipping of an egg white in order to obtain a stable foam. However, as a result of prolonged mechanical action, the egg white begins to flow.
Enzymatic degradation occurs as a result of the use of various enzymatic preparations.
Thermal degradation of proteins is accompanied by the formation of such volatile products as ammonia, hydrogen sulfide, carbon dioxide and other substances.
An exception is the protein of meat and fish raw materials collagen, the destruction of which leads to the formation of glutin, a protein that is soluble in hot water. The amino acid composition of glutin is similar to that of collagen. On their surface, glutins, like protein substances, have functional groups and regions. The functional groups are hydrophilic. (The softening of meat and fish products during thermal cooking is associated with the destruction of connective tissue collagen and its transition to glutin).
1.2 Factors causing the destruction of proteins during the culinary processing of raw materials
The following technological factors influence the transition of collagen to glutin:
a) the temperature of the environment. When frying meat, poultry, fish, when the temperature in the thickness of the product does not exceed 80 - 85 ° C, the transition of collagen to glutin proceeds slowly. In this regard, culinary processing by frying is possible only for such parts of carcasses in which there is relatively little collagen and the morphological structure of the connective tissue is simple (collagen fibers are thin, located parallel to the direction of muscle fibers). Fish collagen undergoes destruction much more easily than meat (beef), since the connective tissue of fish has a relatively simple morphological structure, there is less hydroxyproline in collagen, it undergoes denaturation and destruction at lower temperatures.
b) the reaction of the environment. Acidification of the environment with food acids or products containing these acids accelerates the conversion of collagen to glutin.
The destruction of collagen to glutin is also accelerated in an alkaline environment. This is used in the meat industry to make gelatin, which is dried glutin.
c) grinding. It helps to reduce the hydrothermal stability of collagen. This is explained by the fact that when chopping meat or loosening portioned pieces of meat, collagen fibers are cut into smaller fragments, the contact surface of the protein with the environment increases many times over.
The behavior of protein-glutin in solution depends on temperature. At high temperatures, aqueous solutions of glutin have the properties of a normal (Newtonian) liquid; glutin molecules, regardless of their molecular weight, are in a state isolated from each other. As the solution cools, at a temperature below 40°C, its molecular-dispersed state is disturbed, the properties of an elastic-viscous liquid appear, which are characteristic of pseudo-solutions. Further cooling of the aqueous solution of glutin is accompanied by the gradual appearance of elastic properties with the formation of jelly. In the solution, the process of structure formation takes place, during which glutin molecules form a three-dimensional framework, connecting with each other and providing a certain strength of the system. The stability of the network framework is provided by hydrogen bonds that occur between the hydrophilic regions of glutin and water.
The more polar the glutin molecules are, the stronger they are attracted to each other and the stronger the interaction.
When heated, the jellies turn back into a liquid state. Under the action of heat, water molecules acquire kinetic energy. This energy is higher than the energy of hydrogen bonds of their mutual attraction, and therefore, under the action of water, glutin molecules move away from each other and water comes out.
2. Fat changes in deep frying
The duration of deep-frying foods is short. So, at a deep-frying temperature of 180 ° C, portioned pieces of fish are fried for about 5 minutes, pies, donuts, pasties - 6 minutes. The readiness of the fried product is assessed by the formation of a specific crust on its surface. Thus, the depth of physicochemical changes in fat is influenced not so much by the process of frying products as by the duration of use of the deep fat itself (2-3 shifts or more).
An important factor influencing the course of physicochemical processes in fats is the temperature of the frying fat. So, at a temperature of 200 ° C, the hydrolysis of fat proceeds 2.5 times faster than at 180 ° C. At the same time, the processes of polymerization of glycerides and fatty acids are noticeably accelerated. Overheating of frying fat is possible for two reasons:
Due to its local overheating near the heating elements of the fryer (deep fryer),
During the idle heating period, when the fried product is removed from the fat, and a new batch of product has not yet been incorporated into the fat.
Deep frying can be continuous or intermittent.
In continuous deep frying, fat is constantly removed from the frying pan with the finished product, and its amount is replenished by adding fresh fat. As a result of the replacement of heated fat, its degree of oxidation quickly reaches a stable state and changes little in the future. The greater the coefficient of fat turnover, the slower it undergoes oxidative changes.
The most destructive effect is exposed to fat during periodic deep-frying. In this case, the fat is heated for a long time without product (idle heating) and is periodically used for frying various products. Idle heating also occurs during reheating. Alternating heating and cooling is more damaging to fat than continuous heating for the same amount of time. This is due to the acceleration of autoxidation of previously heated fat during its cooling period.
2.1 Preservation measures for the quality of cooking fats
An important factor in maintaining the quality of frying fats during the frying period is the degree of contact of fat with air oxygen, without which even prolonged heating at 180–200°C does not cause noticeable oxidative changes in fat. An increase in contact with air is facilitated by heating the fat with a thin layer, frying products with a porous structure, intensive foaming and mixing of the fat.
The chemical composition of the fried products also has a noticeable effect on the rate of thermal oxidation of fat. Thus, the proteins included in the products are capable of exerting an antioxidant effect, and some substances formed as a result of melanoidin formation reactions have a reducing effect and can interrupt the chain of oxidative transformations.
A more noticeable oxidation of frying fats during idle heating compared to their oxidation during frying products can be explained by the anti-oxidative effect of other components that are part of the frying products in small quantities (ascorbic acid, some amino acids, glutathione).
At the first stage of deep frying of products, the same physicochemical changes in lipids occur as in conventional frying: acid and peroxide numbers increase, iodine number decreases. Subsequent frying of products in deep fat is accompanied by the decomposition of peroxides, hydroperoxides and hydroxy acids and the formation of thermostable oxidation products: carbonyl and dicarbonyl compounds, fatty acids with conjugated double bonds, polymerization products. Accordingly, the refractive index, iodine number of fat and optical density increase.
Medical and biological studies of recent years have shown that the products of oxidation, pyrolysis and polymerization, which are absent in natural dietary fats, are the greatest danger to humans.
3. Carotenoids and chlorophylls
Carotenoids are highly unsaturated carbohydrates. Their molecules contain a large number of conjugated double bonds. Carotenoids are well soluble in fats, resistant to heat. Therefore, the native (yellow, orange) color of food products subjected to heat treatment does not disappear. Discoloration occurs under the influence of atmospheric oxygen.
Carotene is found in many fruits, vegetables, and green leaves along with chlorophyll and xanthophyll. Carotene is in the form of three isomers. All of them are capable of autoxidation.
The color of lycopene is orange-red, more intense than that of carotene. It has thirteen double bonds and is composed of eight isoprene residues.
Xanthophyll and its isomer zeaxanthin are derivatives of carotene. They are yellow in color and are found in the chloroplasts of green leaves.
Chlorophyll gives green color to fruits and vegetables. The chlorophyll molecule has four pyrrole nuclei and a metal atom - magnesium. There are chlorophyll and chlorophyll. During heat treatment, chlorophyll darkens, since its destruction occurs, and it passes into phyophytin.
3.1 Color change of vegetables and fruits with green and yellow color during their cooking
The green color of vegetables (sorrel, spinach, green peas, legume pods) and some fruits (gooseberries, grapes, renklod plums, etc.) is due to the presence of chlorophyll pigment, mainly b-chlorophyll, in them.
By chemical nature, a-chlorophyll is an ester of dibasic acid and two alcohols: methyl and phytol.
Green vegetables and fruits turn brown when cooked and poached. This happens due to the interaction of chlorophyll with organic acids or acid salts of these acids contained in the cell juice of vegetables and fruits, with the formation of a new brown substance - pheophytin:
In raw products, this reaction does not occur, since chlorophyll is separated from organic acids or their salts contained in vacuoles by the tonoplast.
In addition, chlorophyll, which is in complex with protein and lipids (in chloroplasts), is protected by these substances from external influences. Only when the integrity of the cells of the parenchymal tissue is violated, brown spots appear in the places of damage to the vegetables.
During the thermal cooking of vegetables and fruits, the protein associated with chlorophyll is split off as a result of denaturation, the plastid and tonoplast membranes are destroyed, as a result of which organic acids are able to interact with chlorophyll.
The degree of change in the green color of vegetables and fruits depends on the duration of heat treatment and the concentration of organic acids in the product and cooking medium. The longer green vegetables and fruits are cooked, the more pheophytin is formed and the more noticeable their browning. The color of vegetables with a high content of organic acids (for example, sorrel) changes significantly.
To preserve the color, green vegetables are recommended to be boiled in a large amount of water with the lid open and intense boiling for a strictly defined time required to bring them to readiness. Under these conditions, part of the volatile acids is removed with water vapor, the concentration of organic acids in the products and the cooking medium decreases, and the formation of pheophytin slows down.
The color of green vegetables and fruits is better preserved when cooked in hard water: the calcium and magnesium salts contained in it neutralize some of the organic acids and acid salts of cell sap.
When cooking and stewing, green vegetables and fruits, in addition to brown color, can also acquire other shades due to a change in the already formed pheophytin under the action of certain metal ions. For example, if iron ions are present in the cooking medium, vegetables may turn brown, if aluminum ions - grayish, Cu ions - bright green.
The yellow-orange color of vegetables (carrots, tomatoes, pumpkin) and some fruits is due to the presence of carotenoids in them.
In the process of cooking, the color of these vegetables and fruits does not noticeably change. It is believed that carotenoids are practically not destroyed in this case. In boiled carrots, on the contrary, even more carotenoids are found than in raw ones. The increase in the content of carotenoids during cooking of carrots can be explained by the destruction of protein-carotenoid complexes and the release of carotenoids.
When frying tomatoes, pumpkins and browning carrots, carotenoids are partially converted into fat, as a result of which the color intensity of vegetables decreases somewhat.
List of used literature
1. Technology of catering products. In 2 t. T.1. Physical and chemical processes occurring in food products during their culinary processing / A.S. Ratushny, V.I. Khlebnikov, B.A. Baranov and others / Ed. A.S. Town Hall. - M.: Mir, 2003. - 351 p.
2. Cooking technology / N.I. Kovalev, M.N. Kutkina, V.A. Kravtsov. - M .: Publishing house "Business literature", Publishing house "Omega - L", 2003. - 480 p.
3. Technologies of food production / Ed. A.P. Nechaev. - M.: Publishing house "Koloss", 2005. - 768 p.
4. Mogilny M.P. Technology of catering products: Ref. allowance. - M.: DeLi print, 2005. - 320 p.
5. Food chemistry / A.P. Nechaev, S.E. Traubenberg, A.A. Kochetkova and others / Ed. A.P. Nechaev. - St. Petersburg: "GIORD", 2012. - 672 p.
Hosted on Allbest.ru
Similar Documents
Protein denaturation: the essence of the process, changes in protein properties, types of denaturation. Carbohydrates, which are part of the cell walls of plant products, when exposed to heat treatment. Anthocyanins, their changes in the culinary processing of fruits and vegetables.
test, added 05/21/2014
Organization of the process of preparation of raw materials, products, semi-finished products for complex culinary products from vegetables. Physico-chemical processes occurring during the heat treatment of products. Requirements for the quality of hot vegetable dishes. Calculation of their nutritional value.
term paper, added 01/28/2016
The correct selection of the necessary products and the choice of the method of their culinary processing. Recommended varieties of vegetables, fruits, mushrooms and legumes, signs of their ripeness and freshness. Features of the processing of meat, poultry and game, fish. Auxiliary materials.
abstract, added 06/02/2009
Qualification characteristic of the cook of the 3rd category. Requirements for the acceptance and storage of raw materials entering the enterprise. Ways of culinary processing of foodstuffs. The scheme of mechanical processing of vegetables and mushrooms and the preparation of semi-finished products from them.
practice report, added 05/25/2013
Technology of semi-finished products from vegetables, fruits and mushrooms, meat. Preparation of cold dishes and snacks. Sanitary requirements for the culinary processing of food products. Improving the quality of customer service, introducing progressive forms of service.
practice report, added 12/16/2014
Factors affecting the color change of carotenoids during culinary processing of products. Assortment of hot appetizers from meat and meat products. Formulation and submission rules, quality requirements. Fundamentals of food preparation.
test, added 10/23/2010
Assortment of hot specialty meat dishes, features of their preparation. The structure and composition of muscle tissue of meat. Changes in the structure and color of meat during heat treatment. Formation of the taste and aroma of meat subjected to thermal cooking.
thesis, added 06/17/2013
Characteristics of the range of white base sauce and its derivatives. The process of heat treatment to obtain semi-finished products. Sauce making technology. Physico-chemical changes in food components occurring during the culinary processing of products.
term paper, added 02/17/2015
Studying the principles of organizing jobs in a cold shop. Realization (vacation) of culinary products. Characteristics of foods and vegetables. The value of cold dishes and vegetable snacks. Ways to preserve nutrients during cooking.
term paper, added 12/18/2012
Market analysis of catering services. Characteristics, methods and modes of technological processing of raw materials and products. Assortment and classification of culinary products. Buffet menu plan. Calculation of the nutritional and energy value of dishes. features of their preparation.
Rice. 1.3. Structure of starch grain:
1 - structure of amylose; 2 - structure of amylopectin; 3 - starch grains of raw potatoes; 4 - starch grains of boiled potatoes; 5 - starch grains in raw dough; 6 - starch grains after baking
When heated from 55 to 80°C, starch grains absorb a large amount of water, increase in volume several times, lose their crystalline structure, and, consequently, their anisotropy. The starch suspension turns into a paste. The process of its formation is called gelatinization. Thus, gelatinization is the destruction of the native structure of the starch grain, accompanied by swelling.
The temperature at which the anisotropy of most grains is destroyed is called the temperature gelatinization. The temperature of gelatinization of different types of starch is not the same. Thus, gelatinization of potato starch occurs at 55-65°C, wheat - at 60-80, corn - at 60-71°, rice - at 70-80°C.
The process of gelatinization of starch grains proceeds in stages:
* at 55-70°C grains increase in volume several times, lose optical anisotropy, but still retain a layered structure; a cavity ("bubble") is formed in the center of the starch grain; a suspension of grains in water turns into a paste - a low-concentration amylose sol, in which swollen grains are distributed (the first stage of gelatinization);
* when heated above 70 ° C in the presence of a significant amount of water, starch grains increase in volume by dozens of times, the layered structure disappears, the viscosity of the system increases significantly (the second stage of gelatinization); at this stage, the amount of soluble amylose increases; its solution partially remains in the grain, and partially diffuses into the environment.
With prolonged heating with excess water, starch bubbles burst, and the viscosity of the paste decreases. An example of this in culinary practice is the liquefaction of jelly as a result of excessive heat.
The starch of tuberous plants (potato, Jerusalem artichoke) gives transparent pastes of a jelly-like consistency, and cereals (corn, rice, wheat, etc.) - opaque, milky-white, pasty consistency.
The consistency of the paste depends on the amount of starch: when its content is from 2 to 5%, the paste turns out to be liquid (liquid jelly, sauces, puree soups); at 6-8% - thick (thick jelly). An even thicker paste is formed inside potato cells, in cereals, pasta dishes.
The viscosity of the paste is affected not only by the concentration of starch, but also by the presence of various nutrients (sugars, mineral elements, acids, proteins, etc.). So, sucrose increases the viscosity of the system, salt reduces it, proteins have a stabilizing effect on starch pastes.
When starch-containing products are cooled, the amount of soluble amylose in them decreases as a result of retrogradation (precipitation). In this case, aging of starch jellies (syneresis) occurs, and the products become stale. The rate of aging depends on the type of products, their humidity and storage temperature. The higher the humidity of the dish, the culinary product, the more intensively the amount of water-soluble substances in it decreases. The most rapid aging occurs in millet porridge, slower - in semolina and buckwheat. An increase in temperature slows down the process of retrogradation, so dishes from cereals and pasta, which are stored on food warmers with a temperature of 70-80 ° C, have good organoleptic characteristics for 4 hours.
hydrolysis of starch. Starch polysaccharides are able to break down into the molecules of their constituent sugars. This process is called hydrolysis, as it comes with the addition of water. Distinguish between enzymatic and acidic hydrolysis.
Enzymes that break down starch are called amylases. There are two types of them:
α-amylase, which causes a partial breakdown of starch polysaccharide chains with the formation of low molecular weight compounds - dextrins; with prolonged hydrolysis, the formation of maltose and glucose is possible;
β-amylase, which breaks down starch into maltose.
Enzymatic hydrolysis of starch occurs in the manufacture of yeast dough and baking products from it, boiling potatoes, etc. Wheat flour usually contains β-amylase; maltose, formed under its influence, is a nutrient medium for yeast. α-amylase predominates in flour from sprouted grains, and dextrins formed under its influence give products stickiness and an unpleasant taste.
The degree of hydrolysis of starch under the action of )
