The nutritional value of food. Properties, energy, biological, physiological and organoleptic value, digestibility and good quality
Food products - products used by humans for food in natural or processed form.
Classification:
1. According to the source of receipt:
· animals;
vegetable;
Synthetic
2. By function in the body (according to Petrovsky):
plastic (meat, fish, milk, eggs);
energy (bread, flour and cereal products, fats and products thereof);
Regulatory or biological stimulants (vegetables, fruits, berries, fish oil);
taste (spices, spicy vegetables)
Terms used in the examination of the soundness of products.
In accordance with SanPiN 2.3.2.560-96. The following terminology is currently used:
1. The quality of food products is a set of characteristics that determines the consumer properties of food products and ensures their safety for humans.
2. Quality certificate - a document in which the manufacturer confirms the origin of food products and their compliance with the requirements of regulatory documentation.
3. Safety of food products - the absence of danger to people of present and future generations, determined by the compliance of food products with the requirements of sanitary rules and regulations.
4. Nutritional value - a complex of substances of food products that provides the physiological needs of a person for energy and basic nutrients.
5. Biological value - an indicator of the quality of a food protein, reflecting the degree to which its amino acid composition meets the body's needs for amino acids for protein synthesis.
6. Biological efficiency - an indicator of the quality of fatty components of food products, reflecting the content of polyunsaturated fatty acids in them.
7. Energy value - the amount of energy released in the human body from nutrients, food to ensure physiological functions.
According to their quality, products are divided into:
1. Benign - products that are fully consistent with their receipt and production of the State. The standard and when eaten do not cause pathological changes in the body.
· Standard (fully correspond to state standard specification);
Non-standard (does not meet the requirements of the State Standard, but do not impair the quality of the product and do not have pathogenic properties).
2. Conditionally fit - products that have a defect that makes them hazardous to health and does not allow the use of the product without pre-treatment in order to neutralize or improve organoleptic properties (they increase only due to heat treatment). Product examples: sour milk, forced slaughter meat or Finnose meat (contains larvae, 3 larvae per 40 cm2). The meat is cut into pieces no more than 2.5 kg, no more than 8 cm thick, boiled for at least 2.5 hours with a tightly closed lid, the broth is not used. Meat is used in secondary processing.
3. Poor quality - have a drawback that does not allow the use of a food product. Because it can cause death. These products can be used for feeding to livestock (by the decision of the veterinarian), disposal, destruction (burning, burial).
4. Counterfeit products - products whose natural properties have been changed in order to deceive the buyer or consumer (alcoholic beverages, meat, juices, wines).
5. Surrogates - products produced instead of natural ones (protein caviar, barley coffee, carrot tea).
Product classification by storage stability:
1. Particularly perishable - have a shelf life in the refrigerator (filled products, pate - liver, boiled kodbass, liver - blood sausages);
2. Perishable soon - a longer period (in the refrigerator), can be frozen (meat, fish, dairy products);
3. Sustainable products (not quickly perishable) do not require a refrigerator, humidity is not more than 15% (sugar, cereals).
Examination methods:
● Chemical (ph environment, foreign inclusions);
● Physical (t, viscosity, transparency, density);
● Organoleptic (color, taste, smell);
● Microscopic (morphological structure, fiber structure);
● Bacteriological (degree of microbial contamination);
● Biological;
● Radiometric (degree of radioactive contamination).
Stages of product examination:
1. Acquaintance with the documentation;
2. External inspection of the container with an assessment of its condition and forced opening (at least 10%) and each place with contamination;
3. Organoleptic study (if the first 3 points do not match, then go to point 4);
4. Sampling (we select an average sample, which should characterize the state of the entire batch);
5. Laboratory research and conclusion.
Based on the conclusion, the doctor decides: the state of good quality; recommendations for its use.
Quality- one of the fundamental characteristics of the product, which has a decisive influence on consumer demand and its competitiveness.
Quality is a set of properties of a product that determine its ability to satisfy certain needs in accordance with its purpose.
The main properties of food products that are able to satisfy a person's nutritional needs, are safe for his health, and are reliable during storage are: nutritional value, physical and taste properties, and shelf life.
Nutritional value is a complex property that consists of energy, biological, physiological value, good quality and digestibility of food products.
Energy value is characterized by the energy that the body receives in the process of metabolism. To build tissues and metabolic processes, all the constituent parts of the products are necessary, and the need for energy is satisfied mainly by proteins, fats and carbohydrates.
The energy value of foods is expressed in kilojoules (kJ) or kilocalories (kcal) per 100 g.
Studies have established that during oxidation in the human body, 1 g of protein releases 4.1 kcal (16.7 kJ); 1 g of fat - 2.3 kcal (37.7 kJ); carbohydrates - 3.75 kcal (15.7 kJ).
The human body receives the greatest amount of energy from the oxidation of alcohol and organic acids.
The energy value can be calculated by knowing the chemical composition of the products.
The data on the calorie content of the product put down in the labeling of the product are designed to help the buyer make calculations for a balanced diet.
Biological value is characterized by protein composition and content of vitamins and minerals. The energy consumption of a modern person is small and amounts to approximately 2500 kcal, so the biological value of food is of particular importance.
Physiological value is the ability of products to have an active effect on the digestive, nervous and cardiovascular systems of a person, on the body's resistance to infectious diseases. So, for example, lactic acid and antibiotics secreted by the microflora of lactic acid products prevent the development of putrefactive bacteria that contribute to the aging of the body. Fiber and pectin are regulators of intestinal motility.
Organoleptic value is characterized by such quality indicators as appearance, taste, smell, consistency. In fresh, little stored products, there are more biologically active substances. Products that have an irregular shape, dull color, rough or overly soft texture are less digestible and may even contain substances that are harmful to the human body.
Digestibility is one of the important properties of the nutritional value of products, it depends on their appearance, taste, activity and composition of enzymes. The digestibility of products is influenced by a person's well-being, age, nutritional conditions and many other factors.
The digestibility of proteins with mixed nutrition is 84.5%, carbohydrates - 94.5, fats - 94%.
Only the food digested by the body is used to restore energy. Some food products have a low energy value, but are indispensable in nutrition, as they are a supplier of vitamins and microelements important for the body.
Taste products (spices, seasonings) do not have a high energy value, but they improve the taste, smell, thereby facilitating absorption.
The good quality of food products is characterized by organoleptic and chemical indicators. Food products must be harmless and safe. Food products should not contain harmful compounds (lead, mercury), toxic (poisonous) substances, pathogenic microbes, impurities, glass, etc.
The persistence of food products is the ability to maintain quality without significant loss for a certain period of time established by the standard or other regulatory documents.
The preservation of food products is closely related to safety, especially perishable ones (milk, fish, meat).
By quality, food products are divided into classes:
- Goods suitable for their intended use. These are standard goods that are subject to sale without restrictions;
- goods conditionally suitable for their intended use. Conditionally suitable goods can be sold at reduced prices, sent for industrial processing or for livestock feed;
- goods are dangerous, unsuitable for their intended use. These are non-liquid wastes that are not subject to sale and cannot be sent for industrial processing or for livestock feed. Subject to certain rules, they can be destroyed or disposed of.
In wholesale and retail trade, goods are sold that are suitable for their intended use.
When assessing the quality of food products, various deviations from the specified or expected requirements (defects) can be identified.
Defects in goods can be minor, major or critical.
Minor ones do not significantly affect consumer properties, safety, shelf life of products, these may be deviations in the size and shape of vegetables and fruits. Significant defects worsen the appearance, affect the use of the product for its intended purpose. For example, cracks, tears on the crust of bread; such bread is unacceptable for sale, but can be used for other purposes. Goods with critical defects are not allowed for sale (bombing of canned food).
Defects can be obvious and hidden. For latent defects, there are no rules, methods and means of detection, or their use is inappropriate.
Defects in goods may be repairable or irreparable. Removable defects are defects, after the elimination of which the product can be used for its intended purpose (cleaning the yellowed edge of the butter).
Fatal defects cannot be eliminated (moldy smell of bread).
Quality gradation- consistent division of goods into classes, varieties, categories, etc. in accordance with established quality requirements.
Tasting method- an assessment of quality indicators obtained as a result of testing food products and perfumes.
Single quality indicator- characterizes one of the properties that make up the quality of the product.
Product quality- a set of product characteristics that determine the degree of its ability to satisfy established and implied needs;
The set of consumer properties of the goods (GOST R 51303-99).
Quality management— coordinated activities to direct and control the organization with regard to quality.
Methods for determining product quality indicators- methods by which the quantitative values of the quality indicators of the goods are determined.
Flaw- non-compliance of the goods with the mandatory requirements established by law or in the manner prescribed by it, or the terms of contracts, or the purposes for which goods of this kind are usually used, or the purposes of which the seller was informed by the consumer at the conclusion of the contract, or a sample and (or) description when selling goods according to the sample and (or) according to the description.
Quality assurance— part of quality management aimed at creating confidence that quality requirements will be met.
Organoleptic method- is based on the use of information obtained as a result of the analysis of sensations and perceptions using the human senses - sight, smell, hearing, touch, taste.
Quality planning— part of quality management aimed at establishing quality objectives and determining the necessary operational processes of the product life cycle and the corresponding resources to achieve quality objectives.
Product quality index- a quantitative characteristic of one or more properties of a product, considered in accordance with certain conditions of its operation or consumption.
Quality Policy— the overall intentions and direction of the organization in the field of quality, formally formulated by top management.
Consumer indicator of product quality- a quantitative characteristic of one or more consumer properties of a product, considered in accordance with the conditions of its consumption.
Sensory analysis- used to assess the quality of food products in determining the color, taste, smell, texture of food products.
Product type- gradation of goods of a certain type according to quality indicators and (or) the presence of defects established in regulatory documents.
Major defect of the product- an irreparable defect or a defect that cannot be eliminated without disproportionate costs or time, or has been identified repeatedly, or reappears after its elimination, or other similar shortcomings.
Product quality requirements- the expression of certain requirements in the form of quantitatively or qualitatively established norms of individual characteristics of the goods, which creates the possibility of checking the quality of the goods when used for their intended purpose.
Quality control— part of quality management aimed at meeting quality requirements.
Product quality level- a relative characteristic of the quality of the goods, obtained on the basis of comparing the values of the quality indicators of the evaluated goods with the corresponding indicators of the base sample (base values).
Deterioration of the quality of goods- a decrease in at least one of the indicators characterizing the quality of the goods, caused by defects in raw materials, defects in the material or product, damage, as well as a violation of production technology, storage conditions, transportation and operation rules.
Formation of product quality— establishment, provision and support of the required level of product quality at all stages of its life cycle: production, delivery, storage and consumption.
expert method- determination of quality indicators based on the opinions of qualified specialists - experts. They are used in cases where quality indicators cannot be determined by other methods due to insufficient information, the need to develop special technical tools, etc.
Express method- determination of quality indicators and other characteristics of goods using simple, accelerated methods in a shorter time than with conventional methods.
The quality of goods is one of the fundamental characteristics that have a decisive influence on the creation of consumer preferences and the formation of competitiveness. The quality of food products is understood as a set of properties that reflect the ability of the product to provide organoleptic characteristics, the body's need for nutrients, its safety for health, reliability during manufacture and storage. The main properties of food products, which determine their usefulness and ability to meet human nutritional needs, are nutritional value, physical and taste properties and its persistence.
The nutritional value- this is a complex property that characterizes the fullness of the useful properties of the product, i.e. energy, biological, physiological, organoleptic value, digestibility, good quality.
Energy value products is determined by their content of fats, proteins, carbohydrates. The energy value of food products is expressed in kilojoules (kJ) or kilocalories (kcal) per 100 g. It has been established that during oxidation in the human body, 1 g of fat releases 9.3 kcal (37.7 kJ) of energy; 1 g of proteins - 4.1 kcal (16.7 kJ); carbohydrates - 3.75 kcal (15.7 kJ). The body also receives a certain amount of energy from the oxidation of organic acids and alcohol. Knowing the chemical composition of the product, you can calculate its energy value.
For example. Dutch cheese contains (in%): protein - 23.5; fat - 30.9; carbohydrates - 0.2. The energy value of 100 g of cheese will be: (23.5 x 4.1 kcal) + (30.9 x 9.3 kcal) + (0.2 x 3.75 kcal) = 384.47 kcal.
But the human body, even under the most favorable conditions, does not use all the substances that make up food, since they have different degrees of digestibility.
Biological value is characterized by the presence of biologically active substances in products: essential amino acids, vitamins, macro- and microelements, essential polyunsaturated fatty acids. These components are not synthesized by the enzyme systems of the body and therefore cannot be replaced by other nutrients. They are called essential and must be ingested with food (meat, fish, dairy products, etc.).
Physiological value It is determined by the ability of food products to influence the digestive, nervous, cardiovascular systems of a person and the resistance of his body to diseases. For example, tea, coffee, spices, lactic acid and other products have a physiological value.
Organoleptic value food products determine the quality indicators: appearance, texture, smell, taste, composition, degree of freshness. They increase appetite and better assimilate food products that are optimal in appearance: usually fresh or little stored fruits, dietary eggs, live fish, bakery products from high-quality raw materials, as they contain more biologically active substances. The taste and aroma of foodstuffs are of such great importance that in some cases processing methods (for example, smoking of fish and sausages) are used to achieve them, even causing a slight decrease in the digestibility of protein substances. Worse absorbed products that have a dull color, irregular shape, uneven surface and excessively soft or rough texture; containing less biologically active substances; with low nutritional value. Products with defects in appearance and texture often contain substances that are harmful to the human body.
Digestibility of food products is expressed digestibility factor, showing how much of the product as a whole is used by the body. Digestibility depends on the appearance, texture, taste of the product, the quality and quantity of nutrients contained in it, as well as on age, human well-being, nutritional conditions, habits, tastes and other factors. With a mixed diet, the digestibility of proteins is 84.5%, fats - 94, carbohydrates - 95.6%.
Goodness food products are characterized by organoleptic and chemical indicators (color, taste, smell, texture, appearance, chemical composition), the absence of toxins (toxic substances), pathogenic microbes (salmonella, botulism, etc.), harmful compounds (mercury, lead), seeds poisonous plants and foreign matter (metal, glass, etc.). According to good quality, food products are divided into classes: goods suitable for their intended use (to be sold without any restrictions); goods conditionally suitable for their intended use (non-standard goods or marriage with removable defects); dangerous goods that are unsuitable for their intended use (not subject to sale and must be destroyed or disposed of in compliance with certain rules).
Goods suitable for their intended use can be competitive in the market and provide their manufacturers with confidence in the success of their activities. During the transition period, many Russian enterprises are still unable to establish the production of competitive products, and the main reasons for this situation are the low level of technical equipment of enterprises, insufficient professional training of workers, financial difficulties associated with a rigid taxation system, etc.
Physical properties are taken into account when assessing the quality of goods, determining the terms and conditions of storage.
Physical properties include shape, size, mass, color, transparency, density, viscosity, strength, etc.
Taste properties Food products are made up of a sense of taste and olfactory sensations - smells. There are four types of taste: sweet (sugar), salty (salt), sour (vinegar), bitter (glycoside alkaloids). Smell - sensations perceived by the olfactory organs. The smell is an important indicator in determining the quality of wines and drinks, where the aroma manifests itself in the form of a bouquet of sensations.
Persistence- the property of a product to maintain consumer qualities for a certain period of time (subject to certain conditions) established by a standard or other regulatory document.
Depending on the persistence, all food products are divided into perishable (meat, fish, milk, etc.); suitable for long-term storage (flour, cereals, sugar, canned food, etc.).
The quality of food products is a set of product properties that determine its suitability for meeting certain needs in accordance with its intended purpose. The quality of food products must meet the requirements of standards. The quality of any food product is determined by its characteristic properties, which are called quality indicators.
The most significant influence on the formation and preservation of the quality of food products is exerted by the type and quality of raw materials, methods and conditions of production, packaging and condition of containers, transportation and storage.
The quality of food products is determined by organoleptic and measuring (laboratory) methods.
The organoleptic method determines the quality of products using the senses: sight, touch, smell and hearing. This method establishes the taste, color, smell, texture and appearance of the product. At catering establishments, this method is considered the main one and is supplemented by test cooking or frying a product whose quality is doubtful. For a more objective conclusion about the quality of some products (cheeses, butter), a scoring has been introduced. Its essence lies in the fact that the quality of the product is evaluated by the sum of a certain number of points according to organoleptic indicators, taking into account discounts for defects in the product. At the same time, the main indicators characterizing the quality of the product are taste and smell. Based on the total score, the commercial grade of the product is determined. Commodity Studies: Textbook / Ed. Ed. M.V. Romanovsky. and O.V. Vrublevskaya.- M.: Yurayt, 2011.-p.114.
The measuring (laboratory) method allows using instruments, reagents to determine physical (specific gravity, density of products, their melting and freezing point, viscosity), chemical (mass fraction of moisture, proteins, fats, carbohydrates, organic acids, minerals, harmful and toxic impurities), microbiological (presence of pathogenic and spoiling food microbes), physiological properties, energy value, digestibility, food safety of the product, etc.
To study the quality, an average sample is taken - a sample of a batch of a product from different places of packaging. The sample is sometimes taken with a special probe. The procedure for taking an average sample is indicated in the standards.
In a market economy in a market saturated with goods, producing them by different enterprises and firms, a guaranteed confirmation of the conformity of the goods to a certain level of quality specified in the standard is necessary.
Such confirmation of conformity is given in the form of a certificate of conformity.
A certificate is a document confirming the conformity of product quality with the established requirements of the standard, drawn up according to the rules of the certification system. It includes: code, product type; manufacturer; place of manufacture; data on compliance with safety requirements, relevant standards or regulations; data and approval of the results in the testing laboratory, test report; data on the validity of the certificate, its registration in the register of the Company and the registration number of the Company.
Certification is the activity of independent authorized bodies of the state to confirm the quality of products in accordance with the established requirements of standards.
Certification rules are developed by Gosstandart of Russia and approved by the Law of the Russian Federation.
One of the important documents for issuing a certificate is a hygiene certificate, introduced by a resolution of the State Sanitary and Epidemiological Supervision in 1993.
The purpose of the hygienic certificate is to prevent the adverse effects on human health of hazardous foodstuffs in which the maximum permissible norms of microbiological indicators or the concentration of substances leading to the accumulation of toxins are exceeded. Hygienic certificates must have: food raw materials, food products, food additives, dyes, preservatives.
Any product manufactured in Russia with a quality certificate must have a Conformity Mark on each packaging unit - this is a sign confirming the compliance of the products marked with it with the established requirements of the standard, according to certification.
Food products in their quality must comply with the requirements of state standards, which are abbreviated as GOSTs. G.B. Pole. - M.: UNITI, 2011.- P.123.
The quality indicators of a number of products for which GOSTs have not yet been established are given in temporary technical specifications - VTU.
In the sanitary assessment of a food product, its suitability or unsuitability for food is determined.
Sanitary assessment of food products is carried out by organoleptic and laboratory methods.
In the organoleptic evaluation of the quality of products, the sense organs are used: sight, smell, touch, taste. To better determine the quality, test cooking of dubious products is carried out - meat, fish, cereals, etc. in a sealed container. A stale product has an unpleasant odor during cooking. In doubtful cases, a sample of the product is sent to the laboratory for analysis.
The laboratory research method is more accurate: it is used to determine not only the good quality of products, but also its chemical composition, calorie content, etc.
A product is considered to be of good quality if it is free of signs of spoilage, harmless to health and has an appropriate nutritional value.
In some cases, the harmful properties or impurities of the product may disappear after its appropriate processing. Such a product is considered conditionally suitable; it can be used for food only after neutralization. Conditionally suitable products include, for example, Finnish meat, which can be used as food after disinfection by boiling, curing or freezing in a slaughterhouse.
Unsuitable for food are products with irremovable harmful properties or impurities of toxic substances that are dangerous to human health.
All products entering the warehouse of the enterprise must have quality certificates. When accepting products, it is necessary to find out whether all the documents are in order, what are the deadlines for the sale of products, whether there are any special instructions in the documents regarding the sale and storage of products, for example, instructions from a sanitary worker that products can only be used after cooking. It is necessary to check the date of release of the product by the industrial enterprise, which is especially important for cooked sausages, smoked fish, cream cakes and pastries, milk and dairy products, chocolates, marshmallows, etc.
After checking the documents, food products are carefully examined to determine their good quality. The check is carried out by the storekeeper and the head of production with the participation of an employee of the departmental sanitary service (if any). Food warehouse workers and cooks should be able to determine the quality of food and know the main signs of spoilage.
Product quality is one of the fundamental components of competitiveness. The quality of goods is understood as a set of properties that make up its quality, considered in relation to certain conditions of its creation, operation and consumption. From this definition, we can conclude that its property is taken as the initial characteristic of product quality. All properties of products can be divided into simple and complex.
When assessing the quality of food products, such important indicators as caloric content (energy capacity), biological value, characterized by the content of essential amino acids, polyunsaturated fatty acids, vitamins, mineral salts, tonic substances and other biologically active compounds, as well as organoleptic properties - shape, external appearance, color, texture, taste and smell. For many products, indicators such as readiness for consumption, shelf life, etc. also play a role. The quality of the product as a whole is determined by the sum of all complex indicators, taking into account the coefficient of significance of each of them.
The study of the quantitative characteristics of the quality of food products, i.e. the totality of their properties and values for a person, a special branch of knowledge is engaged in - qualimetry Commodity science: account. Allowance for universities. Ed. N.D. Eriashvili and others - 2nd ed., revised. and additional -M.: UNITY-DANA, law and law, 2013.-p.125.
Each batch of food products coming from industrial enterprises is accompanied by a quality certificate (certificate). The quality of products in public catering establishments is established organoleptically, and in case of doubt, by a laboratory study of selected samples.
A sample that allows you to judge the properties and merits of the entire batch of goods received is called the average. To obtain an average sample, small amounts of product (outputs) are taken from different places of several packaging units, mixed and a sample is taken. When sampling from a liquid, it is thoroughly mixed or excavations are taken from different depths; samples of fine-grained and bulk products, cow's butter, cheeses, ice cream are taken with special probes.
The value of the average sample for each product is set by the standards. If, during the organoleptic assessment at the enterprise, the quality of the product is recognized as meeting the requirements of the standards, then the average sample is returned to the place where it was taken from, and, if necessary, sent to the laboratory for analysis by physical, chemical and other indicators. An average sample is taken from the average sample, which is carefully packed, sealed or sealed. Samples are accompanied by an act and a label indicating the name of the enterprise that produces the product, the name, grade and date of production of the product, the batch number from which the sample was taken, the date of sampling, the positions and names of the persons who took the sample, indicators that must be determined in product, the number of GOST, OST, PCT for this product, the number of the transport document Merchandising: Textbook for universities / Ed. G.B. Pole. - M.: UNITI, 2011.- P.123.
Organoleptic methods determine the quality of products using the senses - smell, touch, taste, sight and hearing.
Before organoleptic examination of products, their packaging, labeling, and appearance are checked. Organoleptic methods allow you to establish the quality of the product in terms of shape, color, surface condition, taste, smell, texture. The determination of these indicators requires the necessary skills, knowledge and extensive practical experience, especially when assessing the taste and smell (tasting) of products. The tasting is held in a bright room with completely clean, odor-free air. Room temperature should be between 15-20°C. Before each taste test, rinse your mouth with clean water or chew a piece of bread that adsorbs flavoring substances remaining in the mouth from the previous test. The sample is not swallowed, but only kept in the mouth until the taste is determined. When tasting wines, special pear-shaped glasses are used; when tasting tea, porcelain cups and teapots are used.
For a more objective organoleptic assessment of the quality of cow butter, hard rennet cheeses and some other products, a 100-point system is used, in which 45-50 points are assigned to taste and smell, and depending on the deficiencies found, appropriate discounts are made from the total number of points and according to the sum of points, the grade of the product and its compliance with the requirements of the standard are judged.
Most of the current scoring systems have shortcomings: in different systems, the same indicator is evaluated by a different number of points; some indicators (appearance, packaging, etc.) appear in some systems, but not in others.
Each considered criterion of a competitive bid or indicator that characterizes the qualifications of a supplier receives an assessment in points on a ten-point scale. For this purpose, the values of the analyzed criterion (indicator) in physical units are ranked for all suppliers. The worst value of the criterion (indicator) is assigned one point, the best - ten points. The use of the interpolation method in the range of 1-10 points allows you to determine the score value of the criterion (indicator) for each type of product.
For some products (wine, tea), organoleptic evaluation is so far the only way to determine their quality and variety. However, the organoleptic quality assessment system does not take into account the nutritional value of the product. Therefore, to identify the nutritional value and safety of the product, the organoleptic study is supplemented by physicochemical and microbiological studies.
Physical methods determine the density, melting point, solidification and boiling point, optical properties, etc.
The density of liquids is determined by a hydrometer or pycnometer; by density, for example, the amount of alcohol in alcoholic beverages, the content of acetic acid, sugar and salt in solutions, the nature of vegetable oil, etc. are established. On some hydrometers (alcohol meters), graduation is made by the percentage of alcohol. Ed. M.V. Romanovsky. and O.V. Vrublevskaya.- M.: Yurait, 2011.-p.137.
Melting, freezing and boiling points are determined with a thermometer.
The concentration of water-soluble sugars and salts, as well as the naturalness and purity of oils and fats, is determined refractometrically by the angle of refraction of a beam of light passed through a thin layer of the test substance, which is enclosed between the refractometer prisms.
To determine the type of sugar and its concentration in a solution, a polarimetric method is used - determining the deviation of a polarized beam that has passed through special prisms and through a solution.
The luminescent method is based on the ability of many substances, after illumination with ultraviolet rays, to emit visible light of various shades in the dark. Since fats, proteins and carbohydrates give a luminescent glow of various colors, changing the composition of the product will correspondingly change the intensity of the glow and color.
The ratio of parts in canned food, the amount of filling in caramel, the amount of impurities in cereals, the weight of piece bread, cakes, ice cream, curds and other products are determined by weighing.
Chemical methods establish compliance with the requirements of standards for the content of water, fat, sugar, salt, ash, alcohol, acids in food products. Deviations in the content of the ingredients of products affect their nutritional value, taste and shelf life.
Humidity is determined by drying, electric moisture meters and other methods. The fat content is determined by the volumetric method in butyrometers after dissolving other constituents of the product in strong acids, followed by distillation of the solvent and weighing the fat. The amount of sodium chloride is determined by titration of the aqueous extract from the product with a solution of silver nitrate. The ash content is determined by burning a certain sample of the product in muffle furnaces. The alcohol content in the products is determined by distilling it from the solution and establishing the percentage of alcohol by its density. Acidity is determined by titrating solutions or aqueous extracts of the product with 0.1 N alkali, as well as using a pH meter.
Microbiological methods for studying the quality of food products are used to establish the total bacterial contamination, the presence of pathogenic, putrefactive and other microbes that are harmful to the human body and accelerate the spoilage of products during storage. Such studies are carried out by food laboratories of sanitary and epidemiological stations that supervise the sanitary condition of food enterprises, trade and public catering enterprises. Textbook for training specialists in customs clearance / D.A. Kirillova, D.V. Mikhailov, R.Ya. Supyan. St. Petersburg: European House, 2012.-p.56.
For nutrition, a person consumes food products of plant, animal and mineral origin, which have a certain usefulness, nutritional value, and digestibility. The usefulness of products is determined primarily by their ability to satisfy human nutritional needs. It depends on the chemical composition and characteristics of the transformations of various substances of these products in the human body and is characterized by such basic consumer properties as nutritional, biological, energy and physiological values.
The nutritional value- a complex of substances that determine their biological and energy value. The nutritional value characterizes the fullness of the useful properties of the product, i.e. good quality (harmlessness), digestibility, content of nutrients (proteins, fats, carbohydrates) and biologically active substances (vitamins, minerals, essential amino acids, etc.).
The nutritional value of products is not the same. The highest nutritional value is possessed by products containing proteins, fats, carbohydrates and biologically active substances in the ratio necessary for the human body. Such products are meat, fish, eggs, fish roe, dairy products, etc. At the same time, a number of products have a reduced nutritional value, since they do not have a complete set of essential substances. Individual products are almost entirely composed of one of some compounds. For example, sugar, starch, molasses contain mainly carbohydrates; according to the content of proteins, meat, fish, grain products, cheese are distinguished; there is a lot of fat in butter, lard, sausages; fruits, vegetables and mushrooms contain large amounts of water.
Products must not have harmful effects on human health. Such an influence is possible if they contain harmful compounds (mercury, lead, etc.), pathogenic microbes (Salmonella, botulinum, etc.), impurities (glass, metal), seeds of poisonous plants, etc.
Energy value products is determined by their content of fats, proteins, carbohydrates and their digestibility. The energy value of the product is measured in kilocalories (kcal) or kilojoules (kJ) per 100 g. product. When oxidized in the body, 1 g of fat releases energy equal to 9 kcal (37.7 kJ), 1 g of protein - 4 (16.7 kJ) and 1 g of carbohydrates - 4 kcal (16.7 kJ).
biological value characterized by the presence of biologically active substances in products: vitamins, macro- and microelements, essential amino acids and polyunsaturated fatty acids. The biological value of food reflects, first of all, the quality of the protein component of food, associated with the balance of its amino acid composition, as well as its ability to be digested, assimilated and used by the body as much as possible. These food substances are not synthesized in the body and therefore cannot be replaced by other food substances.
Physiological value - the effect of substances contained in products on the nervous system, cardiovascular, digestive, on the body's resistance to infectious diseases. Tea, coffee, spices and other products have this ability.
Organoleptic value - it affects the human senses, stimulates or suppresses appetite.
Digestibility - is expressed by the digestibility coefficient, i.e. what part of the product is absorbed by the body. Food digested, absorbed into the blood and used for plastic processes, energy restoration is called assimilated. Digestibility depends both on the objective properties of the product (type, taste, aroma, texture, amount of nutrients, etc.), and on the state of the body, nutritional conditions, habits, tastes, etc. The average digestibility of products is (in%): proteins - 84.5, fat - 94 and carbohydrates - 95.6. Food is never 100% digested. Digestibility of food of animal origin 90%, vegetable 90%, mixed 85%. The food boiled, pureed is acquired better.
Food products are different in chemical composition, digestibility, the nature of the impact on the human body.
Carbohydrates are a source of energy, the consumption rate is 400 grams per day (1g - 4 kcal.) Carbohydrates are found in plant products. They are divided into: monosochorides (glucose, fructose), disaccharides (sucrose, lactose, maltose), polysaccharides (starch, fiber is not digested by the body due to the lack of enzymes. It does not release energy, but removes cholesterol and creates conditions for the microflora of the body.)
Fats - a source of energy (1gr - 9 kcal), it is part of the cells and tissues, affects the taste and juiciness of the product. Excess fat is stored as a reserve substance. With a lack of fat, the protective properties of the body are weakened by disorders of the nervous system, growth slows down and protein synthesis decreases. Fat is made up of glycerol and fatty acids. Fatty acids are divided into saturated and unsaturated. Saturated ones have a low biological value, are easily synthesized in the body, and negatively affect fat metabolism. Promotes the development of atherosclerosis. Unsaturated - oleic, lenoleic and orachidonic. According to their biological properties, they are vital. They increase the elasticity of blood vessels, prevent blockage, thrombus, take part in fat metabolism.
Protein is a complex organic compound made up of amino acids. It is the main plastic material for the body. They form the basis of hormones, enzymes, antibodies. Proteins contribute to normal metabolism and release energy (1g - 4 kcal). With a lack of protein, there may be a slowdown in the growth and development of children, a change in the liver, in the composition of the blood, a weakening of the mental and resistance to infections. Mainly found in animal products. The daily norm of proteins and fats is 80 - 100 grams. Table 1 shows the average values for each class of substances. Exact values may vary slightly from substance to substance.
Table 1 - Energy value of the main components of food
At the same time, it should be borne in mind that ensuring normal life is possible only with a balanced diet, when the proportions of individual food components are determined, taking into account the need for energy and building materials, as well as essential food components that are not synthesized in the human body.
