What is smell? This is a phenomenon associated with the human sense of smell, which to this day has not been fully studied. In many ways, it remains a mystery even to scientists themselves. The concept of smell is inextricably linked not only with physiological processes, but also with the human psyche. Some of the aspects of what this phenomenon is will be discussed in the article.
Perception of smell
What is smell? This is a specific sensation by a person or animal of odorous volatile substances that are in the air. They are found by specific chemicals located in the nasal cavity in humans and animals.
The perception of smell is a complex process that breaks down into many stages. The smells are different in their structure and composition. Some substances are perceived differently by humans, depending on their concentration in the air.
For the vast majority of people, smell is a slightly differentiated, integral (total) sensation. After all, it is determined by the total effect obtained from irritation of receptors such as the olfactory, trigeminal nerve and vomeronasal organ (peripheral section of the additional olfactory system). There is an assumption that the aerosol component of the atmosphere is also involved in the sensation of smell.
Some features
As a rule, the perception of odor is either neutral or pleasant. At the same time, the receptors are loaded at an average level. When the aroma is highly concentrated, it begins to cause unpleasant feelings, so-called sensory overload occurs.
Exposure to some substances causes adaptation quite quickly. In this case, there is a complete loss of the sense of smell from such a substance. For such a case, hydrogen sulfide serves as a typical example. It is easily detected in minimal proportions that are not hazardous to health. But after a short period of time, the intensity of the sensation drops very sharply, and the person becomes unable to feel a concentration that exceeds the maximum permissible concentration in the air.
When multiple odors overlap, significant distortion of the overall scent rating can occur. This phenomenon has been adopted by perfumers; they use it when composing compositions when creating new types of perfumes.
Continuing to study the question of what smell is, let's consider some of its varieties.
Types of odors
Among them are the following:
- Amines. Similar to the smell of fish, ammonia, urine. Easily neutralized with acid.
- Sulfur compounds. Rotten protein, sulfur dioxide, odor found in the metallurgical industry.
- Alcohols. Butanol, isopropyl, amyl alcohol. Can be washed off with water.
- Carboxylic acids and aldehydes. The smell is close to alcohols, but some of them smell quite pleasant and are included in perfumes. For example, anise or cinnamon aldehyde. Some not very pleasant odors include valerian, formaldehyde, and vinegar.
- Esters are compounds of alcohol and acid from which water has been isolated. All these are fruity aromas - the smells of pineapples, pears and some paint solvents, as well as vanillin, which is the most important component of essential oils.
- Terpenes and their esters. These include different pleasant smells of almost all plants. They are also components of essential oils and are used in fragrances.
- Hydrocarbons have a gasoline smell. Many people like them, but they cannot be used as fragrances, as they are poisonous. Sometimes they are included in essential oils.
- which smell of iodine and bleach. These are, for example, bromine, chlorine, fluorine, hydrochloric, nitric acid, ozone. Since odor is strongly related to concentration, hydrogen sulfide, ozone, and butyric acid do not smell too bad in small quantities.
What types of perfume scents are there?
Perfumers use their own classification of scents. The most popular groups of fragrances are:
- Floral - the most common - rose, jasmine, lily of the valley, carnation, lily.
- Eastern, or oriental, are patchouli, vanillin, sandalwood.
- Sea, or ocean, carry a feeling of coolness and freshness.
- Wooden ones are more often used by men. These are myrtle, musk, dry cedar, blue iris.
- Fresh aromas (vegetal). These include the smells of the first spring flowers, lavender, rosemary, leaves, and grass.
- Chypre - resin, sage, oakmoss, patchouli.
- Aldehydes are aromas that do not exist in nature. They are juicy, intense, colorful.
- Citrus fruits - grapefruit, tangerine, bergamot, orange, lemon.
- Fruit - pear, apple, pineapple, apricot, papaya.
- Leather. This is a masculine group of fragrances that recreates the smell of leather, smoke, tobacco, burnt wood. These include the smells of resin, birch, and juniper.
Series title
“The Smell of a Child” is the title of a Turkish series translated into Russian, which can be watched online. It tells about the fate of the girl Zeyno and her best friend Nesrin, whom she considers a sister.
Zeyno lived modestly as a nurse at a children's hospital. She loved a guy named Yusuf, dreaming that they would get married. However, when the girl told her lover that she was pregnant, he suggested that she get rid of the child.
What the girl will do and how her future fate will turn out, you will find out if you watch the series.
Unhealthy air in the apartment
You can often smell an unpleasant house odor, which is very difficult to get rid of. After all, it is not always possible to determine where exactly it comes from. What could be the cause of the unpleasant odor? Among them may be such as, for example:
- Carpets, rugs, furniture, curtains absorbed tobacco smoke.
- Large quantities of dishes not washed on time.
- Clogged and rusted pipes.
- Dirt, grease in the microwave and oven left over after cooking.
- Residues of the vital activity of microorganisms in the refrigerator, formed as a result of long-term storage of food.
- Insufficient cleaning of the bathroom and toilet.
- Not fully washed and cleaned clothes in the wardrobe.
- Stale bed linen.
- Unaired sweat in closed shoes.
- Dust collected in the air after cleaning using a vacuum cleaner.
- Waste that has been sitting in a trash container for a long time.
From what has been said, we can conclude that cleanliness is not only a guarantee of health, but also the enemy of an unpleasant odor.
The role of smells
In conclusion, considering the question of what smell is, it should be noted that it plays a huge role in people’s lives, in their perception of the world - both physiological and psychological. Thus, they can influence labor productivity, appetite, food choice, mood, evoke certain memories, and stimulate shopping.
In the sexual sphere they are also very important. One of the proofs of this, according to scientists, are changes in odor preferences observed when a person reaches puberty. Before puberty, fruity and sweet aromas tend to be more pleasant, followed by a shift toward musky, floral, and oily aromas.
A number of experiments show that men are able to “smell” a woman when she is in a state of sexual arousal. There is also a theory that partners are chosen by smell, which, however, is not sensed by olfactory receptors.
To create scents, perfumers use a huge assortment of fragrant raw materials - there are more than five thousand items in total; Among them, natural aromatic substances obtained from plants occupy a large place.
Fragrant plants for obtaining essential oil from them are grown in the Caucasus, Crimea, Moldova, Central Asia, the Central Black Earth Region, and Ukraine. These are mainly coriander, rose, cumin, fennel, clary sage, geranium, mint, lavender, anise, jasmine, oakmoss, azalea, cistus and others.
Up to 90% of the obtained essential oils are used only by the perfumery and cosmetics industry, the rest - for the food industry and as a fragrance for household chemicals (laundry detergents) and toilet soap.
Natural aromatic substances are obtained from fresh and dried parts of plants mainly by distillation, pressing (squeezing) or extraction with various solvents.
Plants containing a small amount of essential oils are distilled by water vapor: for example, coriander seed (fruit) contains about one percent of essential oil; from one ton of fresh rose petals one to two kilograms of rose oil is obtained. Distillation occurs at high temperatures, and some of the constituents of the oils are lost with the distillation waters, so the smell of the oil changes and is usually significantly worse than the smell of the petals.
The peels of lemons, oranges, tangerines, oranges and others, which contain a significant amount of relatively easily released oil (for example, fresh orange peel contains about 3% oil), are squeezed (pressed).
Some plants - lilac, lily of the valley, acacia flowers - when heated, generally change their smell and produce a completely unusable product, so when processing them, distillation is replaced by extraction with highly volatile solvents or liquefied gases. The solvent is distilled off from the extracts, and the residue is obtained as so-called extract oils. Due to the fact that the solvent is distilled off at a low temperature, the smell of extracted oils corresponds to the smell of the original raw material. Along with aromatic substances, extract oils also contain vegetable waxes and resins transferred from raw materials; Such oils are mostly solid and are called concretes. When concretes are dissolved in alcohol, the waxes and some of the resins precipitate and almost pure, the so-called absolute oil, remains in the solution. Essential oils, concretes and absolutes are obtained from many seeds, flowers, crusts, mosses, leaves, plants (for example, from rose flowers, jasmine and others).
Plant raw materials are often used to prepare alcoholic infusions, especially when it is desirable to better preserve the smell of the raw material and extract accompanying resinous and other substances with it (infusions, for example, of vanilla pods, orris root, cloves, and oak moss are often used).
Of great importance are many fragrant resinous substances obtained as a result of cuts on plants. The most commonly used resins in perfumery are benzoin resin (dewy incense), frankincense, tolu balsam, and styrax.
Resinous substances give a wonderful, long-lasting odor. They are the strongest phytoncides and are suitable for the production of air purifying and disinfecting products.
In the assortment of “fragrant” raw materials, aromatic substances of animal origin also occupy an important place. We are talking about the dried glands of males of some animals (musk ox - musk deer, beaver and, less often, muskrat) and secretions of other organs. The musk deer is found in the forested mountainous regions of Central Asia and Siberia. Civet is the secretion of the glands of the civet cat, found in North Africa and Asia; ambergris - sperm whale secretion (waxy mass).
Musk and amber, used in ancient times as independent olfactory delights, are now used only to enrich perfume compositions. Amber gives the composition a special warmth and bright illumination. Musk, in addition to the influence of its own unique smell, has the ability to ennoble, round out the smell of the composition, and give the perfume sophistication and temperament. The temperament of French perfumes is largely explained by the content in them of a large number of substances with an animal odor. In addition, by influencing the nervous system, musk and amber exacerbate sensitivity and increase the duration of perception of odors.
The role of animal odors in perfumery is so great that it is now difficult to imagine full-fledged perfumes without them; they are an indispensable component of products for scenting skin, hair or dresses.
Aromatic substances of animal origin are also valuable because they establish harmony between the smell of perfume and human skin, as if they make these smells related, serve as intermediaries between them, and make the smell of perfume as if characteristic of a person, inherent in him. In literary works, the idea is often expressed about the emotional influence of the wonderful smells of healthy, clean skin and hair, but for some reason in everyday life they are sometimes bashfully silent about this. Meanwhile, this influence must not be forgotten, since perfumes that do not harmonize with the smell of skin and hair make an unpleasant impression. Perfumers remember this well and consumers should not forget about it.
Until the beginning of the 19th century, it was believed that essential oils were a substance of homogeneous composition, more or less contaminated with some impurities. However, it turned out that this is far from true: essential oils are a combination of a large (and often very large) number of chemically individual fragrant substances, each of which has its own smell, but they are dominated by one or two substances that determine the main smell of the essential oil. At the same time, they contain small impurities with a weak odor or no odor, which play a large role, “rounding out” the odor or giving it persistence.
Even small admixtures of “pollution” change the smell of essential oil, sometimes beyond recognition.
The impetus for the development of the industrial synthesis of fragrant substances was the synthesis of vanillin. Through the work of domestic and foreign scientists, the components of many essential oils were isolated in their pure form. The study of their chemical composition began, which led to the synthesis of the main aromatic substances that determine the pleasant smell of these oils.
Currently, about 80% of synthetic fragrances are used in the perfumery, cosmetics, soap, food and other industries. The production of synthetic aromatic substances became possible only thanks to the high development of chemical science and industry. Scientists have synthesized a huge number of fragrant substances, both having analogues in nature and those not found. The production of not only aromatic substances, the synthesis of which was carried out for the first time by foreign scientists, was organized, but also completely new aromatic substances: such as tibetolide, musten, sangalidol, myrcenol and many others, making it possible to replace natural aromatic substances (for example, santhalidol largely replaces sandalwood oil) and create high quality products.
It should be taken into account that the synthesis of fragrant substances refers to a delicate, very complex chemical technology, and even minor impurities, the presence of which is sometimes impossible to determine by conventional chemical or physical methods, are easily detected by the sense of smell; and thus prevent the use of the entire product.
Of the most widely used synthetic aromatic substances in perfumery, we note only a few, indicating the basis of the smell: benzyl acetate (the smell of jasmine), vanillin (the smell of vanilla), geraniol, phenylethyl alcohol and citronellol (the smell of roses), citral (the smell of lemon), hydroxycitronellal and linalool ( the smell of lily of the valley), terpineol (the smell of lilac), heliotropin (the smell of heliotrope), yonone (the smell of violets), coumarin (the smell of hay) and many others.
It is appropriate to ask the question: can synthetic fragrances completely replace natural fragrances? No! Synthetic fragrant substances, if they are of a floral nature, determine only the main feature of the smell of plants (and even then not completely); they only resemble the smell of this or that plant substance, but this is not the smell itself. They lack that charm of smell, that color (timbre), sonority, velvety, “orchestration” of smell that is inherent in natural aromatic substances.
It is impossible to completely replace natural fragrant substances with synthetic ones: only a combination of both makes it possible to create truly complete works.
Synthetic aromatic substances deservedly occupy a very significant place in modern perfumery: without them, perfumery would, perhaps, remain mainly at the level of the Middle Ages.
All perfumes, cosmetics and toilet soaps contain synthetic fragrances. Without them, it would be impossible to obtain all the variety of high-quality products that we currently have. The word “synthetics” in this case implies not only the replacement of natural fragrant substances with artificial ones, but also the creation of substances with new odors that do not exist in nature, and new valuable properties (persistence, originality and beauty of smell). The abundance of synthetic and natural fragrant substances required, in order to facilitate and enhance the creativity of the perfumer, the search for some so-called intermediate compositions, or bases, which are a harmonious combination of fragrant substances. These bases are unfinished compositions, they play the same role as chords and melodies in music. These are separate sketches, fragments that perfumers use in their further creativity.
As we have already said, there are about five thousand names of fragrant substances in total, and the bases consist of many (mostly within ten or even more) fragrant substances. Therefore, when choosing the basis for a new scent or improving an existing one, the perfumer does not need to remember the smells of all fragrant substances and dissipate his attention.
Bases - leading or auxiliary "segments" of a smell - are independent, complete, therefore modern perfumery cannot exist without these bases.
The largest percentage of perfumery raw materials is ethyl (wine) alcohol of the highest purity. It plays the role of a solvent for aromatic substances, a refresher and a disinfectant. The alcohol strength in perfumes ranges from 96.2 to 60%, and in colognes - from 75 to 60%.
From all these fragrant substances, by harmoniously combining them, perfumers prepare compositions - complete works of perfumery art, which reach the consumer in the form of perfumes, colognes, eau de toilette and other things.
Our nose “knows how” to catch odors. They are different, some are pleasant for us, and some are very bad. How can we define what smell is? Smell is an impulse that is sent from our nose to the brain. There this information is analyzed and it happens very quickly. The nose is a special organ of perception. A small child cannot see yet, but he can recognize his mother by smell. Our ancestors used smell to find food for themselves. By smell we detect danger to ourselves, for example, a fire or the smell of gas.
Odor perception
When the molecules of a substance come into contact with the nerve endings of our nose, then we perceive a smell. The hairs that cover the mucous membrane of our nose have receptors for olfactory nerve cells. All the air we draw in through our nose passes through the upper part of the nasopharynx, where these hairs are located. But if we sniff on purpose, then we draw in the air ourselves. If a substance enters the olfactory zone, an impulse immediately goes to the brain, and the smell is assessed there. A person recognizes five types of odors:
- the one associated with flowers;
- burnt;
- specific;
- rotten;
- ethereal.
Sometimes people confuse what smell is and what taste is. When we eat, the smell of food irritates our olfactory receptors. For example, if we eat sausage and don’t smell it, then we won’t feel its taste. Therefore, food has no taste when it is cold. Because of the cold, the sense of smell is blocked, and it seems to us that food has no taste.
Doesn't smell
It often happens that we hear from people: “It doesn’t smell.” Is there anything that has no smell? Yes, I have. For example, natural gas is odorless. But in order to distinguish it from other odors, substances are added to it that have an unpleasant, pungent odor. Also, human sweat is also odorless. Only when bacteria appear in it does it begin to smell.
People cannot explain every time the reason why they like this or that smell. Scientific analyzes do not always produce results.
There is such a science as aromatherapy, with the help of which experts have developed a method for the influence of odors on the human body. Aromatherapists say that essential oils have an effect on nervous and hormonal reactions. Thus, using natural aromas, we can restore processes in the body. After all, many people know that there are smells that calm us down, and there are smells that give us vigor and efficiency.
Anyone can easily distinguish the smell of vanilla from the smell of smoked fish. And it is the aroma that contributes to the attractiveness of the dish. This is why flavors are so important to the modern food industry. A Business Petersburg correspondent visited the Chemical and Food Aromatics Plant (CPHA) and found out what the smell of chocolate is made of and why “natural” flavors are an element of marketing rather than a healthy lifestyle.
Remember the children's poem: “Every business has a special smell, the bakery smells of dough and baked goods”? Smell and taste are of particular importance for food products; they are what attract the buyer. Therefore, the modern food industry cannot do without flavorings. And from this point of view, the abstract concepts of “taste” and “smell” turn into a well-defined system of various substances that introduce a complex perception of taste and smell into products, what is called the “aroma of a food product.”
Pyrazine+vanillin=chocolate
As KPHA specialists say, any flavoring is a combination of flavoring substances (alcohols, ethers, aldehydes, etc.) and flavoring preparations (extracts, essential oils). In total, flavorings include 10-15 substances and preparations, which are divided into several groups. Key substances determine the characteristic of the flavor, additional substances enhance the characteristic of the aroma, tint substances give certain shades.
In order for the flavor to be evenly distributed throughout the food product, carrier solvents (triacentin, 1,2-propylene glycol, glycerin, etc.) are often added to them. It is thanks to solvents that the smell does not disappear instantly, thereby increasing the stability of the flavor.
Flavorists develop fragrances. It is they who select from thousands of substances those that, when combined, will form the necessary taste and aroma. When developing a flavoring agent, the flavorist focuses on the composition of the corresponding natural product, which includes up to 700 flavoring and aromatic substances. However, not all are needed to get the smell in the finished product. As mentioned above, there are key substances that create the immediately recognizable taste of a product. For example, for pear it is isoamyl acetate, for chocolate it is pyrazine and vanillin. And additional and shading substances help make the smell more specific, for example, create not just the aroma of an apple, but an apple of a certain variety, color and even ripeness. All these nuances are captured by tasters who evaluate, describe the flavor and help achieve exactly the taste that the consumer will like.
Complex technology
Most often, liquid flavorings are used in the food industry, but there are also more complex forms: powdered, emulsion, etc. Their task is to simplify the technological process of adding flavoring to a product or to create an attractive appearance by adding color or turbidity. To create such flavors, more complex equipment is used: high-pressure homogenizers, spray dryers, dispersants, etc. It makes it possible to obtain more stable flavors, simplify the application process, and create new, more interesting flavors.
Nature and chemistry
The ingredients in a flavor also vary depending on whether it is natural or not. If the flavoring is natural, then it can contain only those substances that are isolated from natural plant products without the use of chemical methods. Natural components are obtained by drying, evaporation, cooking, squeezing, filtration, etc.
Unnatural flavors contain substances obtained by chemical means. However, as noted in the KPHA, a flavoring substance obtained from natural products does not differ in composition from the same substance obtained chemically - from the point of view of safety for humans. All substances that can be used in the production of flavors are listed in the list of permitted substances in the technical regulations of the Customs Union.
The only significant difference between “natural” and “artificial” flavoring is the price, which can differ several times, the plant claims. At the same time, they say that requests for the creation of natural flavors are being received more and more often, but this is due more to the struggle for the buyer than the struggle for a healthy lifestyle.
And how many flavorings do people actually “eat” in a year? According to statistics from the European Union and the United States, an adult consumes about one ton of food products annually. At the same time, approximately 500 g of flavoring substances enter his body, but of this, only 10-20 g are flavorings, and the remaining 96% are substances naturally present in products. Considering that the composition of the substances included in flavorings does not differ from substances from natural products, it is natural to conclude that the use of flavorings in food products cannot pose a danger to human health.
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