- dor or fragrens; It is caused by one or more volatile chemical compounds, which are usually at very low concentrations, which are sensed by people and other animals by the sense of smell. Fragrances are also called essences, which express both pleasant and unpleasant odors. Fragrens and aroma terms are often used to describe fragrances in the cosmetics and food industry and are sometimes used to refer to perfumes. On the contrary, the terms fragrance, odor, smoking, and the terms of the horizon are also used to describe the undesirable odors, sometimes the term funk can also be used to identify unwanted odors. In the United States, the term odor has more negative meanings such as odor, bad odor, or smoking, such that the essence or aroma terms are used for pleasant odors.
Basic knowledgeFeeling of smell; it enables the detection of odors through the olfactory nerves. Olfactory receptor (OR) cells are neurons that are present on the olfactory epithelium, a small piece of tissue in the posterior part of the nasal cavity. There are olfactory receptor neurons in millions acting as sensory signal cells. Each neuron has a cilia in direct contact with air. The olfactory nerves are considered to be the odor mediator, while the axon connects the brain to the outside air. Fragrant molecules act as a chemical stimulant. Molecules initiate an electrical signal to bind to the receptor proteins exiting the silica.The primary sequences of thousands of olfactory receptors are known from the genomes of more than a dozen organisms: there are seven-helical transmembrane proteins, but there is no known structure of any OR (as of July 2011). In the tripodal metal ion-binding area there is a series of high levels of protection in roughly three quarters of all ORs and Suslick; He suggested that ORs are in fact metalloproteins (probably zinc, copper and possibly manganese ions) that act as a Lewis Acid site for the binding of many fragrance molecules. Earlier in 1978 Crabtree; He suggested that Cu (I) is the düzenleyici most likely candidate for a metallo-receptor site for odor “for strong odorous volatiles, which are good metal-regulatory ligands such as thiols. In 2012, Zhuang, Matsunami and Block confirmed the Crabtree / Suslick recommendation for a specific case of MOR244-3, a mouse OR önemli, indicating that copper is important for the identification of certain thiols and other sulfur containing compounds. Thus, due to the fact that copper was not used by the receptors, the authors used a chemical that binds copper in the mouse nose, indicating that the mice did not detect thiols. However, these authors also found that MOR244-3 lacked a specific metal ion binding domain proposed by Suslick rather than showing a different motif in the EC2 domain.
When the signal reaches the threshold level, the neuron comes alive by sending a signal that moves along the olfactory bulb axon, which is part of the brain’s limbic system. The interpretation of odor begins by associating the fragrance with past experiences and the substance (s) absorbed. The olfactory bulb acts as a transport station by connecting the nose to the olfactory cortex in the brain. The olfactory information is then processed and reflected via a pathway to the central nervous system (CNS) which controls emotions and behaviors along with basic thinking processes.
Odor sensation is usually based on the available concentration of olfactory receptors (number of molecules). A single fragrance stimulant type is typically identified by multiple receptors, and different fragrances are identified by combinations of neuron signals patterns and receptors that aid in the identification of fragrance. The olfactory system interprets the entire fragrance mixture, not a single compound, which is not related to the concentration or density of a single component.
The widest odor range; contains organic compounds; certain carbon-free compounds such as hydrogen sulfide and ammonia are also fragrances. Detection of an odor effect is a two-stage process. The first is the physiological part in which the stimulus determination by the receptors in the nose is involved. Stimuli are operated by the part of the human brain responsible for the inflammation. Therefore, it is not possible to measure the smell objectively and analytically. The sense of smell is completely personal, so that individual reactions are associated with gender, age, health, and personal history.
The smells that people are accustomed to, such as their own body odors, are less perceived by individuals than from outside or other unusual odors. This is caused by habits; The smell is quickly lost after exposure to the continuous odor, but is immediately recovered after the stimulus is lost.
Habits; Separate odors after continuous exposure
affect the ability to t. The sensitivity and ability to distinguish odors disappear with exposure, and the brain tends to ignore continuous stimuli and focus on differences and change a certain odor sensation. When the odorants are mixed, the conditioned odor agent is blocked for habit. This is based on the strength of the fragrance substances in the mixture, which can alter the detection and processing of a fragrance. This process; This helps to balance the sensitivity of the complex stimuli and to classify similar odors.
Fragrance process for many inexperienced people; provides a small amount of information about specific components of a fragrance. Odor perceptions mainly reveal information about the emotional effect. But odor chemists and perfumers can even distinguish the chemicals in complex mixtures by simply smelling them.
Odor detection is a fundamental sensation. Feeling of smell; It can be found in the subconscious, warning of danger, finding nutrients or recognizing predators. People have an astonishingly good sense of smell, blinded by the evolutionary decline in the sense of smell (albeit only 350 genes in mice compared to 1,300 functional olfactory receptor genes). A person’s noteworthy sense of smell is as good as many animals, and they can distinguish odors from about 10,000 essences. Bushdid et al. Reported that people could distinguish as many as a trillion odors. The reason is the retro nasal pathway in humans to enhance the sensation. However, animals such as dogs, especially those using short chain components, exhibit more fragrance sensitivity than humans. Higher cognitive brain mechanisms and more olfactory brain regions; allows people to distinguish better odor from other mammals, despite less olfactory receptor genes.
Amongst others, different categorization of primary odors based on seven basic odors has been proposed: (with examples)
Scented – perfume / shaved lotion
Putrid – decayed eggs
Sharp – vinegar
Etersi – dry cleaning liquid
Floral – Rose
Peppermint chewing gum
Although there have been recent advances, the notion of basic feelings and therefore the concept of primary odors is controversial.
The ability to identify odors varies among people and decreases in proportion to age. The studies show that there are differences between sexes in distinguishing odors; women are generally better than men. In pregnant women, fragrance sensitivity increases with unusual tastes and odor sensations, sometimes resulting in extravagance or disgust. Odor deficiencies also increase with age as the prevalence of taste problems (smell of smell tends to dominate the sense of taste). Chronic odor problems; In the second decade of life, the number of people in their mid-twenties has been reported to be low, with steadily increasing numbers starting with the general tenderness that has started to diminish, and then they begin to deteriorate significantly after the 70s.
In Germany; Since the 1870s, the concentrations of fragrances have been defined by a device called ine Olfaktometrie “which helps to analyze the olfactory sensation of people using the following parameters: concentration, odor density and hedonic evaluation of fragrance.
To determine odor concentration, an olfactometer test that uses the human nose panel as sensors is used. Olfactometer test procedure; A group of participants in a natural fragrant environment is lathered with an odorous mixture (separately as a reference) to a odorous mixture which is separately diluted from the deodorizing channels. The panel participants were asked to compare the gases emitted from each sniffing channel after they were asked to report the presence of fragrance with confidence levels such as estimation, detection or accuracy of their assessments. The gas-dilution rate was then reduced by two times (ie, the chemical concentration was doubled). The panel participants were asked to repeat their decisions. This continued until the number of dilution levels. The responses of the panel participants in the range of dilution settings were used to calculate the odor concentration in terms of European Odor Units (ouE / m³). The main panel calibration gas used is butan-1-ol, which gives 1 ouE / m³ at a certain dilution.
Analytical methods; physical, gas chromatography and chemical sensory methods.
When measuring odor, there is a difference between emission and imission measurements. Emission measurement; olfactometry using an olfactometer to dilute the odor sample. On the other hand, the olfactometry method; rudiment
n is used. The same measurement principles are used, but the determination of the amount of air is carried out without diluting the samples.
Odor management is important for regulating and controlling odor. An odor emission usually involves a complex mixture of many fragrance compounds. Analytical display of the independent chemical compounds present in such a fragrance is generally not practical. Consequently, sensory odor methods are normally used instead of instrumental methods to measure such odors. Sensory odor methods enable the monitoring of odor from the source emissions or from the air in the environment. These two different conditions require different approaches to measuring odor. Collection of odor samples is carried out more easily for a source emission than an odor present in the ambient air.
Area measurement with portable olfactometers seems to be more effective, but the use of Field Olfactometers; Although popular in the US and Canada, it has not yet been licensed in Europe so many States; the dilution-threshold value (D / T) unit as defined by the unit along the perimeter of the odor absorbing facilities or in the receptor areas.
Different odor factors; or by quantitative methods such as assessing concentration or apparent density.
Entering a room for the first time reveals the most accurate sense of smell before the habit begins to change the sense of smell.
Feeling of smell; it has 4 characteristics with respect to threshold and tolerance: odor concentration, odor density, quality of odor and hedonic tone.
The odor concentration is the state of smell at all times. To quantify the smell, a smell is diluted in certain amounts to achieve the detection or recognition threshold. The detection threshold is the odor concentration in the air when 50% of a population can distinguish odorous samples with an odorless sample. Recognition threshold; is the concentration of odor in the air when 50% of a population can distinguish an odorless sample with an odorous sample. The odor recognition threshold is usually 2-5 times higher than the detection threshold.
Measurement of odor concentration is the most commonly used method for quantifying odors. CEN EN 13725: 2003 has been standardized. Method; it is based on dilution of a odor sample to the odor threshold (where the odor is detectable by 50% of the test panel only). The numerical value of odor concentration; equal to the dilution factor required to reach the odor threshold. The unit is European Fragrance Unit, OUE. Hence, the odor concentration at the odor threshold is 1 OUE by definition.
An olfactometer was used for a group of panel participants to determine the odor concentration. A diluted odor mixture and odorless gas (as a reference) were given to the panel participants through the odor channels. In order to compare the odor given from each channel, the panel participants were asked whether they could determine the difference between the channels. The rate of gas-dilution was then reduced by 1.4 or two (ie, the concentration was increased in direct proportion). The panel participants were asked to repeat their decisions. This continued until the panel responders answered correctly and correctly twice in a row. These responses were used to calculate odor concentration with European Odor Units (OUE / m3).
Testers must meet certain requirements, eg those relating to sensing sensitivities. The main panel calibration gas used to verify this requirement is b-butanol (1 OUE / m3 kal40 ppb / v n-butanol).
To collect a fragrance sample, samples are collected using special sample bags made of an odorless material, such as Teflon. The most recognized technique for collecting odor samples is the lung technique, in which the sample bag is placed in an insulated barrel and the vacuum is placed on the barrel as the bag expands, filling the sample bag, and the sample is drawn from the bag to the source. All components that are critically contacted with odor samples should be odorless, including sample lines and assemblies.
The odor-determining threshold of a person is variable. Repeated exposure to a fragrance substance results in improved olfactory sensitivity and reduction of the detection threshold for different fragrances. In one study, it was seen that people who never identified androstenon smell could identify after repeated exposure.
People can distinguish between two fragrances with a concentration difference of as low as 7%.
There are issues to be overcome by sampling, which include: – If the source is under vacuum – if the source is at high temperature – if the source has high humidity
Pre-dilution or dynamic dilution techniques in subjects such as temperature and humidity
can be overcome using.
Odor density is the perceived force of fragrance sensitivity. This density characteristic is used to determine the source of odors and perhaps to directly disturb annoying odors.
The perceived force of odor sensitivity is measured together with the odor concentration. Weber-Fechner’s Law: I = a * log (c) + b .
I is the perceived physiological density in the butanol scale during the dilution step, a is the Weber-Fechner coefficient, C is the chemical concentration and b is the intersection constant (0.5 by definition)
Odor density; is defined using the odor density scale, which is the verbal description of the odor sensitivity in which a numerical value is assigned.
Odor density can be divided into the following categories based on density:
0 – odorless
1 – very weak (odor threshold)
2 – weak
3 – prominent
4 – strong
5 – very strong
6 – irresistible
This method is carried out in the laboratory and is carried out by observers / panel participants who are trained to properly define the intensity.
Hedonic tone assessment
Hedonic evaluation fragrances are a very pleasant process of grading that starts at the very beginning of the runway. It is important to note that the density and hedonic tone, although similar, indicate different states. In other words, it means the strength (density) of the fragrance and the sweetness of the fragrance (hedonic tone). Detecting a smell; the increased concentration, intensity, duration, frequency and past experience of a specific odor may vary from pleasant to unpleasant, as all factors determine a response.
The whole quality set can sometimes be defined as ası FIDOL factors Location (Frequency, Intensity, Duration, Offense and Location).
The character of a scent is a critical factor in the evaluation of odor. This feature; it is the ability to distinguish different odors and is only descriptive. First, a basic description is used such as sweet, sharp, flavored, hot, dry or bitter. Then the smell; a source, such as a waste or an apple, with reference to a specific chemical such as acids or gasoline.
More commonly, a set of standard descriptors that can vary in the aroma and waste odor range is used. Although the method is quite simple, it is important to understand the FIDOl factors by the person recording the character. This method is most commonly used to identify the odor character that can then be compared to other odors. It is common for olfactometry laboratories to report the character as an additional factor after sample analysis.
Interpretation of dispersion modeling
In many countries, odor modeling is used to determine the magnitude of the effect in an odor source. These; The modeled concentration is a function of the mean duration (the time during which the model steps are repeated (typically hourly)) and the percentage slice. The percentages are related to the number of hours a statistical representation is made per year, and the concentration of C can be exceeded by the mean time.
Sampling from field sources
There are two basic odor sampling techniques, direct odor sampling and indirect route odor sampling technique. The indirect pathway refers to the collection of samples from the air flow through the emitted surface.
The term direct; refers to the placement of a box over or through the emitter surface from which the samples are collected, and an odor emission rate is determined.
The most commonly used direct methods are wind tunnels containing the Fluks Reservoir and the UNSW Wind tunnel. There are many other techniques and some factors need to be considered before selecting the appropriate method.
A source with implications for this method; sources such as bark bed biofilter with vertical velocity component. For such resources, the most appropriate method should be considered. A common technique is to measure the odor concentration at the emitted surface and to combine this with the volumetric flow rate of the air inlet to the biofilter, which constitutes the emission rate.
Indirect sampling is usually referred to as back-calculation. It includes the use of a mathematical formula for predicting an emission rate.
Many methods are used, but they all use the same inputs, such as surface roughness, arrival and departure concentrations of wind, stability class (or a different similar factor), wind speed and direction.
Man’s sense of smell is the main factor in the feeling of comfort. As a sensory system, olfactory exposes awareness of the presence of airborne chemicals. Some chemicals inhaled; They act as stimulants and are volatile compounds that trigger unwanted reactions such as nose, eye and throat irritation. Perception of odor and irritation is individual and recalling past experiences of exposure to similar chemicals or physical conditions
differs from the result. The specific threshold of a person prior to the odor; it also becomes an inconvenience based on frequency, concentration, odor time.
The perception of irritation from the smell of smell is difficult to investigate because exposure to a volatile chemical reveals a different response based on sensory and physiological signals and interpretation of experience, expectations, personality or status factors. Volatile organic compounds (VOCs); Due to the limited infiltration of fresh air compared to the external environment, they may be present in higher concentrations in confined indoor spaces and may result in higher potentials for toxic health exposures due to various chemical compounds. Health effects of odor; The fragrance is determined by the substance itself or by the sense of smell. Health effects and symptoms; the eye, nose or throat irritation, coughing, chest compression, dizziness, and mood swings may vary, and all of those indicated decrease as the odor disappears. Fragrances can also trigger diseases such as asthma, depression, stress-induced diseases, or hypersensitivity. Study skills may decrease and other social / behavioral changes may occur.
Residents; they should wait for improvement to be carried out against unexpected and disturbing odors that affect concentration, destroy productivity, cause symptoms and often increase hatred for a particular environment. It is important to determine the exposure limits (OELs) during the mission to ensure the health and safety of workers, together with the convenience of exposure to chemicals; may cause biochemical and physiological changes in the upper respiratory tract. When exposure is not reported, standards can be difficult to determine and measurement can be difficult. In labor force populations; levels of discomfort to odors due to exposure history or habits may vary and may not be aware of the potential risks of exposure to chemicals that produce specific odors.