Olfactometric Methods Research Articles

Exploring the Efficacy of Four Essential Oils as Potential Insecticides against Thrips flavus

Plant essential oils are important alternatives in green integrated pest management. This study examined the chemical composition, bioactivity, and control efficacy of four Lamiaceae essential oils (EOs) against Thrips flavus Schrank in laboratory conditions with the goal of exploiting plant-derived insecticides to control Thrips flavus. The four EOs tested were marjoram oil (Origanum majorana L.), clary sage oil (Salvia sclarea L.), perilla leaf oil (Perilla frutescens (L.) Britt.), and spearmint oil (Mentha spicata L.). All these EOs exhibited a certain degree of insecticidal activity against Thrips flavus. The median lethal concentration (LC50) was determined after treatment by the leaf-dipping method in laboratory bioassays, and its values were 0.41 mg/mL for marjoram oil, 0.42 mg/mL for clary sage oil, 0.43 mg/mL for perilla leaf oil, and 0.54 mg/mL for spearmint oil. In the pot experiment, the number of dead insects was recorded at 1, 3, and 7 days post-application, and the control efficacy of EOs against Thrips flavus was calculated. The concentration of 900.00 g a.i.·hm−2 of spearmint oil was 100% lethal against Thrips flavus after treating potted plants for seven days. The Y-tube olfactometer method was used to test for the attraction or repellent response of EOs against Thrips flavus. The spearmint oil significantly attracted female adults in the olfactory test. Furthermore, gas chromatography–mass spectrometry (GC–MS) was used to examine the chemical composition of the EOs. Linalool (24.52%), isopropyl myristate (28.74%), (+)-limonene (32.44%), and (+)-carvone (70.3%) were their primary ingredients. The findings suggest that all four EOs are highly effective against Thrips flavus and may be a possible alternative in the management of Thrips flavus, especially when considering reducing the use of synthetic pesticides.

Study of geotropism versus hydrotropism in green bean radicles (Vigna radiata L.) by Oblique Olfactometer method

Plants respond to external stimuli which often involve constant movement of the plant. The movement of plant organs in response to external stimuli is responsible for the production of energy sources. Research on the nature of the radicle tropics aims to find out whether the roots actually grow downwards due to geotropism or hydrotropism. The mung bean species (Vigna radiata L.) is used because the germination process of this species does not require a long time and the seeds of this species are suitable for growing on olfactometer planting media and are suitable for growing in the climatic and geographical conditions in Indonesia. The method chosen in this research is the tilted olfactometer method, which is a planting method carried out using an aquarium hose and olfactometer connector which is tilted 30 degrees because this research aims to see the direction of growth of the radicles of mung beans (Vigna radiata L.) so this method was chosen; because the seeds can be positioned in the three-pronged olfactometer at an angle so that the final growth results can be distinguished between the tendency of the geotropism factor or the hydrotropism factor. It is proved that radicles tips would growth upward to wet cotton, against the geotropic effect.

Assessment of environmental odor pollution using a dispersion model in an industrialized urban area of Kocaeli, Turkey

AbstractThe main goal of the present study was to highlight how crucial odor evaluation methods may be for raising the general standard of living in a region. For this, the dispersion of odor concentrations detected by an olfactometric method in an area of Kocaeli, Turkey, where odor problems are frequently experienced, was investigated using the AERMOD atmospheric dispersion modeling system. According to the findings of the olfactometric measurement, the mean odor concentrations in the industrial area was high at 1342 OU m–3, while in the residential areas the values were lower, at 578 OU m–3 within the selected study area. As a result of the modeling study, the maximum odor concentration was 2081 OU m–3 at the 1 h. The model also showed that the coordinate points where the maximum odor concentration was observed changed with time, and that the concentrations recorded at the 1 h may decrease by as much as 88%–91% at the 24 h. In the study, a survey was also conducted to identify possible effects of odor pollution on people. The survey findings showed a statistically significant difference (p < 0.05) between the two areas (industrial and residential) for seven variables of a total 28. We suggest that measuring odor concentrations, modeling their distribution, and conducting surveys are effective methods when managing the urban planning process.

Research on air pollutants and odour emissions from paving hot-mix asphalt with end-of-life tyre rubber

This article discusses different types of pollution from the paving process and the influence of using hot mix asphalt without and including end-of-life tyre rubber. This new composition type is one of the possible solutions to reduce the amount of used transport tyres and a new way to use less valuable raw materials. The research carried out involved analyzers applied under conditions of a mobile laboratory and handheld particle counters. Odour samples were taken using a vacuum chamber in Tedlar containers, and the level of odours was analyzed adopting the olfactometric method. Exposure to gaseous carbon, nitrogen and sulphur oxides and particulate matter up to 10 µm, fractions from 0.3 µm to 10 µm, as well as the odours emitted that cover the soil surface with the hot-mix asphalt-rubber mixture was examined. The average decrease in pollution using the asphalt-rubber mixture is about 3.8–4 % of nitrogen oxides, 10 % of particulate matter of 1.5–10, and an increase is approximately 9 % for particulate matter of 0.8–1 µm and 15 % for sulphur dioxide. The level of odour of compacted asphalt is around 2.8times lower than that in the case of level asphalt.

Treatment of Olfactory Disorders After SARS - CoViD 2 Virus Infection.

The benefit of a nasal corticosteroid in the treatment of persistent post-infectious smell disorders is not as clear in previous studies as is assumed for olfactory training. This study would therefore like to describe the treatment strategies using the example of a persistent olfactory dysfunction as a result of a proven infection with SARS-CoViD-2-virus. Twenty patients (average age of 33.9 ± 11.9years) with hyposmia were included in this study from December 2020 to July 2021. Every second patient received additionally a nasal corticosteroid. The two resulting randomized groups of equal size were screened with the TDI test, a 20-item taste powder test for the assessment of retronasal olfaction and otorhinolaryngological examination. The patients were asked to train twice daily using a standardized odor training kit and followed up after 2months and 3months, respectively. We documented a significant overall improvement in olfactory ability over the investigation period in both groups. While the TDI score steadily increased on average under the combination therapy, the rise under olfactory training alone was initially steeper. This short-term interaction effect over mean two months was not statistically significant. According to Cohen, however, a moderate effect (eta2 = 0.055, Cohen`s d = 0.5) can still be assumed. This effect could be explained by a possibly higher compliance at the beginning of the sole olfactory training due to the lack of further drug treatment offers. When the training intensity decreases, the recovery of the sense of smell stagnates. Adjunctive therapy ultimately outweighs this short-term benefit. The results reinforce the recommendation of early and consistent olfactory training on patients with dysosmia due to COVID-19. For continuous improvement of the sense of smell, an accompanying topical treatment seems at least to be worth consideration. The results should be optimized with larger cohorts and using new objective olfactometric methods.

Evaluation of bioscrubber and biofilter technologies treating wastewater foul air by a new approach of using odor character, odor intensity, and chemical analyses

The treatment of raw foul air that could escape to the atmosphere from the head space of the incoming wastewater into a Southern California Water Resource Recovery Facility was evaluated by using a 1/20th scale pilot unit consisting of five different biological media technologies, operating side by side, under different operating conditions. The removal of six different odor characters from eight chemical odorants present in the foul air were assessed. These were rotten egg (Hydrogen Sulfide), rotten vegetables (Methyl Mercaptan), canned corn (Dimethyl Sulfide), rotten garlic (Dimethyl Disulfide), earthy/musty (2-Methyl Isoborneol and 2-Isopropyl 3-Methyl Pyrazine) and fecal (Skatole and Indole). This is the first time a study evaluates specific odors by simultaneously employing sensory analyses using the Odor Profile Method, which defines the different odor characters and intensities, together with chemical analyses of the compounds causing these odors, known as odorants.The paper discusses the efficiencies in removing odor characters as well as odorants by two different bioscrubbers (reticulated polyurethane cube foam and polypropylene mesh with layered polyester foam) and three different biofilters (engineered media, seashells, and lava rock).The results show that the two bioscrubbers, even with greater empty bed gas retention times, did not provide significant improvement in odor intensity and odorant removal. However, the biofilters showed that larger empty bed gas retention times provided significant improvements in diminishing the odor intensities and better odorant removal.The biofilter with lava rock media at 45 s empty bed gas retention time provided the best treatment among the technologies tested, achieving the following odorant reductions: 99.8% for hydrogen sulfide, 98.4% for methyl mercaptan, 57.0% for dimethyl sulfide, and 52.7 for dimethyl disulfide. This biofilter also achieved the following odor intensity reductions: 47% for rotten vegetable odors, 50% for earthy/musty odors, and 100% for fecal odors. The odor panel detected odors by the Odor Profile Method that were below the detection limit of the corresponding chemical analytical method for specific chemical compounds causing these odors.Differences were observed between the performances of bioscrubbers and biofilters, based on odorant removal compared to those based on sensorial analyses, indicating that both analyses are required to understand more fully the odor dynamics. Furthermore, a total odor removal of 99.2% was observed by the dilution to threshold olfactometer method even though nearly half of the rotten vegetable and earthy/musty odors remained based upon the Odor Profile Method. This shows the olfactometer method did not correctly define the degree of odor nuisance in the foul air in this study.Bioscrubbers have in general a better economic return when used at low EBGRTs and as preliminary (first stage) treatment systems. Biofilters are more effective when used at high EBGRTs and can be used as stand-alone or polishing systems.

Ergonomic and Olfactometric Assessment of Anti-Odour Filtering Half-Masks under Real-Life Workplace Conditions

The presence of vapours and gases of chemical compounds in the atmospheric air contributes to mental discomfort as well as irritation of the respiratory tract and eyes. The technical solutions applied, such as collective protection measures, namely the encapsulation of processes or local ventilation equipped with appropriate air filters, are often insufficient. In such a case, respiratory protective equipment (RPE) is the basic and, in many cases, the only technical means that protects humans against the harmful effects of this type of harmful substance. The study evaluated the ergonomic and anti-odour properties of a novel filtering half-mask model with an oxygen indicator in functional workplace tests. In addition, the subjective anti-odour assessment results from functional tests were statistically compared with the results of olfactometric tests. The differences identified are attributable to the fact that the olfactometric method excludes subjects with olfactory impairments. Moreover, statistical analysis indicated significant differences in anti-odour properties between a reference half-mask and the filtering half-mask model with a nonwoven adsorbent layer (91% odour reduction). The filtering half-mask developed was found to provide high and very high levels of user comfort and exhibited excellent protective and functional properties, with a filtration performance of 96% and breathing resistance of 147 Pa. Those parameters qualify the filtering half-mask presented for protection class FFP2. In addition, the half-mask effectively absorbed the vapours of malodorous substances up to 3 h and displayed oxygen concentration in the breathing zone. It should be noted that currently no such device is commercially available either in Poland or in the European Union.

Evaluation of Inoculated Waste Biological Stabilization Degree by Olfactometric Methods

As a result of compounds’ transformation in the waste biostabilization phases, there is an increase in odor nuisance and health problems among people exposed to odorants. Linking the odor concentration to the degree of waste biostabilization may be an important tool for the assessment of individual technological variants of biostabilization. The study aimed to link the odor emissions to the biostabilization degree in individual process variants that differed in the inoculum. The tests were carried out on inoculated windrows on the waste mechanical-bological treatment open site. Odor concentrations were measured during the entire seven-week process of biostabilization (weeks 1–7) and compared with kinetics parameters of organic compounds’ decomposition. The olfactometric tests showed the necessity of using the preparation to reduce the value of odor concentration. Research proved that the decrease of odor concentration values could be useful to indicate the particular phases of biostabilization. Also, the proposed method provides an opportunity to optimize the process concerning the function related to the low degree of odor nuisance of the technologies, including selection of environmentally safe inoculum. This issue has application values that may result in the implementation of new control systems for waste stabilization bioreactors and the evaluation of applied technological solutions.

Role of gas chromatography and olfactometry to understand the wine aroma: Achievements denoted by multidimensional analysis.

The human nose has been used as a detector in gas chromatography analysis to evaluate odoriferous compounds related to aroma and quality of wine. Several olfactometric techniques are available to access the description, intensity, and/or duration of the odor of each compound. Olfactometry can be associated with one-dimensional gas chromatography or multidimensional gas chromatography, including heart-cut gas chromatography and comprehensive two-dimensional gas chromatography. Multidimensional gas chromatography may help to resolve coeluted compounds and detect important trace components for the aroma. The identification of odor-active compounds may help to differentiate wines according to terroir, grapes cultivars used in winemaking or types of aging, understand the role of fungal infection of grapes for wine quality, find the best management practices in vineyard and vinification to obtain the greatest quality. In addition, when the instrumental techniques are combined with sensory analysis, even more accurate information may be obtained regarding the overall wine aroma. This review discloses the state of the art of olfactometric methods and the analytical techniques used to investigate odor-active compounds such as one-dimensional gas chromatography, multidimensional gas chromatography, and comprehensive two-dimensional gas chromatography. The advances in knowledge of wine aroma achieved with the use of these techniques in the target and profiling approaches were also discussed.

INHIBITORY ACTIVITY, REDUCING LOSS AND REPULSIVE OF METHANOLIC EXTRACTS FROM SHEETS OF PLECTRANTHUS GLANDULOSUS AGAINST SITOPHILUS ZEAMAIS

The extracts of the leaves of Plectranthus glandulosus were evaluated on population growth, the losses caused to the seeds by Sitophilus zeamais and their repulsive effect were also tested. The reference insecticide Delvap Super® (Dichlorvos 1%, Cypermethrin 0.36% [PI]) was applied as a positive control at the recommended dose (0.1 g / kg), while the extracts were used at four different doses (5, 10, 20 and 40 g / kg). The growth rate of S. zeamais and the losses caused to the seeds were recorded. The methanolic extracts of the leaves of P. glandulosus significantly reduced the growth of of S. zeamais from 61.67 to 100% and the losses from 84.12 to 100% comparable to the inhibitory and reducing effect of the losses of Delvap Super® 100% saved with its recommended dose. The maximum repulsion rate (83.33%) for S. zeamais was recorded with the highest dose (40 g / kg) after 2 hours of exposure by the olfactometer method. In view of these results, we could affirm that these extracts could be recommended as alternatives to synthetic insecticides against S. zeamais in storage.

Synthesis and application of natural sorbents with silver nanoparticles in reducing the emission of odours

Abstract The paper concerns the applicability of silver nanoparticles for reducing the emission of odours. Silver nanoparticles were successfully adsorbed on three different dolomitic limestone samples. In the next stage, wastewater from the meat industry was mixed with sorbents modified with a variable content of silver nanoparticles. After 4 days and 7 days, the concentration of ammonia was examined spectrophotometrically. Also, the degree of reduction of total odour concentration by olfactometric method was carried out. Depending on the concentration of the silver nanoparticles on the sorbents, the concentration of ammonia was 15-42 μg/cm3 for nAg content equal to 0.08%, while for sorbents containing approximately 36% of nAg the concentration of ammonia was 0.09-16 μg/cm3. A leaching test of nanosilver from sorbents confirmed that the particles were bound with the sorbents by strong bonds. The percentage of eluted silver increased from 0.67% to 11%, with increased initial concentrations of nAg on the sorbents from 0.18% to 0.37%.

Screening barrier plants to reduce crop attack by sweet potato weevil (Cylas formicarius).

Sweet potato weevil, Cylas formicarius (Fabricius) attacks stems and storage roots of sweet potato, Ipomoea batatas, and is a major pest of this globally significant crop. To minimize the immigration of weevils into sweet potato fields from nearby donor habitat, we assessed scope for a barrier plant approach. Here, we report a novel, two-stage, multiple choice olfactometer method to screen candidate barrier plant species and a field study of the effects of shortlisted barrier plants of weevil movement and plant damage. Initial work established that a combination of sweet potato foliage and storage root was significantly more attractive to adult C. formicarius than either tissue alone in the distal chamber of choice arms. Among 15 candidate barrier plant species in intermediate chambers in arms, spring onion, oregano, chilli, basil, sweetcorn, fennel, lime mint and lemongrass significantly reduced passage of C. formicarius. Of these, sweetcorn and lime mint significantly reduced the numbers of oviposition holes in sweet potato storage roots. A field study showed that basil and chives were effective barrier plants for reducing weevil damage to sweet potato storage roots. Our method has utility for screening additional candidate plants, and suggests that weevil dispersal and subsequent oviposition are affected by passage through some plants, suggesting scope for barrier plants to contribute to the management of this major pest. © 2019 Society of Chemical Industry.

Use of Biochar-peat Mixture to Reduce Odour from Animal Farms

Abstract. Odour from agriculture causes local nuisance to the neighborhood. Litter and cover materials can be used in animal housing and in storage of manure to reduce the odour problem. The use of biochar as a covering for animal manures is a new innovation and enhances the possibility to minimize the emissions from animal farms. (Research purpose) To study the possibility of using a mixture of biochar and peat as a manure covering, in order to reduce the intensity of odor on livestock farms. (Materials and methods) The potential of a mixture of biochar and peat for the odour control was tested in a laboratory study. A 10 cm layer of fresh mink manure was placed on the bottom of a 5 liter test bucket and the manure was covered with biochar-peat mixture (mixed in 50/50 ratio by volume) using five different covering thicknesses. Uncovered manure was used as a reference. The odour emission was measured with an olfactometric method that is based on odour sensation of a person. Also the character of the odour was described. (Results and discussion) The results show that a biochar-peat covering of at least 3 cm is able to considerably reduce the odour from the manure. The character of the odour was at first peat-like for all covered buckets but with thin coverings it was changed to more manure-like after 2 days. The odour from buckets with thicker covers remained peat-like during the whole testing period. (Conclusion) It is recommended to apply a biochar-peat covering to neutralize ammonia and the unpleasant manure odour on livestock farms. The author has shown that the frequency of use and the thickness of a covering layer depend on the ambient temperature; therefore, it is not necessary to cover manure in winter.

Analysis of Odour Interactions in Model Gas Mixtures using Electronic Nose and Fuzzy Logic

Measurement and monitoring of air quality in terms of odour nuisance is an important problem. Although the source of these nuisances is different (e.g. wastewater treatment plants, municipal landfills), their common feature is that they are a complex mixture of odorants with different odour thresholds. An additional problem is occurrence of the odour interactions between mixture components. From a practical point of view, it would be most valuable to directly link the odour intensity with the results of analytical air monitoring. This would allow the on-line odour monitoring using electronic noses, which perform a holistic analysis of the gas mixtures composition (like olfactometric methods). The paper presents the possibility of application of fuzzy logic to determine the odour intensity and indicate odour interactions in model, five-component gas mixtures (acetone, a-pinene, formaldehyde, toluene and triethylamine) using electronic nose prototype. As the results of the studies, it was found the electronic nose prototype along with the fuzzy logic pattern recognition system can be successfully used for this application. The results obtained using fuzzy logic are consistent with sensory analysis results in 80%.

Critical comparison of selected olfactometric methods for the determination of impact odorants. Proposal of a new representation of olfactometric results

AbstractRepresentation of olfactory data is a key parameter in GC‐O to simplify interpretation. Actual presentation of hybrid results, taking into account both detection frequency and odor intensity, can be improved to be more informative. We propose in this study a new way of representing olfactograms taking into account the three dimensions: detection frequency, odor intensity and odor description using bubble charts. Odor description is represented by colors that were associated to the 25 olfactory families defined in this work using binomial probability statistics without any smelling step.

Impact of processing on odour-active compounds of a mixed tomato-onion puree.

Gas chromatography-olfactometry revealed thirty-two odour-active compounds in a heat-processed tomato-onion puree, among which twenty-seven were identified by gas chromatography-olfactometry-mass spectrometry (GC-O-MS) and comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOF MS). Based on the results of two olfactometric methods, i.e. detection frequency and aroma extract dilution analysis, the most potent aroma components include: dipropyl disulfide, S-propyl thioacetate, dimethyl trisulfide, 1-octen-3-one, methional, dipropyl trisulfide, 4,5-dimethylthiazole, 2-phenylacetaldehyde and sotolone. Processing of mixed vegetable systems can add complexity in their aroma profiles due to (bio)chemical interactions between the components. Therefore, the impact of different processing steps (i.e. thermal blanching, all-in-one and split-stream processes) on the volatile profile and aroma of a mixed tomato-onion puree has been investigated using a GC-MS fingerprinting approach. Results showed the potential to control the aroma in a mixed tomato-onion system through process-induced enzymatic modulations for producing tomato-onion food products with distinct aroma characteristics.

Chemical Mass Balance model applied to an olfactory annoyance problematic.

The source-receptor model Chemical Mass Balance (CMB) generally used for air pollution studies is applied for the first time to solve odor signature issues. The olfactory annoyance perceived at a receptor site of an industrial area is often the result of a combination of different smells, emitted by several industrial sources. To identify the main responsible for the inconvenience, tools able to determine the contribution of each source directly where the annoyance is perceived are widely developed and deployed. In this work, the contributions of volatile organic compound sources, coming from a waste treatment plant containing three potential sources of olfactory annoyance (waste storage, production of biogas, and compost piles of green wastes) and perceived at a village located downwind, are studied by chemical analyses. The CMB methodology is applied, and the results are finally compared to olfactometric methods, in order to validate whether it is appropriate to use this model for olfactory problems or not.

OLFAKTOMETRICKÉ ZAŤAŽENIE OVZDUŠIA

This paper describes the olfactometric assessment of volatile organic compounds emitted by coating films.It describes the measurements of concentration, intensity, hedonic tone and character of odor caused by emissions of volatile organic compounds. VOCs’ emitted in to the small-space chamber with capacity of 1 m3 were tested by dynamic olfactometric method. Paper also contains a comparison of olfactometric air pollution of two different types of coating films. The work is aimed to determine the relationships and dependencies between the measured values of volatile organic compounds obtained by the gas chromatography and reported sensation.

APPLICATION OF CHEMICAL MASS BALANCE METHODOLOGY TO IDENTIFY THE DIFFERENT SOURCES RESPONSIBLE FOR THE OLFACTORY ANNOYANCE AT A RECEPTOR-SITE

The olfactory annoyance perceived at a receptor site of an industrial area is often the result of a combination of different smells, emitted by several industrial sources. The major issue in the case of complaints is to identify the main responsible of such pollution. For this purpose, tools able to determine the contribution of each source directly where the annoyance is perceived would simplify this identification. In this work, we use the source-receptor model CMB (Chemical Mass Balance) generally used for air pollution studies, by applying it for the first time to odour signatures. The contributions of VOC sources, coming from a waste treatment plant containing 3 potential sources of olfactory annoyance (waste storage, production of biogas, and compost piles of green wastes), and perceived at a village located downwind, are studied by chemical analyses and finally compared to olfactometric methods.

Approaches to regulation of odours in the ambient air at the territory of the Russian federation based on olfactometric odour measurements relating to industrial emissions

This work presents results of odour concentration measurements performed by an olfactometric method in respect to industrial emissions, which are the source of offensive odour substances released into atmosphere. Moreover, this work also includes the measured odour concentrations at major sources of a wastewater treatment plant, as well as at heat and power plants. Related measurements were performed in the course of technological operations regarding fuel oil discharge and steam cleaning of railroad tank cars. Finally, this work introduces several approaches to further development of the odour regulation system in Russia. These approaches are based both on the foreign experience and the national sanitary regulation system regarding pollutant substances in ambient air of inhabited territories.