Odor Concentration Research Articles

Periodontitis is associated with impaired olfactory function: Aclinical study.

To explore the association between periodontitis and olfactory disorders. Clinical data were collected from 198 individuals between the ages of 18 and 60 years living in Denmark. The exposure was periodontitis, and the outcome was olfactory function (Threshold, Discrimination, Identification - TDI score), both measured clinically. Covariates included sex, age, education level, income, usage of nasal spray, tongue coating, halitosis, xerostomia, smoking, and history of COVID-19. Structural equation modeling was used to estimate the association between periodontitis and olfactory function. Periodontitis was defined using the AAP/EFP classification and dichotomized into "no" (healthy subjects) and "yes" (Stages I, II, and III). Olfactory function was treated as a one-factor latent variable, including the different olfactory scores. In addition, extra models were performed considering each olfactory component as a separate outcome and the TDI Global Score. The results showed that periodontitis was associated with a lower olfactory function [standardized coefficient (SC) -0.264, 95% CI -0.401, -0.118]. Additionally, periodontitis was also associated with a lower olfactory Threshold (odorant concentration required for detection) (SC -0.207, 95% CI -0.325, -0.089), Discrimination (ability to discriminate between odorants) (SC -0.149, 95% CI -0.270, -0.027), Identification (ability to identify odorants) scores (SC -0.161, 95% CI -0.277, -0.045), and TDI Global Score (SC -0.234, 95% CI -0.370, -0.099). This study suggests that periodontitis is associated with olfactory impairment.

Downstream natural gas composition across U.S. and Canada: implications for indoor methane leaks and hazardous air pollutant exposures

Previous research has shown that natural gas (NG) leaks from residential appliances are common, affecting greenhouse gas emission inventories and indoor air quality. To study these implications, we collected and analyzed 587 unburned NG samples from 481 residences over 17 North American cities for hydrocarbons, hazardous air pollutants, and organosulfur odorants. Nearly all (97% of) gas samples contained benzene (between-city mean: 2335 ppbv [95% CI: 2104, 2607]) with substantial variability between cities. Vancouver, Los Angeles, Calgary, and Denver had at least 2x higher mean benzene concentrations than other cities sampled, with Vancouver exhibiting a nearly 50x greater mean benzene level than the lowest-concentration city (Boston). We estimate that current U.S. and Canadian emissions inventories are missing an additional 25 000 [95% CI: 19 000, 34 000] and 4000 [95% CI: 3700, 5200] lbs benzene yr−1 through downstream NG leakage, respectively. Concentrations of odorants added for leak detection varied substantially across cities, indicating a lack of standardization. Houston, for instance, had 5x higher mean tert-butyl mercaptan levels than Toronto. Using these odorant measurements, we found that methane emissions as high as 0.0080–0.28 g h−1 and indoor benzene enhancements 0.0096–0.11 ppbv could go undetected by persons with an average sense of smell, with large uncertainties driven by smelling sensitivity, gas composition, and household conditions. We also observed larger leaks (>10 ppm ambient methane) in ∼4% of surveyed homes, confirming that indoor leakage occurs at varying degrees despite the presence of odorants. Overall, our results illustrate the importance of downstream NG composition to understand potential emissions, exposures, and odor-mediated leak detection levels. Given methane’s global warming potency, benzene’s toxicity, and wide variation in smelling abilities, our findings highlight the deficiencies regarding the sole reliance on odorization to alert and protect all occupants from indoor leaks.

A canine model to evaluate the effect of exercise intensity and duration on olfactory detection limits: the running nose.

Detection canines serve critical roles to support the military, homeland security and border protection. Some explosive detection tasks are physically demanding for dogs, and prior research suggests this can lead to a reduction in olfactory detection sensitivity. To further evaluate the effect of exercise intensity on olfactory sensitivity, we developed a novel olfactory paradigm that allowed us to measure olfactory detection thresholds while dogs exercised on a treadmill at two different exercise intensities. Dogs (n = 3) showed a decrement in olfactory detection for 1-bromooctane at 10-3 (v/v) dilutions and lower under greater exercise intensity. Dogs' hit rate for the lowest concentration dropped from 0.87 ± 0.04 when walking at low intensity to below 0.45 ± 0.06 when trotting at moderate intensity. This decline had an interaction with the duration of the session in moderate intensity exercise, whereby dogs performed near 100% detection in the first 10 min of the 8 km/h session, but showed 0% detection after 20 min. Hit rates for high odor concentrations (10-2) were relatively stable at both low (1 ± 0.00) and moderate (0.91 ± 0.04) exercise intensities. The paradigm and apparatus developed here may be useful to help further understand causes of operationally relevant olfactory detection threshold decline in dogs.

Electronic nose for odor monitoring at a landfill fenceline: Training and validation of a model for real-time odor concentration measurement

In recent years, electronic noses, or more generally Instrumental Odor Monitoring Systems (IOMS), have aroused increasing interest in the field of environmental monitoring.One of the most interesting applications of these instruments is the real-time estimation of the odor concentration at plant fencelines to continuously monitor odor emissions and identify anomalous conditions. In this type of application, it is possible to setting a “warning” threshold, enabling the continuous check of proper functioning of the plant and sudden intervention in case of malfunctions, preventing, at the same time, the risk of odor events at the receptors. For this purpose, it is necessary to provide a continuous, fast and reliable measurement of the odor concentration, which is nowadays one of the main challenges of this technology.In this context, this work proposes the development of a quantification model for quantifying odors detected at the fenceline of a landfill characterized by very different odor fingerprints. A double-step quantification model, firstly identifying the different odor classes to which the ambient air monitored at the fenceline by the IOMS belong to, and then developing different specific PLS regression models for each of the odor classes identified, was developed. The results of the proposed quantification model were compared to the ones obtained developing a “global” quantification model, which implements the regression on the globality of the training set, without differentiating between the odor classes. Then, they were further evaluated by comparison with the odor events detected at the sensitive receptor by another electronic nose. Moreover, the combined evaluation of the odor events at the plant fenceline and the receptor, respectively, together with the meteorological data highlighted the need of identifying variable warning thresholds for the odor concentrations at the fenceline according to effectively account for meteorological conditions and produce an output that is more correlated with the probability that an odor is perceived outside of the plant.

Key Odorants Forming Aroma of Polish Mead: Influence of the Raw Material and Manufacturing Processes.

Mead was analyzed by using the concept of molecular sensory science for the identification of key odorants. A total of 29 odor-active compounds were identified in mead by using gas chromatography olfactometry (GCO). Flavor dilution (FD) factors of identified compounds ranged from 1 to 16,384, compounds with FD factors ≥32 were quantitated by using stable isotopically substituted odorants as internal standards or external standard method, and odor activity values (OAVs) were calculated. Fifteen compounds showed OAVs ≥1: aldehydes (2-phenylacetaldehyde, 3-(methylsulfanyl)propanal), 4-hydroxy-3-methoxybenzaldehyde), esters (ethyl 3-methylbutanoate, ethyl propanoate, ethyl octanoate), alcohols (2-phenylethan-1-ol, 3- and 2-methylbutan-1-ol, 3-(methylsulyfanyl)propan-1-ol), furanons (4-hydroxy-2,5-dimethylfuran-3(2H)-one, 3-hydroxy-4,5-dimethylfuran-2(5H)-one), acids (3- and 2-methylbutanoic acid, acetic acid), 1,1-diethoxyethane, and 4-methylphenol. 2-Phenylacetaldehyde (OAV, 3100) was suggested as the compound with the biggest influence on the aroma of mead, followed by 4-hydroxy-2,5-dimethylfuran-3(2H)-one (OAV, 1900), 3-(methylsulfanyl)propanal (OAV, 890), and 2-phenylethan-1-ol (OAV, 680). Quantitative olfactory profile analysis revealed strong honey, malty, and alcoholic impressions. Omission experiments revealed that 3-(methylsulfanyl)propanal, 2-phenylethan-1-ol, 4-hydroxy-2,5-dimethylfuran-3(2H)-one, ethyl propanoate, ethyl 3-methylbutanoate, 2-phenylacetaldehyde, 3- and 2-methylbutanoic acid, 3-hydroxy-4,5-dimethylfuran-2(5H)-one, and 4-hydroxy-3-methoxybenzaldehyde were the key odorants in the mead. Determining concentrations of key odorants in important production steps showed that the fermentation and maturation stages had the strongest effect on the formation of mead aroma.

Chemical and olfactometric inventory of gaseous spot vents in Mt. Amiata volcanic-geothermal area (Italy)

Geothermal areas are typically characterised by the presence of gases and odours in the background atmosphere, stemming from natural emissions and possible mining exploitation of the area. This study presents the first olfactometric investigation of endogenous gas emissions from natural and archaeo-industrial vents in a geothermal area. Mt. Amiata is known for its complex geology and historical cinnabar mining. This study offers an inventory of spot gas emissions, not only in terms of odour and chemical concentration but also including flux data, a ground-breaking achievement in this field. The primary challenge of this investigation was estimating the emitted flow from ground holes or mine entrances, posing the risk of hazardous anoxic conditions. To address this challenge, an innovative and adaptive approach was adopted. The main breakthrough method involved the adaptation of a balometer, typically employed for indoor ventilation systems, to measure the flow of endogenous gases. Field surveys revealed odour concentrations that can exceed 106 of ouE/m3, surpassing industrial emission level considerably. Chemical concentrations, primarily consisted of CO2 (80/90 %v/v) and CH4 (∼10%v/v), providing critical insights into the global warming potential (GWP) associated with natural emissions. Moreover, these spots, often located at ground level and lacking a substantial atmospheric dilution, pose potential risks to nearby individuals, with concentrations of gases such as H2S surpassing safety thresholds. Total emissive flux of the investigated spot vents in the Mt. Amiata area, showed that the emission rate of H2S is notably substantial (55 kg/h), roughly equivalent to emissions from approximately four 20 MW geothermal plants, as along with odour emission rates in the order of 107 ouE/s. Considering the GWP derived from emitted gases, the total inventory assessment of the spot vents resulted in 36 t/h or 23 t/h CO2eq, depending on the time horizon considered (GWP20 or GWP100 respectively).

Effects of swine manure dilution with lagoon effluent on microbial communities and odor formation in pit recharge systems

Pit recharge systems (PRS) control odor by managing organic solids in swine manure. However, there needs to be more understanding of PRS's effect on the microbiome composition and its impact on odor formation. A study was conducted to understand how recharge intervals used in PRS impact manure microbiome and odor formation. Bioreactors dynamically loaded simulated recharge intervals of 14, 10, and 4 days by diluting swine manure with lagoon effluent at varying ratios. Treatment ratios tested included 10:0 (control), 7:3 (typical Korean PRS), 5:5 (enhanced PRS #1), and 2:8 (enhanced PRS #2). Manure microbial membership, chemical concentrations, and odorant concentrations were used to identify the interactions between microbiota, manure, and odor. The initial microbial community structure was controlled by dilution ratio and manure barn source material. Firmicutes and Proteobacteria were the dominant microbial phyla in manure and lagoon effluent, respectively, and significantly decreased or increased with dilution. Key microbial species were Clostridium saudiense in manure and Pseudomonas caeni in lagoon effluent. Percentages of these species declined by 8.9% or increased by 17.6%, respectively, with each unit dilution. Microbial community composition was controlled by both treatment (i.e., manure dilution ratio and barn source material) and environmental factors (i.e., solids and pH). Microbiome composition was correlated with manure odor formation profiles, but this effect was inseparable from environmental factors, which explained over 75% of the variance in odor profiles. Consequently, monitoring solids and pH in recharge waters will significantly impact odor control in PRS.

Distinct information conveyed to the olfactory bulb by feedforward input from the nose and feedback from the cortex

Sensory systems are organized hierarchically, but feedback projections frequently disrupt this order. In the olfactory bulb (OB), cortical feedback projections numerically match sensory inputs. To unravel information carried by these two streams, we imaged the activity of olfactory sensory neurons (OSNs) and cortical axons in the mouse OB using calcium indicators, multiphoton microscopy, and diverse olfactory stimuli. Here, we show that odorant mixtures of increasing complexity evoke progressively denser OSN activity, yet cortical feedback activity is of similar sparsity for all stimuli. Also, representations of complex mixtures are similar in OSNs but are decorrelated in cortical axons. While OSN responses to increasing odorant concentrations exhibit a sigmoidal relationship, cortical axonal responses are complex and nonmonotonic, which can be explained by a model with activity-dependent feedback inhibition in the cortex. Our study indicates that early-stage olfactory circuits have access to local feedforward signals and global, efficiently formatted information about odor scenes through cortical feedback.

Odor emission measurements: The role of n-butanol as a reference material and origins of large inter-laboratory variability

Malodors negatively impact the quality of life of people who are exposed to them. In order to enforce legal emission limit values that aim to reduce these adverse effects, reliable methods for the quantification of odor emissions are needed. The standard EN 13725 describes a method to quantify odor concentration, which is based on the use of human assessors as sensors. Previously published work that studied the performance characteristics of this method indicates that the variability of results between different laboratories is higher than expected and that the uncertainty associated with this method may be underestimated. We analyze here a unique data set, which contains the response of 368 assessors that participated in 21 odor proficiency tests performed in 2016–2022. By investigating the response of the smallest unit of an odor measurement by EN 13725, namely the individual assessor, as opposed to the panel, we gain unprecedented insight into the sources of inter-laboratory variations in odor measurements. Our results indicate that the assessor sensitivity to n-butanol is not transferable to other odorants and odor mixtures, which is contrary to the assumption made in EN 13725. By Monte-Carlo simulation coupled with our data set, we investigate how the responses of individual assessors transfer to panel responses, focusing on the influence of panel size, panel selection strategy and number of rounds. We find that for the laboratories investigated, larger panels only modestly reduce the inter-laboratory variability and we attribute this effect to non-random selection of assessors for the panels of these laboratories. The present work provides new insight into the sources of inter-laboratory variability in odor emission monitoring and is expected to be useful in the further development of reliable methods for odor concentration measurements and odor abatement technology.

Curry-Odorants and Their Metabolites Transfer into Human Milk and Urine.

The excretion of dietary odorants into urine and milk is evaluated and the impact of possible influencing factors determined. Furthermore, the metabolic relevance of conjugates for the excretion into milk is investigated. Lactating mothers (n=20) are given a standardized curry dish and donated one milk and urine sample each before and 1, 2, 3, 4.5, 6, and 8h after the intervention. The concentrations of nine target odorants in these samples are determined. A significant transition is observed for linalool into milk, as well as for linalool, cuminaldehyde, cinnamaldehyde, and eugenol into urine. Maximum concentrations are reached within 1h after the intervention in the case of milk and within 2-3h in the case of urine. In addition, the impact of glucuronidase treatment on odorant concentrations is evaluated in a sample subset of twelve mothers. Linalool, eugenol, and vanillin concentrations increased 3-77-fold in milk samples after treatment with β-glucuronidase. The transfer profiles of odorants into milk and urine differ qualitatively, quantitatively, and in temporal aspects. More substances are transferred into urine and the transfer needs a longer period compared with milk. Phase II metabolites are transferred into urine and milk.

Does experience of music enhance olfaction: music as a potential nutrition intervention?

Olfaction, the sense of smell, is under recognised and underappreciated despite being vital in wellbeing. It confers a major influence on the feeding process being the major contributor of flavour and has a direct involvement in the cephalic phase responses. Along with its influence on food and nutrition, olfaction is directly associated with cognitive function and impacts social communication and safety(1). Loss of olfactory acuity, commonly occurring in aging and frailty, significantly influences dietary behaviour and food selection(2). Unlike the senses of vision and audition, interventions are lacking. We propose in a proof-of-concept that crossmodal integration of olfaction and audition could inhibit olfactory decline in lifelong musicians through encouraging neuroplasticity of the olfactory brain centres. Ethical approval was obtained from The University of Adelaide Human Research Ethics Committee. Male musicians with a lifetime experience of music (ME) and naïve non-musicians (NM) aged 55 years and over were recruited through music organisations and controls through the Australian Men’s Shed network. The initial target sample size was twenty per cohort. Olfactory acuity was assessed with Sniffin’ sticks® (Odofin, Groningen, The Netherlands), a well validated system of a battery of three tests regimes. Sniffin’ sticks represent ‘felt tipped pens’ impregnated with odourants presented 20mm below the nose of participants who were then prompted to ‘sniff’. Assays determined participant ‘Threshold’, ‘Discrimination’ and ‘Identification’ of test odours (3). Measurement of Threshold and Discrimination were undertaken in triplet fifteen seconds apart with eyes closed; measurement of Threshold being conducted in an ascending ‘staircase’ to detect lowest odour concentration detectable, whereas measurement of Discrimination selected the ‘odd-man-out’ of a triplet comprising two identical and one different odour. Measurement of Identification, with eyes open, selected the odour of a single ‘pen’ from a prompt list of four. All tests demanded selection. Each of the test batteries were scored out of sixteen along with total aggregate of Threshold, Discrimination, and Identification (TDI). Twenty-six participants completed the study (18 ME and 8 NM); numbers were limited owing to active COVID-19. Mean and standard deviations (SD) of Threshold, Discrimination, Identification and TDI were derived and compared between groups using ‘t’-test. For ME, Threshold, Discrimination, and Identification values were 6.2 (SD ± 3.7), 10.6 (SD ± 1.9), and 12.9 (SD ± 1.6). The respective values for NM were 5.0 (SD ± 2.3), 8.8(SD ± 2.9), and 10.8 (SD ± 2.5). The ME group showed a significantly higher Discrimination (p = 0.164). Significant differences were not seen for Threshold, Identification, and overall TDI scores, however the small sample size may have accounted for this. Based on this proof-of-concept, further exploration of music is warranted as an intervention to enhance olfactory acuity to potentially improve the intake of food and nutrition, and enrich pleasure of eating and drinking, and quality of life.

Towards real-time monitoring of odour emissions from waste treatment plants: a case study

The most recent Best Available Techniques (BAT) for waste treatment plants indicate odour as environmental pollutants to be monitored and controlled. In Italy, the prescription of permanent installations of electronic noses (or Industrial Odour Monitoring Systems - IOMS) in the environmental permit of waste treatment plants (WTPs) is becoming more and more frequent. IOMS are intended to provide a real-time estimation of the odour concentration at the fenceline of the plant. Although this type of IOMS application is becoming very common, it is far from being state-of-the-art. In this context, this paper describes a research project aimed at the implementation at the fenceline of a WTP of an IOMS network, comprising two IOMS and a meteorological station. The paper focuses on presenting the experimental procedure involved for training IOMS and verifying their performance in the field. 5 olfactometric campaigns were carried out at the plant to build IOMS calibration models aimed at WTP odours detection, classification, and quantification. Results of field performance testing proved, with classification accuracies above 95% achieved by both IOMS, a very good capability of properly trained IOMS to recognize WTP odours. Moreover, they pointed out a great agreement between the estimations of the odour concentration provided by the IOMS and the odour concentration assessed by dynamic olfactometry, thereby boosting the research in this field. Finally, the paper reports the results of 1-year monitoring at the WTP with the purpose of evaluating the possibility to define an alarm threshold for the odour concentration.

Occurrence of Designated Odor Substances in Wastewater Treatment Plant and Industrial Estate

Objectives : Odor emissions pose a challenge due to the diversity of odor-producing substances, their various sources, and the complex interactions between different compounds. Moreover, people's perception of odor intensity can vary based on their living environment and psychological state, making it difficult to effectively manage and develop mitigation measures for odors, in contrast to other air pollutants. To address this issue, this study focuses on two prominent sources of residential odors, namely wastewater treatment plant and industrial estate.Methods : Through on-site data collection, the study aims to investigate the characteristics of odor emissions and analyze seasonal trends in odor generation. Ultimately, the study seeks to assess the substances contributing to odors in wastewater treatment plant and industrial estate through odor contribution analysis.Results and Discussion : The research findings reveal that wastewater treatment plants predominantly emit high concentrations of fatty acid substances such as Propionic acid, iso-Valeric acid, and n-Valeric acid. In contrast, industrial estates release a variety of odor-causing substances, including Toluene, Xylene, Butyraldehyde, Trimethylamine, and iso-Valeraldehyde.Conclusion Significant differences are observed both in terms of odor concentration and odor contribution. These disparities are attributed to the specific characteristics of wastewater treatment plants and industrial processes that induce odors. Nevertheless, in both types of facilities, Trimethylamine is identified as a major contributor to odors.

A mechanosensory feedback that uncouples external and self-generated sensory responses in the olfactory cortex

Sampling behaviors have sensory consequences that can hinder perceptual stability. In olfaction, sniffing affects early odor encoding, mimicking a sudden change in odor concentration. We examined how the inhalation speed affects the representation of odor concentration in the main olfactory cortex. Neurons combine the odor input with a global top-down signal preceding the sniff and a mechanosensory feedback generated by the air passage through the nose during inhalation. Still, the population representation of concentration is remarkably sniff invariant. This is because the mechanosensory and olfactory responses are uncorrelated within and across neurons. Thus, faster odor inhalation and an increase in concentration change the cortical activity pattern in distinct ways. This encoding strategy affords tolerance to potential concentration fluctuations caused by varying inhalation speeds. Since mechanosensory reafferences are widespread across sensory systems, the coding scheme described here may be a canonical strategy to mitigate the sensory ambiguities caused by movements.

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.

Odor Impact Assessment via Dispersion Model: Comparison of Different Input Meteorological Datasets

Dispersion modeling is a useful tool for reproducing the spatial–temporal distribution of pollutants emitted by industrial sites, particularly in the environmental odor field. One widely used tool, accepted by regulatory agencies for environmental impact assessments, is the CALPUFF model, which requires a large number of input variables, including meteorological and orographical variables. The reliability of model results depends on the accuracy of these input variables. The present research aims to discuss a comparative study of odor dispersion modeling by initializing the CALMET meteorological processor with different input data: surface and upper air observational meteorological data, 3D prognostic data, and a blend of prognostic and measured data. Two distinct sources (a point and an area source) and two different simulation domains in Cuba and Italy are considered. The analysis of results is based on odor impact criteria enforced in some Italian regions by computing the 98th percentile of odor peak concentrations on an annual basis. For the area source, simulation results reveal that the ‘OBS’ and ‘HYBRID’ modes are largely comparable, whereas prognostic data tend to underestimate the odor concentrations, likely due to a reduced percentage of wind calms. For point sources, different input meteorological settings provide comparable results, with no significant differences.

Study on changes of Styrax varieties

Styrax is a commonly used imported traditional Chinese medicinal material in China. It was introduced to China in the Han Dynasty and was first described as a traditional Chinese medicine in Miscellaneous Records of Famous Physicians(Ming Yi Bie Lu). In this paper, by combing ancient and modern Chinese and foreign herbal medicine books and modern literature, combined with the results of field investigations on the origin of Styrax, the changes of Styrax involving the name, quality evaluation, origin, place of origin, and harvesting and processing were systematically verified. The results show that since ancient times, the origin and place of origin of Styrax have been unclear. The medical scientists of all dynasties in China have evaluated the quality of Styrax from four aspects: texture, viscosity, odor concentration, and color. The varieties of Styrax changed twice. The first change may have occurred during the Sui and Tang Dynasties, and the base changed from Styrax officinalis to Liquidambar orientalis. The second change was in modern times, and the base changed from L. orientalis to L. styraciflua. At the same time, the place of origin changed for the first time, from Turkey, Syria, and other countries in southern Asia Minor to Honduras, Guatemala, and other countries in Central America and southern North America. This paper studied the historical evolution of Styrax in terms of quality evaluation, origin, place of origin, character, and harvesting and processing. At the same time, it summarized the application of Styrax in the western countries, which can provide a historical basis for the further development and utilization of Styrax.

Deodorisation of Ventilated Air from a Fat-Processing Plant Using Different Types of Biofilter Fillings and Membranes

The aim of the research is to assess changes in odour concentration in the ventilated air of a production hall, using different types of biofilter fillings and different types of membranes. Deodorisation was carried out using a mobile combined biofilter at a plant producing lard and liquid oils. Ventilated air from the hall contained organic and inorganic pollutants. Two types of fillings were used for technological tests: stumpwood chips mixed with pine bark and a mix of stumpwood chips with pine bark and green waste compost. Two types of membranes were also used, differing in thickness, permeability, and water resistance. The subjects of the research were the air supplied to the filter, lifted directly from the bed, and the air above the membranes. The deodorisation efficiency—the percentage reduction in the odour concentration value as a result of air flow through the bed and membranes—was calculated. The filtration methods used allowed the selection of the most advantageous technological variant from the point of view of deodorisation effectiveness: a mix of stumpwood chips with pine bark and the Pro Eko Tex UV membrane. It has a total odour reduction efficiency of 99.3–99.9% and has been added to full-scale implementation works.

Environmental Odor Analysis in West and East Java’s Ambient Air and Odor Reduction Using Biofilter Model

The odor affects both one’s health and quality of life. This study measures and analyzes odor concentration and odor sources in ambient air, the correlation between odor gas concentration and the hedonic scale, and the design of an odor-reduction instrument. The research commenced from February to May 2022 in the small industrial area (SIA) of Magetan Regency and compost bins of Bogor City. Data was collected through chemical analysis, and the hedonic scale was measured at four points divided into radii one and two. The concentration of odor parameters in Magetan and Bogor City is below the quality standard, while the correlation between ammonia gas concentration and the hedonic scale is low. Regarding the biofilter, its odor reduction efficiency is 35% for rotten fish, 70% for goat manure, 82% for compost waste, and 47% for chicken carcasses.

Conching of dark chocolate – Processing impacts on aroma-active volatiles and viscosity of plastic masses

The conching process plays a key role in determining the sensory and rheological properties of dark chocolate. To further understand this process, changes in the chocolate mass during plastic conching were investigated on a time-resolved basis with varying conching temperature, shear direction, and with or without the presence of residue from previous trials (pre-charge) on the conche vessel wall. Six selected odorants (acetic acid, benzaldehyde, linalool, 2,3,5,6-tetramethylpyrazine, 2-phenylethanol, 2-phenylethyl acetate) were quantified in fat and particle phases of chocolate masses. Particularly at elevated conching temperature, the odorant concentrations were found to decrease (up to 78.0% in the fat phase). The highest concentrations of desired odorants were determined mostly after conching without pre-charge. During conching, odorants were observed to accumulate increasingly in the fat phase (up to 91.7%) with decreasing odorant polarity. Similarly, it was found that conching temperature and the absence of pre-charge had the highest impact on the rheological properties of the chocolate mass, resulting in lowest and highest complex viscosity, respectively. In conclusion, some positive outcomes of conching, namely the retention of desired odorants and the reduction of viscosity, were inversely related at elevated temperature or in the absence of pre-charge, necessitating compromises to achieve optimal flow properties and flavor. Our results contribute to a deeper understanding of the influence of conching on the quality of dark chocolate by providing insights into the complexity of aroma migration and rheological changes during conching.