Browsing by Subject "Geruch"

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Beurteilung von Geruchsimmissionen aus der Tierhaltung
(2011) Gallmann, Eva; Jungbluth, Thomas
Odours from farm animal production can cause significant problems. It is therefore appropriate to develop suitable procedures for their assessment and limitation in the sense of immission control. The challenge comprises the objectification of the odours, bearing in mind that their effect is very individual, subjective and emotion-based. The resultant work offers a contribution towards the classification and further development of procedures for assessment of odours from farm animal production. The latest knowledge of the various aspects of measurement and evaluation of farm animal production odour immissions will be analysed in detail through ongoing literature assessment and from results of own investigations. The perceived nuisance effect relies on multiple stimulus-based variables associated with context and person. Measuring the associated effect can take place through psychometric surveys. Assessment of a significant nuisance effect within a group is conventionally based on the proportion of subjected persons that can be regarded as tolerable. Odours from farm animal production in particular are considered on the basis of investigations and data concerning odour components and their emission, transmission and immission. The extent of available data including results from own odour emission measurements give a high degree of scatter. This scatter is caused by the multiplicity of influences on emissions and also through the imprecision of measurements based on olfactometry. There are limitations on the extent to which reduction measures can be quantified. Dispersion modelling is an important tool for assessing odour immissions, but is also associated with limitations as shown by validation and sensitivity investigations. Particularly decisive are the appropriate illustration of the transmission and the choice and modification of the model structure and input parameters. The modelling of diffuse and varying sources near the ground surface remains a challenge. The consideration of cold air outflows is essential for immission assessment. The common odour threshold distances from pig and cattle production units determined via odour plume measurements are discussed using numerous trial results as examples. The results of own grid measurements at four locations are detailed, also with regard to the effect of a plausibility control, the variation of the odour hour criterion, and compared with dispersion calculations. Grid measurements help in the differentiated measurement of the immission situation. In the interpretation of absolute values, the imprecision area around the real value must be considered. The effect of immission reduction measures is hardly quantifiable nor able to be generalised. The knowledge is based, above all, on flow simulations and on experience. Main points of influence are the dilution of outflow air, the transmission conditions and the location circumstances. The immission hedonics from farm animal production odours were compared and recorded for own investigations and within the framework of a cooperative project “Odour assessment in agriculture“. The hedonic differences were not, however, nuisance-relevant as shown by evaluation of the exposition effect relationships within the same trial framework. The differences regarding type of farm animal are, however, relevant. The results from various epidemiological studies were thoroughly analysed because these were oriented on the assessment procedure for immissions and their effects. The starting point for assessing odour emissions from farm animal production can differ more through source-oriented distance rules or immission regulations for the limitation of odour hour frequency or odour concentration. Both points provide possibilities for recognition of animal type differences via factor weighting of animal mass, animal numbers or key immission figures. The assessment principle for distance standards that apply to all types of farm animals with factor weighting for source, transmission and immission parameters, or as empirical distance model, are explained and assessed based on examples from Switzerland, Austria and Germany. The methods and the establishment of factors are less well able to be appreciated as the degree of differentiation increases. The determinations within the odour immission guideline are compared with the regulations for odour exposition limits in the Netherlands, and in other countries. The suitability of the assessment bases and procedures for assessment are finally evaluated for assessment in practical conditions and recommendations for further developments suggested.
Characterization of the aroma properties in fragrant rapeseed oil and aroma variation during critical roasting phase
(2023) Zhang, Youfeng; Zhang, Yanyan
Rapeseed oil is one of the third most-produced vegetable oil in the world, which is appreciated for its characteristic flavor and high nutritional value. Fragrant rapeseed oil (FRO) produced by a typical roasting process is popular for its characteristic aroma, which has an annual consumption exceeding 1.5 million tons. However, the changes in aroma blueprint of FRO during the typical roasting processing are still unclear, which challenges rapeseed oil quality and consumer acceptance. Accordingly, the aim of this work was to investigate the aroma characteristics and their precursors pyrolysis behavior of FRO to provide a basis and guidance for the control of FRO aroma quality during production processing. First, a systematic review on summarizing, comparing, and critiquing the literature regarding the flavor of rapeseed oil, especially about employed analysis techniques (i.e., extraction, qualitative, quantitative, sensorial, and chemometric methods), identified representative/off-flavor compounds, and effects of different treatments during the processes (dehulling, roasting, microwave, flavoring with herbs, refining, oil heating, and storage) was performed. One hundred and thirty-seven odorants found in rapeseed oil from literature are listed, including aldehydes, ketones, acids, esters, alcohols, phenols, pyrazines, furans, pyrrolines, indoles, pyridines, thiazoles, thiophenes, further S-containing compounds, nitriles, and alkenes, and possible formation pathways of some key aroma-active compounds are also proposed. Nevertheless, some of these compounds require further validation (e.g., nitriles) due to lack of recombination experiments in the previous work. To wrap up, advanced flavor analysis techniques should be evolved toward time-saving, portability, real-time monitoring, and visualization, which aims to obtain a “complete” flavor profile of rapeseed oil. Aparting from that, studies to elucidate the influence of key roasting processing on the formation of aroma-active compounds are needed to deepen understanding of factors resulting in flavor variations of rapeseed oil. Following, a systematic comparison among five flavor trapping techniques including solid-phase microextraction (SPME), SPME-Arrow, headspace stir bar sorptive extraction (HSSE), direct thermal desorption (DTD), and solvent-assisted flavor evaporation (SAFE) for hot-pressed rapeseed oil was conducted. Besides, methodological validation of these five approaches for 31 aroma standards found in rapeseed oil was conducted to compare their stability, reliability, and robustness. For the qualification of the odorants in hot-pressed rapeseed oil, SAFE gave the best performance, mainly due to the high sample volumes, but it performed worse than other methods regarding linearity, recovery, and repeatability. SPME-Arrow gave good performances in not only odorant extraction but also quantification, which is considered most suitable for quantifying odorants in hot-pressed rapeseed oil. Taking cost/performance ratio into account, SPME is still an efficient flavor extraction method. Multi-method combination of flavor capturing techniques might also be an option of aroma analysis for oil matrix. Afterwards, by application of the Sensomics approach the key odorants in representative commercial FRO samples were decoded. On the basis of the aroma blueprint, changes of overall aroma profiles of oils and their key odorants were studied and compared in different roasting conditions. To better simulate industrial conditions, high temperatures (150-200 ºC) were used in our roasting study, which was rarely studied before. Identification and quantitation of the key odorants in FRO were well performed by means of the Sensomics concept. Glucosinolate degradation products were a special kind of key odorants existing in rapeseed oil. Most of the odorants showed first rising and then decline trends as the roasting process progressed. Aroma profile results showed that high-temperature-short time and low-temperature-long time conditions could have similar effects on the aroma profiles of roasted rapeseed oils, which could provide a reference for the time cost savings in industrial production. To gain the fundamental knowledge of the aroma formation in FRO, the thermal degradation behavior of progoitrin (the main glucosinolate of rapeseed) and the corresponding generated volatile products were investigated in liquid (phosphate buffer at a pH value of 5.0, 7.0, or 9.0) and solid phase systems (sea sand and rapeseed powder). The highest thermal degradation rate of progoitrin at high temperatures (150-200 ºC) was observed at a pH value of 9.0, followed by sea sand and then rapeseed powder. It could be inferred that bimolecular nucleophilic substitution reaction (SN2) was mainly taken place under basic conditions. The highest degradation rate under basic conditions might result from the high nucleophilicity of present hydroxide ions. Under the applied conditions in this study, 2,4-pentadienenitrile was the major nitrile formed from progoitrin during thermal degradation at high temperature compared to l-cyano-2-hydroxy-3-butene, which might be less stable. The possible formation pathways of major S-containing (thiophenes) and N-containing (nitriles) volatile (flavor) compounds were proposed. Hydrogen sulfide, as a degradation product of glucosinolates, could act as a sulfur source to react further with glucose to generate thiophenes. Overall, the present work comprehensively documented the effects of thermal conditions and matrices on the aroma characteristics, aroma profiles, and key odorants of hot-pressed rapeseed oil, which could provide data and theoretical basis for the flavor control of FRO under thermal treatment at actual production temperatures (150-200 °C).
Odorantrezeptoren in Axonen olfaktorischer Sinneszellen : in vitro Studien an Explantatkulturen
(2008) Luxenhofer, Georg; Breer, Heinz
Olfactory sensory neurons (OSN) expressing a particular odorant receptor (OR) are widely scattered throughout the olfactory epithelium (OE) of the nose and send their axon into a small number of common glomeruli in the olfactory bulb (OB). In a spatially well conserved pattern these axons establish synaptic contacts to second order neurons. The molecular mechanisms underlying the precise wiring are still not well understood. To generate a system which may facilitate the investigation of distinct aspects of this complex process, an in vitro culture with tissue explants from the olfactory system was established in the present work. The use of tissues from transgenic mice which enabled the visualisation of OSN and their processes by intrinsic fluorescence allowed a continuous observation of distinct axonal populations under defined and manipulable conditions. Cells within an explant from the OE harvested at the embryonic stage 14 (E14) extended numerous axonal processes within a few days which grew out radially and without fasciculation. During the initial culture period the explants contained mainly progenitor cells; after several days in culture cells differentiated to OMP-positive, thus mature OSN. Using receptor specific transgenic mouse lines the expression of distinct OR genes in a subpopulation of OSN could be detected. Altogether, the culture conditions thus allowed the differentiation of progenitor cells into OSN with characteristic gene expression. Concerning the key question of how axons of OSN interact with their target tissue, co-culture experiments with OB tissue were performed; they showed that axons were initially repelled by their target. A precultivation of OB tissue, however, resulted in an attraction of axons even from larger distances. Moreover, the bulb tissue exerted a positive effect on the growth rate of OSN axons. During their growth these axons formed bundles which defasciculated in the vicinity of the OB explants. These results showed that characteristic parameters in the generation of OSN, their axonal growth and interactions with the target tissue were recapitulated by the in vitro culture system, thus, providing optimal conditions for the examination of key questions regarding the molecular mechanisms involved in establishing the unique projection pattern. Subsequently, the explant culture system was used to investigate the role of the odorant receptor protein in the process of path finding. Expression of genetically modified receptor variants in the explants revealed novel insights into the subcellular localisation of the odorant receptor mOR256-17. An mOR256-17-EGFP fusion protein could be detected in vesicles transported into the dendrite of OSN, resulting in an accumulation of the OR in the cilia. Using this technique it was possible to observe for the first time OR proteins in vesicles which were transported anterogradely and retrogradely along the entire axon. The OR could be visualised within the growth cones and the attached filopodia. Taking advantage of a novel detection method in which proteins integrated into the plasma membrane were selectively marked, retrogadely transported vesicles containing internalised mOR256-17 protein could be observed. The generation of an OR variant, in which the G-protein binding domain was mutated resulted in a disturbed localisation of the OR protein within OSN. Hence, by developing an improved in vitro explant system, an important tool was generated that allowed novel insights into the function of distinct molecular components and should be valuable for future studies aimed at understanding the complex processes that lead to the precise connection of OSN with their target.
With all my senses : restorative environments through holistic sensory impressions
(2017) Sona, Brid; Steidle, Anna
Growing awareness of psychological health problems is resulting in various research areas exploring new approaches to fostering personal resources. Restorative Environments Theory (RET) has shown that mundane natural environments support personal resources. Although other restorative environments may exist besides mundane natural environments, their systematic examination is still lacking. In the real world, users experience environments through all their senses. However, most of the recovery research focuses on investigation of single sensory impressions. Thus, concrete insights into how various ambient qualities of an environment may affect users’ perception are still needed. The main aim of this doctoral thesis is to enhance the existing theoretical framework of restorative environments and to give an overview of research while pointing out where more research is needed. Further, the thesis includes identification of restorative environments and their specific ambient qualities. Based on the explored environments, the present research will point out psychological pathways to obtain recommendations for the design of restorative environments. The first research project was an explorative study to identify restorative places and their ambient qualities. In accordance with restoration research, participants described natural outdoor environments which they sought for recovery. In addition, they described indoor environments. Depending on the type of depletion and the environmental setting, specific environments and ambient qualities were evaluated as more important for the restorative potential of the place than others. This explorative research supports theory building and enables creation of restorative environments through holistic sensory impressions. Finally, strengths, limitations and practical implications for designing and improving restorative environments are discussed. The second research project takes up the findings of the first project by simulating sensory-enriched break environments. Based on the impact of holistic sensory impressions, this project is one of the first to reveal the impact of the recovery process of simulated environments on personal resources through congruent sensory impressions. Analyses confirmed that sensory-enriched environments were perceived as more pleasant and more restorative than less enriched environments, which in turn facilitated the recovery of personal resources. The results point out the relevance of holistic sensory impressions to fostering recovery. Implications and limitations of sensory enrichment in break environments are discussed. To broaden generalizability, the third research project comprises three field experiments investigating recovery during break interventions which offered virtual restorative environments with differing degrees of immersion and different types of environments. Building on previous research (Grimshaw, 2014), the third project posited that a higher degree of immersion in the simulated environment increases perceived realism, which becomes apparent in higher positive perceptions and recovery outcomes. Moreover, environments with different degrees of stimulation were anticipated to evoke distinct successful recovery. Previous research had mainly focused on calming environments for recovery. Additionally, this project also tested whether stimulating environments promote recovery outcomes. Results mainly confirmed the proposed hypotheses. The relevance of immersion and the impact of different types of natural environments on recovery are discussed. Overall, the current research emphasizes the impact of holistic sensory impressions in enhancing positive perceptions of the environment and, consequently, various recovery outcomes. The conducted studies uncover the psychological pathway from the processes of sensory perception to environmental recovery perception, followed by recovery outcomes. Beside these theoretical insights, the current research delivers concrete recommendations for designing restorative (virtual) environments in the workplace.