Negative Odor Research Articles

Odor awareness modulates the association between perceived stress and chemosensory anhedonia in women.

Chronic stress alters reward sensitivity and contributes to anhedonia. Chemosensation is dominated by a hedonic dimension, but little is known about the association between chronic perceived stress and hedonic chemosensation in non-clinical populations. In the current study, 325 participants (201 females) completed a questionnaire-based survey measuring their chronic perceived stress (Perceived Stress Scale; PSS), chemosensory pleasure (Chemosensory Pleasure Scale; CPS), and olfactory metacognitive abilities (odor awareness, affective impact of odor, importance of olfaction). For females, higher PSS scoressignificantly predicted lower CPS scores, which is mediated by the positive odor awareness. Moreover, negative odor awareness was identified as a moderator underlying the relationship between PSS and CPS scores in females but not in males. For females, higher PSS predicted lower CPS for those with lower, but not for those with higher levels of negative odor awareness. These results show that the link between chronic perceived stress and chemosensory anhedonia is pronounced in females, with olfactory perception playing a key role. The current study provides insights into the understanding of stress-related anhedonia and into the development of effective treatments.

Children’s multisensory experiences in museums: how olfaction interacts with color

This case study was designed to engage children’s sense of smell through a story-related museum exhibition. Children’s responses to the exhibition, with particular attention to their olfactory perceptions of the odors at the exhibition, were solicited through researcher-child interviews and children’s drawings. Responses from 28 children (girls N = 14, boys N = 14) aged between 4.5–8 years were analyzed after they visited the exhibition using the cross-modal association and multisensory theories. Interview data showed that dark (brown and black) colors elicited children’s negative olfactory associations for both positive and negative odors. Children’s drawings did not seem to make references to the odors at the exhibitions but rather their preferences for the different story characters. We theorize about the associations between smell and colors in children’s responses and distil some key learnings for multisensory museology.

Negative valence encoding in the lateral entorhinal cortex during aversive olfactory learning

Olfactory learning is widely regarded as a substrate for animal survival. The exact brain areas involved in olfactory learning and how they function at various stages during learning remain elusive. Here, we investigate the role of the lateral entorhinal cortex (LEC) and the posterior piriform cortex (PPC), two important olfactory areas, in aversive olfactory learning. We find that the LEC is involved in the acquisition of negative odor value during olfactory fear conditioning, whereas the PPC is involved in the memory-retrieval phase. Furthermore, inhibition of LEC CaMKIIα+ neurons affects fear encoding, fear memory recall, and PPC responses to a conditioned odor. These findings provide direct evidence for the involvement of LEC CaMKIIα+ neurons in negative valence encoding.

Exploration of the evolution and production of volatile compounds in grouper (Epinephelus coioides) during cold storage

Microbial growth, protein degradation and lipid oxidation played an important role in the flavor of grouper during cold storage. In order to study the relationship between volatile compounds (VOCs) and microorganisms, proteins and lipids in grouper during cold storage, headspace-solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to analyze the VOCs of grouper during cold storage. The total viable counts (TVC), Pseudomonas count, total sulfhydryl (SH) content, carbonyl content, TBARs, total free fatty acids (FFAs) content and free amino acids (FAAs) were measured. The results showed that the indicators related to microorganisms, proteins and lipids deteriorated to different degrees during cold storage. A total of 67 VOCs were identified in the grouper. After screening, 10 key VOCs were found, 8 of which had a negative odor and were highly correlated with the deterioration of grouper quality. Through further correlation analysis, the source of key VOCs was basically determined, and the main factors affecting VOCs production were determined to be microbial growth, followed by protein degradation and lipid oxidation. It laid a foundation for regulating the flavor formation of grouper during cold storage from the source in the future.

CO2 packaging increases shelf life through reduction of off-odor production by CO2 tolerant bacteria in addition to growth inhibition of the spoilage bacteriota

Optimized packaging conditions to improve the shelf life of chicken fillets is important to prevent food spoilage and food waste. Anaerobic packaging with CO2 or by vacuum packaging is commonly used to increase the shelf life of skinless chicken fillets, but the literature is inconsistent about the spoilage bacteriota. The aim of this work was to determine which bacterial genera that spoil raw chicken fillets packaged under two common packaging conditions and how the packaging gas itself affects the production of off odors for these genera.The spoilage potential of Pseudomonas, Carnobacterium, Hafnia, Serratia, Brochothrix and Shewanella isolated from spoiled chicken fillets was evaluated. Fresh chicken fillets were inoculated with mono- and multi genera strain cocktails (4 log CFU/cm2) and packaged with 100% N2 or 60% CO2/40% N2, stored at 4 °C, and bacterial numbers, bacteriota, gas in headspace and sensory profiles assessed. Additionally, the effect of CO2 on the production of off-odors from fillets inoculated with similar levels of Shewanella spp. or Brochothrix spp. was determined by both sensory profiling and measuring volatile organic components.All bacterial cocktails grew relatively well in chicken meat packed with 100% N2, while 60% CO2/40% N2 resulted in growth inhibition of all isolates compared to 100% N2. All genera except Serratia and Pseudomonas gave rise to off-odors after 11 days of storage in 100% N2. During storage in 60% CO2/40% N2, only fillets with Carnobacterium spp. and Brochothrix spp. showed significantly higher intensities of off-odors compared to the reference fillets. Shewanella spp. and Brochothrix spp. also exhibited significantly higher intensities of negative odor attributes during storage in 100% N2 compared to 60% CO2/40% N2, at a similar total bacterial count. Thus, CO2 improves shelf life not only by reduction of the growth of CO2 tolerant and sensitive bacteria, but also through inhibition of the production of off-odors.

The Effect of Hot-Air Dried Lentinula edodes on the Quality and Oranoleptic Properties of Rolled-Dumplings.

The effect of hot-air dried Lentinula edodes pileus (DLE) on the quality and organoleptic properties of rolled-dumplings was evaluated. DLE was prepared by drying at 60°C for 24 h and added (Non, 7%, and 9%) to rolled-dumplings. The proximate composition, pH, color (CIE L*, a*, b*), and cooking yield were analyzed. Texture profile analysis, electronic-nose (e-nose), electronic-tongue (e-tongue), and organoleptic evaluation were also conducted. The cooking yield of dumplings with 9% DLE was significantly lower than that of the congeners without DLE, whereas 7% DLE did not lead to significant differences compared without DLE. With increasing DLE addition, the pH and lightness of the dumplings decreased significantly, whereas the redness tended to increase. The texture profile was significantly higher for the dumplings with DLE compared to those without DLE. E-nose analysis confirmed that DLE addition led to the positive odors (methanethiol: meaty, sulfurous; 3-methylbutanal: malty, toasted) and the negative odors (trimethylamine: ammoniacal; acetic acid: acidic, sour). E-tongue analysis showed that DLE addition decreased the intensity of the sourness and increased the intensity of the saltiness and umami of rolled-dumplings. DLE addition improved the overall organoleptic properties, but 9% DLE can be recognized as a foreign substance in organoleptic acceptance. Consequently, DLE has the potential to serve as a flavor and odor enhancer for rolled-dumplings, and the addition of DLE can positively improve consumer acceptance by improving the quality and organoleptic properties.

Характерологические функции неопрятности в произведениях Ф.М. Достоевского и его современников

The article is the continuation of a study on Dostoevsky’s olfactory in the cultural and historical context of the second half of the 19th century. The involvement of public consciousness in the formation of new hygienic standards led to fundamental changes in the olfactory of Russian literature. The gradual overcoming of aesthetic prohibitions made it possible to use unpleasant odors associated with human activity as an artistic detail with negative assessment. Smell rating (pleasant/ unpleasant) is a cultural phenomenon that largely depends on the historical, national, religious, and economic characteristics of a society. In addition, the assessment of smell is also one of the elements of tidiness, a historically established sign system that determines a group identity. Deviations from established cultural norms (untidiness) determine the social boundaries of society at the olfactory level as well. The smell of untidiness, to which Dostoevsky’s contemporaries actively address, consist a specific stench of unwashed body, smells of sweat, urine and other biological secretions, the smell of unclean clothes, the stinking smell of breath, including the smell of wine fumes. In addition, the use of smells inappropriate for the bodily sphere or the smells of illness for the comparative description of “smells like” forms an extensive negative metaphorical field. Dostoevsky’s use of olfactory details to define his characters follows, on the one hand, general patterns, and on the other, has a number of personal features, including his close attention to the cleanliness of the characters’ underwear. This detail is present in almost every description of appearance. Direct references to the connection between unclean underwear and unpleasant odor can be found in a very small group of descriptions, nevertheless, indications of unclean underwear and the untidy appearance of a character have olfactory properties, as they generate a sense of expected unpleasant smell. In addition, the article considers the peculiarity of the use of negative body odors in the novel The Brothers Karamazov by Dostoevsky and in Leskov’s stories.

Odor valence modulates cortico-cortical interactions: a preliminary study using DCM for EEG.

Olfaction and emotions share common networks in the brain. However, little is known on how the emotional content of odors modulate dynamically the cortico-cortical interactions within these networks. In this preliminary study, we investigated the effect of odor valence on effective connectivity through the use of Dynamic Causal Modeling (DCM). We recorded electroencephalographic (EEG) data from healthy subjects performing a passive odor task of odorants with different valence. Once defined a fully-connected a priori network comprising the pyriform cortex (PC), orbitofrontal cortex (OFC), and entorhinal cortex (EC), we tested the modulatory effect of odor valence on their causal interactions at the group level using the parametric empirical bayes (PEB) framework. Results show that both pleasant and the unpleasant odors have an inhibitory effect on the connection from EC to PC, whereas we did not observe any effect for the neutral odor. Moreover, the odor with positive valence has a stronger influence on connectivity dynamics compared to the negative odor. Although preliminary, our results suggest that odor valence can modulate brain connectivity.

The human olfactory bulb processes odor valence representation and cues motor avoidance behavior

Determining the valence of an odor to guide rapid approach-avoidance behavior is thought to be one of the core tasks of the olfactory system, and yet little is known of the initial neural mechanisms supporting this process or of its subsequent behavioral manifestation in humans. In two experiments, we measured the functional processing of odor valence perception in the human olfactory bulb (OB)-the first processing stage of the olfactory system-using a noninvasive method as well as assessed the subsequent motor avoidance response. We demonstrate that odor valence perception is associated with both gamma and beta activity in the human OB. Moreover, we show that negative, but not positive, odors initiate an early beta response in the OB, a response that is linked to a preparatory neural motor response in the motor cortex. Finally, in a separate experiment, we show that negative odors trigger a full-body motor avoidance response, manifested as a rapid leaning away from the odor, within the time period predicted by the OB results. Taken together, these results demonstrate that the human OB processes odor valence in a sequential manner in both the gamma and beta frequency bands and suggest that rapid processing of unpleasant odors in the OB might underlie rapid approach-avoidance decisions.

Different Brain Activation in Response to Repeated Odors of Pleasantness and Unpleasantness

Brain activation in response to olfactory stimuli has been studied using functional magnetic resonance imaging (fMRI), but there is little knowledge about processing repeated olfactory information which is usual in daily life. This fMRI study was designed to investigate brain response to repeated odorant stimulation with positive and negative valences in 12 healthy right-handed volunteers. There was a 25-min rest interval between two fMRI runs with identical stimulation paradigms with two odors, as phenylethyl alcohol (PEA) and isovaleric acid (IVA), and the two odors were released alternately. There was a similar activation pattern in regions of primary and secondary olfactory cortex induced by odors of both valences, especially by negative odor. Weakened activation of the brain is responsive to repeated both pleasant and unpleasant smell. Nevertheless, the repeated unpleasant odor has a more intimate relationship with the piriform cortex, amygdala, and hippocampus. We conclude that asymmetric brain activation in response to repeated odorant stimulation depended on valences and that the unpleasant odor can evoke more negative emotion and profound memory. We explore the central processing about repeated olfactory information applied fMRI for the first time, revealing asymmetric brain activation in response to repeated odors of pleasantness and unpleasantness.

Olfaction and social illness in the Prostituta tetralogy by Eduardo López Bago

This article explores the Madrid of Eduardo López Bago’s Prostituta tetralogy through his construction of social illness by means of olfaction. Contrary to the expected Naturalist ascription of negative odors to the body of the prostitute, López Bago codes her positively, placing the locus of social illness instead in the sensory construction of powerful male characters. Inverting the gendering of pathologized, societally fraught morality in this way both complicates the current critical discourse about gender representation and construction in finisecular Spain and suggests López Bago as an author meriting further and more focused examination by scholars of this critical period in peninsular literature.

Implicit Affective Rivalry: A Behavioral and fMRI Study Combining Olfactory and Auditory Stimulation.

Aversive odors are highly salient stimuli that serve a protective function. Thus, emotional reactions elicited by negative odors may be hardly influenceable. We aim to elucidate if negative mood induced by negative odors can be modulated automatically by positively valenced stimuli. We included 32 healthy participants (16 men) in an fMRI design combining aversive and neutral olfactory stimuli with positive and neutral auditory stimuli to test the influence of aversive olfactory stimuli on subjective emotional state and brain activation when combined with positive and neutral auditory stimuli. The behavioral results show an interaction of negative olfactory stimuli on ratings of disgust, perceived valence of music, and subjective affective state, while positive auditory stimulation did not show this interaction. On a neuronal level, we observed main effects for auditory and olfactory stimulation, which are largely congruent with previous literature. However, the pairing of both stimuli was associated with attenuated brain activity in a set of brain areas (supplementary motor area, temporal pole, superior frontal gyrus) which overlaps with multisensory processing areas and pave the way for automatic emotion regulation. Our behavioral results and the integrated neural patterns provide evidence of predominance of olfaction in processing of affective rivalry from multiple sensory modalities.

Identification and quantification of glue-like off-odors in elastic therapeutic tapes.

Elastic therapeutic tapes are an important tool in the field of physical therapy and medicine. These tapes contain types of adhesive. However, sensory evaluations revealed the release of pronounced and irritating odors of the tapes. Negative odors were, amongst others, reported in elastic therapeutic tapes containing acrylic adhesives. In this study, the odor of four different tape samples was evaluated applying a descriptive analysis approach carried out by a trained sensory panel. Afterwards, the volatile compounds were recovered from the samples by solvent extraction and isolated by solvent-assisted flavor evaporation (SAFE). The obtained distillates were subsequently analyzed by gas chromatography-olfactometry (GC-O) and two-dimensional GC-O coupled with mass spectrometry (2D-GC-MS/O). To determine the most potent odorants in the distillates, odor extract dilution analyses (OEDA) were carried out. Thirty-one odorants were successfully identified using this approach, which were all described for the first time as odorants in tapes. Amongst the set of volatiles, unsaturated and saturated aldehydes were present, eliciting fatty, soapy, and citrus-like odor impressions, as well as a range of glue-like, moldy, and fruity smelling odor-active volatiles, such as 2-ethyl-1-hexanol, butyl benzoate, and 3-phenyltoluene. Based on their relative intensities, the concentrations of the glue-like smelling substances were determined: 2-ethyl-1-hexanol, present in all samples, was determined with concentrations ranging from 10 to 200mg/kg in the investigated tapes.

State-dependent judgement bias in Drosophila: evidence for evolutionarily primitive affective processes.

Affective states influence decision-making under ambiguity in humans and other animals. Individuals in a negative state tend to interpret ambiguous cues more negatively than individuals in a positive state. We demonstrate that the fruit fly, Drosophila melanogaster, also exhibits state-dependent changes in cue interpretation. Drosophila were trained on a Go/Go task to approach a positive (P) odour associated with a sugar reward and actively avoid a negative (N) odour associated with shock. Trained flies were then either shaken to induce a purported negative state or left undisturbed (control), and given a choice between: air or P; air or N; air or ambiguous odour (1 : 1 blend of P : N). Shaken flies were significantly less likely to approach the ambiguous odour than control flies. This ‘judgement bias’ may be mediated by changes in neural activity that reflect evolutionarily primitive affective states. We cannot say whether such states are consciously experienced, but use of this model organism's versatile experimental tool kit may facilitate elucidation of their neural and genetic basis.

P283 Effects of odours on electrophysiological responses to laser pain stimuli

Background Previous studies have shown increases in subjective experience and electrophysiological processing of experimental pain during induction of negative emotions with concurrent multi-modal sensory stimuli. The goal of the present study was to analyse spatio-temporal activation patterns underlying processing of acute pain during exposures to affectively valenced odour stimuli. Methods Negative, positive, and neutral (clean air) odour pulses were presented to 17 healthy participants via an olfactometer whilst brief noxious laser stimuli were administered to the dorsum of the left hand. Brain activity was monitored using electroencephalography (EEG) and participants rated the quality and intensity of pain and odour stimuli following each trial using visual analogue scales. Subjective ratings of pain stimuli and laser evoked potentials (LEPs) were analysed to evaluate the influence of valenced odours on subjective and electrophysioloigical aspects of pain processing. Results Analysis of pain ratings revealed no difference in pain intensity, or specific pain qualities across the different odour conditions. Individual LEP components demonstrated expected correlations with specific aspects of pain perception, but did not differ between odour conditions. Conclusions Contrary to research from other sensory modalities, the findings of the present study suggest that affectively valenced odours do not overtly influence aspects of subjective pain perception or electrophysiological processing of acute pain. This may be due to the influence of top-down factors affecting split perception between competing sensory stimuli, which may interact differently for pain and olfactory perception compared to other modalities.

Resolving the chemical structures of off-odorants and potentially harmful substances in toys-example of children's swords.

Most children's toys on the market are primarily made out of plastic and other complex composite materials. Consumer complaints about offensive odors or irritating effects associated with toy products have increased in recent years. One example is the strongly perceivable negative odor reported for a particular series of toy swords. Characterizing the presence of contaminants, including those that have the potential to be deleterious to health, in such products is a significant analytical challenge due to the high baseline abundance of chemical constituents of the materials used in the products. In the present study, the nature of offensive odorants associated with toy sword products was examined by gas chromatography (GC). After initial sensory evaluations, the volatile compounds from the toy products were recovered using solvent extraction and solvent-assisted flavor evaporation. The extracts were analyzed using GC-olfactometry (GC-O) and two-dimensional GC-O coupled with mass spectrometry (GC-GC-MS/O). A total of 26 odor-active compounds, including aromatic hydrocarbons and phenols, were identified among numerous non-odorous volatile by-products. These substances also included polycyclic aromatic hydrocarbons, which were analyzed by GC-MS. Representative substances were naphthalene and 1,2-dihydronaphthalene that exhibited moldy, mothball-like odor impressions, and phenol derivatives with leather-like, phenolic, horse-stable-like smells. The odorants detected correlated with the assigned attributes from the sensory analyses. This study clearly shows that the detection and identification of such odorous contaminants can provide key indications of potentially harmful yet unknown substances in everyday products such as toys. Graphical abstract ᅟ.

Olfactory identification in patients with schizophrenia – the influence of β-endorphin and calcitonin gene-related peptide concentrations

BackgroundThe relationship between the olfactory system and emotional processing is an area of growing interest in schizophrenia research. Both the orbitofrontal cortex and amygdala are involved in the processing of olfactory information, and olfactory deficits may be also influenced by endogenous opioids and calcitonin gene-related peptide (CGRP), which is probably involved in dopaminergic transmission. However, the relationship between endorphins and dopaminergic transmission has not been fully explored. MethodsOdor identification performance and valence interaction was evaluated among 50 schizophrenic patients and 50 controls. Schizophrenia symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). All study participants were subjected to the University of Pennsylvania Smell Identification Test (UPSIT), blood β-endorphin (BE) and CGRP measurement. ResultsInsignificantly higher BE concentrations were observed in the patient group, while significantly higher UPSIT scores were seen in controls (mean UPSIT 32.48 vs 26.82). The patients demonstrated significantly more identification errors for pleasant (P=0.000) and neutral (P=0.055) odors than for unpleasant odors. Patients with higher BE concentrations made more identification errors concerning pleasant (Rs=−0.292; P=0.04) and neutral odors (Rs=−0.331; P=0.019). Although the concentration of CGRP was significantly higher in the patient sample (P<0.001), no relationship was observed between concentration and UPSIT performance. A strong negative correlation was observed between PANSS N score and UPSIT total score (Rs=−0.646; P=0.000), between PANSS N score and identification by valence for pleasant and neutral odors (UPSIT n/16: Rs=−0.450, P=0.001; UPSIT n/15: Rs=−0.586, P=0.000), and a weak negative correlation between PANSS N score and identification of unpleasant odors (UPSIT n/9: Rs=−0.325, P=0.021). ConclusionsSchizophrenic patients present a unique pattern of smell identification characterized by aberrant hedonic ratings for pleasant odors but not unpleasant ones. Individuals with predominant negative symptoms and higher BE concentrations are most able to identify negative odors.

The Influence of Olfactory Contexts on the Sequential Rating of Odor Pleasantness.

When we sequentially evaluate the characteristics of sensory stimuli, our evaluation of a current stimulus is influenced by those preceding it. One such effect is called hedonic contrast, whereby stimuli are rated more negatively (negative contrast) or positively (positive contrast) if they are preceded by more or less pleasant stimuli. The present study investigated the characteristics of hedonic contrast for olfaction and compared these characteristics with those of a more oft-studied modality, vision. The results from two experiments indicated that both positive and negative contrasts occurred in the sequential rating of picture pleasantness, whereas only negative contrast occurred for olfactory ratings. Notably, overrating of hedonically negative odors following a positive olfactory context was observed even when participants had already rated these same negative odors beforehand; conversely, this did not occur for positive contrast for either sense. These findings indicate that negative odors are more strongly influenced than positive ones, and the rating of positive stimuli may be adjusted to the preceding rating independent of stimulus context. The findings of this study revealed the unique characteristics of hedonic contrast for the olfactory senses.

Intramodal Olfactory Priming of Positive and Negative Odors in Humans Using Respiration-Triggered Olfactory Stimulation (RETROS).

Priming describes the principle of modified stimulus perception that occurs due to a previously presented stimulus. Although we have begun to understand the mechanisms of crossmodal priming, the concept of intramodal olfactory priming remains relatively unexplored. Therefore, we applied positive and negative odors using respiration-triggered olfactory stimulation (RETROS), enabling us to record the skin conductance response (SCR) and breathing data without a crossmodal cueing error and measure reaction times (RTs) for olfactory tasks. RT, SCR, and breathing data revealed that negative odors were perceived significantly more arousing than positive ones. In a second experiment, 2 odors were applied during consecutive respirations. Here, we observed intramodal olfactory priming effects: A negative odor preceded by a positive odor was rated as more pleasant than when the same odor was preceded by a negative odor. Additionally, a longer identification RT was found for the second compared with the first odor. We interpret this as increased "perceptual load" due to incomplete first odor processing while the second odor was presented. Furthermore, intramodal priming can be considered a possible reason for the increase of identification RT. The use of RETROS led to these novel insights into olfactory processing beyond crossmodal interaction by providing a noncued unimodal olfactory test, and therefore, RETROS can be used in the experimental design of future olfactory studies.

Gender Differences in Time Perception During Olfactory Stimulation

In this study, we conducted two experiments to evaluate the effect of different types of odors on a time reproduction task, comparing performances of males to those of females. In the first experiment, subjects had to estimate short (510, 600, 690 ms) and long (1700, 2000, 2300 ms) interval durations under three odor conditions: positive, negative and neutral. A gender specific effect of olfactory stimulation on time estimation was found only for short durations. Namely, females were less accurate (overestimated) in reproducing short time intervals during the unpleasant odor presentation. This effect was confirmed and strengthened in the second experiment in which the intensity of the negative odor was enhanced. The present findings suggest that the neural network underlying time estimation is more “sensitive” to context manipulations in females than in men. Practical Applications The first important point is that there might be relevant gender differences in the processing of time (time estimation) that are mediated by olfactory stimulation. This new evidence might have important implications and applications in health issues and especially in workplace safety, for example in jobs or contexts in which fast processing and rapid decisions or choices are required. Therefore, the knowledge that females are more influenced by unpleasant odors than males during time estimation should be seriously considered in situations in which time plays a crucial role such as during rapid decision-making, where automatic processes should be efficiently activated. Overall, the higher sensitivity to specific olfactory stimulation observed in women probably reflects individual differences in a complex process such as time processing.