Chemical composition of household malodours - an overview

Smells Like Teen Spirit-A Model to Generate Laundry-Associated Malodour In Vitro

Although malodour formation on textiles and in washing machines has been reported to be a very relevant problem in domestic laundry, the processes leading to bad odours have not been studied intensively. In particular, the smell often described as "wet-and-dirty-dustcloth-like malodour" had not been reproduced previously. We developed a lab model based on a bacterial mixture of Micrococcus luteus, Staphylococcus hominis, and Corynebacterium jeikeium, which can produce this odour type and which might allow the detailed investigation of this problem and the development of counteractions. The model uses bacterial strains that have been isolated from malodourous textiles. We could also show that the three volatile compounds dimethyl disulfide, dimethyl trisulfide, and indole contribute considerably to the "wet-fabric-like" malodour. These substances were not only found to be formed in the malodour model but have already been identified in the literature as relevant malodourous substances.

Biological and Chemical Processes that Lead to Textile Malodour Development

The development of malodour on clothing is a well-known problem with social, economic and ecological consequences. Many people still think malodour is the result of a lack of hygiene, which causes social stigma and embarrassment. Clothing is washed more frequently due to odour formation or even discarded when permastink develops. The malodour formation process is impacted by many variables and processes throughout the textile lifecycle. The contact with the skin with consequent transfer of microorganisms, volatiles and odour precursors leads to the formation of a distinctive textile microbiome and volatilome. The washing and drying processes further shape the textile microbiome and impact malodour formation. These processes are impacted by interindividual differences and fabric type as well. This review describes the current knowledge on the volatilome and microbiome of the skin, textile and washing machine, the multiple factors that determine malodour formation on textiles and points out what information is still missing.

Olfaction scaffolds the developing human from neonate to adolescent and beyond

The impact of the olfactory sense is regularly apparent across development. The fetus is bathed in amniotic fluid (AF) that conveys the mother's chemical ecology. Transnatal olfactory continuity between the odours of AF and milk assists in the transition to nursing. At the same time, odours emanating from the mammary areas provoke appetitive responses in newborns. Odours experienced from the mother's diet during breastfeeding, and from practices such as pre-mastication, may assist in the dietary transition at weaning. In parallel, infants are attracted to and recognize their mother's odours; later, children are able to recognize other kin and peers based on their odours. Familiar odours, such as those of the mother, regulate the child's emotions, and scaffold perception and learning through non-olfactory senses. During juvenility and adolescence, individuals become more sensitive to some bodily odours, while the timing of adolescence itself has been speculated to draw from the chemical ecology of the family unit. Odours learnt early in life and within the family niche continue to influence preferences as mate choice becomes relevant. Olfaction thus appears significant in turning on, sustaining and, in cases when mother odour is altered, disturbing adaptive reciprocity between offspring and carer during the multiple transitions of development between birth and adolescence. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.

The Impact of Indoor Malodor: Historical Perspective, Modern Challenges, Negative Effects, and Approaches for Mitigation

Malodors, odors perceived to be unpleasant or offensive, may elicit negative symptoms via the olfactory system’s connections to cognitive and behavioral systems at levels below the known thresholds for direct adverse events. Publications on harm caused by indoor malodor are fragmented across disciplines and have not been comprehensively summarized to date. This review examines the potential negative effects of indoor malodor on human behavior, performance and health, including individual factors that may govern such responses and identifies gaps in existing research. Reported findings show that indoor malodor may have negative psychological, physical, social, and economic effects. However, further research is needed to understand whether the adverse effects are elicited via an individual’s experience or expectations or through a direct effect on human physiology and well-being. Conversely, mitigating indoor malodor has been reported to have benefits on performance and subjective responses in workers. Eliminating the source of malodor is often not achievable, particularly in low-income communities. Therefore, affordable approaches to mitigate indoor malodor such as air fresheners may hold promise. However, further investigations are needed into the effectiveness of such measures on improving health outcomes such as cognition, mood, and stress levels and their overall impact on indoor air quality.

Characterization of hazardous and odorous volatiles emitted from scented candles before lighting and when lit

Scented candles are known to release various volatile organic compounds (VOCs) including both pleasant aromas and toxic components both before lighting (off) and when lit (on). In this study, we explored the compositional changes of volatiles from scented candles under various settings to simulate indoor use. Carbonyl compounds and other VOCs emitted from six different candle types were analyzed under 'on/off' conditions. The six candle types investigated were: (1) Clean cotton (CT), (2) Floral (FL), (3) Kiwi melon (KW), (4) Strawberry (SB), (5) Vanilla (VN), and (6) Plain (PL). Although a large number of chemicals were released both before lighting and when lit, their profiles were noticeably distinguishable. Before lighting, various esters (n = 30) showed the most dominant emissions. When lit, formaldehyde was found to have the highest emission concentration of 2098 ppb (SB), 1022 ppb (CT), and 925 ppb (PL). In most lit scented candles, there was a general tendency to show increased concentrations of low boiling point compounds. For some scented candle products, the emission of volatiles occurred strongly both before lighting and when lit. For instance, in terms of TVOC (ppbC), the highest concentrations were observed from the KW product with their values of 12,742 (on) and 2766 ppbC (off). As such, the results suggest that certain scented candle products should act as potent sources of VOC emission in indoor environment, regardless of conditions--whether being lit or not.

Odor and VOC emissions from pan frying of mackerel at three stages: raw, well-done, and charred

Many classes of odorants and volatile organic compounds that are deleterious to our wellbeing can be emitted from diverse cooking activities. Once emitted, they can persist in our living space for varying durations. In this study, various volatile organic compounds released prior to and during the pan frying of fish (mackerel) were analyzed at three different cooking stages (stage 1 = raw (R), stage 2 = well-done (W), and stage 3 = overcooked/charred (O)). Generally, most volatile organic compounds recorded their highest concentration levels at stage 3 (O), e.g., 465 (trimethylamine) and 106 ppb (acetic acid). In contrast, at stage 2 (W), the lowest volatile organic compounds emissions were observed. The overall results of this study confirm that trimethylamine is identified as the strongest odorous compound, especially prior to cooking (stage 1 (R)) and during overcooking leading to charring (stage 3 (O)). As there is a paucity of research effort to measure odor intensities from pan frying of mackerel, this study will provide valuable information regarding the management of indoor air quality.