Volatile Odorants Research Articles

Characterization of Key Odor-Active Compounds in Draft Beers for the Chinese Market Using Molecular Sensory Science Approaches.

Beer is a popular alcoholic beverage worldwide. However, limited research has been conducted on identifying key odor-active components in lager-type draft beers for the Chinese market. Therefore, this study aims to elucidate the odor characteristics of the four most popular draft beer brands through a sensory evaluation and an electronic nose. Subsequently, the four draft beers were analyzed through solid-phase microextraction and liquid-liquid extraction using a two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry analysis (GC×GC-O-MS). Fifty-five volatile odor compounds were detected through GC×GC-O-MS. Through an Aroma Extract Dilution Analysis, 22 key odor-active compounds with flavor dilution factors ≥ 16 were identified, with 11 compounds having odor activity values > one. An electronic nose analysis revealed significant disparities in the odor characteristics of the four samples, enabling their distinct identification. These findings help us to better understand the flavor characteristics of draft beer and the stylistic differences between different brands of products and provide a theoretical basis for objectively evaluating the quality differences between different brands of draft beer.

Development of active hydrogel absorbent pads based on sodium alginate/potassium-doped carbon dots for chilled pork preservation

In this study, potassium-doped carbon dots (K-CDs) were added to sodium alginate (NaAlg) hydrogel to yield high-strength, antibacterial, antioxidant NaAlg hydrogel absorbent pads (NaAlg/K-CDs) to absorb chilled pork exudate during storage. The results revealed that the swelling rates of the NaAlg/K-CDs peaked at 3286.83%, a figure exceeding that of the commercial absorbent pads. Based on the bacterial diversity and richness results, Pseudomonas aeruginosa (P. aeruginosa) was evidently the dominant spoilage organism during chilled pork storage. On storage day 6, the P. aeruginosa population in the NaAlg/K-CDs hydrogel absorbent pad group was 82% of that in the control group. The total volatile basic nitrogen (TVB-N) value of the NaAlg/K-CDs group remained lower than 0.15 mg/g on day 8. The pH, TVB-N, total viable count (TVC), cooking loss, and volatile odour values of the chilled pork in the NaAlg/K-CDs hydrogel absorbent pad group were significantly lower than those in other absorbent pad groups. Moreover, the colour change and shear force values of the chilled pork in the NaAlg/K-CDs hydrogel absorbent pad group were lower than those in the control and wood fiber paper absorbent pad groups. These results indicate that the shelf life of the NaAlg/K-CDs-packaged chilled pork was extended by 2 days compared with that of the control. Therefore, the NaAlg/K-CDs hydrogel absorbent pads potentially inhibited microbial growth and improved the storage quality of chilled pork. This study provides an alternative solution against traditional chilled pork absorbent pads, further promoting the advancement of fresh meat preservation techniques.

Accentuation of the browning characteristics and functional properties of aged tomatoes (Solanum lycopersicum cv.)

Moisture-assisted aging technology (MAAT) is a green process that improves browning characteristics and functionalities. This study investigated the physicochemical and functional characteristics of aged tomatoes. MAAT modulated carotenoids biotransformation from esterified to free form (Fourier-transform infrared spectroscopy 1738, 2851, and 2922 cm−1) and generated primary and secondary oxidation volatiles, such as 4-terpineol, α-terpineol, and γ-terpineol (Headspace solid-phase microextraction gas chromatography-mass), which contributed woody and clove odors. Total flavonoids and α-glucosidase activity inhibitory were significantly increased from 1207.729 to 2318.204 mg RE/100 g DW and 77.703% to 86.851%, respectively. We discovered different synthesis pathways of 5-HMF and furfural under different water activities; this breakthrough may set furfural as an important factor in quality control of MAAT products in the future. Thus, MAAT can modulate the chemical form of tomato carotenoids, improve functionalities, and generate unique woody odor volatiles. These results may be applied to health food development in the food industry.

The impacts of cold plasma on the taste and odor formation of dried silver carp products

This study investigated non-thermal pretreatment (cold plasma, CP) on the flavor (taste and odor) profiles of dried fish products. CP treatment of 5 min contributed to accumulation of umami nucleotides adenosine 5′-monophosphate (AMP) from 30.96 to 40.82 μg/g and inosine 5′-monophosphate (IMP) from 2009.29 to 2132.23 μg/g, and significant reduction of bitter hypoxanthine ribonucleoside (HxR) and hypoxanthine (Hx), respectively (P < 0.05) in the dried fish products. A noticeable enhancement in sweet glycine (from 429.41 to 490.03 mg/100 g) and umami glutamic acid (from 55.68 to 67.76 mg/100 g) accompanied with the CP treatment (P < 0.05) based on taste activity value (TAV > 1). And the characteristic odor volatiles (nonanal, hexanal and 1-octen-3-ol) were strengthened 2.13-, 2.16- and 2.17- folds, respectively (P < 0.05). The results of equivalent umami concentration and Gibbs free energy calculation, combining with the correlation analysis, indicate that nucleotides and free amino acids synergically enhanced the taste improvement of dried fish products. Moderate lipids oxidation favored the formation of characteristic volatiles. The CP pretreatment offered new strategies for enhancing flavor of dried fish products.

Antifungal activity of bio-active cell-free culture extracts and volatile organic compounds (VOCs) synthesised by endophytic fungal isolates of Garden Nasturtium

Antimicrobial resistance in fungal pathogens (both human and plant) is increasing alarmingly, leading to massive economic crises. The existing anti-fungal agents are becoming ineffective, and the situation worsens on a logarithmic scale. Novel antifungals from unique natural sources are highly sought to cope sustainably with the situation. Metabolites from endophytic microbes are the best-fitted alternatives in this case. Endophytes are the untapped sources of ‘plants’ internal microbial population’ and are promising sources of effective bio-therapeutic agents. Fungal endophytes were isolated from Tropaeolum majus and checked for antifungal activity against selected plant and human pathogens. Bioactive metabolites were identified through chromatographic techniques. The mode of action of those metabolites was evaluated through various spectroscopic techniques. The production of antifungal metabolite was optimized also. In particular VOCs (volatile organic compounds) of TML9 were tested in vitro for their anti-phytopathogenic activity. Ethyl acetate (EA) extract of cell-free culture components of Colletotrichum aenigma TML3 exhibited broad-spectrum antifungal activity against four species of Candida and the major constituents reported were 6-pentyl-2H-pyran-2-one, 2-Nonanone, 1 propanol 2-amino. The volatile metabolites, trans-ocimene, geraniol, and 4-terpinyl acetate, produced from Curvularia lunata TML9, inhibited the growth of some selected phyto pathogens. EA extract hampered the biofilm formation, minimised the haemolytic effect, and blocked the transformation of Candida albicans (MTCC 4748) from yeast to hyphal form with a Minimum Fungicidal Concentration (MFC) of 200–600 µg mL−1. Central carbohydrate metabolism, ergosterol synthesis, and membrane permeability were adversely affected and caused the lethal leakage of necessary macromolecules of C. albicans. Volatile metabolites inhibited the growth of phytopathogens i.e., Rhizoctonia solani, Alternaria alternata, Botrytis cinerea, Cercospora beticola, Penicillium digitatum, Aspergillus fumigatus, Ceratocystis ulmi, Pythium ultimum up to 89% with an IC50 value of 21.3–69.6 µL 50 mL−1 and caused leakage of soluble proteins and other intracellular molecules. Citrusy sweet odor volatiles of TML9 cultured in wheat-husk minimised the infections of Penicillium digitatum (green mold), in VOC-exposed sweet oranges (Citrus sinensis). Volatile and non-volatile antifungal metabolites of these two T. majus endophytes hold agricultural and pharmaceutical interests. Metabolites of TML3 have strong anti-Candida activity and require further assessment for therapeutic applications. Also, volatile metabolites of TML9 can be further studied as a source of antifungals. The present investigational outcomes bio-prospects the efficacy of fungal endophytes of Garden Nasturtium.

Olfactory Responses of Asproparthenis punctiventris Germar to Leaf Odours of Amaranthaceae Plants.

Understanding the stimuli used by insect pests to find their food plants can be a first step towards manipulating their behaviour and, thus, controlling them. We investigated the responses of the sugar beet weevil Asproparthenis punctiventris (Coleoptera: Curculionidae) to the volatile leaf odours of its food plants, including Beta vulgaris subsp. vulgaris (Altissima and Cicla groups), Atriplex hortensis, Chenopodium album, and Amaranthus retroflexus, in a four-arm olfactometer. A bioassay procedure was developed, and the frequency of visits and time spent by adult weevils in the quadrant of the olfactometer with leaf volatiles was recorded, as was their first choice of quadrant. Females and males were equally attracted to the leaf odours of young B. vulgaris subsp. vulgaris plants, i.e., sugar beet and chard, as indicated by the overall picture of the behavioural parameters analysed. Males, but not females, responded positively to the leaf odour of the garden orache (A. hortensis), and no response was observed when the weevils were tested with the leaf odours of fat hen (C. album) or common amaranth (A. retroflexus). These results suggest that A. punctiventris uses leaf odours to locate sugar beet and other food plants. Knowledge of the olfactory responses of this pest can provide a basis for improved monitoring or mass trapping strategies.

Aviation Mutagenesis Alters the Content of Volatile Compounds in Dahongpao (Camellia sinensis) Leaves and Improves Tea Quality.

Aviation mutagenesis is a fast and efficient breeding method. In this study, we analyzed the effect of aviation mutagenesis on volatile compounds and odor characteristics in Dahongpao fresh leaves and gross tea for the first time. The results showed that aviation mutagenesis significantly increased the total volatile compounds of Dahongpao fresh leaves and gross tea. Aviation mutagenesis most critically significantly increased the content of beta-myrcene in Dahongpao fresh leaves, prompting its conversion to beta-pinene, cubebol, beta-phellandrene, zingiberene, (Z,Z)-3,6-nonadienal, and 6-pentyloxan-2-one after processing, which in turn enhanced the fruity, green, spicy, and woody odor characteristics of the gross tea. This study provided a reference for further exploration of aviation mutagenic breeding of Camellia sinensis.

Volatile organic compounds and odor emissions from typical building materials and air sample storage time analysis

Building materials are the main sources of indoor volatile organic compounds (VOCs) and odors, which significantly impact indoor air quality and perceived air quality. In this study, gas chromatography-mass spectrometry was used to measure VOC emissions from 34 building materials, while an untrained panel assessed odor intensity (OI) and acceptability (ACC). The total VOC (TVOC) concentrations ranged from 156.5 to 3572.0 μg/m3, with alkanes identified as the predominant types of VOCs. Formaldehyde and n-hexane were found to be the most abundant compounds. Aldehydes are the dominant odorants, with hexanal being the most prevalent one according to the odor activity value (OAV). OI ranged from 2.35 to 4.69, while ACC ranged from −0.49 to 0.36. Adhesives exhibited both the highest TVOC concentration as well as a strong odor compared to other building materials; furniture boards emitted the lowest TVOC concentrations; wall coverings emitted minimal levels of odors. The effects of storage time on VOC concentrations and odor assessments were analyzed after sample collection for different durations: 6 h, 24 h or 48 h. A storage time period of 24 h was determined to be sufficient for assessing OI and ACC whereas shorter durations may be required when analyzing VOC concentrations or OAV values. The data provided in this study could help regulate VOC and odor emissions from building materials, as well as facilitate developing a model correlating subjective assessment results of OI and ACC with objective measurements of VOC concentrations and OAV.

Chemical Characterization of Human Body Odor Headspace Components

This study focused on evaluating human body odor volatiles using a chamber approach. Ten participants were asked to sit inside the chamber for 1 h, while using SPME as the extraction technique for vapor sampling. A total of 105 compounds were detected across participants, with nonanal having the highest frequency. PCA statistical analysis depicted tighter clustering in female whole-body odor profiles when compared to males, thus corroborating gender odor differences. Concurrently, various biospecimens (hand, axillary, breath) from the same participants allowed for a comparison between whole-body and individual biospecimen odor signatures. When comparing whole-body sampling and distinctive biospecimens, nonanal and decanal were the only odor volatiles shared. Statistical clustering depicted higher similarity within the odor profiles of individual biospecimens compared to odor profiles of the whole body, indicating distinctiveness of the odor chemical landscape as a function of sampling region. Overall, this study demonstrated that SPME-GC/MS methodology was successful in the extraction, detection, and identification of previously reported human scent volatiles when employing the human chamber for whole-body sampling. Our presented testing paradigm allows for a direct comparison of odor volatiles across the full body and specific body locations that allows odor markers to be furthered exploited for diagnostic and biological detection contexts.

Odorant-binding proteins as recognition elements for smell exploration

The sense of smell in animals enables them to detect and discriminate among many volatile odor molecules in complex environments. This task is accomplished by the family of G-proteins (olfactory receptor proteins, odorant-binding proteins, and chemosensory proteins). Here, we mechanistically elucidate how odors bind to odorant-binding proteins (OBPs) by studying the binding properties of 50 odorant ligands to six OBPs. We confirmed that OBP7 from Ailuropoda melanoleuca and OBP9 from Anopheles gambiae have binding affinities for 16 odors, and further analyzed the structures and protein-ligand interactions by homology modeling and molecular docking. This study found that OBP7 had an affinity for nonanol and camphor, and the docking results indicated that Glu120 was a residue that played a key role in the binding process of OBP7 to odorant ligands. We also explored the binding properties between OBP9 and ligands as well as the binding mechanism, and found that OBP9 bound well to some odorant molecules with repellent efficacy, such as nonanol, camphor, and citral. These findings not only contributed to our understanding of how OBPs were sensitively bound to odorant ligands but also promoted them as suitable targets for applied research in various industrial fields such as pesticides, cosmetics, and pharmaceuticals.

Development of an automated human scent olfactometer and its use to evaluate detection dog perception of human scent.

Working Dogs have shown an extraordinary ability to utilize olfaction for victim recovery efforts. Although instrumental analysis has chemically characterized odor volatiles from various human biospecimens, it remains unclear what perceptually constitutes human scent (HS) for dogs. This may be in part due to the lack of methodology and equipment to train and evaluate HS perception. The aims of this research were 1) to develop an automated human scent olfactometer (AHSO) to present HS to dogs in a controlled setting and 2) use the AHSO to evaluate dogs' response to different scented articles and individual components of HS. A human volunteer was placed in a clear acrylic chamber and using a vacuum pump and computer-controlled valves, the headspace of this chamber was carried to one of three ports in a different room. Dogs were trained to search all three ports of the olfactometer and alert to the one containing HS. In Experiment 1 and 2, the AHSO was validated by testing two dogs naïve to HS (Experiment 1) and five certified Search and Rescue (SAR) teams naïve to the apparatus (Experiment 2). All dogs showed sensitivity and specificity to HS > 95% in the apparatus. In Experiment 3, we used a spontaneous generalization paradigm to evaluate generalization from the HS chamber to different scented articles exposed to the same volunteer and to a breath sample. Dogs' response rate to the different scented articles was < 10% but exceeded 40% for the breath sample. In Experiment 4, we replicated this result by re-testing spontaneous generalization to breath and when the volunteer had breath exhausted/removed from the chamber. Dogs' response rate to breath alone was 88% and only 50% when breath was removed. Altogether, the data indicate that exhaled breath is an important and salient component of HS under these conditions.

Impact of processing and storage on rancidity markers in commercial and novel cultivar candidates of intermediate wheatgrass (Thinopyrum intermedium)

AbstractBackground and ObjectivesBreeding of intermediate wheatgrass (Thinopyrum intermedium, IWG) culminated in the release of a commercial cultivar (MN‐Clearwater) with attractive environmental and nutritional benefits. Determining the impacts of ambient storage and common postharvest processing on the stability of IWG flour is essential to promote it as a food ingredient. Accordingly, MN‐Clearwater and two other potential cultivars, selected for their unique chemical composition, were subjected to extrusion and germination followed by 8 months of storage. Antioxidants, lipase and lipoxygenase activity, free fatty acid (FFA), peroxide value (PV), and volatile odor compounds (VOC) were analyzed at different timepoints.FindingsWhile germination caused a significant increase in lipase activity (~threefold in MN‐Clearwater), extrusion resulted in complete lipase degradation. Additionally, lipase activity was more consequential to hydrolytic rancidity than fat content. Regardless, results indicated that the endogenously abundant antioxidants can combat rancidity facilitated by enzymes and autoxidation as evidenced by significant losses in carotenoids between 3 and 6 months of storage (with 70%–80% reduction after 6 months of storage), when steep increases in FFA (up to 40% oleic acid/100 g fat), PV (two‐fourfolds increase after 6 months of storage), and VOC (hexanal and 2‐pentyl‐furan) occurred.Significance and NoveltyThe findings of this work serve as an impetus for IWG breeding advancements since enzymes and antioxidants can be traits that breeders may consider when selecting cultivar candidates. Results can be also utilized to understand the impact of postharvest processing of the grain on the storage stability of its flour.

Evolution remodels olfactory and mating-receptive behaviors in the transition from female to hermaphrodite reproduction

Male/hermaphrodite species have arisen multiple times from a male/female ancestral state in nematodes, providing a model to study behavioral adaptations to different reproductive strategies. Here, we examined the mating behaviors of male/female (gonochoristic) Caenorhabditis species in comparison with male/hermaphrodite (androdiecious) close relatives. We find that females from two species in the Elegans group chemotax to volatile odor from males, but hermaphrodites do not. Females, but not hermaphrodites, also display known mating-receptive behaviors such as sedation when male reproductive structures contact the vulva. Focusing on the male/female species C.nigoni, we show that female chemotaxis to males is limited to adult females approaching adult or near-adult males and relies upon the AWA neuron-specific transcription factor ODR-7, as does male chemotaxis to female odor as previously shown in C.elegans. However, female receptivity during mating contact is odr-7 independent. All C.nigoni female behaviors are suppressed by mating and all are absent in young hermaphrodites from the sister species C.briggsae. However, latent receptivity during mating contact can be uncovered in mutant or aged C.briggsae hermaphrodites that lack self-sperm. These results reveal two mechanistically distinct components of the shift from female to hermaphrodite behavior: the loss of female-specific odr-7-dependent chemotaxis and a sperm-dependent state of reduced receptivity to mating contact. Hermaphrodites from a second androdioecious species, C.tropicalis, recover all female behaviors upon aging, including chemotaxis to males. Regaining mating receptivity after sperm depletion could maximize hermaphrodite fitness across their lifespan.

Volatile organic compounds and odor emissions characteristics of building materials and comparisons with the on-site measurements during interior construction stages

Indoor air quality (IAQ) of newly constructed buildings is mainly affected by volatile organic compounds (VOCs) emitted from building materials introduced during interior construction. However, there are few studies in which detailed information is available on both the construction process and individual building materials, which are essential for simulating and validating indoor VOC emissions. In this study, eight building materials used in the interior construction of a finished residential unit in Nanjing, China, were tested in an environmental chamber. The VOCs and odor emission characteristics of the materials were analyzed and compared with the on-site measurements. Emission parameters of the building materials were regressed, the emission rate and total emission amount were calculated. The results showed that aldehydes were the main compounds in all the materials, accounting for 35.21% of emissions, on average. Among the aldehydes, formaldehyde was the main component, with a relative proportion ranging 32.91%–91.38% of total aldehydes. “Wet” materials were the main source of short-term VOC emissions at 24 h, and the wood floor was the main source of long-term emissions at 720 h. The “wet” materials contributed more to odor than “dry” materials. Aldehydes were the main target odorants, octanal was the largest odor contributor. The odor effect may last longer than the VOC concentration, according to the odor activity value variations. The differences in the material substrate, ambient conditions, and ventilation conditions may be the reasons for the difference in VOCs and odor source identification results between the construction stage and the environmental chamber test.

Modulation of marble-burying behavior in adult versus adolescent C57BL/6J mice of both sexes by ethologically relevant chemosensory stimuli.

The marble-burying test is a pharmacologically validated paradigm used to study anxiety-like behaviors in laboratory rodents. Our laboratory has employed this assay as part of a behavioral screen to examine drug-induced negative affective states. Historically, the majority of our prior binge alcohol-drinking studies employed male subjects exclusively and reliably detected adolescent-adult differences in both basal and alcohol withdrawal-induced negative affect. However, age-related differences in marble-burying behavior were either absent or opposite those observed in our prior work when female subjects were included in the experimental design. As chemosensory cues from females are reported to be anxiolytic in males, the present study examined how odors from adult members of the opposite and same sex (obtained from soiled bedding) influence marble-burying behavior in adult, as well as adolescent, mice. Control studies examined the responsiveness of mice in the presence of novel neutral (vanilla) and aversive (tea tree) odors. Adult males exhibited reduced signs of anxiety-like behavior in the presence of female-soiled bedding, while adult females and adolescent mice of both sexes increased marble-burying behavior in the presence of both male- and female-soiled bedding. All mice exhibited increased burying in the presence of an aversive odor, while only adolescents increased marble-burying in response to the novel neutral odor. These data indicate sex by age interactions in the effects of volatile and nonvolatile odors from sexually-naive adult conspecifics on indices of anxiety-like behavior in the marble-burying test of relevance to the experimental design and procedural timing of experiments including sex as a biological variable.

Production and purification of water using natural based adsorbent from plantain peels

Activated charcoal or carbon commonly employed as filter examinant of water, and air with surface area of 300–2,000m2/g, adsorbs a wide range of impurities and contaminants. This study was undertaken to produce adsorbent from plantain peels (Natural based), for the treatment of water samples, subsequently tested. Pyrolysis activation method was adopted using H3P04 and KOH. Water samples of wells from Gonigora, boreholes from Ungwan Romi, fishponds from Kawo and Kaduna Polytechnic, river water from river Kaduna, rain, tap from Tudun Wada and Eva water from Coca-Cola were used for the analysis. Which include water treatment, pH determination, total suspended, total dissolved, and total volatile solids, colour and odour determination. The results showed activated carbon effectiveness on pH of water samples well within 7.00, for borehole, Tap, and 7.02, for pond, rain and Eva waters, while 7.10 for river water. This indicated that the adsorbent is active and compared favorably with the standard adsorbent which pH of the water samples treated were 7.00 for pond, rain, tap and Eva, while 7.02 and 7.04 for borehole and river water respectively. This validated the production of granular natural based adsorbent via pyrolysis of plantain peels at 4500C by chemical activation method. Therefore an economical adsorbent obtained naturally based as cheap, readily available waste material for future commercial purification application.

Effects of Dendrobium officinale on physicochemical and flavor properties of yogurt during different fermentation time

Dendrobium officinale (DO), a valuable Chinese herb exhibiting enormous health benefits, has gained recognition as a functional food. DO contains abundant bioactive compounds, such as polysaccharides, dendrobine, flavonoids, amino acids, and volatile compounds and has been used to enhance the flavor and bioactive compounds in yogurt. This study aimed to explore the effects of DO on the physicochemical characteristics and flavor properties of yogurt at different fermentation times. The volatile compound profiles, concentration, and odor activity value (OAV) of yogurt at different fermentation times were assessed. The addition of DO reduced the pH and increased the acidity, apparent viscosity, and water-holding capacity. Furthermore, DO addition had a significant effect on the volatile compounds in fermented milk, which also significantly changed during the fermentation process. 2-Heptanone was identified as the major contributor to yogurt flavor at different fermentation times. Hierarchical cluster analysis revealed two significantly different clusters for the samples based on the concentration of the main compounds in samples obtained at different fermentation time points. Cluster 1 comprised the samples obtained at 1, 3.5, and 3 h of fermentation, whereas the other cluster comprised the samples at 1.5, 2, 2.5, and 4 h of fermentation. Additionally, certain unique compounds emerged or diminished depending on the fermentation time. These findings offer valuable insights for future reference in the development and quality control processes of DO-supplemented yogurt.

Changes of the volatile compounds and odors in one-stage and three-stage infant formulas during their secondary shelf-life

The odor of infant formula changes due to alterations in its volatile composition during the shelf life. However, there is currently a lack of research on whether the odor changes in infant formula during the secondary shelf life, which refers to the period of repeated opening and usage in daily life. This study used headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-electrostatic orbitrap high-resolution mass spectrometry (GC-Orbitrap-MS) to investigate the volatile composition changes in one-stage and three-stage infant formulas during different stages (0 day, 3 days, and 7 days during the secondary shelf-life, i.e. simulated daily use). A total of 32 volatiles were identified, including nine aldehydes, seven ketones, four alcohols, three furans, two sulfur compounds, two esters, and five terpenoids. Of these, 16 compounds changed significantly in one-stage samples and 23 compounds in three-stage samples within 7 days of the secondary shelf-life. Further the odor of the three-stage infant formula samples was found changed substantially after 3 days of simulated use by using the triangle test. This study highlighted the considerable alterations in volatile compound composition and sensory changes during the simulated daily use and provided valuable insights for consumers in selecting and using infant formula products, as well as a new perspective for enterprises to improve the sensory quality of their products.

Oxi-1 is required for chemotaxis to odorants sensed by AWA but not AWC neurons.

This study examines the role of the oxi-1 UBE3B gene in chemotaxis of C. elegans to volatile odorants. Compared to wild type worms, oxi-1 mutants showed no difference in chemotaxis to the AWC-specific odorant, isoamyl alcohol but a significant decrease in chemotaxis compared to odr-7 mutants. Both oxi-1 and odr-7 mutants exhibited significant decreases in chemotaxis to AWA-specific odorants, pyrazine and diacetyl. For thiazole, which is sensed by both AWA and AWC neurons, only odr-7 mutants showed significantly decreased chemotaxis. These data demonstrate oxi-1 is required for chemotaxis to AWA- but not AWC-specific odorants, the mechanisms of which should be investigated.

Can humans smell tastants?

Although studies have shown that olfaction may contribute to the perception of tastant, literature is scarce or circumstantial, especially in humans. This study aims to (i) explore whether humans can perceive solutions of basic prototypical tastants through orthonasal and retronasal olfaction and (ii) to examine what volatile odor compounds (VOCs) underlie this ability. Solutions of 5 basic tastants (sucrose, sodium chloride, citric acid, monosodium glutamate [MSG], quinine) dissolved in water, and 2 fatty acids (oleic and linoleic acid) dissolved in mineral oil were prepared. Triangle discrimination tests were performed (n = 41 in duplicate) to assess whether the tastant solutions can be distinguished from blanks (solvents) through ortho- and retronasal olfaction. Participants were able to distinguish all tastant solutions from blank through orthonasal olfaction. Only sucrose, sodium chloride, oleic acid, and linoleic acid were distinguished from blank by retronasal olfaction. Ethyl dichloroacetate, methylene chloride, and/or acetone were identified in the headspace of sucrose, MSG, and quinine solutions but not in the headspace of water, sodium chloride, and citric acid solutions. Fat oxidation compounds such as alcohols and aldehydes were detected in the headspace of the oleic and linoleic acid solutions but not the mineral oil. We conclude that prototypical tastant solutions can be discriminated from water and fatty acid solutions from mineral oil through orthonasal olfaction. Differences in the volatile headspace composition between blanks and tastant solutions may have facilitated the olfactory discrimination. These findings can have methodological implications for future studies assessing gustatory perception using these prototypical taste compounds.