Odor Threshold Research Articles

Evaluation of the Perceptual Interaction among Ester Odorants and Nonvolatile Organic Acids in Baijiu by GC-MS, GC-O, Odor Threshold, and Sensory Analysis.

By applying the aroma extract dilution analysis, 13 esters were found to have high FD factors in the Laobaigan flavor type of Baijiu. These were then quantified using GC-MS. In addition, 35 nonvolatile organic acids were quantified by a derivatization method combined with GC-MS. The perceptual interactions of lactic acid and ethyl lactate and that of lactic acid and ethyl acetate were studied through the olfactory threshold. The S curve was used to evaluate the changes in the olfactory thresholds. After adding lactic acid (1142, 20 000, and 53 703 mg/L), the olfactory thresholds of ethyl lactate (1000, 724, and 295 mg/L) and ethyl acetate (398, 324, and 257 mg/L) decreased obviously, which revealed that lactic acid gave additive or synergistic odor effects for the two esters. Furthermore, it was discovered that as the concentrations of lactic acid increased, the extent of the interaction among these compounds was also greater in the mixture.

Feasibility of a culture-specific Moroccan Smell Identification Test (MoroSIT): a proposal using the case of Parkinson disease

Introduction: Olfactory problems are frequent in Parkinson disease. Their early onset relative to motor problems makes them a potential biomarker for the disease, yet no culture-specific standardized tests exist in Morocco. Aim: To use indigenous plant extracts generated in our laboratory to investigate olfactory impairment in patients with Parkinson disease. Method: Our study is a cross-sectional case-controlled analytical investigation in a group of 69 patients with Parkinson disease and another group of 66 healthy volunteers in order to assess odor threshold, odor identification, and odor discrimination in these two groups using Mentha pulegium and Lavandula latifolia extracts. Results: We found a marked decrease of the threshold of odor detection in patients compared to controls (p<0.001). A statistically significant difference was found between the ability to discriminate odors, with more patients with Parkinson disease unable to distinguish between odors (p<0.001). For the odor identification test, 70% of control subjects versus 36% of patients were able to correctly identify the test products. The difference was statistically significant (p<0.001). Conclusions: Our study points to the potential for the elaboration of a standardized smell identification screening battery using indigenous products with which patients are familiar.

Synthesis of amine grafted Cu-BTC and its application in regenerable adsorption of ultra-low concentration methyl mercaptan

Purification of volatile sulfur compounds is a hot topic since these malodorous gases with low odor thresholds are generated in both community and industry. Adsorption is an effective method, but adsorbent regeneration is usually difficult because of the strong bond between adsorbent and malodorous gases. In this work, an amine-grafted metal–organic framework was synthesized and applied in cyclic adsorption of ultra-low concentration methyl mercaptan (MM). As a result, MM was effectively purified to below 50 ppb for 1062 min, resulting in a breakthrough capacity of 84.9 mg/g. In comparison, the breakthrough time and capacity without grafting amine were 777 min and 58.6 mg/g, respectively. After detailed characterizations, Cu2+ site and amine group were both attributed to MM removal. Although Cu2+ site was unregenerable, the amine group was regenerable with a capacity of 17.9–19.4 mg/g since the N-H bond was weak between amine and MM. In addition, competitive gases CO and CO2 only decreased the breakthrough time and capacity by 10%. The main result of this work is in favor of applying a regenerable adsorbent for purification of ultra-low concentration malodorous gas.

Scent of knowledge: The molecular fingerprint of volatiles in an emblematic historical library in Italy.

Heritage guidelines recognize odors as a value associated with a place. This study aims to clarify the connection between heritage and volatile organic compounds at the molecular level. At variance with previous studies, usually focused only on book-related compounds from accelerated degradation tests, the whole air of one of the most significant historical libraries in Italy was studied. A sampling of the volatiles off-gassing from the two most iconic rooms, respectively open and forbidden to visitors, was performed via a non-invasive, nondestructive green method, solid-phase-micro-extraction. The gas-chromatographic analyses resulted in the appraisal of olfactory contributions from books, storage environment, and, for the first time, anthropic activities and pollution.Concerning the paper decay process, for the very first time, the presence of 2-ethyl-1-hexanol in the chromatographic signature of the library air is rationalized according to the Guerbet reaction. The presence of all other compounds is explained by the paper decay process, anthropic sources, and pollution. Indoor air comprises analytes related to paper decay, identified by previous studies, and additional compounds never found before.Most volatile compounds are aliphatic and aromatic hydrocarbons, aldehydes, alcohols, terpenes, and terpenoids. Odor contributions from a selected number of analytes were pinpointed. Alkanes dominate the volatiles chromatographic signature, and impart a slight hydrocarbon smell. Aromatics supplement their characteristic aromatic odor. Aldehydes' very low odor threshold makes them strongly contribute to both fruity and fatty descriptors. Benzaldehyde, furfural, vanillin, and camphor add, respectively, an hint of almond, bread, vanilla, and camphor. Alcohols such as 2-ethyl hexanol have a floral scent. Wood-related terpenes and terpenoids contribute to the woody smell of the library.The digital molecular fingerprint of the "scent of knowledge" enables documentation, conservation, and future chemical reproduction of the historical library odor.

Management of post-COVID olfactory disorder: Is olfactory training effective on recovery of olfactory mucosal function?

BACKGROUND: The number of patients presenting with sudden onset and persistant anosmia and other olfactory disorders, which is a finding related to coronavirus disease has been increased considerably. In this study, we aimed to evaluate the efficacy of olfactory training in patients with persistent anosmia after Covid-19 infection.
 METHODS: Forty-six patients who applied for sudden loss of smell after Covid-19 infection and still had olfactory disorders were included in the study. Odor threshold and odor identification tests were performed on the patients before the treatment. As olfactory training, 4 scent bottles included the following groups: phenyl ethyl alcohol, eucalyptol group, citronellal group and eugenol group were given to patients and patients instructed to sniff the odors twice a day, for 5 seconds each, when they woke up in the morning and before they went to sleep and make a daily check that they applied the treatment. Patients who continued the training for 12 weeks were re-evaluated with the odor threshold test and odor identification test.
 RESULTS: The pre-training mean olfactory threshold score of the patients was 1.65±1.74, and the post-training mean olfactory threshold score was 3.89±2.73. It was observed that the olfactory threshold scores increased significantly after the olfactory training (p

Influence of elongation and desaturation on chemosensory properties in acrylates and their corresponding 1-alken-3-ones

Acrylates as well as 1-alken-3-ones are both known to be odour active substances but are generally identified in different materials. Nonetheless, butyl acrylate and 1-octen-3-one were both found to elicit a similar mushroom-like odour in previous studies. This led to the question of whether acrylates and enones with the same overall chain length generally elicited similar odours and whether they had similar odour thresholds. Overall, most of the investigated substances showed a mushroom-like, geranium-like or fruity odour. In contrast, short chained substances elicited garlic-like, lighter gas-like or glue-like, odour qualities, suggesting a correlation between the odour quality and the overall chain length. The results showed that only between the analogue structures butyl acrylate and 1-octen-3-one as well as hexyl acrylate and 1-decen-3-one could similar odour qualities be observed. All investigated substances showed low odour threshold values in air between 0.0032 ng/lair (1-hexen-3-one) and 55 ng/lair (1-dodecen-3-one). Overall, 1-alken-3-ones revealed a higher dependency on the chain length when compared to their respective acrylates. The introduction of a second terminal double bond led to a decrease of OT values in case of the acrylates and to an increase in case of the ketones that neither contained a second terminal double bond nor a double bond located close to the carbonyl group. Despite their structural similarities, the results suggest that both substance classes are perceived in a different manner and are therefore likely to be recognized by different types of receptors or are related to different activation patterns in multi-receptor stimulation processes.Graphical abstract

Optimized Solid-Phase Mesh-Enhanced Sorption from Headspace (SPMESH) for Rapid Sub-ng/kg Measurements of 3-Isobutyl-2-methoxypyrazine (IBMP) in Grapes.

Parallel extraction of headspace volatiles from multiwell plates using sorbent sheets (HS-SPMESH) followed by direct analysis in real-time high-resolution mass spectrometry (DART-HRMS) can be used as a rapid alternative to solid-phase micro-extraction (SPME) gas-chromatography mass-spectrometry (GC-MS) for trace level volatile analyses. However, an earlier validation study of SPMESH-DART-MS using 3-isobutyl-2-methoxypyrazine (IBMP) in grape juice showed poor correlation between SPMESH-DART-MS and a gold standard SPME-GC-MS around the compound’s odor detection threshold (<10 ng/kg) in grape juice, and lacked sufficient sensitivity to detect IBMP at this concentration in grape homogenate. In this work, we report on the development and validation of an improved SPMESH extraction approach that lowers the limit of detection (LOD < 0.5 ng/kg), and regulates crosstalk between wells (<0.5%) over a calibration range of 0.5–100 ng/kg. The optimized SPMESH-DART-MS method was validated using Cabernet Sauvignon and Merlot grape samples harvested from commercial vineyards in the central valley of California (n = 302) and achieved good correlation and agreement with SPME-GC-MS (R2 = 0.84) over the native range of IBMP (<0.5–20 ng/kg). Coupling of SPMESH to a lower resolution triple quadrupole (QqQ)-MS via a new JumpShot-HTS DART source also achieved low ng/kg detection limits, and throughput was improved through positioning stage optimizations which reduced time spent on intra-well SPMESH areas.

Volatile composition of the morning breath

We have measured the composition of volatile organic compounds (VOCs) in the morning breath of 30 healthy individuals before and after tooth brushing. The concentrations of VOCs in the breath samples were measured with proton-transfer-reaction time-of-flight mass spectrometry (MS) and further identification was performed with a combination of solid phase microextraction and offline gas chromatography–MS. We hypothesize that compounds, whose concentrations significantly decreased in the breath after tooth brushing are largely of microbial origin. In this study, we found 35 such VOCs. Out of these, 33 have been previously connected to different oral niches, such as salivary and subgingival bacteria. We also compared the concentrations of the 35 VOCs found in increased amounts in the morning breath to their respective odor thresholds to evaluate their ability to cause odor. Compounds that could contribute to the breath odor include many volatile sulfur compounds, such as methanethiol, hydrogen sulfide, dimethyl sulfide, and 2-methyl-1-propanethiol, but also other VOCs, such as acetic acid, butyric acid, valeric acid, acetaldehyde, octanal, phenol, indole, ammonia, isoprene, and methyl methacrylate.

Association between environmental air pollution and olfactory functioning among Italian adolescents and young adults in Northern Italy

BACKGROUND AND AIM Olfaction is a critical physiological process with various functions in humans and olfactory impairments are associated with neurodegenerative disease and decreased quality of life. Olfactory receptors are in direct contact to ambient air, and thus, olfactory function is uniquely vulnerable to airborne pollutants. Here, we investigate associations between ambient air pollutant exposure and olfactory function in adolescents and young adults in the province of Brescia, Italy. METHODS This study included 207 subjects (52.7% female, 15-25 years) enrolled in the ongoing longitudinal Public Health Impact of Metals Exposure (PHIME) study. All participants completed a baseline (2008-2014) and follow-up (2017-2021) olfactory performance assessment using the &amp;#x22;Sniffin’ Sticks”, a psychophysical test to assess odor threshold, discrimination and identification. Spatial annual average concentrations of particulate matter (PM) PM10, PM2.5 and nitrogen dioxide (NO2) were estimated for the target area between 2016-2019 on a 4 x 4 km2 spatial resolution grid by means of the Chemical Transport Model ARIA Regional. We applied multivariable beta regression models to test for associations between each pollutant and olfactory functions. RESULTS All air pollution annual average values were below European air quality standards (mean +/- SD g/m3 PM2.5 = 18.4 +/- 5.1; PM10 = 21.0 +/- 5.3; NO2 = 32.1 +/- 9.8). We observed a significant negative association between NO2 and olfactory threshold score; a 14% decrement (approximately 2 score points) for each 10 unit increase in NO2 (p = 0.042), adjusting for age, sex, Sniffin’ identification baseline score, having a cold and/or allergic rhinitis, IQ and passive smoking exposure. CONCLUSIONS These results suggest increased NO2 exposure is associated with reduced olfactory function in these Italian adolescents and young adults. The identification of risk factors for olfactory functions can help prevent reduced quality of life and improve recovery. KEYWORDS Olfactory functions; air pollution; NO2; PM2.5; PM10

Sensory relevance of seven aroma compounds involved in unintended but potentially fraudulent aromatization of wine due to aroma carryover

Bottling regular wines following aromatized wines on the same filling lines bears the risk of unintentional aroma carryover, which has led to accusations of illegal aromatization. Obeying guidelines of good manufacturing practice, aroma carryover with no sensory relevance shall be considered as a technical unavoidable transfer having no legal consequences. To detect sensory relevance, odor activity values greater than one are proposed. Odor detection thresholds (OTs) were determined in water, model wine, and white wine for three lactones, α-ionone, ethyl 2-methylbutanoate, trans-cinnamaldehyde, and eugenol. Using different matrices OTs varied by factors of 2 for α-ionone and up to 23000 for ethyl 2-methylbutanoate. For α-ionone, being most prone for carryover, the three times higher OT of consumers did not trigger any preference for the aromatized wines, but rejection at 300 µg/L. Assessing α-ionone spiked wines by descriptive analysis, significant changes in sensory attributes only occurred at concentrations 10 times above OT.

Acetobacter sp. improves the undesirable odors of fermented noni (Morinda citrifolia L.) juice

To clarify the role of Acetobacter sp. in fermented noni juice, the physiochemical properties, main active ingredients and volatile constituents were comprehensively analyzed. The sugar content and acidity tended to be stable after 12 days of fermentation. Acetobacter sp. had no significant influence on major active ingredients of products. The headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) were performed to describe the characteristic flavor profiles during fermentation. A total of 55 flavor compounds were screened with odour threshold and Kruskal-Wallis p < 0.05. Among them, 14 different biomarkers were selected with Variable Importance in Projection (VIP) greater than 1. The concentrations of ketones and aldehydes increased significantly, mainly contributing to the floral, fruit and green features. The content of hexanoic acid, octanoic acid and butanoic acid as the main source of peculiar odor were significantly reduced, indicating Acetobacter sp. could improve the unpleasant odor of fermented noni juice.

Smell as a Disease Marker in Multiple Sclerosis.

Existing data suggest that people with multiple sclerosis (pwMS) are at an elevated risk for experiencing olfactory impairment. We investigated if smell dysfunction can be used as an MS disease marker. This is a cross-sectional, case–control study. All data were collected prospectively from 171 participants, 115 pwMS and 56 controls (age and sex stratified and matched to the patients), who reported smell, taste, and nasal breathing, and completed the Greek-validated questionnaires for nasal obstruction (NOSE), nasal-symptoms QoL (SNOT-22), and olfaction-associated QoL (QOD). The smell was assessed with the “Sniffin’ sticks” (odor threshold (OT), discrimination (OD), identification (OI) test, and total TDI). We recorded the pwMS disease characteristics (Expanded Disability Status Scale-EDSS, the disease type and duration), cognitive function, emotional status, fatigue, and impact of MS in everyday activities. A TDI < 30.75 (hyposmia) was detected in 30.8% of the patients. The patients’ OD and TDI scores were significantly lower than the controls’ (p = 0.005, and 0.015, respectively). The hyposmia correlated with disease severity and duration. The EDSS score correlated negatively with OD (r = −0.299, p = 0.001) and TDI (r = −0.242, p = 0.01). The disease duration correlated negatively with OD (r = −0.305, p = 0.001, OI (r = −0.253, p = 0.008) and TDI (r = −0.3, p = 0.001). The information processing speed (SDMT) correlated with OD, OT, and TDI (r = 0.302, p = 0.002; r = 0.242, p = 0.016; r = 0.326, p = 0.001). The olfactory function is changing in MS in accordance with disease progression.

Enhanced aroma and flavour profile of fermented Tetragonula pagdeni Schwarz honey by a novel yeast T. delbrueckii GT-ROSE1 with superior fermentability

Beside a source of bioactive compounds, honey represents untapped-reservoir of beneficial microbes. Next generation sequencing technology was applied to aid the discovery of newly-isolated flavour yeast Torulaspora delbrueckii strain GT-ROSE1 from honey samples. Owing to the presence of natural duplicate regulatory sites in aromatic genes, it was used to create value-added fermented honey with unique aroma-flavour profile. This osmophilic strain could assimilate different carbons and tolerated to low pHs, high ethanol and sugars, exhibiting useful traits for food and alcoholic fermentation of sugar-based industries. Global analysis of aroma-flavour profile revealed higher total concentrations of key compounds after fermentation by GT-ROSE1, compared to commercial wine yeasts. Twenty-four volatile compounds were identified using a nontargeted HS-SPME-GC-MS method. High odour activity values and quantitative sensory analysis indicated fruity and rose flowery aroma of key compounds nonanol and 2-phenylethanol, respectively. Importantly, fermented Tetragonula pagdeni Schwarz honey with observed excellent antioxidant property displayed appealing characteristic of enhanced 2-phenylethanol of rose-like flavour with odour threshold of 16.08. Thus, flavour yeast could be used to improve chemical content and enhance sensory value of local food products.

Heterofermentative lactic acid bacteria such as Limosilactobacillus as a strong inhibitor of aldehyde compounds in plant-based milk alternatives

Reduction of greenhouse gas emissions is important to limit climate change. Because ruminant animals emit greenhouse gases, the worldwide plant-based alternative market is an emerging trend for eating less meat and dairy products. To produce plant-based dairy products such as yogurt alternatives, certain lactic acid bacterial species, which are used for cow's milk fermentation, are often used. Substrate changes from cow's milk to plant-based milk caused nutritional changes, and unsaturated fatty acids are more enriched in plant-based milk alternatives than in cow's milk. Unsaturated fatty acids can lead to the formation of aldehydes, some of which are off-flavors; therefore, substrate changes have the potential to alter the suitable lactic acid bacterial species used for fermentation to control flavor formation, such as aldehyde compounds. However, differences in the effect of the fermentation processes on aldehyde compounds have not been evaluated among lactic acid bacterial species. In this study, we comprehensively evaluated the effect of lactic acid bacterial fermentation on aldehyde compounds in synthetic medium and plant-based milk alternatives using 20 species of lactic acid bacteria. Heterofermentative lactic acid bacteria such as strains belonging to Limosilactobacillus had a strong aldehyde-reducing ability, likely from differences in alcohol dehydrogenase function. Because the odor detection threshold of ethanol compounds was lower than that of their equivalent aldehyde compounds, our findings are valuable for the fermentation of plant-based milk alternatives with lactic acid bacteria with the goal of decreasing off-flavors derived from aldehyde compounds.

Principles for the selection of a sensory panel for the evaluation of car interior materials

AbstractVehicle interior air quality has gained importance since the 1990s. One of the most widely accepted methods to measure emissions in this respect is the VDA 270—Determination of the odor characteristics of trim materials in motor vehicles. So far, it describes the odor evaluation procedure, but not the selection of the sensory panel. Therefore, the aim of this study was to investigate principles that might be applicable for the selection of a VDA 270 panel. Based on this work, a dedicated three‐step approach is detailed to aid in selecting a panel. It comprises of an odor threshold determination, a hedonic tone evaluation and a reproducibility test. In addition, a “Screening 12” test was performed to verify the assessors' olfactory function. The selection was not specific to gender and the age of the candidates ranged from 19 to 55 years. Out of 26 volunteers, only 10 were able to meet all of the self‐developed criteria for the panel. With this approach, the individual ratings of the selected panelists did not deviate by more than two odor grades for the selected polyolefin samples considering the VDA 270 scale.Practical ApplicationsA meaningful comparison and interpretation of VDA 270 data requires objective test results. This is challenging as the VDA 270 scale is, at least partly, subjective and only a small minimum number of panelists is defined. The terminology used in the 6‐point scale itself was investigated in order to deduce potential tests for the panel selection procedure. Relevant international standards that are linked to the topic of interior air quality were screened to compare related guidelines for the panel selection. The implementation of a selection procedure needs to consider practical aspects in an industrial environment, too. Therefore, feasibility and quality issues are discussed to overcome some of those problems. As fundamental questions of sensory testing are involved this work might be relevant for other olfactory screening applications in an industrial setup. However, where hedonic tone measurements are required only consumer panels can provide reliable information.

Assessment of postviral qualitative olfactory dysfunction using the short SSParoT in patients with and without parosmia.

PurposeTo examine if the short formed Sniffin Sticks Parosmia Test (SSParoT), a test for parosmia can distinguish cases with parosmia from cases without parosmia.MethodsIn this study, 63 patients with postviral olfactory dysfunction were investigated including both COVID and non-COVID cases. The age, symptom duration, degree of parosmia/phantosmia was collected. For olfactory function, the Sniffin Sticks olfactory score was obtained including scores for odor threshold, discrimination and identification. For assessment of parosmic changes, the short SSParoT was adopted and both hedonic range (HedRang) and direction (HedDir) was calculated.ResultsThe mean HedRang of patients with parosmia (2.35, standard deviation, SD = 1.40) and without parosmia (2.78, SD = 1.09) was smaller than that in controls (4.5, SD = 2.15). However, the mean HedDir of both parosmia (− 0.32, SD = 0.98) and non-parosmia patients (0.04, SD = 1.07) was similar to controls (− 0.1, SD = 1.55). When considering that the 10th percentile of the distribution of SSParoT score should distinguish between patients with and without parosmia, the sensitivity of the HedRang was 29% and specificity was 67%. For HedDir, the sensitivity was 6% and specificity was 100%. Only the odor identification score (r = 0.34, p = 0.01) discriminated parosmia and non-parosmia while other measures including HedRang and HedDir did not.ConclusionThe present study showed that the short SSParoT score could not distinguish patients with parosmia from patients without parosmia. Although the SSParoT represents an innovative approach to assess parosmia, and could be useful in the tracking of parosmic changes, the development of measures to diagnose parosmia in an objective way remains a challenge.

Long-term quality-of-life impairment in patients with more than 1-year COVID-19-related olfactory dysfunction.

Long-term quality-of-life impairment in patients with more than 1-year COVID-19-related olfactory dysfunction.

Decoding the Specific Roasty Aroma Wuyi Rock Tea (Camellia sinensis: Dahongpao) by the Sensomics Approach.

Aroma extract dilution analysis was performed on volatile fractions extracted from a freshly prepared Dahongpao (DHP) tea infusion using solvent-assisted flavor evaporation, yielding 65 odor-active domains with flavor dilution factors ranging between 32 and 32,768. In addition, six aromatic substances were captured by headspace analysis. Quantitation of 54 compounds by an internal standard method and stable isotope dilution assays revealed that the concentrations of 32 odorants exceeded their respective orthonasal odor threshold values in tea infusion. The results of odor activity values (OAVs) suggested that 2-metylbutanal (malty) and γ-hexalactone (coconut-like) had the highest OAVs (248 and 154). Eight odorants including γ-hexalactone (OAV 154), methyl 2-methylbutanoate (59), phenylacetic acid (7.2), acetylpyrazine (5.7), 2-methoxyphenol (3.4), p-cresol (2.7), 2,6-diethylpyrazine (2.7), and vanillin (1.8) were newly identified as key odorants in DHP tea infusion. An aroma recombination model in a non-volatile matrix extracted from tea infusion satisfactorily mimicked the overall aroma of DHP tea infusion, thereby confirming the identification and quantitative experiments. Omission experiments verified the obvious significance of 6-methyl-5-hepten-2-one (OAV 91), 2-ethyl-3,5-dimethylpyrazine (19), 4-hydroxy-2,5-dimethylfuran-3(2H)-one (13), and acetylpyrazine (5.7) as key odorants for the special roasty and caramel-like aroma of DHP tea.

Interactions between kafirin and pickle-like odorants in soy sauce flavor Baijiu: Aroma profile change and binding mechanism

The pickle-like odor, which was caused by the excess volatile sulfur compounds (VSCs), is an undesirable odor in soy sauce flavor Baijiu (SSB). The aim of this study was to explore the suppressing effect of kafirin, the internal prolamin of the raw material of Baijiu, on the pickle-like odor of SSB. The instrumental analysis (comprehensive two-dimensional gas chromatography, ultraviolet and visible spectrophotometry), human perceptions (aroma profile, odor thresholds) and in silico analysis methods (molecular docking) were combined to detect the changes of the pickle-like odor. After the addition of kafirin, the aroma profile of the pickle-like SSB changed and approached to that of the normal SSB. The volatility and the odor thresholds of VSCs decreased 22.05%-64.28% and increased 87.29%–232.57%, respectively. In conclusion, kafirin exhibited a significant suppressing effect on the pickle-like off-odor of SSB, and this effect could be used to reduce the off-odor of SSB and SSB-derived alcoholic beverages.

Chemical Composition, Physical Properties, and Aroma Profile of Ethanol Macerates of Mistletoe (Viscum album)

Maceration parameters such as alcohol and mistletoe content were studied to obtain high-quality macerates to produce biska, a traditional Istrian herbal spirit. An ethanol–water solution containing 25, 40, 55, and 70 v/v% ethanol and 20, 40, and 80 g/L mistletoe was macerated and pH, total acids, extract content, and color parameters were measured. Volatile compounds were determined by GC/MS. More than 150 different volatile compounds were detected. The composition of the ethanol–water solution and mistletoe content affects the values of total extract, total acids, and color. Samples with lower alcohol content have a higher number of different acids, aldehydes, alcohols, esters, and ketones, while macerates with higher alcohol content are rich in hydrocarbons and terpenes. Ethyl decanoate; ethyl hexynoate; ethyl octanoate; benzaldehyde; hexanal; octanal; and the terpene compounds limonene, cymene, menthone, humulene, eucalyptol, linalol, and borneol contribute significantly to the aroma of the macerates due to a low odor threshold. Ylangene and α- and β-bourbonene are tentatively determined new terpene molecules that are not found in the mistletoe literature, as well as thujone, which was also detected. For the preparation of aromatic macerates, 40–50 v/v% ethanol and about 40 g/L mistletoe should be used.