Comparison evaluation pretreatments on the quality characteristics, oxidative stability, and volatile flavor of walnut oil.

In this study, we applied various thermal pretreatment methods (e.g., hot-air, microwave, and stir-frying) to process walnut kernels, and conducted comparative analysis of the physicochemical properties, nutritional components, in vitro antioxidant activity, and flavor substances of the extracted walnut oil (WO). The results indicated that, thermal pretreatment significantly increased the extraction of total trace nutrients (e.g., total phenols, tocopherols, and phytosterols) in WO. The WO produced using microwave had 2316.71 mg/kg of total trace nutrients, closely followed by the stir-frying method, which yielded an 11.22% increase compared to the untreated method. The WO obtained by the microwave method had a higher Oxidative inductance period (4.05 h) and oil yield (2.48%). After analyzing the flavor in WO, we found that aldehydes accounted for 28.77% of the 73 of volatile compounds and 58.12% of the total flavor compound content in microwave-pretreated WO, these percentages were higher than those recorded by using other methods. Based on the comprehensive score obtained by the PCA, microwave-pretreatment might be a promising strategy to improve the quality of WO based on aromatic characteristics.

Effect of industrial wastewater treatment system upgrade on the composition of emitted odorants and volatile organic compounds from a cheese production facility.

This study investigates the rarely studied volatile organic compound emissions from a cheese production facility and the impact of its wastewater treatment system upgrade on the composition of emitted odorants. Wastewater grab samples were collected from six separate wastewater channels before (2019) and after (2021) the system upgrade and analyzed for volatile organic compounds, pH, total dissolved solids, and electrical conductivity. Results showed that the channel from hard cheese production in 2021 had the highest number of volatile organic compounds (35), followed by the fresh cheese production channel (22). Following the industrial wastewater treatment system upgrade, a mineral oil contamination occurred; however, the number of odorants with nasal impact frequency (NIF) ≥ 0.5 in the effluent decreased from 11 to 5. 2-Propenoic acid butyl ester (NIF 0.75) stood out as the most prominent compound, described as fruity, waxy, or green. After the industrial wastewater treatment system upgrades, we observed a decrease in the number of odorants. However other measures must be taken to ensure proper wastewater processing. PRACTITIONER POINTS: More than 60 VOCs were identified in 6 channels from the cheese production facility.15 odorants in cheese production wastewater were detected by SPME-GC-MS/O. The most potent odorants before and after the system upgrade were 1-octen-3-ol and 2-propenoic acid butyl ester, respectively. The upgrades of the industrial wastewater treatment system had a positive impact on reducing the number of odorants and their odor intensity.

Effect of enzymatic Maillard reaction conditions on physicochemical properties, nutrition, fatty acids composition and key aroma compounds of fragrant rapeseed oil.

BACKGROUND: A new enzymatic hydrolysis-based process inspired by the Maillard reaction can produce strong flavored, high-value rapeseed oil that meets safety requirements. In the present study, the effect of reaction time (10-30 min) and temperature (130-160 °C) on the physicochemical properties, nutritional status, fatty acids composition and key aroma compounds of fragrant rapeseed oil (FRO) was investigated. RESULTS: An increasing reaction time and temperature substantially decreased the total tocopherol, polyphenol and sterol contents of FRO, but increased benzo[a]pyrene content, as well as the acid and peroxide values, which did not exceed the European Union legislation limit. Among the volatile components, 2,5-dimethyl was the main substance contributing to the barbecue flavor of FRO. The 150 °C for 30 min reaction conditions produced a FRO with a strong, fragrant flavor, with high total tocopherol (560.15 mg kg-1 ), polyphenol (6.82 mg kg-1 ) and sterol (790.65 mg kg-1 ) contents; acceptable acid (1.60 mg g-1 ) and peroxide values (4.78 mg g-1 ); and low benzo[a]pyrene (1.39 mg g-1 ) content. These were the optimal conditions for the enzymatic Maillard reaction, according to the principal component analysis. Furthermore, hierarchical cluster analysis showed that reaction temperature had a stronger effect on FRO than reaction time. CONCLUSION: The optimal enzymatic Maillard reaction conditions for the production of FRO are heating at 150 °C for 30 min. These findings provide new foundations for better understanding the composition and flavor profile of FRO, toward guiding its industrial production. © 2023 Society of Chemical Industry.

Volatile organic compounds (VOCs) of essential oils for the control of Fusarium oxysporum in cherry tomato seeds.

Fusarium oxysporum is the causal agent of Fusarium wilt in tomato plants. The most common form of control of this disease is through seed chemical treatment. However, the present work presents an alternative method, through the fumigation technique with essential oils. The pathogen F. oxysporum was inoculated on organic cherry tomato seeds through contact with sporulated Petri® plates. Thereafter, seeds were placed in stainless steel crucibles containing a 1.0 x 1.0 cm filter paper adhered to the lid and kept for 24 hours. This paper received 20 µL of each essential oil: tea tree, chia, citronella, lavender, anise basil, clove basil, and deionized water as control. This process was called "seed fumigation by essential oil". After this process, a germination test was carried out in germ boxes with Germitest® paper to verify the variables Germination Speed Index (GSI), Germination (G%), and Mean time to germination (MGT). Mycelial growth was verified in Petri® plates containing PDA medium. The plates containing mycelial growth were observed through scanning electron microscopy to verify possible morphological damage in the hyphae of the pathogen. Tea tree essential oil was the one that allowed the greatest suppression of the phytopathogen. Therefore, new tests were carried out with this specific oil. In germ boxes, tests of germination (G%), Abnormal seedlings count (ASC), and percentage of seedlings with mycelial growth were carried out. In addition, plant elicitation tests were performed in tomato seedlings through the analysis of chitinase, glucanase, and total proteins. All tests were carried out in completely randomized designs with four replications. All data were submitted to the Lilliefors normality test, followed by the analysis of variance, and Tukey's HSD (5% significance) for mean comparison. It was found that tea tree essential oil inhibited the mycelial growth of F. oxysporum without affecting the germination of cherry tomato seeds. Subsequent tests with this oil also demonstrated that there is a reduction in mycelia present in the seeds and a reduction in abnormal seedlings compared to the control. There was no significant difference between the variables tested for plant elicitation.

Distribution of and Temporal Variation in Volatiles in Tea (Camellia sinensis) Flowers during the Opening Stages.

Tea (Camellia sinensis) flowers emit a large amount of volatiles that attract pollinators. However, few studies have characterized temporal and spatial variation in tea floral volatiles. To investigate the distribution of volatiles within tea flowers and their variation among opening stages, volatile components from different parts of tea flowers and different opening stages were collected by headspace solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. A total of 51 volatile compounds of eight chemical classes were identified in the tea flowers. Volatile compounds were most abundant in tea flowers of the Shuchazao cultivar. Acetophenone, 1-phenylethanol, 2-phenylethanol, and benzyl alcohol were the most abundant volatiles. Terpenes were common in the sepals, and benzoids were common in the stamens. The fatty acid derivatives were mainly distributed in the pistils and receptacles and were less abundant in the petals, sepals, and stamens. During the opening phase of tea flowers, the volatile content increased 12-fold, which mainly stemmed from the increase in benzoids. These results enhance our understanding of the formation of volatiles in tea flowers.

Effect of continuous instant pressure drop treatment on the rheological properties and volatile flavor compounds of whole highland barley flour.

Continuous instant pressure drop (CIPD) treatment effectively reduces microbial contamination in whole highland barley flour (WHBF). Base on it, this study further investigated its effects on flour properties (especially rheological properties) and volatile compounds (VOCs) profile of WHBF, and compared it with that of ultraviolet-C (UV-C), ozone and hot air (HA) treatments. The results showed that the damaged starch content (6.0%) of CIPD-treated WHBF was increased, leading to a rough surface and partial aggregation of starch particle, thereby increasing the particle size (18.06 µm of D10, 261.46 µm of D50 and 534.44 µm of D90). Besides, CIPD treatment exerted a positive influence on the structure and rheological properties of WHBF, including an elevation in pasting temperature and viscosity. Notably, CIPD-treated WHBF exhibited higher storage modulus and loss modulus compared to the other three groups of sterilization treatments, contributing to the formulation of a better-defined and stable gel strength (tan δ = 0.38). UV-C and ozone, as cold sterilization techniques, also induced alterations in specific characteristics of WHBF. UV-C treatment led to changes in WHBF's crystallinity, while ozone treatment caused modifications in the secondary protein structure of WHBF. A total of 68 VOCs were identified in raw WHBF (including 3 acids, 19 alcohols, 25 aldehydes, 1 alkene, 8 esters, 2 ethers, 3 furans, and 7 ketones). The maximum flavor-contributing VOC in CIPD-treated WHBF remained dimethyl sulfide monomer (cabbage aroma), consistent with the raw WHBF. Conversely, in HA-treated WHBF, the maximum flavor-contributing VOC shifted to 2-furanmethanethiol monomer (roasted coffee aroma), altering the initial flavor presentation. These findings will provide strong support for the application of CIPD technology in the powdery foods industry.

Characteristic aroma-active components of fried green onion (Allium fistulosum L.) through flavoromics analysis.

Green onion (Allium fistulosum L.) is a perennial herb with a characteristic allium aroma. Meanwhile, fried green onion oil has a rich flavor that is popular in traditional Chinese cuisine. In this work, the key aroma components of fried green onion oil were focused via flavoromics analysis. The oil samples had a low score of a green aroma but a high score of salty, greasy aromas. Whereafter, a total of 36 aroma-active substances with flavor dilution (FD) factors ranging from 1 to 6561 were identified in fried green onion oil, while 42 were detected in fried green onion residue with FD factors ranging from 1 to 19683. Additionally, the recombination and omission tests revealed that furaneol, dimethyl trisulfide, allyl methyl trisulfide, (E,E)-2,4-decadienal, etc., were the key aroma compounds in fried green onion oil. Furthermore, the observation of the reaction of thioethers at high temperatures revealed that dimethyl disulfide undergoes polymerization to form dimethyl trisulfide. The research results can provide a theoretical basis for the standardization and industrial production of Chinese cuisine.

Effects of brewing water on the volatile composition of tea infusions.

There is a huge demand for brewing water in tea consumption, and the sensory flavor of tea infusion is significantly affected by the water used for brewing. To investigate the impact of brewing water on the aroma of tea infusions made from Camelia senensis, the three tea infusions of green, oolong and black tea brewed by six different drinking waters were analyzed by sensory evaluation, solid-phase microextraction, gas chromatography-mass spectrometry, and chemometrics. Brewing water with high pH values (>8.10) and high TDS content (>140 ppm) resulted in a lower overall aroma acceptability for tea infusion, where HCO3-, Ca2+ and Mg2+ were key influencing ions. A total of 86, 106, and 131 volatiles were identified in green, oolong and black tea infusions, respectively, which were strongly influenced by six different brands of waters. Decanal, dimethyl sulfide, ß-ionone and linalool were potent volatiles in tea aroma changes caused by brewing water.

The characteristic of the key aroma-active components in white tea using GC-TOF-MS and GC-olfactometry combined with sensory-directed flavor analysis.

BACKGROUND: White tea has become more and more popular with consumers due to its health benefits and unique flavor. However, the key aroma-active compounds of white tea during the aging process are still unclear. Thus, the key aroma-active compounds of white tea during the aging process were investigated using gas chromatography-time-of-flight-mass spectrometry (GC-TOF-MS) and gas chromatography-olfactometry (GC-O) combined with sensory-directed flavor analysis. RESULTS: A total of 127 volatile compounds were identified from white tea samples with different aging years by GC-TOF-MS. Fifty-eight aroma-active compounds were then determined by GC-O, and 19 of them were further selected as the key aroma-active compounds based on modified frequency (MF) and odor activity value (OAV). CONCLUSION: Aroma recombination and omission testing confirmed that 1-octen-3-ol, linalool, phenethyl alcohol, geraniol, (E)-ß-ionone, α-ionone, hexanal, phenylacetaldehyde, nonanal, (E, Z)-(2,6)-nonadienal, safranal, γ-nonalactone and 2-amylfuran were the common key aroma-active compounds to all samples. Cedrol, linalool oxide II and methyl salicylate were confirmed peculiar in new white tea, while ß-damascenone and jasmone were peculiar in aged white tea. This work will offer support for further studies on the material basis of flavor formation of white tea. © 2023 Society of Chemical Industry.

Recent Advances of VOCs Catalytic Oxidation over Spinel Oxides: Catalyst Design and Reaction Mechanism.

Volatile organic compounds (VOCs) harm the environment and human health and have been of wide concern and purified efficiently by catalytic oxidation. Spinel oxides, mainly composed of transition metal elements with low price and extensive sources, have been widely investigated as efficient and stable catalysts for VOCs oxidation due to their adjustable element composition, flexible structure, and high thermal/chemical stability. However, it is necessary to dissect the design of the spinel in a targeted way to satisfy the removal of different types of VOCs. This article systematically summarizes the recent advances regarding the application of spinel oxides for VOCs catalytic oxidation. Specifically, the design strategies of spinel oxides were first introduced to clarify their effect on the structure and properties of the catalyst. Then the reaction mechanism and degradation pathway of different kinds of VOCs on the spinel oxides were in detail summarized, and the characteristic requirements of the spinel oxides for various VOCs purification were analyzed. Furthermore, the practice applications were also discussed. Finally, the prospects were proposed to guide the rational design of spinel-based catalysts for VOCs purification and intensify the understanding of reaction mechanisms.

Effect of thermal process on the key aroma components of green tea with chestnut-like aroma.

BACKGROUND: Chestnut-like aroma is one of the unique qualities of Chinese green tea and has become an important factor influencing consumer decisions. However, the chemical formation mechanism of chestnut-like aroma during green tea processing remains unclear. In this study, the dynamic changes of key components contributing to chestnut-like aroma and their precursors were analyzed in fresh leaves, fixation leaves, first baking tea leaves, and green tea. RESULTS: The thermal process had an important effect on volatile components in tea leaves, causing a significant decrease of alcohols and esters and a significant increase of ketones, acids, phenols, and sulfur compounds. Furthermore, 31 volatiles were identified as the key odorants responsible for chestnut-like aroma of green tea, including dimethyl sulfide, methyl isobutenyl ketone, 2-methylbutanal, 2,4-dimethylstyrene, d-limonene, methyl 2-methylvalerate, linalool, decanal, longifolene, phenylethyl alcohol, l-α-terpineol, jasmone, and so on. And the majority of these odorants were only formed in the drying stage. Additionally, isoleucine, theanine, methionine, and glucose were found to be involved in the formation of chestnut-like aroma of green tea. CONCLUSION: The drying process played a vital important role in the formation of chestnut-like aroma of green tea. © 2022 Society of Chemical Industry.

Variation in Volatile Compounds of Raw Pu-Erh Tea upon Steeping Process by Gas Chromatography-Ion Mobility Spectrometry and Characterization of the Aroma-Active Compounds in Tea Infusion Using Gas Chromatography-Olfactometry-Mass Spectrometry.

Steeping process is an important factor for aroma release of tea, which has rarely been investigated for the aroma changes of raw Pu-erh tea (RAPT). In addition, the comprehensive aroma characteristics identification of RAPT infusion is necessary. In this study, GC-IMS coupled with principal component analysis (PCA) was used to clarify the difference of volatile profiles during the steeping process of RAPT. Furthermore, the volatiles contained in the RAPT infusion were extracted by three pretreatment methods (HS-SPME, SBSE, and SAFE) and identified using GC-O-MS. According to the odor activity value, 28 of 66 compounds were categorized as aroma-active compounds. Aroma recombination and omission experiments showed that "fatty", "green", "fruity", and "floral" are considered to be the main aroma attributes of RAPT infusion with a strong relationship with 1-octen-3-one, 1-octen-3-ol, (E)-2-octenal, ß-ionone, linalool, etc. This study will contribute a better understanding of the mechanism of the RAPT steeping process and volatile generation.

Characterization of Warmed-Over Flavor Compounds in Surimi Gel Made from Silver Carp (Hypophthalmichthys molitrix) by Gas Chromatography-Ion Mobility Spectrometry, Aroma Extract Dilution Analysis, Aroma Recombination, and Omission Studies.

The warmed-over flavor (WOF) in surimi gels was characterized by gas chromatography-ion mobility spectrometry, aroma extract dilution analysis, aroma recombination, and omission studies. Surimi gels with different WOF levels were prepared by different gelling temperatures, and surimi gels heated at 90, 100, and 121 °C were considered as the samples with light, strong, and medium WOF, respectively. Based on the quantification and odor activity values, 14 aldehydes, 2 ketones, 3 alcohols, 2 benzene-containing compounds, 2 N-containing compounds, 3 S-containing compounds, 3 lactones, undecanoic acid, and 4-methylphenol were recombined to build a spiked model for surimi gels with the strongest WOF, which showed the highest similarity with the original sample. Finally, a triangle test involving omission of the aroma compounds from the spiked model proved that the WOF in surimi gels was attributed to (E,E)-2,4-decadienal, heptanal, octanal, nonanal, decanal, (E)-2-nonenal, (E)-2-octenal, (E)-2-decenal, (E,E)-2,4-heptadienal, 2,3-pentanedione, 2,6-dimethylpyrazine, 2-propylpyridine, benzothiazole, 2-methoxybenzenethiol, and 2-furfurylthiol.

Time Depletion Effects on the Volatile Compounds from the Distillation Extracts of Prunella vulgaris and the Dynamics of their Extraction.

BACKGROUND: Prunella vulgaris (PV) is a low-growing perennial herb, which can be found in different parts of the world as Asia, Europe and North America. It is traditionally used for medicinal treatment in various cultures in India, China, Japan, Korea, Russia, and Eastern Europe for treating different ailments, such as fever, and healing wounds. In our previous article, we showed the anti-tumorous effect of the volatile organic compounds (VOCs) of PV and characterized the steam distillation process in the extraction of VOCs from PV. This has never been done before as we are aware of. To use the VOCs as drugs, there is a question of how much of the VOCs are lost before the prepared drugs reach the patients. Thus, the first aim of the present article is to try to explore the time depletion effect on the VOCs in the PV extracts. Then, the second aim is to extend the work in the previous paper and further understand the dynamics of the distillation process of PV by changing the steam flow rate in the extraction process. METHODS: To achieve the first aim to explore the aging effect of how much VOCs are depleted after they are extracted, the VOCs were first extracted by the same method as before, i.e., using steam distillation. Then, tubes of the aqueous solution containing the VOCs were then stored in a 5°C refrigerator. They were then taken out for GC-MS analysis according to a preplanned schedule up to 8 weeks after the VOCs were extracted. The chemical composition of the distillate could then be evaluated. This revealed the changes in the abundance of VOCs with aging. At the same time, the cell viability of SCC154 oral squamous cells treated by these herbal solutions, which were at different aging stages, was evaluated using a tetrazolium-based colorimetric reagent, Cell Counting Kit-8. To achieve the second aim of exploring the dynamics of the steam distillation process, the steam flow rate was adjusted by changing the temperature setting of the hot plate. GC-MS was again used to quantify the chemical constituents of the distillates. RESULTS: By using GC-MS to measure the abundance of volatile compounds at different time points after the distillation process, it was found that the volatile compounds persist for a very long time, or over 8 weeks, which was the longest period of our experiment. The aging of the distillates also did not depreciate much the cell cytotoxicity of the PV distillate on the cancer cells. With respect to the dynamics of the steam distillation process, it was found that, at a low steam flow rate, volatile compounds of lower molecular weight are more efficient to be extracted, while at a high steam flow rate, volatile compounds of higher molecular weight are more efficiently extracted. CONCLUSION: Our findings demonstrate that the VOC compounds extracted and present in aqueous form do not deplete much for at least 2 months after the extraction process, neither they exhibit cell cytotoxicity. The experiments on the dynamics of the steam distillation process demonstrate that the mass of herb present in the flow path of the steam has significant effects on the relative amounts of VOCs extracted.

Electroantennogram and machine learning reveal a volatile blend mediating avoidance behavior by Tuta absoluta females to a wild tomato plant.

Tomato cultivation is threatened by the infestation of the nocturnal invasive tomato pinworm, Tuta absoluta. This study was based on field observations that a wild tomato plant, Solanum lycopersicum var. cerasiforme, grown in the Mount Kenya region, Kenya, is less attacked by T. absoluta, unlike the cultivated tomato plants like S. lycopersicum (var. Rambo F1). We hypothesized that the wild tomato plant may be actively avoided by gravid T. absoluta females because of the emission of repellent allelochemical constituents. Therefore, we compared infestation levels by the pest in field monocrops and intercrops of the two tomato genotypes, characterized the headspace volatiles, then determined the compounds detectable by the insect through gas chromatography-linked electroantennography (GC-EAG), and finally performed bioassays using a blend of four EAG-active compounds unique to the wild tomato. We found significant reductions in infestation levels in the monocrop of the wild tomato, and intercrops of wild and cultivated tomato plants compared to the monocrop of the cultivated tomato plant. Quantitative and qualitative differences were noted between volatiles of the wild and cultivated tomato plants, and between day and night volatile collections. The most discriminating compounds between the volatile treatments varied with the variable selection or machine learning methods used. In GC-EAG recordings, 16 compounds including hexanal, (Z)-3-hexenol, α-pinene, ß-myrcene, α-phellandrene, ß-phellandrene, (E)-ß-ocimene, terpinolene, limonene oxide, camphor, citronellal, methyl salicylate, (E)-ß-caryophyllene, and others tentatively identified as 3,7,7-Trimethyl-1,3,5-cycloheptatriene, germacrene D and cis-carvenone oxide were detected by antennae of T. absoluta females. Among these EAG-active compounds, (Z)-3-hexenol, α-pinene, α-phellandrene, limonene oxide, camphor, citronellal, (E)-ß-caryophyllene and ß-phellandrene are in the top 5 discriminating compounds highlighted by the machine learning methods. A blend of (Z)-3-hexenol, camphor, citronellal and limonene oxide detected only in the wild tomato showed dose-dependent repellence to T. absoluta females in wind tunnel. This study provides some groundwork for exploiting the allelochemicals of the wild tomato in the development of novel integrated pest management approaches against T. absoluta.

Chemical and sensory characterization of coffee from Coffea arabica cv. Mundo Novo and cv. Catuai Vermelho obtained by four different post-harvest processing methods.

BACKGROUND: After the harvest, green coffee beans are dried on the farm using several methods: the wet process, natural process, pulped natural process, or mechanical demucilaging. This study evaluated how the choice of a specific processing method influenced the volatile organic compounds of the coffee beans, before and after roasting, and the sensory characteristics of the beverage. Coffea arabica beans of two varieties (cv. Mundo Novo and cv. Catuai Vermelho) were subjected to these four processing methods on a single farm in the Cerrado area of Brazil. RESULTS: Analysis by gas chromatography-mass spectrometry headspace solid-phase microextraction identified 40 volatile organic compounds in green coffee beans and 37 in roasted beans. The main difference between post-harvest treatments was that naturally processed green beans of both varieties contained a different profile of alcohols, acids, and lactones. In medium-roasted beans, those differences were not observed. The coffee beverages had similar taste attributes but distinct flavor profiles. Some of the treatments resulted in specialty-grade coffee, whereas others did not. CONCLUSION: The choice of a specific post-harvest processing method influences the volatile compounds found in green beans, the final beverage's flavor profile, and the cupping score, which can have a significant impact on the profitability of coffee farms' operations. © 2022 Society of Chemical Industry.

Electrophysiological and behavioural responses of Stegobium paniceum to volatile compounds from Chinese medicinal plant materials.

BACKGROUND: Stegobium paniceum (Coleoptera, Anobiidae) is an important pest of stored products causing severe damage to dried Chinese medicinal plant materials (CMPMs). Plant volatiles play an important role in host-searching of insects. The olfactory responses of S. paniceum to the most abundant volatile components of some drugstore attractant CMPMs such as Panax notoginseng, Angelica sinensis, Gastrodia elata and Peucedanum praeruptorum, namely falcarinol, 3-n-butylphthalide, p-cresol and ß-pinene, respectively, were studied by electroantennography (EAG) and behavioural bioassays in six- and four-arm olfactometers. RESULTS: EAG recordings showed that male and female antennae are able to perceive the test compounds in a wide range of concentrations and in a dose-dependent manner. Moreover, for each dose of different compounds tested, no significant differences were found between the mean male and female EAG responses. In six-arm olfactometer bioassays, S. paniceum exhibited positive responses to falcarinol, 3-n-butylphthalide, p-cresol and ß-pinene at doses of 1, 10, 100, 500 and 1000 µg. The most attractive dose was 500 µg for falcarinol, 100 µg for 3-n-butylphthalide, 500 µg for p-cresol and 1000 µg for ß-pinene. Olfactory preferences of S. paniceum, based on comparison of these four compounds at their optimally attractive concentrations in a four-arm olfactometer, were 3-n-butylphthalide > p-cresol > falcarinol > ß-pinene. CONCLUSION: The results indicated that the four volatiles of CMPMs are perceived by the peripheral olfactory system of S. paniceum adults and are able to individually elicit a positive chemotaxis in S. paniceum adults confirming the role of chemical cues in host-plant detection and selection of this pest. Further field studies are needed to evaluate the potential of the attractive compounds identified in this study, particularly 3-n-butylphthalide, to be applied as a novel monitoring and control tool against this storage-beetle pest. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Volatile Constituents of Some Selected Plant Species Traditionally Used as Tea in the Sharri Mountains (Kosovo).

The study evaluates the chemical composition of the volatile constituents of ten plant species traditionally used as herbal tea in the Sharri Mountain regions (Kosovo and North Macedonia). Volatile constituents responsible for the flavour and fragrance of selected species (Crataegus monogyna, Cydonia oblonga, Malus sylvestris, Matricaria chamomilla, Morus alba, Morus nigra, Rosa canina, Sambucus nigra, Tilia cordata, and Vaccinium myrtillus) were separated and then identified using GC-MS, whereas GC-FID is employed for the quantitative analysis. Experimental data revealed different patterns of volatile constituents depending on plant species. Monoterpenes, sesquiterpenes, diterpenes, and norisoprenoids were the most abundant volatile constituents. Principal component analysis (PCA) was deployed for data analysis and resulted in grouping these ten species in four principal clusters. The combination of various volatile constituents present in specific plant species may play an important role in the specific aroma and taste sensation of these species used as recreational teas.

Rapid Identification of Adulteration in Extra Virgin Olive Oil via Dynamic Headspace Sampling and High-Pressure Photoionization Time-of-Flight Mass Spectrometry.

High-pressure photoionization time-of-flight mass spectrometry (HPPI-TOFMS) combined with dynamic headspace sampling was developed for rapid identification of adulteration in extra virgin olive oil (EVOO). The volatile organic compound (VOC) fingerprints of EVOO, refined rapeseed oil (r-RO), peanut oil (PO), corn oil (CO), fragrant rapeseed oil (f-RO), and sunflower oil (SO) were obtained in just 1.5 min, which enabled satisfactory classification of different edible oils. 1,4-Bis(methylene)cyclohexane and dimethyl disulfide were unique VOCs in r-RO and f-RO, respectively, while 2,5-dimethylpyrazine and 2-methylpyrazine were distinctive VOCs in PO. Percentages as low as 3% r-RO, 1% PO, and 1% f-RO in r-RO-EVOO, PO-EVOO, and f-RO-EVOO mixtures, respectively, were successfully identified based on the characteristic VOCs. Linear regression equations of these VOCs were established and utilized for predicting the adulteration proportions. The good agreements between the actual adulteration proportions and the predicted ones demonstrated that HPPI-TOFMS was reliable for the quantification of EVOO adulteration.

Identification of aroma-active compounds responsible for the floral and sweet odors of Congou black teas using gas chromatography-mass spectrometry/olfactometry, odor activity value, and chemometrics.

BACKGROUND: Floral and sweet odors are two typical characteristic aromas of Congou black tea, but their aroma-active compounds are still unclear. Characterizing the key aroma-active compounds can provide a theoretical foundation for the practical aroma quality evaluation of Congou black tea and directional processing technology of high-quality black tea with floral or sweet odors. Gas chromatography-olfactometry (GC-O) combined with odor activity value (OAV) is often used to screen key aroma-active substances, but the interaction between aroma components and their impact on the overall sensory quality is ignored. Therefore, in this study, OAV combined with variable importance in projection (VIP) and Spearman correlation analysis (SCA) were used to characterize the aroma-active components of Congou black teas with floral and sweet odors. RESULTS: Eighty-five volatiles were identified in these samples using gas chromatography-mass spectrometry (GC-MS). Twenty-three compounds were identified as potential markers for the floral and sweet odors of Congou black teas from orthogonal partial least squares discriminant analysis (OPLS-DA). Eighteen compounds were selected as candidate aroma compounds based on GC-O analysis and OAV calculations. In addition, 26 compounds were screened as crucial aroma compounds based on SCA. Finally, 19 compounds were evaluated as key aroma compounds by the comprehensive evaluation of VIP, OAV, and SCA. Terpenoids are the main active compounds that contribute to the floral odor of Congou black tea, whereas aldehydes are the key compounds for the sweet odor. CONCLUSION: The proposed method can effectively screen the aroma-active compounds and can be used for comprehensive quality control of products. © 2022 Society of Chemical Industry.