Organ-specific volatiles from Sonoran desert Krameria flowers as potential signals for oil-collecting bees

The evolution of flowers that offer oils as rewards and are pollinated by specialized bees represents a distinctive theme in plant-pollinator co-diversification. Some plants that offer acetylated glycerols as floral oils emit diacetin, a volatile by-product of oil metabolism, which is utilized by oil-collecting bees as an index signal for the presence of floral oil. However, floral oils in the genus Krameria (Krameriaceae) contain β-acetoxy-substituted fatty acids instead of acetylated glycerols, making them unlikely to emit diacetin as an oil-bee attractant. We analyzed floral headspace composition from K. bicolor and K. erecta, native to the Sonoran Desert of southwestern North America, in search of alternative candidates for volatile index signals. Using solid-phase microextraction, combined with gas chromatography-mass spectrometry, we identified 26 and 45 floral volatiles, respectively, from whole flowers and dissected flower parts of these two Krameria species. As expected, diacetin was not detected. Instead, β-ionone emerged as a strong candidate for an index signal, as it was uniquely present in dissected oil-producing floral tissues (elaiophores) of K. bicolor, as well as the larval cells and provisions from its oil-bee pollinator, Centris cockerelli. This finding suggests that the floral oil of K. bicolor is perfused with β-ionone in its tissue of origin and retains the distinctive raspberry-like scent of this volatile after being harvested by C. cockerelli bees. In contrast, the elaiophores of K. erecta, which are not thought to be pollinated by C. cockerelli, produced a blend of anise-related oxygenated aromatics not found in the elaiophores of K. bicolor. Our findings suggest that β-ionone has the potential to impact oil-foraging by C. cockerelli bees through several potential mechanisms, including larval imprinting on scented provisions or innate or learned preferences by foraging adults.

Study of Glycosidically Bound Volatile Precursors as Variety Markers to Reveal Not-Allowed Practices in White Wines Winemaking

Liquid chromatography/high-resolution mass spectrometry (LC/HRMS) can provide identification of grape metabolites which are variety markers. White grapes are poorer in polyphenolics, and the main secondary metabolites which contribute the sensorial characteristics of wines are the glycosidically bound volatile precursors and their aglycones. The profiles of three white grape juices (Pinot grigio, Garganega, and Trebbiano) were characterized by LC/HRMS, and 70 signals of putative glycosidic terpenols, norisoprenoids, and benzenoids were identified. Four signals found only in Pinot grigio corresponded to a norisoprenoid hexose-hexose, 3-oxo-α-ionol (or 3-hydroxy-β-damascone) rhamnosyl-hexoside, monoterpene-diol hexosyl-pentosyl-hexoside, and hexose-norisoprenoid; three signals were found only in Garganega (putative isopropyl alcohol pentosyl-hexoside, phenylethanol rhamnosyl-hexoside, and norisoprenoid hexose-hexose isomers), and a monoterpenol pentosyl-hexoside isomer only in Trebbiano. These variety markers were then investigated in juice blends of the three varieties. This approach can be used to develop control methods to reveal not-allowed grape varieties and practices in white wines winemaking.

First investigation on polyphenols and glycosidic aroma precursors in a spontaneous colour mutant of 'Glera', the principal grape variety of Prosecco sparkling wine

BACKGROUND

Somatic mutations in Vitis spp. are relatively frequent and can generate new agronomically interesting phenotypes. We report the discovery, genetic and chemical characterization of 'Glera rosa', a mutant for the berry skin colour of 'Glera', the main white cultivar used to produce Prosecco wine.

RESULTS

We ascertained the relationship between the skin colour of 'Glera rosa' and the polymorphisms in the Myb-gene transcription factors involved in polyphenol biosynthesis. We established that VvMybA1 was homozygous (VvMybA1a/VvMybA1a) in 'Glera' but heterozygous (VvmybA1a/VvmybA1b) in the 'Glera rosa' mutant. We verified that the VvMybA1a non-functional allele contained Grapevine Retrotransposon 1 (Gret1), while in the VvmybA1b allele Gret1 was missing, and the gene function was partially restored. The effects of mutation on 'Glera rosa' grape metabolites were studied by high-resolution mass spectrometry and gas chromatography/mass spectrometry analysis. Fifteen anthocyanins and five unique flavonols were found in the 'Glera rosa' mutant. The mutation also increased the contents of trans-resveratrol and its derivatives (i.e., piceatannol, E-ε-viniferin, cis- and trans-piceid) and of some flavonols in grape. Finally, the mutation did not significantly affect the typical aroma precursors of Glera grape such as glycosidic monoterpenes, norisoprenoids and benzenoids.

CONCLUSION

'Glera rosa' could be an interesting genetic source for the wine industry to produce Prosecco DOC rosé typology (made by adding up to 15% of 'Pinot Noir'), which was introduced to the market in 2020 with a worldwide massive success. © 2022 Society of Chemical Industry.

Enantioselective Total Synthesis of (R,R)-Blumenol B and d9-(R,R)-Blumenol B

C₁₃-norisoprenoids are of particular importance to grapes and wines, as these molecules influence wine aroma and have been shown to significantly contribute to the distinct character of various wine varieties. Blumenol B is a putative precursor to a number of important wine aroma compounds, including the well-known compounds theaspirone and vitispirane. The enantioselective synthesis of (R,R)-blumenol B from commercially available 4-oxoisophorone was achieved using a short and easily scaleable route, which was then successfully applied to the synthesis of poly-deuterated d9-blumenol B.

Genetic architecture of berry aroma compounds in a QTL (quantitative trait loci) mapping population of interspecific hybrid grapes (Vitis labruscana × Vitis vinifera)

BACKGROUND

Although grapes accumulate diverse groups of volatile compounds, their genetic regulation in different cultivars remains unelucidated. Therefore, this study investigated the volatile composition in the berries of an interspecific hybrid population from a Vitis labruscana 'Campbell Early' (CE) × Vitis vinifera 'Muscat of Alexandria' (MA) cross to understand the relationship among volatile compounds and their genetic regulation. Then, a quantitative trait locus (QTL) analysis of its volatile compounds was conducted.

RESULTS

While MA contained higher concentrations of monoterpenes and norisoprenoids, CE contained higher concentrations of C6 compounds, lactones and shikimic acid derivatives, including volatiles characteristic to American hybrids, i.e., methyl anthranilate, o-aminoacetophenone and mesifurane. Furthermore, a cluster analysis of volatile profiles in the hybrid population discovered ten coordinately modulated free and bound volatile clusters. QTL analysis identified a major QTL on linkage group (LG) 5 in the MA map for 14 monoterpene concentrations, consistent with a previously reported locus. Additionally, several QTLs detected in the CE map affected the concentrations of specific monoterpenes, such as linalool, citronellol and 1,8-cineol, modifying the monoterpene composition in the berries. As for the concentrations of five norisoprenoids, a major common QTL on LG2 was discovered first in this study. Several QTLs with minor effects were also discovered in various volatile groups, such as lactones, alcohols and shikimic acid derivatives.

CONCLUSIONS

An overview of the profiles of aroma compounds and their underlying QTLs in a population of interspecific hybrid grapes in which muscat flavor compounds and many other aroma compounds were mixed variously were elucidated. Coordinate modulation of the volatile clusters in the hybrid population suggested an independent mechanism for controlling the volatiles of each group. Accordingly, specific QTLs with significant effects were observed for terpenoids, norisoprenoids and some volatiles highly contained in CE berries.

The Varietal Influence of Flavour Precursors from Grape Marc on Monoterpene and C13-Norisoprenoid Profiles in Wine as Determined by Membrane-Assisted Solvent Extraction (MASE) GC-MS

The winemaking by-product grape marc (syn. pomace) contains significant quantities of latent flavour in the form of flavour precursors which can be extracted and used to modulate the volatile composition of wine via chemical hydrolysis. Varietal differences in grapes are widely known with respect to their monoterpene content, and this work aimed to extend this knowledge into differences due to cultivar in volatiles derived from marc precursors following wine-like storage conditions. Marc extracts were produced from floral and non-floral grape lots on a laboratory-scale and from Muscat Gordo Blanco marc on a winery -scale, added to a base white wine for storage over five to six months, before being assessed using a newly developed membrane-assisted solvent extraction gas chromatography-mass spectrometry (GC-MS) method. The geraniol glucoside content of the marc extracts was higher than that of juices produced from each grape lot. In all wines with added marc extract from a floral variety, geraniol glucoside concentration increased by around 150–200%, with increases also observed for non-floral varieties. The relative volatile profile from extracts of the floral varieties was similar but had varied absolute concentrations. In summary, while varietally pure extracts would provide the greatest control over flavour outcomes when used in winemaking, aggregated marc parcels from floral cultivars may provide a mechanism to simplify the production logistics of latent flavour extracts for use in the wine sector.

Optimization of SPME-Arrow-GC/MS Method for Determination of Free and Bound Volatile Organic Compounds from Grape Skins

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples.

UPLC-QTof-MSE Metabolomics Reveals Changes in Leaf Primary and Secondary Metabolism of Hop (Humulus lupulus L.) Plants under Drought Stress

The hop (Humulus lupulus L.) is an important specialty crop used in beer production. Untargeted UPLC-QTof-MS^E metabolomics was used to determine metabolite changes in the leaves of hop plants under varying degrees of drought stress. Principal component analysis revealed that drought treatments produced qualitatively distinct changes in the overall chemical composition of three out of four genotypes tested (i.e., Cascade, Sultana, and a wild var. neomexicanus accession but not Aurora), although differences among treatments were smaller than differences among genotypes. A total of 14 compounds consistently increased or decreased in response to drought stress, and this effect was generally progressive as the severity of drought increased. A total of 10 of these marker compounds were tentatively identified as follows: five glycerolipids, glutaric acid, pheophorbide A, abscisic acid, roseoside, and dihydromyricetin. Some of the observed metabolite changes likely occur across all plants under drought conditions, while others may be specific to hops or to the type of drought treatments performed.

Changes in Red Wine Composition during Bottle Aging: Impacts of Grape Variety, Vineyard Location, Maturity, and Oxygen Availability during Aging

This work investigated the influence of grape variety, vineyard location, and grape harvest maturity, combined with different oxygen availability treatments, on red wine composition during bottle aging. Chemometric analysis of wine compositional data (i.e., wine color parameters, SO₂, metals, and volatile compounds) demonstrated that the wine samples could be differentiated according to the different viticultural or bottle-aging factors. Grape variety, vineyard location, and grape maturity showed greater influence on wine composition than bottle-aging conditions. For most measured wine compositional variables, the evolution patterns adopted from the viticultural factors were not altered by oxygen availability treatment. However, contrasting evolution patterns for some variables were observed according to specific viticultural factors, with examples including dimethyl sulfide, phenylacetaldehyde, maltol, and β-damascenone for vineyard locations, 2-methylbutanal, 1,4-cineole, and linalool for grape variety, and methanethiol, methional, and homofuraneol for grape maturity.

Impact of UV-C treatment and thermal pasteurization of grape must on sensory characteristics and volatiles of must and resulting wines

UV-C treatment is a commonly known technique to inactivate microorganisms. The objective of this work was to investigate the impact of UV-C treatment of grape must on the sensory characteristics of the resulting wine and on the profile of volatile compounds of grape must and wine. Different UV-C doses were applied to Riesling must and compared with thermal pasteurization. The sensory off-flavor "ATA" and a content of 0.5 µg/L 2-aminoacetophenone were determined in the grape must and in the resulting wine after UV-C treatment with a high dose of 21 kJ/L. Sensory off-flavors did neither occur after thermal pasteurization nor after UV-C treatment with a dose of 2 kJ/L, which is sufficient for the inactivation of microorganisms. Minor changes in the volatiles' profiles of grape must and wine, involving e.g. terpenes and C13-norisoprenoids, occurred in musts treated with thermal pasteurization as well as with a UV-C dose of 2 kJ/L.

Direct Analysis of Glycosidic Aroma Precursors Containing Multiple Aglycone Classes in Vitis vinifera Berries

Ultra-high-performance liquid chromatography (UHPLC) accurate mass tandem mass spectrometry is a powerful tool for identifying and profiling plant metabolites. Here, we describe an approach to characterize glycosidically bound precursors of monoterpenoids, norisoprenoids, volatile phenols, aliphatic alcohols, and sesquiterpenoids in grapes. Chromatographic separation of glycosylated compounds was evaluated using phenyl-hexyl (reverse phase), glycan/hydrophilic interaction, and porous graphitic carbon (PGC) stationary phases. PGC provided the best UHPLC separation for 102 tentatively identified aroma precursors in Vitis vinifera L. cv. Riesling and Muscat of Alexandria berries. Monoterpene-triol, monoterpene-tetraol, and sesquiterpenol glycosides were tentatively identified for the first time in grapes, and a C6-alcohol trisaccharide was tentatively identified for the first time in any plant. Comparison of glycosylated aroma molecules in Riesling and Muscat of Alexandria grapes showed that the two varieties were distinguishable based on relative abundances of shared glycosides and the presence of glycosides unique to a single variety.

Recovery of Natural α-Ionone from Fermentation Broth

Recently, the market value of aromas has constantly been rising. Because the supply from natural feedstock is limited, the biotechnological production has received more interest. Thus far, only a few attempts have been made to produce α-ionone, a valued essential aroma of raspberry, biotechnologically. This study reports a production process for enantiopure (R)-α-ionone from lab scale (2-150 L) with typical titer of 285 mg/L broth to industrial scale (up to 10 000 L) with a titer up to 400 mg/L broth, focusing on the development of a downstream process with a maximized yield at minimized effort. The developed recovery consists of solid-liquid extraction from the biomass at φ = 0.4 g of n-hexane/g of biomass for 90 min at ambient temperature and adsorption from the aqueous supernatant at Φ = 0.5 g of Diaion HP-20/mg of α-ionone, followed by desorption at Ψ = 30 g of n-hexane/g of Diaion HP-20. Altogether, natural α-ionone could be gained in substantial quantity and purity of >95%.

Volatile terpenoids, norisoprenoids and benzenoids as markers of fine scale vineyard segmentation for Corvina grapes and wines

In this study, the diversity existing at the very small scale of single vineyard parcels in volatile composition of grapes and wines from a single estate in the Valpolicella wine region has been studied. Corvina grapes from eight contiguous vineyards were used for the study and vinified with the same protocol. The compounds analyzed by GC-MS were representative of the terpenoid, norisoprenoid and benzenoid chemical families. Free and bound compounds analysis showed that differences between parcels were relatively small on grapes samples, whereas after fermentation larger differences between wine samples were highlighted. Multivariate statistical analysis of wine volatiles highlighted the existence of similarities between wine volatile profiles, which reflected to a good extent the geographical location of the corresponding vineyard parcels. The main drivers of this diversity were the monoterpene alcohols linalool, α-terpineol, linalool oxide; the benzenoids vanillin, ethyl vanillate and methyl vanillate; and the norisoprenoid β-damascenone. Wine from one vineyard parcel was not correctly classified, possibly due to the influence of the peculiar training system applied to this parcel. With aging the vineyard parcel geographical diversity was still reflected by the chemical diversity of wines, even if the separation was less fine. As many reactions occurred, some drivers of the diversity were changed after aging. They were benzenoids: ethyl vanillate, methyl vanillate and vanillin; the norisoprenoid 3-oxo-α-ionol; the terpenes linalool oxide, linalool, p-methane-1,8-diol, α-terpineol, and the precursors of nerol, geraniol, linalool.

Characterization of Key Odorants in Hoary Mountain Mint, Pycnanthemum incanum

Pycnanthemum incanum, a species of wild mountain mint endemic to North America, has a pungent mint-like odor that has not been fully characterized. Due in part to its high terpene content, P. incanum has broad potential for health-promoting, cosmetic, culinary, and food flavoring applications. Therefore, odorants of P. incanum were identified by coupling solvent assisted flavor evaporation (SAFE) and aroma extract dilution analysis (AEDA), which afforded 24 odorants including 14 odorants with flavor dilution (FD) factors ≥4. Selected odorants, including those with FD factors ≥16, were quantitated by stable isotope dilution assays (SIDAs), and odor activity values (OAVs) were determined. The odorants with the highest OAVs included β-ionone (floral, violet; OAV 300), myrcene (terpeny, OAV 120), linalool (floral, citrus; OAV 79), and pulegone (mint, medicinal; OAV 58). An odor-simulation model based on the quantitation closely matched the sensory attributes of the original P. incanum plant material. In addition, enantiomeric proportions of chiral odorants in P. incanum were determined by chiral chromatography.

Response of Taste and Odor Compounds to Elevated Cyanobacteria Biomass and Temperature

Taste and odor (T&O) compounds are frequently reported during black blooms, however, their production mechanisms and influencing factors are far from clear. In this study, laboratory simulation experiment was carried out to investigate the formation processes of T&O compounds under the influences of temperature, cyanobacteria biomass and their combined effects. The decay of cyanobacteria blooms caused increased T&O compounds loading to water. Results showed the maximum dimethyl sulfide (DMS) release concentration was observed at 35°C compared with that at 25 and 30°C. DMS release concentration under cyanobacteria biomass of 25000 g/m³ demonstrated the highest production, whereas the minimum DMS production were obtained under 7500 g/m³. Similar patterns were observed for dimethyl disulfide, dimethyl trisulfide, β-cyclocitral and β-ionone production. Therefore, higher temperature and higher cyanobacteria biomass can enhance the concentration of T&O compounds. Furthermore, there were synergistic effects of cyanobacteria biomass and temperature on the production of T&O compounds.

Volatile profile of Greek dried white figs (Ficus carica L.) and investigation of the role of β-damascenone in aroma formation in fig liquors

BACKGROUND

During an investigation of the chemical profile of Greek figs (Ficus carica L.), several aqueous ethanol extracts (liquors) were prepared from dried Smyrna fig varieties cultivated in the two major fig-producing geographical areas in Greece: Peloponnese and Evia Island. The distinctive aroma observed among the prepared fig liquors led to the investigation of the odor profile of the different fig cultivars through HS-SPME coupled with GC/MS analysis, with focus on the factors that affect it before and during the preparation of the respective liquors.

RESULTS

Significant variation in volatiles was noticed among all fig cultivars, as also between each fig cultivar pulp and the respective liquor. The observed diversity was a result of chemical reactions taking place in the ethanol matrix during the preparation of the liquor. The 'key' odor compound of dried fig aroma was found to be β-damascenone. Owing to its low detection threshold and minute quantity in fig cultivars, the presence of β-damascenone was furthermore confirmed through GC/MS/MS and GC/TOF-MS. β-Damascenone was identified in variable quantities among fig varieties and their liquors, predominating in Kalamon fig cultivar of Peloponnese region, while its amount was found to be dependent on the postharvest storage time and preservation process of dried figs.

CONCLUSION

Each of the studied fig cultivars and liquors showed a unique aroma profile, and the obtained results were used for the preparation of the first dried fig liqueur for potential commercial use with the highest content of β-damascenone. © 2017 Society of Chemical Industry.

Spatial distributions of β-cyclocitral and β-ionone in the sediment and overlying water of the west shore of Taihu Lake

After large-scale outbreaks of algal blooms in eutrophic water, considerable amounts of algae residue accumulate in near-shore zones before fermenting rapidly and becoming malodorous. Taste and odor pollution caused by secondary metabolites from cyanobacterial blooms has become a serious and widespread environmental problem. Two typical odorous compounds, β-cyclocitral and β-ionone, have gained increasing attention in recent years. In this paper, the spatial distributions of β-cyclocitral and β-ionone in the sediments and overlying water off the west shore of Taihu Lake were investigated. The results showed that β-cyclocitral, β-ionone and nutrients are released during the degradation of fresh cyanobacteria, especially in the early stages. The odorous compounds and nutrients greatly decreased as the depth of sediment increased, indicating that reed roots can absorb β-cyclocitral, β-ionone and nutrients. Furthermore, removing cyanobacteria and dredging sludge might reduce the release of β-cyclocitral and β-ionone.

Characterization of the Key Aroma Compounds in Chinese Vidal Icewine by Gas Chromatography-Olfactometry, Quantitative Measurements, Aroma Recombination, and Omission Tests

The key aroma compounds of Chinese Vidal icewine were characterized by means of gas chromatography-olfactometry (GC-O) coupled with mass spectrometry (MS) on polar and nonpolar columns, and their flavor dilution (FD) factors were determined by aroma extract dilution analysis (AEDA). A total of 59 odor-active aroma compounds in three ranks of Vidal icewines were identified, and 28 odorants (FD ≥ 9) were further quantitated for aroma reconstitution and omission tests. β-Damascenone showed the highest FD value of 2187 in all icewines. Methional and furaneol were first observed as important odorants in Vidal icewine. Aroma recombination experiments revealed a good similarity containing the 28 important aromas. Omission tests corroborated the significant contribution of β-damascenone and the entire group of esters. Besides, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (furaneol) and 3-(methylthio)-1-propanal (methional) also had significant effects on icewine character, especially on apricot, caramel, and tropical fruit characteristics.

Harvest date effects on aroma compounds in aged Riesling icewines

BACKGROUND

Riesling icewine is an important product of the Ontario wine industry. The objective of this study was to characterize concentrations in aroma compounds in aged icewines associated with three harvest dates (H1, H2, H3) using stir bar sorptive extraction-gas chromatography-mass spectrometry and to make inferences, where appropriate, with respect to their roles in potential wine quality.

RESULTS

Delaying harvest decreased concentrations of many odorants, but increased many critical odor-active compounds; e.g. 1-octen-3-ol, ethyl benzoate, ethyl octanoate, cis-rose oxide, and β-ionone. H1 wines had higher concentrations of four aldehydes, three alcohols, nine esters, seven terpenes, γ-nonalactone, p-vinylguaiacol, β-damascenone, and 2-furanmethanol. However, many of these compounds, with some exceptions, have relatively high odor thresholds. Fourteen compounds were above their odor thresholds, including decanal, 1-octen-3-ol, phenylethyl alcohol, four ethyl esters, cis-rose oxide, linalool, γ-nonalactone, p-vinylguaiacol, ethyl cinnamate, β-damascenone, and 1,1,6-trimethyl-1,2-dihydronaphthalene. H3 wines contained higher concentrations of highly odor-active compounds, e.g. 1-octen-3-ol, cis-rose oxide, and β-ionone. Only phenylethyl alcohol [H3 odor activity value (OAV) = 0.33 (honey, spice, rose)] and linalool [H3 OAV = 0.92 (floral, lavender)] had H3 OAVs < 1.

CONCLUSIONS

Early harvest increased many esters and aliphatic compounds, but delayed harvest appeared to substantially increase concentrations of several highly odor-active compounds. © 2016 Society of Chemical Industry.

Major Chemical Constituents of Bamboo Shoots (Phyllostachys pubescens): Qualitative and Quantitative Research

Bamboo shoots are a delicacy in Asia. Two novel compounds, adenine-(1'R,2'R,3'R)-cyclic butanetetraol carbonate (16) and (-)-(7R,8S)-(4-hydroxy-3-methoxyphenylglycerol 9-O-β-D-[6-O-4-hydroxy-3-methoxybenzoyl])-glucopyranoside (20), together with 12 known nucleosides (1-12), 3 amino acids (13-15), β-carboline (17), and 2 megastigmane glycosides (18, 19) were isolated from bamboo shoots (Phyllostachys pubescens). Their structures and absolute configurations were rigorously determined by detailed spectroscopic analysis, and the composition of carbohydrates in bamboo shoots was qualitatively detected and quantitatively analyzed with ion chromatography. A simple, rapid, sensitive, and accurate HPLC-UV analysis was built for routine edible quality control of bamboo shoots, and 12 major components of bamboo shoots were quantitatively analyzed. The major chemical constituents of bamboo shoots were determined to be carbohydrates, amino acids, and nucleotides. These findings are correctives to the usual view of bamboo shoots chemical composition, and the previous research reports about the chemical composition of bamboo shoots may have taken the aromatic amino acids and nucleotides for flavonoids and phenolic acids.

Discrimination of honeys using colorimetric sensor arrays, sensory analysis and gas chromatography techniques

Aroma profiles of six honey varieties of different botanical origins were investigated using colorimetric sensor array, gas chromatography-mass spectrometry (GC-MS) and descriptive sensory analysis. Fifty-eight aroma compounds were identified, including 2 norisoprenoids, 5 hydrocarbons, 4 terpenes, 6 phenols, 7 ketones, 9 acids, 12 aldehydes and 13 alcohols. Twenty abundant or active compounds were chosen as key compounds to characterize honey aroma. Discrimination of the honeys was subsequently implemented using multivariate analysis, including hierarchical clustering analysis (HCA) and principal component analysis (PCA). Honeys of the same botanical origin were grouped together in the PCA score plot and HCA dendrogram. SPME-GC/MS and colorimetric sensor array were able to discriminate the honeys effectively with the advantages of being rapid, simple and low-cost. Moreover, partial least squares regression (PLSR) was applied to indicate the relationship between sensory descriptors and aroma compounds.

Spatial and Temporal Variations of Taste and Odor Compounds in Surface Water, Overlying Water and Sediment of the Western Lake Chaohu, China

The seasonal variations of taste and odor (T&O) compounds in western Lake Chaohu were evaluated from July to December 2013. High values were detected in particulate fractions, with peak values 28.25 ng/L for geosmin (GEO), 45.18 ng/L for dimethyltrisulfide (DMTS), 714.77 ng/L for β-cyclocitral, 11.23 ng/L for β-ionone in surface water, and 14.21 ng/L for GEO, 103.68 ng/L for DMTS, 11.97 ng/L for β-ionone in overlying water, all exceeding their odor thresholds. The maximum off-flavor concentrations in sediment ranged from 2010.76 ng/kg for GEO to 1.7 ng/kg for β-ionone. Positive correlations could be found not only between Anabaena and particulate GEO (r = 0.813, p < 0.01), but also between Microcystis and total β-cyclocitral (r = 0.652, p < 0.01) or β-ionone (r = 0.560, p < 0.01) in surface water. TP, TN, PO4-P, Chl-a and organic matter contributed significantly to the variations of T&O compounds in water or sediment. The cause of the variations of T&O compounds was the accumulation and degradation of cyanobacteria in water rather than nutrient-rich sediment.

Oxygen Consumption by Red Wines. Part II: Differential Effects on Color and Chemical Composition Caused by Oxygen Taken in Different Sulfur Dioxide-Related Oxidation Contexts

Chemical changes caused by oxidation of red wines during 5 consecutive air-saturation cycles have been assessed. In order to investigate the existing relationship between the effects caused by O2 and the levels and consumption rates of wine SO2, the total oxygen consumed by the wines (16-25 mg/L) was subdivided into different nonmutually exclusive categories. The ones found most influential on chemical changes were the O2 consumed in the first saturation without equivalent SO2 consumption (O2preSO2) and the O2 consumed when levels of free SO2 were below 5 mg/L (radical forming O2). Chromatic changes were strongly related to both O2 categories, even though anthocyanidin degradation was not related to any O2 category. Radical forming O2 prevented both formation of red pigments and reduction of epigallocatechin and other proanthocyanidins, induced accumulation of phenolic acids, and caused losses of β-damascenone and whiskylactone without evidence of acetaldehyde formation. O2preSO2 seemed to play a key role in the formation of blue pigments and in the decrease of Folin index and of many important aroma compounds.

Occurrence of Theaspirane and its Odorant Degradation Products in Hop and Beer

In model oxidized media, six theaspirane-derived compounds were identified by gas chromatography-high resolution mass spectrometry: 4-hydroxy-7,8-dihydro-β-ionone, 6-hydroxy-7,8-dihydro-α-ionone, dihydrodehydro-β-ionone, two monoepoxides, and a derived alcohol. Only 4-hydroxy-7,8-dihydro-β-ionone and dihydrodehydro-β-ionone have been described previously in the literature. Investigation of hop revealed five of these compounds in free form together with theaspirane (especially in the Mosaic variety), while the Citra and Amarillo hop varieties emerged as very interesting for the release of theaspirane, 4-hydroxy-7,8-dihydro-β-ionone, and dihydrodehydro-β-ionone from glucoside precursors. For the first time, theaspirane, 4-hydroxy-7,8-dihydro-β-ionone, 6-hydroxy-7,8-dihydro-α-ionone, and both monoepoxides were found in a fresh commercial top fermentation beer (only theaspirane, 4-hydroxy-7,8-dihydro-β-ionone, and dihydrodehydro-β-ionone have recently been mentioned as Gueuze constituents).

Isolation and Functional Characterization of Carotenoid Cleavage Dioxygenase-1 from Laurus nobilis L. (Bay Laurel) Fruits

Bay laurel (Laurus nobilis L.) is an agriculturally important tree used in food, drugs, and the cosmetics industry. Many of the health beneficial properties of bay laurel are due to volatile terpene metabolites that they contain, including various norisoprenoids. Despite their importance, little is known about the norisoprenoid biosynthesis in Laurus nobilis fruits. We found that the volatile norisoprenoids 6-methyl-5-hepten-2-one, pseudoionone, and β-ionone accumulated in Laurus nobilis fruits in a pattern reflecting their carotenoid content. A full-length cDNA encoding a potential carotenoid cleavage dioxygenase (LnCCD1) was isolated. The LnCCD1 gene was overexpressed in Escherichia coli, and recombinant protein was assayed for its cleavage activity with an array of carotenoid substrates. The LnCCD1 protein was able to cleave a variety of carotenoids at the 9,10 (9',10') and 5,6 (5',6') positions to produce 6-methyl-5-hepten-2-one, pseudoionone, β-ionone, and α-ionone. Our results suggest a role for LnCCD1 in Laurus nobilis fruit flavor biosynthesis.

Influence of viticulture practices on grape aroma precursors and their relation with wine aroma

BACKGROUND

The effects of two different operations in the vineyard (basal leaf plucking and head trimming) on the synthesis of aromatic precursors in the grape and their impact on wine aroma have been studied and compared with a control sample. The study was carried out over two consecutive years with four different varieties. Glycosidic precursors were analysed in grapes and volatile compounds were studied in the wines. ANOVA studies were performed to study the effect of the vintage, variety and treatment for each of the compounds released from their precursors.

RESULTS

Regarding treatment, the highest values in the concentration of free aroma compounds were achieved in the leaf plucking grapes, except for Chardonnay. Significant and positive correlations between aromatic precursors of terpenes present in grapes and their released form in wines were found for all varieties. For norisoprenoids, significant and positive correlations were exclusively found for Chardonnay and for phenols and vanillins in the year 2010 the correlations were high in three of the four varieties studied.

CONCLUSION

In the assays of the 2 years, more precursors were synthesised in Merlot, Gewurztraminer and Tempranillo grapes if the vineyards were plucked.

Influence of cluster zone leaf removal on Pinot noir grape chemical and volatile composition

The influence of cluster-zone leaf removal on Pinot noir vine growth and fruit chemical and volatile composition was investigated in 3 years. Different severities of leaf removal (0%, 50%, 100%) were imposed during the pea-size stage of development from the cluster zone. Results show that cluster-zone leaf removal had little influence on vine growth, crop load, or grape maturity in terms of total soluble solids (TSS), pH or titratable acidity (TA) at harvest. However, 100% leaf removal resulted in higher concentrations of quercetin glycoside in grapes compared to 0% leaf removal. The 100% leaf removal also increased concentrations of petunidin- and malvidin-3-monoglucoside anthocyanins in two out of 3 years (2010 and 2012) by an average of 62% and 53%, respectively. In addition, 100% leaf removal resulted in higher concentrations of β-damascenone, and some bound-form terpenoids. The increases in β-damascenone were positively correlated to the increased sunlight exposure.

Validated modeling for German white wine varietal authentication based on headspace solid-phase microextraction online coupled with gas chromatography mass spectrometry fingerprinting

An untargeted analytical approach combined with chemometrics using the volatiles of German white wine was investigated regarding the usefulness for verifying botanical origin. A total of 198 wine samples of Riesling, Müller-Thurgau, Silvaner, Pinot Gris, and Pinot Blanc were examined applying headspace solid-phase microextraction online coupled with gas chromatography mass spectrometry. The resultant three-dimensional raw data were processed by available metabolomics software. After data treatment, a partial least-squares discriminant analysis (PLS-DA) model was validated. External samples were correctly classified for 97% Silvaner, 93% Riesling, 91% Pinot Gris/Blanc, and 80% Müller-Thurgau. This model was related to monoterpenoids, C13-norisoprenoids, and esters. Further, 100% prediction for a two-class model of Riesling versus Pinot Gris/Blanc was confirmed by 74 additional samples measured independently. Hence, the strategy applied was, in particular, reliable and relevant for white wine varietal classification. In addition, the superior classification performance of the Riesling class was revealed.

Characterization of the key aroma compounds in two bavarian wheat beers by means of the sensomics approach

Application of aroma extract dilution analysis (AEDA) on the volatiles isolated from a commercial Bavarian wheat beer (WB A) eliciting its typical aroma profile, best described by a clove-like, phenolic odor quality, revealed 36 odorants in the flavor dilution (FD) factor range from 16 to 4096. Among them, 2-methoxy-4-vinylphenol (clove-like) and 2-phenylethanol (flowery) showed the highest FD factors. AEDA of a second wheat beer (WB B), somewhat lacking the typical wheat beer odor note, revealed 32 odor-active components in the FD factor range from 32 to 8192. Among them, 2-phenylethanol, (E)-β-damascenone (cooked apple-like) and 3-methylbutanol (malty) were detected with the highest FD factors. Next, all odorants evaluated with an FD factor ≥32 were quantitated by stable isotope dilution assays in both beers, and the odor activity values (OAVs; ratio of concentration to odor threshold) were calculated. Thereby, ethanol, (E)-β-damascenone, 3-methylbutyl acetate, ethyl methylpropanoate, and ethyl butanoate showed the highest OAVs in WB A, followed by acetaldehyde, 3-methylbutanol, and dimethyl sulfide. In WB B, ethanol, (E)-β-damascenone, ethyl methylpropanoate, ethyl butanoate, and 3-methylbutyl acetate showed the highest OAVs. Whereas most aroma compounds were present in the same order of magnitude in both beer samples, in particular, 2-methoxy-4-vinylphenol and 4-vinylphenol (smoky, leather-like) were by factors of 13 and 15, respectively, higher in WB A. For the first time, the overall aroma of wheat beer (WB A) was successfully simulated on the basis of 27 reference compounds in their natural concentrations using water/ethanol (95:5; v/v) as the matrix.

Characterization of the key aroma compounds in Bartlett pear brandies by means of the sensomics concept

The aroma compounds in two commercial Bartlett pear brandies clearly differing in their overall aroma profiles were detected in the volatile fractions by the aroma extract dilution analysis. In brandy A eliciting the more intense pear-like, fruity aroma, ethyl (S)-2-methylbutanoate, (E)-β-damascenone, 1,1-diethoxyethane, 2- and 3-methylbutanol, (S)-2- and 3-methylbutanoic acid, and 2-phenylethanol were found with the highest Flavor Dilution (FD) factors. In brandy B judged to have a weaker overall aroma, also (E)-β-damascenone, ethyl (S)-2-methylbutanoate, and 2-phenylethanol revealed high FD factors, while many odorants showed lower FD factors. Fourty-four odor-active compounds were quantitated by stable isotope dilution assays, and the odor activity values (OAVs; ratio of concentrations to odor thresholds) confirmed (E)-β-damascenone and ethyl (S)-2-methylbutanoate as important aroma compounds in brandy A, while the OAVs of most odorants were much lower in brandy B. By aroma recombination studies, the aromas of both brandies could be matched using reference odorants in the same concentrations as they occurred in the spirits. In 15 commercial Bartlett pear brandies ethyl (E,Z)-2,4-decadienoate and (E,E)-2,4-decadienoate eliciting a pear-like aroma showed a reasonable correlation of their concentrations with the overall aroma quality.

Increase in β-ionone, a carotenoid-derived volatile in zeaxanthin-biofortified sweet corn

Carotenoids are responsible for the yellow color of sweet corn (Zea mays var. saccharata), but are also potentially the source of flavor compounds from the cleavage of carotenoid molecules. The carotenoid-derived volatile, β-ionone, was identified in both standard yellow sweet corn ('Hybrix5') and a zeaxanthin-enhanced experimental variety ('HZ') designed for sufferers of macular degeneration. As β-ionone is highly perceivable at extremely low concentration by humans, it was important to confirm if alterations in carotenoid profile may also affect flavor volatiles. The concentration of β-ionone was most strongly correlated (R(2) > 0.94) with the β-arm carotenoids, β-carotene, β-cryptoxanthin, and zeaxanthin, and to a lesser degree (R(2) = 0.90) with the α-arm carotenoid, zeinoxanthin. No correlation existed with either lutein (R(2) = 0.06) or antheraxanthin (R(2) = 0.10). Delaying harvest of cobs resulted in a significant increase of both carotenoid and β-ionone concentrations, producing a 6-fold increase of β-ionone in 'HZ' and a 2-fold increase in 'Hybrix5', reaching a maximum of 62 μg/kg FW and 24 μg/kg FW, respectively.

Induced mutation in β-CAROTENE HYDROXYLASE results in accumulation of β-carotene and conversion of red to orange color in pepper fruit

Pepper fruit is typically red, but green, orange and yellow cultivars are gaining consumer acceptance. This color variation is mainly due to variations in carotenoid composition. Orange color in pepper can result from a number of carotenoid profiles, but its genetic basis is only partly known. We identified an EMS-induced orange-fruited mutant using the wild-type blocky red-fruited cultivar 'Maor' as progenitor. This mutant accumulates mainly β-carotene in its fruit, instead of the complex pattern of red and yellow carotenoids in 'Maor'. We identified an A(709) to G transition in the cDNA of β-CAROTENE HYDROXYLASE2 in the orange pepper and complete co-segregation of this single-nucleotide polymorphism with the mutated phenotype. We therefore hypothesized that β-CAROTENE HYDROXYLASE2 controls the orange mutation in pepper. Interestingly, the expression of β-CAROTENE HYDROXYLASE2 and additional carotenogenesis genes was elevated in the orange fruit compared with the red fruit, indicating possible feedback regulation of genes in the pathway. Because carotenoids serve as precursors for volatile compounds, we compared the volatile profiles of the two parents. The orange pepper contained more volatile compounds than 'Maor', with predominant elevation of norisoprenoids derived from β-carotene degradation, while sesquiterpenes predominated in the red fruit. Because of the importance of β-carotene as a provitamin A precursor in the human diet, the orange-fruited mutant might serve as a natural source for pepper fruit biofortification. Moreover, the change in volatile profile may result in a fruit flavor that differs from other pepper cultivars.

Profiling and characterization of volatile components from non-fumigated and sulfur-fumigated Flos Lonicerae Japonicae using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry coupled with chemical group separation

Flos Lonicerae Japonicae (FLJ) is a popular herb used for many centuries in Traditional Chinese Medicine as a treatment of fever and inflammation. Non-fumigated processing of FLJ has been the traditional approach used in post-harvest preparation of the commodity for commercial use. However, in recent years, natural drying processing of FLJ has been replaced by sulfur-fumigation for efficiency and pest control. Sulfur-fumigation can induce changes in the volatile compounds of the herb, altering its medicinal properties. A comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOF/MS) method was established for the resolution and determination of volatile components in non-fumigated and sulfur-fumigated FLJ. In this paper, analysis of the volatile oils in non-fumigated and sulfur-fumigated (including lab-prepared sulfur- fumigated and industrial sulfur-fumigated) FLJ was performed using GC×GC-TOF/MS. Seventy-three representative volatile components were identified, including furans, alkalies, acids, aldehydes, ketones, alcohols, terpenes, esters, and others, as the main components of FLJ volatile oils. The proposed method was successfully applied for rapid and accurate quality evaluation of FLJ and its related medicinal materials and preparations.

Floral markers of cornflower (Centaurea cyanus) honey and its peroxide antibacterial activity for an alternative treatment of digital dermatitis

Cornflower (Centaurea cyanus) honey can be characterized by a greenish yellow color and an intense flavor with a bitter aftertaste. Because cornflower honey contains only a limited amount of pollen for the verification of its floral origin, one objective was the characterization of its polyphenol and norisoprenoid contents to assign floral markers. Here, lumichrome (18.8-43.5 mg/kg), 7-carboxylumichrome, (Z/E)-3-oxo-retro-α-ionol, and 3-oxo-α-ionol appeared to be quite suitable for distinguishing cornflower honey from other unifloral honeys. Additionally, due to its comparably high hydrogen peroxide content (0.5-0.9 mM/h) and the associated antibacterial activity, cornflower honey was used as an alternative treatment of digital dermatitis on an organic dairy farm. Cows affected by this hoof disease often show severe lameness and a subsequent decline in milk yield and loss of body condition. The cows' hooves treated with cornflower honey showed significantly faster healing than the control group without any treatment.

[Influence of processing methods on the chemical composition of the essential oil from Aucklandia lappa]

OBJECTIVE

To investigate the effects of different processing methods on chemical compositions of essential oil from Aucklandia lappa.

METHODS

4 different methods, frying without additional ingredients (1), stir-heating with bran (2), roasting surrounded with bran (3), and roasting wrapped in wet paper (4) were used to process raw Radix Aucklandiae and the contents and chemical compositions of essential oil were compared in the processed products with those in the raw drug. The essential oils were extracted wtih supercritical CO2 and analyzed by GC-MS.

RESULTS

Except method 1, processing lowered the content of the essential oil in Radix Aucklandiae significantly. 29, 33, 32, 34, and 33 compounds were identified, respectively, in the essential oils from raw Radix Aucklandiae and the processed products of Radix Aucklandia with method 1, 2, 3, and 4. The chemical compositions of essential oil of Radix Aucklandiae changed a lot in processing,some components disappeared, such as alpha-phellandrene; Some came into being, such as alpha-ionone, alpha-caryophyllene, beta-sesquiphellandrene, alpha-longifolene,and so on, some increased in contents,such as elemene, dihydro-a-ionone, beta-caryophyllene, and so on. The contents of costunolide and dehydrocostuslactone in Radix Aucklandiae decreased in processing with method 2, 3, and 4.

CONCLUSION

As a perfume meterial, Radix Aucklandiae should be processed by roasting surrounded with wheat bran, while as a drug to treat epigastric pain, the raw drug should be processed by stir-heating.

Classification and characterization of manuka honeys based on phenolic compounds and methylglyoxal

Manuka honey from New Zealand is often considered to be a medicinal product of special value due to its high level of antimicrobial activity. Therefore, the distinct authentication of its botanical origin is of great importance. Aside from the common pollen analysis, it is in this respect particularly the analysis of the phenolic acids, flavonoids, and norisoprenoids that is described as useful. In the present study, numerous manuka honeys were analyzed by UPLC-PDA-MS/MS after solid-phase extraction and compared to other kinds of honey to define marker substances characteristic for manuka honeys. The PDA profiles obtained differed markedly from each other so that the individual honey samples could be assigned to three groups. For the honeys of group 1 the comparably high concentrations of 4-hydroxybenzoic acid, dehydrovomifoliol, and benzoic acid proved to be typical, whereas the profiles of group 2 showed high kojic acid and 2-methoxybenzoic acid intensities. The manuka honeys of group 3, on the other hand, yielded high amounts of syringic acid, 4-methoxyphenyllactic acid, and methyl syringate. Furthermore, the comprehensive comparison of manuka honeys to other unifloral honeys revealed that especially kojic acid, 5-methyl-3-furancarboxylic acid, leptosin, unedone, 2-methoxybenzoic acid, 4-methoxyphenyllactic acid, 3-hydroxy-1-(2-methoxyphenyl)penta-1,4-dione, and methyl syringate were useful for distinguishing manuka honeys from the other kinds of investigated honeys. Moreover, kojic acid, unedone, 5-methyl-3-furancarboxylic acid, 3-hydroxy-1-(2-methoxyphenyl)penta-1,4-dione, and lumichrome were identified in manuka honey for the first time.

Essential oil composition of Prasium majus from Croatia

The essential oils from the aerial parts of Prasium majus L., collected during two years in Croatia, were analysed by GC and GC/MS. Fifty-two compounds were identified, representing 90.3-91.8% of the total oils. The major constituents in both samples were fatty acids (particularly hexadecanoic acid and (Z)-octadec-9-enoic acid), lower aliphatic alcohols, aldehydes and acids (major ones oct-1-en-3-ol and (E,E)-hepta-2,4-dienal) and phenylpropane derivatives (e.g. eugenol). Beta-Caryophyllene was the most abundant terpene and (E)-beta-ionone was the major norisoprenoid.

Evaluation of key odorants in sauvignon blanc wines using three different methodologies

In this study three different approaches were employed to identify key odorants in Sauvignon blanc wines. First, the concentrations of the odorants were compared to their respective aroma detection thresholds. The resulting odor activity values (OAV) were transformed into a normalized and weighted measure that allows the aroma profiles of different wines to be compared and the contribution of a single aroma in a complex mixture to be evaluated. Based on their OAV, 3-mercaptohexanol and 3-mercaptohexyl acetate were the two most important aroma compounds in many Marlborough Sauvignon blanc wines. Due to limitations with the OAV approach, the study was extended to include aroma extract dilution analysis (AEDA), which revealed that β-damascenone, together with the varietal thiols, esters, and higher alcohols, are key odorants in Sauvignon blanc wines. The final approach undertaken was aroma reconstitution and omission tests using a deodorized wine base and the creation of a model Marlborough Sauvignon blanc. Single compounds and groups of compounds were omitted from the model to study their impact on the sensory properties of the model wine. Reconstitution and omission confirmed that varietal thiols, esters, terpenes, and β-damascenone are all important contributors to Sauvignon blanc aroma. The methoxypyrazines showed an important but relatively low impact in all three of the approaches undertaken in this study.

Chemical composition and in vitro cytotoxic, genotoxic effects of essential oil from Urtica dioica L

The aim of this study was to determine the chemical composition of Urtica dioica essential oil, and to evaluate its cytotoxic and genotoxic effects, using cytogenetic tests such as the cytokinesis-block micronucleus assay and chromosomal aberration analysis in human lymphocyte cultures in vitro. GC-MS analysis of U. dioica essential oil identified 43 compounds, representing 95.8% of the oil. GC and GC-MS analysis of the essential oil of U. dioica revealed that carvacrol (38.2%), carvone (9.0%), naphthalene (8.9%), (E)-anethol (4.7%), hexahydrofarnesyl acetone (3.0%), (E)-geranyl acetone (2.9%), (E)-β-ionone (2.8%) and phytol (2.7%) are the main components, comprising 72.2% of the oil. A significant correlation was found between the concentration of essential oil and the following: chromosomal aberrations, micronuclei frequency, apoptotic cells, necrotic cells, and binucleated cells.

Aroma evaluation of gamazumi (Viburnum dilatatum) by aroma extract dilution analysis and odour activity value

INTRODUCTION

Viburnum dilatatum (gamazumi) is widely distributed in Japan and China. Recently, juice from V. dilatatum fruits has been manufactured in Japan. Concerning the aroma of V. dilatatum, phenethyl alcohol, 3Z-hexenol and l-linalool have been identified in the essential oil from the flowers of V. dilatatum, however, there are no detailed reports on the aroma of V. dilatatum elucidated using sensory evaluation.

OBJECTIVE

To clarify odourants contributing to the characteristic aroma, the aroma extract dilution analysis (AEDA) method was performed through gas chromatography olfactometry (GC-O) analysis.

METHODOLOGY

The aroma-active compounds were identified by GC-O and AEDA, and in order to determine the relative contribution of each compound to the aroma of V. dilatatum, odour activity value (OAV) has been used.

RESULTS

The hydrodistillation of the leaf and branch of V. dilatatum afforded pale yellowish oils, with yields of 0.008 and 0.015% (w/w). The main components of the leaf oil were 3Z-hexenal (12.7%) and linalool (10.8%). In branch oil, palmitic acid (18.3%) and linoleic acid (8.2%) were identified. With regard to aroma components, 24 and 14 compounds were identified in the leaf and branch oils respectively, by GC-O analysis.

CONCLUSION

On the basis of AEDA, OAVs and sensory evaluations, nonanal is estimated as the main aroma compound of leaf and branch oil, as the other aroma compounds, C₆ compounds and 2-pentyl furan make green odour; linalool, eugenol and β-ionone play important role in the sweet odour of leaf oil. In branch oil, cis-furanlinalool oxide and eugenol make sweet odour, and β-eudesmol contributes to woody odour.

Main odorants in Jura flor-sherry wines. Relative contributions of sotolon, abhexon, and theaspirane-derived compounds

The aromatic profile of Jura flor-sherry wines (also called "yellow wines") has been little studied. Only acetaldehyde, diethoxy-1,1-ethane, and sotolon have been described as key odorants. In the present work, three wines (vintages 2002 and 2003) were investigated by gas chromatography-mass spectrometry and gas chromatography-olfactometry (GC-O) aroma extract dilution analysis. The goal was to assess the relative impact of varietal, fermentation, and oak-barrel compounds by using two complementary extraction procedures. No grape terpenoids were found after the long barrel aging (6 years and 3 months). On the other hand, two candy/fruity esters issued from yeast exhibited high flavor dilution factor (FD) values: ethyl isobutyrate (64-1024) and ethyl isovalerate (128-1024). As expected, many oak-related odorants were found in the XAD 2 flavor extracts, mainly homofuraneol [2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone] (cotton candy, FD = 16-256) and cis-β-methyloctalactone (butter, woody, FD = 256). Most probably issued from oxidation of the grape constituent theaspirane, an exceptional grenadine odor was perceived by GC-O up to dilution 64-1024. Chemical oxidation experiments and GC-high-resolution mass spectrometry (HRMS) allowed us to identify it as 4-hydroxy-7,8-dihydro-β-ionone (RI(CPsil5CB) = 1373), a hydrolysis-derived product of dihydrodehydro-β-ionone. With an extraction dedicated to hydrophilic compounds, the key role of sotolon was confirmed (112-387 μg/kg; FD = 256-1024). This procedure enabled us to also evidence its ethyl analogue, abhexon (31-74 μg/kg; FD = 64-256).

Volatile compounds in honey: a review on their involvement in aroma, botanical origin determination and potential biomedical activities

Volatile organic compounds (VOCs) in honey are obtained from diverse biosynthetic pathways and extracted by using various methods associated with varying degrees of selectivity and effectiveness. These compounds are grouped into chemical categories such as aldehyde, ketone, acid, alcohol, hydrocarbon, norisoprenoids, terpenes and benzene compounds and their derivatives, furan and pyran derivatives. They represent a fingerprint of a specific honey and therefore could be used to differentiate between monofloral honeys from different floral sources, thus providing valuable information concerning the honey's botanical and geographical origin. However, only plant derived compounds and their metabolites (terpenes, norisoprenoids and benzene compounds and their derivatives) must be employed to discriminate among floral origins of honey. Notwithstanding, many authors have reported different floral markers for honey of the same floral origin, consequently sensory analysis, in conjunction with analysis of VOCs could help to clear this ambiguity. Furthermore, VOCs influence honey's aroma described as sweet, citrus, floral, almond, rancid, etc. Clearly, the contribution of a volatile compound to honey aroma is determined by its odor activity value. Elucidation of the aroma compounds along with floral origins of a particular honey can help to standardize its quality and avoid fraudulent labeling of the product. Although only present in low concentrations, VOCS could contribute to biomedical activities of honey, especially the antioxidant effect due to their natural radical scavenging potential.

A systematic study on spatial and seasonal patterns of eight taste and odor compounds with relation to various biotic and abiotic parameters in Gonghu Bay of Lake Taihu, China

A systematic study was conducted on seasonal and spatial patterns of taste and odor (T&O) compounds with relation to biotic and abiotic parameters at fifteen sites in Gonghu Bay of Lake Taihu in 2008. We developed a sensitive and automated method to simultaneously analyze eight T&O compounds (boiling points ranging from 38°C to 239°C) by using Purge-and-Trap (P&T) coupled with GC/MS. Maximum particulate dimethyl trisulfide (DMTS, 69.6 ng/L) exceeded its odor threshold concentrations (OTC, 10 ng/L) and maximum dissolved DMTS was 6.1 ng/L, but still far below concentration in the drinking water pollution incident of Wuxi City in 2007 when DMTS reached 1768-11,399 ng/L. Geosmin (GEO), 2-methylisoborneol (MIB), β-cyclocitral, β-ionone and 2-isobutyl-3-methoxypyrazine (IBMP) occasionally or frequently exceeded their OTCs, whereas 2-isopropyl-3-methoxypyrazine (IPMP) and dimethyl sulfide (DMS) did not. We found for the first time significant correlations between particulate β-cyclocitral and β-ionon concentrations and intracellular and extracellular microcystin concentrations. Spatially, Nanquan Waterworks faced more risk by T&O contamination than Xidong Waterworks. High concentrations of NO(3)-N, TDN and TN could be risky signs of taste and odor events by DMS, DMTS, IPMP, IBMP and GEO.

Carotenoid content impacts flavor acceptability in tomato (Solanum lycopersicum)

BACKGROUND

Tomatoes contain high levels of several carotenoids including lycopene and β-carotene. Beyond their functions as colorants and nutrients, carotenoids are precursors for important volatile flavor compounds. In order to assess the importance of apocarotenoid volatiles in flavor perception and acceptability, we conducted sensory evaluations of near-isogenic carotenoid biosynthetic mutants and their parent, Ailsa Craig.

RESULTS

The carotenoid contents of these tomatoes were extremely low in the r mutant, increased in lycopene in old gold, and higher in tetra-cis-lycopene and ζ-carotene in tangerine. The volatiles derived from these carotenoids (β-ionone, geranylacetone and 6-methyl-5-hepten-2-one) were proportionally altered relative to their precursors. Fruits were also analyzed for soluble solids, sugars, acids and flavor volatiles. Consumer panels rated the r mutant lowest for all sensory attributes, while Ailsa Craig was generally rated highest. Old gold and tangerine were rated intermediate in two of the three harvests.

CONCLUSIONS

Several chemicals were negatively correlated with at least one of the hedonic scores while several others were positively correlated with tomato flavor acceptability. The results permitted identification of positive and negative interactions of volatiles with tomato flavor.

Composition of sulla (Hedysarum coronarium L.) honey solvent extractives determined by GC/MS: norisoprenoids and other volatile organic compounds

Samples of unifloral sulla (Hedysarum coronarum L.) honey from Sardinia (Italy) were analysed. To investigate the chemical composition of the honey volatiles two solvent systems were used for ultrasonic solvent extraction (USE): 1) a 1:2 (v/v) pentane and diethyl ether mixture and 2) dichloromethane. All the extracts were analysed by GC and GC/MS. These procedures have permitted the identification of 56 compounds that include norisoprenoids, benzene derivatives, aliphatic compounds and Maillard reaction products. Norisoprenoids were the major compounds in both extracts, dominated by vomifoliol (5.3-11.2%; 9.6-14.0%) followed by minor percentages of other norisoprenoids such as α-isophorone, 4-ketoisophorone, 3-oxo-α-ionol or 3-oxo-α-ionone. Other abundant single compounds in the extracts were 3-hydroxy-4-phenylbutan-2-one (0.8-5.4%; 0.6-5.7%) and methyl syringate (3.0-5.7%; 2.2-4.1%). The composition of the volatiles and semi-volatiles in the obtained extracts suggests that sulla honey is quite distinctive relative to the other honeys that have been chemically studied by GC/MS, but no specific markers of the honey botanical origin were found.

An alternative method for irones quantification in iris rhizomes using headspace solid-phase microextraction

INTRODUCTION

The essential oil obtained from iris rhizomes is one of the most precious raw materials for the perfume industry. Its fragrance is due to irones that are gradually formed by oxidative degradation of iridals during rhizome ageing.

OBJECTIVE

The development of an alternative method allowing irone quantification in iris rhizomes using HS-SPME-GC.

METHODOLOGY

The development of the method using HS-SPME-GC was achieved using the results obtained from a conventional method, i.e. a solid-liquid extraction (SLE) followed by irone quantification by CG.

RESULTS

Among several calibration methods tested, internal calibration gave the best results and was the least sensitive to the matrix effect. The proposed method using HS-SPME-GC is as accurate and reproducible as the conventional one using SLE. These two methods were used to monitor and compare irone concentrations in iris rhizomes that had been stored for 6 months to 9 years.

CONCLUSION

Irone quantification in iris rhizome can be achieved using HS-SPME-GC. This method can thus be used for the quality control of the iris rhizomes. It offers the advantage of combining extraction and analysis with an automated device and thus allows a large number of rhizome batches to be analysed and compared in a limited amount of time.

Timing of cluster light environment manipulation during grape development affects C13 norisoprenoid and carotenoid concentrations in Riesling

Sunlight exposure of winegrape clusters is frequently reported to increase C(13)-norisoprenoids in resulting wines, but the timing and mechanism of this influence is not well understood. Fruit zone leaf removal was applied to Vitis vinifera cv. Riesling at three timings: 2, 33 and 68 days past berry set (PBS), and compared to an untreated control. Free and total 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), vitispirane and beta-damascenone were measured in juice and wines, and carotenoid profiles were determined in grapes at midseason and maturity. Significantly higher total TDN was observed in grapes from the 33-day PBS treatment compared to the control and other treatments (195 microg/L vs 54-87 microg/L). Total vitispirane in juice was also significantly increased in the 33-day PBS treatment, while total beta-damascenone was reduced in the 68-day PBS treatment compared to the control. Existing HPLC protocols were modified to allow for quantification of zeaxanthin in V. vinifera berries, and zeaxanthin was determined to be significantly higher in the 33-day PBS treatment than the control or other treatments (p < 0.05). Total TDN in juice correlated with free TDN in wine, with 11.0% +/- 2.5% of total juice TDN converted to free TDN in wine. In contrast, total vitispirane increased significantly during fermentation, and was not correlated with vitispirane in juice. In summary, leaf removal at 33 days PBS significantly increased zeaxanthin in Riesling grapes midseason, total TDN and vitispirane in the juice of mature Riesling grapes, and free and total TDN in finished wine, while earlier or later leaf removal had no effect.

Volatile composition of Brassica oleracea L. var. costata DC leaves using solid-phase microextraction and gas chromatography/ion trap mass spectrometry

Volatile and semi-volatile components of internal and external leaves of Brassica oleracea L. var. costata DC, grown under different fertilization regimens, were determined by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography/ion trap mass spectrometry (GC/ITMS). Forty-one volatiles and non-volatile components were formally identified and thirty others were tentatively identified. Qualitative and quantitative differences were noticed between internal and external leaves. In general, internal leaves exhibited more aldehydes and sulfur volatile compounds than external ones, and less ketone, terpenes and norisoprenoid compounds. The fertilization regimens influenced considerably the volatile profile. Fertilizations with higher levels of sulfur produced Brassica leaves with more sulfur volatiles. In opposition, N and S fertilization led to leaves with lower levels of norisoprenoids and terpenes.

Online gas chromatography combustion/pyrolysis-isotope ratio mass spectrometry (HRGC-C/P-IRMS) of (+/-)-Dihydroactinidiolide from tea ( Camellia sinensis ) and rooibos tea ( Aspalathus linearis )

Online capillary gas chromatography-isotope ratio mass spectrometry in both the combustion and the pyrolysis modes (HRGC-C/P-IRMS) was employed to perform authentication studies of the flavoring agent (+/-)-dihydroactinidiolide. Thus, the delta(13)C(V-PDB) and delta(2)H(V-SMOW) values of synthetic (ex synthetic beta-ionone and natural beta-carotene) as well as enzymatically (ex synthetic and natural beta-carotene) produced references were studied in comparison with those of the natural substance isolated from black (n = 17) and green teas (n = 6) ( Camellia sinensis ) as well as Rooibos tea ( Aspalathus linearis ) (n = 7). The isotope values determined for both the synthetic and enzymatically produced samples of (+/-)-dihydroactinidiolide reflected the influence of the origin of their educts. Hence, in cases when synthetic educts were used, the delta(13)C(V-PDB) and delta(2)H(V-SMOW) values ranged from -27.0 to -28.4 per thousand and from -28 to -169 per thousand, respectively, whereas the use of natural educts led to ranges from -30.3 to -31.6 per thousand and from -154 to -228 per thousand, respectively. As to the tea samples, delta(13)C(V-PDB) and delta(2)H(V-SMOW) values ranging from -29.0 to -34.1 per thousand and from -153 to -274 per thousand, respectively, were recorded for (+/-)-dihydroactinidiolide from black and green teas, whereas that from Rooibos tea showed (2)H/(1)H ratios ranging from -189 to -210 per thousand as well as slightly enriched values in the (13)C/(12)C ratios ranging from -24.4 to -27.1 per thousand.

Changes in some carotenoids and apocarotenoids during flower development in Boronia megastigma (Nees)

The carotenoid profile of an acetone extract from the flowers and leaves of Boronia megastigma (Nees) was examined. A comparison was made of the major carotenoids found in boronia flowers and leaves. The C-40 carotenoids beta-carotene, zeaxanthin, lutein, and neoxanthin were positively identified in boronia flowers using known standards, UV-vis spectra, and mass spectrometry. Two other carotenoids were tentatively assigned as the palmitic acid ester of 3-hydroxy-10'-apocaroten-10'-oic acid and 9,15,9'-tri-cis-zeta-carotene. Additionally, changes in the levels of C-40 carotenoids, C-27 apocarotenoids, and beta-ionone during flower development were measured. Significant increases in beta-carotene and apocarotenoids that could be derived from cleavage in the 9,10-position, including beta-ionone and various C-27 apocarotenoids, were observed at the time of flower opening. An increase in lutein, which is derived through an alternative biosynthetic pathway, was not observed during flower opening, thus indicating the possibility that the beta-carotene pathway was activated during flower opening in boronia. The understanding of these processes may assist in optimizing harvest and postharvest processes useful to the boronia extraction industry.