C13 Norisoprenoids Research Articles

Identification of key odor volatile compounds in the essential oil of nine peach accessions

Volatile compounds, together with sugars and acids, are the main chemical species determining the characteristic aroma and flavor of food. In peach, more than 100 volatiles have been identified. The essential oil of six peach and three nectarine accessions used in Italian breeding programs was obtained by steam distillation, and the volatiles were investigated. A total of 47 known volatiles, two unidentified compounds and nine hydrocarbons were identified, including 12 aldehydes, six alcohols, three acids, three esters, six terpenes, two phenylalanine derivates, two C(13) norisoprenoids, one ketone (C(9)) and 10 lactones. A wide variation in the number of volatiles and in their concentration was observed among the nine accessions. Twenty-one compounds presented odor activity values (OAVs) higher than 1 in at least one of the accessions and were therefore putatively considered as key odorants in the peach volatile composition. This study reports the identification, quantification and potency, based on the OAVs, of the most important volatile compounds, along with fruit quality characteristics, of nine different peach/nectarine accessions and will help future peach volatile breeding programs for the selection of odor-rich accessions to be used in the development of new improved cultivars.

Global grape aroma potential and its individual analysis by SBSE–GC–MS

Abstract Among the aroma compounds present within grapes, a significant part is assumed to come from specific odourless precursors found mainly as glycosidic compounds which are known as bound fraction. In this paper, the individual composition of non-aromatic red grape bound fraction has been assayed for first time by SBSE–GC–MS and compared with the global total aroma potential measured spectrophotometrically at the wineries, in which the anthocyanins interferences have been removed. Glycosidic aroma compounds have been extracted by macerating grapes with different extractants (EtOHaq or SO2) at different times and subjected to acidic hydrolysis at 70 °C for 2 h. The best extraction condition, expressed as the higher aroma compounds concentration (terpenes + C13 norisoprenoids + 2-phenylethanol + C6 compounds), was the ethanolic aqueous extraction carried out for 2 h, reducing considerably the extraction times proposed in the literature. The method was successfully used to discriminate non-aromatic red grape varieties, (Petit-Verdot, Merlot and Monastrell) being limonene, linalool, 2-hexen-1-ol, TDN and 2-phenylethanol the aromas that contributed most to the differentiation. An aromatic white table grape such as Early sugar was also assayed to check its higher volatile composition in comparison with the other red varieties. The percentage of favourable aromas (terpenes + C13 norisoprensoids + bencene derivates) is always higher than the unfavourable ones (C6) for all tested varieties, especially Early Sugar. It has also been observe that the spectrophotometric measurements are overestimated when compared with SBSE–GC–MS, probably due to the free sugar content and other glycosidic compounds.

Generation of Norisoprenoid Flavors from Carotenoids by Fungal Peroxidases

To biotechnologically produce norisoprenoid flavor compounds, two extracellular peroxidases (MsP1 and MsP2) capable of degrading carotenoids were isolated from the culture supernatants of the basidiomycete Marasmius scorodonius (garlic mushroom). The encoding genes were cloned from genomic DNA and cDNA libraries, and databank homology searches identified MsP1 and MsP2 as members of the so-called "DyP-type" peroxidase family. Wild type enzymes and recombinant peroxidases expressed in Escherichia coli were employed for the release of norisoprenoids from various terpenoid precursor molecules. Carotenes, xanthophylls, and apocarotenals were subjected to the enzymatic degradation. Released volatile products were characterized by GC-FID and GC-MS, whereas nonvolatile breakdown products were analyzed by means of HPLC-DAD and HPLC-MS. C13 norisoprenoids together with C10 products proved to be the main volatile degradation products in each case.

Key Compounds of Provence Rosé Wine Flavor

The aromas of French Provence rosé wines were subject to in-depth gas chromatography and sensory analyses at the Research and Experimentation Center on Rosé Wine (Centre de Recherche et d’Expérimentation sur le Vin Rosé). The study has demonstrated the olfactive contribution of different volatile compounds of fermentative and varietal origins. Dearomatization and reconstitution of flavor has revealed the preponderant character of ethyl esters and higher alcohol acetates, which are simple to determine and are at the origin of the fruity and amylic notes of rosé wines. Moreover, the search for specific varietal compounds—well known in other types of wines—has made it possible to identify some key compounds of rosé wine flavor: two volatile thiols (3-mercaptohexanol and 3-mercaptohexyl acetate), two furanic compounds (furaneol and homofuraneol), and one C13 norisoprenoid (β-damascenone). These compounds have now been measured in most of the experiments conducted at the Center on Rosé Wine and are used as qualitative indicators in evaluation protocols for the exploitation of vines or for rosé winemaking techniques.

Effects of Elevated CO2 on Grapevine (Vitis vinifera L.): Volatile Composition, Phenolic Content, and in Vitro Antioxidant Activity of Red Wine

The impact of elevated carbon dioxide concentration ([CO2]) on the quality of berries, must, and red wine (with special reference to volatile composition, phenolic content, and antioxidant activity) made from Touriga Franca, a native grape variety of Vitis vinifera L. for Port and Douro wine manufacturing grown in the Demarcated Region of Douro, was investigated during 2005 and 2006. Grapevines were grown either in open-top chambers (OTC) with ambient (365 +/- 10 ppm) or elevated (500 +/-16 ppm) [CO2] or in an outside plot. In general, the increase of [CO2] did not affect berry characteristics, especially the total anthocyan and tannin concentrations. However, the total anthocyan and polyphenol concentrations of the red wine were inhibited under elevated [CO2]. The antioxidant capacity of the wines was determined by DPPH, ABTS, and TBARS assays and, despite the low concentrations of phenolics, the elevated [CO2] did not significantly change the total antioxidant capacity of the red wines. Thirty-five volatile compounds belonging to seven chemical groups were identified: C6 alcohols, higher alcohols, esters, terpenols, carbonyl compounds, acids, volatile phenols, and C13 norisoprenoids. Generally, the same volatile compounds were present in all of the wines, but the relative levels varied among the treatments. The effect of elevated [CO2] was significant because it was detected as an increase in ethyl 2-methylbutyrate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, butyric acid, and isovaleric acid concentrations and a decrease in ethyl acetate concentration when compared to wines produced in ambient [CO2] in 2005. In elevated [CO2], wines from 2006 had lower methionol, 1-octanol, and 4-ethylguaiacol and higher ethyl lactate and linalool concentrations. The increase in [CO2] did not significantly affect C6 alcohols, citronellol, carbonyl compounds, and beta-damascenone concentrations. This study showed that the predicted rise in [CO2] did not produce negative effects on the quality of grapes and red wine. Although some of the compounds were slightly affected, the red wine quality remained almost unaffected.

Effects of cold storage on aroma compounds of white- and yellow-fleshed peaches

The stir bar sorptive extraction (SBSE) technique was used to determine volatile constituents in two peach cultivars, one yellow-fleshed (cv. Spring Lady) and one white-fleshed (cv. Regina Bianca). For both cultivars four distinct experimental samples were considered, each formed by fruits obtained with four different cultivation practices. In order to investigate the effects of cold storage on the volatile profile, on all peach experimental samples changes in aroma compounds after 1 and 2 weeks of storage at 1°C, plus 1 day at ambient temperature, were monitored; moreover, only on the four experimental samples from cv. Regina Bianca, the effect of a prestorage hot water treatment (46°C for 25 min) was also evaluated. On the isolate obtained by SBSE, 24 compounds were identified and quantified by GC-MS: saturated and unsaturated lactones, aldehydes, C13 norisoprenoids, monoterpenes, alcohols and esters. The profile of the white-fleshed cultivar was characterised by a higher level of C13 norisoprenoids, and, in particular, of 8,9-dehydrotheaspirone. In all experimental samples after 1 week of storage, plus 1 day at ambient temperature, a marked increase (on average by 89%) in total lactones was observed. This increase was due to a noticeable accumulation of saturated lactones with longer side chains (γ- and δ-decalactone) and unsaturated lactones ((Z)-dec-7-en-5-olide and γ-jasmolactone). Peaches analysed after 2 weeks of storage showed total lactone levels close to those detected in the samples at harvest, suggesting that increasing storage times reduced fruit ability to accumulate these character impact compounds of peach aroma. A similar effect of cold storage, although less marked, was also observed on C13 norisoprenoid fraction, but only on cv. Regina Bianca. On the other hand, we did not find univocal effects of cold storage on C6 aldehydes, whereas linalool, detected only in samples of cv. Spring Lady at harvest, disappeared quickly during the first days of storage. In samples of cv. Regina Bianca peaches subjected to hot water treatment, after 1 week of storage, lactone level was significantly reduced in comparison with untreated fruits, denoting a possible inhibition effect on lactone accumulation and on aroma development.

Establishment of the varietal volatile profile of musts from white Vitis vinifera L. varieties

AbstractMusts from four white Vitis vinifera L. varieties of Bairrada Appellation (Fernão‐Pires, Bical, Cerceal and Arinto) were analysed over two harvests (1998 and 1999). The free volatile components were extracted using a liquid–liquid continuous method and were analysed by gas chromatography/mass spectrometry. The potential volatile compounds (PVC) were determined after a heat treatment followed by an enzymatic treatment. The PVC fraction contained the compounds released by the enzymes from the glycosidically linked components plus the compounds produced by the heat treatment at the must pH (3.2) as well as compounds arising from the thermal degradation of sugars. Based on three varietal chemical groups, namely terpenoids, C13 norisoprenoids and aromatic alcohols, the volatile profile of each of the four varieties was established, which allowed their aroma potential to be defined. Fernão‐Pires exhibited a profile significantly different from those of the other varieties, with a higher number and concentration of volatile compounds. As a consequence of the fact that the four varieties exhibit different volatile composition patterns (different components and different distributions between free and PVC forms), winemaking technologies should be specifically developed for each variety for the improvement of wine aroma quality. Owing to the complexity of the data, including the harvest effect, a contrast data pre‐treatment was applied before the utilisation of principal component analysis. The results suggest that it is possible to establish markers (volatiles) for the characterisation of must varieties independently of the harvest effect. Copyright © 2007 Society of Chemical Industry

Quantification of Selected Aroma-Active Compounds in Pinot Noir Wines from Different Grape Maturities

Effect of grape maturity on aroma-active compounds in Pinot noir wine was investigated using stir bar sorptive extraction-gas chromatograph-mass spectrometry (SBSE-GC-MS). High correlation coefficient (> 0.95) and low standard deviation (< 10%) were obtained for all aroma-active compounds of interest. Two vintages of Pinot noir wines with three different grape maturities each were analyzed. Statistical analysis showed that both grape maturity and growing year significantly affected the aroma composition of the final wine. Analysis of wine samples from the same vintage indicated that grape maturity could affect aroma compounds in different ways, based on their biochemical formation in the wines. For most short-chain fatty acid esters, there were no obvious trends with grape maturity, however, the concentrations of ethyl 2-methylpropanoate and ethyl 3-methylbutanoate consistently decreased with grape maturity. The decreasing trend was also observed for other esters including ethyl cinnamate, ethyl dihydroxycinnamate, and ethyl anthranilate, with the exception of ethyl vanillate, while C13 norisoprenoids, monoterpenes, and guaiacols had increasing trends with grape maturation.

Chemical Constituents of the Aquatic Plant Schoenoplectus lacustris: Evaluation of Phytotoxic Effects on the Green Alga Selenastrum capricornutum

Forty-nine secondary metabolites were isolated from aqueous and alcoholic extracts of the aquatic plant Shoenoplectus lacustris. All compounds were characterized based on spectroscopic data. Eleven free and glycosylated low-molecular polyphenols, 17 cinnamic acid and dihydrocinnamic acid derivatives, 11 flavonoids, and 10 C13 nor-isoprenoids were identified. The structure of the new compound, 1-benzoyl-glycerol-2-alpha-L-arabinopyranoside, was elucidated by 2D NMR experiments (COSY, HSQC, HMBC, NOESY). To evaluate potential phytotoxic effects, all compounds were tested on the green alga Selenastrum capricornutum, a unicellular organism commonly used in tests of toxicity as a bioindicator of eutrophic sites. The most active compound was (-)-catechin, showing an inhibition similar to that of the algaecide CuSO4.

C13 Norisoprenoids from Brassica Fruticulosa

Five C13 norisoprenoids, one of them glucosilated, have been isolated from the leaves of Brassica fruticulosa (Brassicaceae). The structure (3S,4R,7E,9S)-3,4,9-trihydroxy-5,7-megastigmadiene, has been assigned to the new compound. All the structures have been determined by spectroscopic means and chemical correlations.

Varietal flavour compounds of four grape varieties producing Madeira wines

Boal, Malvasia, Sercial and Verdelho are the main white grape varieties used in Madeira wine production. To estimate the free fraction of varietal aroma compounds of these varieties, 39 samples of musts were analysed to determine their content of monoterpenols and C13 norisoprenoids (terpenoids), using dynamic headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry. The r-values for linearity studies of the analytical method used, varied between 0.977 (nerolidol) and 0.999 (linalool). The repeatability for each compound varied between 2.5% (citronellol) and 11.8% (β-ionone). The mean values from three vintages (1998, 1999 and 2000) confirmed that these musts have differentiated contents of terpenoids. In opposition to Verdelho musts, Malvasia showed the highest free terpenoids content. In order to establish relations between the compounds and the varieties under investigation, principal component analysis and linear discriminant analysis were applied to the data, revealing a good separation and classification power between the four groups as a function of varietal origin.

Nor-isoprenoids profile during port wine ageing?influence of some technological parameters

Nor-isoprenoid compounds, such as β-damascenone, β-ionone, 2,2,6-trimethylcyclohexanone (TCH), 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and vitispirane were determined in 14 young port wines and 45 old port wines. As between the two groups of wines levels of these compounds are quite different, an experimental protocol was performed in order to determine which technological parameter (dissolved O2, free SO2 levels, pH and time/temperature) was related with the formation/consumption of these molecules. The five nor-isoprenoids were equally affected by the selected parameters and a similar profile with time was observed. The synergistic effects of increasing temperature and lowering pH had the largest impact. For samples treated with high oxygen regimes (saturation), the levels of all considered nor-isoprenoids decreased after a certain concentration of oxygen consumed (e.g. 10 mg l−1). Nevertheless, during barrel port wine ageing, corresponding to the 45 wines, two different behaviours can be observed: TDN, vitispirane and TCH increase significantly whilst a decrease of levels of β-ionone and β-damascenone with port barrel ageing was observed. It was also calculated that “over 40 year” old port wines have, respectively, 15, 5 and 3 times higher levels of TDN, vitispirane and TCH than the young ports. For these three compounds the respective rates of formation are higher than those of degradation, which suggests a higher number or higher concentration of precursors than those involved for the megastigame C13 nor-isoprenoids β-damascenone and β-ionone.

Nor-isoprenoids profile during port wine ageing—influence of some technological parameters

Nor-isoprenoid compounds, such as β-damascenone, β-ionone, 2,2,6-trimethylcyclohexanone (TCH), 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and vitispirane were determined in 14 young port wines and 45 old port wines. As between the two groups of wines levels of these compounds are quite different, an experimental protocol was performed in order to determine which technological parameter (dissolved O 2, free SO 2 levels, pH and time/temperature) was related with the formation/consumption of these molecules. The five nor-isoprenoids were equally affected by the selected parameters and a similar profile with time was observed. The synergistic effects of increasing temperature and lowering pH had the largest impact. For samples treated with high oxygen regimes (saturation), the levels of all considered nor-isoprenoids decreased after a certain concentration of oxygen consumed (e.g. 10 mg l −1). Nevertheless, during barrel port wine ageing, corresponding to the 45 wines, two different behaviours can be observed: TDN, vitispirane and TCH increase significantly whilst a decrease of levels of β-ionone and β-damascenone with port barrel ageing was observed. It was also calculated that “over 40 year” old port wines have, respectively, 15, 5 and 3 times higher levels of TDN, vitispirane and TCH than the young ports. For these three compounds the respective rates of formation are higher than those of degradation, which suggests a higher number or higher concentration of precursors than those involved for the megastigame C13 nor-isoprenoids β-damascenone and β-ionone.

β-Damascenone-yielding precursor(s) from Cabernet Sauvignon grapes

β-Damascenone, a potent aroma component of in a variety of grapes and wines, has a sensory threshold of approximately 2ng/L in water. This C13 norisoprenoid ketone is principally generated from hydrolyzable precursors, which was glycosidically bound. Isolation of β-damascenone-yielding precursors from Cabernet Sauvignon grape skins using C18 reversed phase chromatography followed by droplet countercurrent chromatography yielded multiple chromatographically distinguishable precursor fractions. The existence of multiple precursors was further evident from the varying ratios of 3-hydroxy- β-damascone (the by-product): β-damascenone generated upon acid hydrolysis of the chromatographically distinguishable precursor fractions.

The aroma of Muscat of Frontignan grapes: effect of the light environment of vine or bunch on volatiles and glycoconjugates

Effects of the modification of whole vine or individual cluster light environment by shade cloth from berry set to maturity were studied on the volatiles and glycoconjugates in Muscat (Muscat of Frontignan; Vitis vinifera L) berries over 2 years. Whole vines were shaded with 50 and 70% shade cloth, while bunches were shaded with 90% shade cloth. The sun-exposed berries were chosen as control berries, and the berries naturally shaded under foliage were also studied. The natural shading of bunches under foliage did not decrease the levels of free and bound compounds in Muscat berries compared to sun-exposed berries. The artificially shaded bunches showed lower levels of monoterpenols and C13 norisoprenoids than sun-exposed berries and berries from naturally shaded bunches. Moreover, the effect of vine shading on the aroma composition of Muscat berries was lower compared to artificial bunch shading. In 1996 the leaf area/fruit yield ratio was modified by decreasing the bunch number per vine. This change did not influence the total amounts of glycosidically bound compounds, except for monoterpenic glycoconjugates. However, the higher monoterpenic glycoconjugate levels in these berries were likely related to their early maturity. Under our experimental conditions, berry aroma composition did not appear to be affected by foliage shade. © 2000 Society of Chemical Industry

Isolation and Structural Elucidation of Aroma Constituents Bound as Glycosides from Sage (Salvia officinalis)

Four glycosidic bound flavor precursors, (1S,2R,4R)-1,8-epoxy-p-menthan-2-yl-O-β-d-glucopyranoside, (6R,9R)-3-oxo-α-ionol β-d-glucopyranoside, (6R,9S)-3-oxo-α-ionol β-d-glucopyranoside, and eugenylglucoside, were isolated from the ethanol extract of Dalmatian sage. Their structures were elucidated by spectral methods (NMR and MS). All four compounds are new to the constituents of sage. Keywords: Sage; flavor precursors; monoterpenes; C13 norisoprenoid; Salvia officinalis

Comparison of Free and Glycosidically Linked Volatile Components from Polyembryonic and Monoembryonic Mango (Mangifera indica L.) Cultivars

Free and glycosidically linked volatile components of four mango cultivars of polyembryonic (M'Bingue and Tete de Chat) and monoembryonic (Amelie and Palmer) seed origins were examined. Eighty-five free volatile components were identified in the four cultivars, of which 33 are newly described as mango volatile compounds. Terpene hydrocarbons (104, 139, 26, and 35 mg/kg of fresh pulp, respectively) were the major volatiles of all four cultivars (>90% of the total volatiles), the dominant terpenes being (Z,E)-ocimenes (70%) in Amelie and car-3-ene (80%) in the other cultivars. Free oxygenated volatiles, mainly represented by monoterpenoids, and C13 norisoprenoids were present in all cultivars, the African Tete de Chat cultivar being by far the richest (12.3 mg/kg). Of the 29 aglycons characterized, 12 were identified for the first time as mango bound volatiles. Again, the Tete de Chat cultivar was the richest (2.1 mg/kg) with monoterpenoids and C13 norisoprenoids as the main glycosidically linked volatile c...

Microfiltration and Reverse Osmosis Affect Recovery of Mango Puree Flavor Compounds

ABSTRACTFlavor compounds from ripe mango puree were studied upon cross‐flow microfiltration on microporous alumina membrane and subsequent concentration of the permeate by reverse osmosis. Terpene hydrocarbons, the major (−98%) volatiles of the puree, were qualitatively and quantitatively recovered in the pulpy microfiltration retentate. The more polar volatiles (−2%) were diversely affected. Most of the oxygenated terpene derivatives were also retained in the microfiltration retentate. C13 norisoprenoids and phenols increased, likely by chemical degradation of carotenoids and phenolic acids, respectively.

Identification and Enantiodifferentiation of C13 Norisoprenoid Degradation Products of Glycosidically Bound 3-Hydroxy-.alpha.-ionol from Stinging Nettle (Urtica dioica L.)

Acid-catalyzed degradation (simultaneous distillation-extraction ; pH 2.5) of glycosidically bound 3-hydroxy-α-ionol from stinging nettle (Urtica dioica L.) yielded 2,2,6-trimethyl-7-methylenebicyclo-[4.3.0]nona-4,8-diene and 2,2,6,7-tetramethylbicyclo[4.3.0]nona-4,7,9-triene as well as ylidene)-2,6,6-trimethylcyclohexa-2,4-diene (1), 1-(2.butenylidene)-6,6-dimethyl-2-methylenecyclohex-3-ene (2), and isomeric 4-(2,6,6-trimethylcyclohexa-2,4-dien-1-yl)but-3-en-2-ol (2,3-didehydro-α-ionol) (3a-d) and 4-(6,6-dimethyl-2-methylenecyclohex-3-en-1-yl)but-3-en-2-ol (3,4-didehydro-γ-ionol) (4a-d), which were identified by comparison of their chromatographic and spectral (MS ; vapor phase FTIR) data with those of synthesized reference compounds. Configuration of the butenylidene chain of and 2 was established by NOE experiments. The absolute configuration of the stereoisomers of 3 and 4 was elucidated using optically pure reference compounds. Enantiodifferentiation carried out by on-line coupled multidimensional gas chromatography-mass spectrometry revealed the occurrence of 1'R,2R and 1'R,2S diastereomers (3a/3c and 4a/4c) in stinging nettle.

Generation of oxidation artifacts during the hydrolysis of norisoprenoid glycosides by fungal enzyme preparations

The glycosidic fraction of a Vitis vinifera cv. Chardonnay juice was hydrolyzed with three fungal enzyme preparations, i.e., Rohapect C, Rohapect D5L, and Novoferm 12, and also with almond emulsin. The concentrations of nine of the aglycons, all C13 norisoprenoids, varied according to the conditions of the hydrolysis. 3-Hydroxy-beta-damascone, megastigm-5-en-7-yne-3,9-diol, 3-hydroxy-beta-ionone, megastigm-5-ene-3,9-diol, 3-hydroxy-5,6-epoxymegastigm-7-en-9-one diminished significantly in concentration when the glycosidic fraction was treated with increasing levels of Rohapect C. Loss of these 3-hydroxymegastigmanes was accompanied by the formation of 3-oxo-alpha-damascone, 3-oxo-beta-damascone, and 9-hydroxymegastigma-4,6,7-trien-3-one and an increase in concentration of dehydrovomifoliol. Pure samples of 3-hydroxy-beta-damascone and its beta-D-glucopyranoside were partially oxidized by Rohapect C to the corresponding oxodamascones. Similar oxidative artifacts were observed when the Chardonnay glycosidic fraction was treated with Rohapect D5L and Novoferm 12. No oxidation was observed with almond emulsin.