Studies on aroma generation in lulo (Solanum quitoense): enzymatic hydrolysis of glycosides from leaves

New lignan tyramide, phenolics, megastigmanes, and their glucosides from aerial parts of New Zealand spinach, Tetragonia tetragonoides

Twenty compounds, including a new lignan amide, were isolated from the aerial parts of New Zealand spinach, Tetragonia tetragonoides (Pall.) Kuntze, which is an edible halophyte. These compounds were identified by mass spectrometry and nuclear magnetic resonance experiments to be N-2,3-dihydroxy-3-(3,4-dihydroxyphenol)tyramine (new compound), methyl 4-hydroxybenzoate, syringaldehyde, ethyl 4-hydroxybenzoate, 3,4-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, coniferyl alcohol, methyl caffeoate, trans- and cis-coumaroyl-β-d-glucopyranosides, trans- and cis-feruloyl-β-d-glucopyranosides, caffeic acid, staphylionoside E, canabiside D, apocyanol A, megastima-5,7-diene-3,4,9-triol, 1-O-oleoyl-3-O-β-d-galactopyranosyl-sn-glycerol, 5,5'-dimethyl-lariciresinol, and kaempferol 3-O-β-d-glucopyranoside. These compounds were identified in New Zealand spinach for the first time.

Gas chromatography-mass spectrometry in the taxonomy of Miscanthus

Chemotaxonomy as a system approach deals with intra- and interspecific polymorphism of a group of taxa in order to clarify their taxonomic positions or to select material for selection or introduction. In this study we performed chemotaxonomic analysis of specimens of Miscanthus sinensis and M. sacchariflorus collected in the Russian Far East and of hybrid plants of both natural and artificial origin. We found 153 substances and identified 143 of them in extracts of eleven Miscanthus plants by gas chromatography-mass spectrometry (GC-MS). These substances can be grouped into alkanes (20 compounds), fatty acids (34), phenols (13), sterols (18) toсopherols (8), norterpenoids (12), and phytols (13), as well as their derivatives. The main components of the extracts of miscanthus samples are fatty acids and their derivatives (total content 19.94–41.02 %), dominated by palmitic and linolenic acids, and sterols (mainly β-sitosterol, stigmasterol, and α-amyrin), which constitute 17.15–31.73 %. The values of the CPI “oddness index” for the alkane components of the extracts were within 1.55–7.18, with extracts from leaves of the Far Eastern samples characterized by the lower half of this range (1.55–2.74), while extracts from leaves of hybrids fell to the upper half (5.78–7.18). Principal component analysis of extraction profiles allowed us to separate three distinct clusters: M. sinensis, M. sachariflorus, and their hybrids, as well as to verify the origin of one of the natural hybrids. The results of chemotaxonomic analysis mostly matched those of DNA sequencing of a fragment of the plastid genome, which, moreover, allowed us to identify the species nature of the maternal plants used to obtain these hybrids. Chemotaxonomic analysis using GC-MS was found to be an efficient additional technique to delimit various morphological forms of M. sinensis, M. sachariflorus, and their hybrids.

Gene-Metabolite Networks of Volatile Metabolism in Airen and Tempranillo Grape Cultivars Revealed a Distinct Mechanism of Aroma Bouquet Production

Volatile compounds are the major determinants of aroma and flavor in both grapes and wine. In this study, we investigated the emission of volatile and non-volatile compounds during berry maturation in two grape varieties (Airén and Tempranillo) throughout 2010 and 2011. HS-SPME coupled to gas chromatography and mass spectrometry was applied for the identification and relative quantitation of these compounds. Principal component analysis was performed to search for variability between the two cultivars and evolution during 10 developmental stages. Results showed that there are distinct differences in volatile compounds between cultivars throughout fruit development. Early stages were characterized in both cultivars by higher levels of some apocarotenoids such as β-cyclocitral or β-ionone, terpenoids (E)-linalool oxide and (Z)-linalool oxide and several furans, while the final stages were characterized by the highest amounts of ethanol, benzenoid phenylacetaldehyde and 2-phenylethanol, branched-amino acid-derived 3-methylbutanol and 2-methylbutanol, and a large number of lipid derivatives. Additionally, we measured the levels of the different classes of volatile precursors by using liquid chromatography coupled to high resolution mass spectrometry. In both varieties, higher levels of carotenoid compounds were detected in the earlier stages, zeaxanthin and α-carotene were only detected in Airén while neoxanthin was found only in Tempranillo; more variable trends were observed in the case of the other volatile precursors. Furthermore, we monitored the expression of homolog genes of a set of transcripts potentially involved in the biosynthesis of these metabolites, such as some glycosyl hydrolases family 1, lipoxygenases, alcohol dehydrogenases hydroperoxide lyases, O-methyltransferases and carotenoid cleavage dioxygenases during the defined developmental stages. Finally, based on Pearson correlation analyses, we explored the metabolite-metabolite fluctuations within VOCs/precursors during the berry development; as well as tentatively linking the formation of some metabolites detected to the expression of some of these genes. Our data showed that the two varieties displayed a very different pattern of relationships regarding the precursor/volatile metabolite-metabolite fluctuations, being the lipid and the carotenoid metabolism the most distinctive between the two varieties. Correlation analysis showed a higher degree of overall correlation in precursor/volatile metabolite-metabolite levels in Airén, confirming the enriched aroma bouquet characteristic of the white varieties.

Chemical and sensory comparison of fresh and dried lulo (Solanum quitoense Lam.) fruit aroma

The odour-active volatile compounds of lulo fruit (Solanum quitoense Lam.) were isolated by solvent extraction followed by solvent-assisted flavour evaporation (SAFE). GC-O and GCMS analyses as well as quantitation by internal standard method showed that (Z)-3-hexenal, ethyl butanoate, 3-sulphanylhexyl acetate, and ethyl hexanoate were key aroma compounds in this fruit. Other odorants with relevance because their contribution (high OAVs) to the overall aroma were 4-hydroxy-2,5-dimethyl-3(2H)-furanone, methyl benzoate, (E)-2-hexenal, and hexanal. Lulo fruit pulp in presence of maltodextrin DE-20 was dried by using four different types of drying methods: hot air-drying (HD), spray drying (SD), lyophilisation (LD), and ultrasonic convective hot air-drying (HUD). LD sample exhibited the highest sensory rank (lulo-like) in comparison with fresh fruit pulp. Hot-air drying processes (HD and HUD) changed adversely the aroma of lulo fruit pulp.

Quantitative solid phase microextraction--gas chromatography mass spectrometry analysis of five megastigmatrienone isomers in aged wine

Megastigmatrienone is a key flavor compound in tobacco. It has also been detected in wine, where it may contribute to a tobacco/incense aroma, but its importance and concentration in wines had never previously been evaluated. A method was developed and validated for quantifying the five megastigmatrienone isomers in red and white wines. Megastigmatrienone isomers were extracted by headspace solid-phase microextraction (HS-SPME), with a 65 μm film thickness polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber and analyzed using gas chromatography-mass spectrometry (GC/MS) in selected ion monitoring mode (SIM). Several parameters affecting the length of the adsorption process (i.e., adding salt, extraction time and extraction temperature) were tested. The optimum analytical conditions were established. The LOQ were between 0.06 μg L(-1) and 0.49 μg L(-1) for white wine and 0.11 μg L(-1) and 0.98 μg L(-1) for red wine, repeatability in both types of wine was less than 10% and recovery ranged from 96% for white wine to 94% for red wine. The five isomers of megastigmatrienone were quantified in red and white wines for the first time. Concentrations ranged from 2 μg L(-1) to 41 μg L(-1) in both red and white wines. Initial results revealed a link between wine aging and megastigmatrienone levels, indicating that megastigmatrienone may be a component in wine "bouquet".

Identifying carotenoids and phenolic compounds in naranjilla (Solanum quitoense Lam. var. Puyo hybrid), an Andean fruit

The naranjilla or lulo (Solanum quitoense Lam.) is a little known fruit that originated in the Andes. Commonly consumed as a fresh drink, it is particularly appreciated for its aroma. Besides its organoleptic qualities, the naranjilla also seems to have good antioxidant properties. We therefore studied the physicochemical characteristics of variety "Puyo hybrid"; determined its juice composition; identified its carotenoids and phenolic compounds, using HPLC-DAD and HPLC/ESI-MS, respectively, in each fruit part; and measured the antioxidant capacities of each part, using the ORAC and DPPH methods. We found the following bioactive compounds: all-trans-beta-carotene, 13-cis-beta-carotene, and 9-cis-beta-carotene and the lutein (carotenoids); chlorogenic acids and their hexosides in the flesh and placental tissues, and flavonol glycosides in the skin (phenolic compounds); and many dihydrocaffeoyl spermidines in all three parts of the fruit. The naranjilla appeared to be a fruit with good nutritional potential that can provide the basis for a new fruit-drink flavor or other fruit derived-products.

Characterization of odor-active volatiles in champa (Campomanesia lineatifolia R. and P.)

Volatile extracts from pulp, peels, leaves, and seeds of champa (Campomanesia lineatifolia R. and P.) were obtained by continuous liquid-liquid extraction with pentane/dichloromethane (1:1), and their chemical composition was determined by using HRGC and HRGC-MS. Differences between C. lineatifolia volatile extracts with regard to the identified compounds are presented; however, in all of them the beta-triketones were detected as major constituents (between 50 and 60% of total extract). An odor profile description of volatiles isolated in all of the extracts was obtained by HRGC-O. These analyses showed that beta-triketones contributed to the fruity, floral, and green odor notes in the flavor of fruit. Application of AEDA to pulp volatile extract revealed 2,5-dimethyl-4-methoxy-3(2H)-furanone, 2-phenylethanol, and 2,3-dihydro-5-hydroxy-6,8,8-trimethyl-2-phenyl-4H-1-benzopyran-4,7(8H)-dione (champanone C) to have the highest flavor dilution factors. In a similar way, (E)-cinnamyl alcohol, 2,5-dimethyl-4-methoxy-3(2H)-furanone, and 2,3-dihydro-5-hydroxy-6,8,8-trimethyl-2-phenyl-4H-1-benzopyran-4,7(8H)-dione (champanone C) were identified as key odorant compounds in the fruit peel volatile extract. This is the first time that the volatile composition in champa is reported and also the sensory odor importance of beta-triketones.

Astonishing diversity of natural surfactants: 3. Carotenoid glycosides and isoprenoid glycolipids

Carotenoid glycosides and isoprenoid glycolipids are of great interest, especially for the medicinal, pharmaceutical, food, cosmetic, flavor, and fragrance industries. These biologically active natural surfactants have good prospects for the future chemical preparation of compounds useful as antimicrobial, antibacterial, and antitumor agents, or in industry. More than 300 unusual natural surfactants are described in this review article, including their chemical structures and biological activities.