Search Results (4)

Scented green tea (Camellia sinensis) is a type of reprocessed green tea produced by scenting with flowers. To investigate the differences in the volatiles of scented green tea processed with four different flowers (Jasminum sambac, Osmanthus fragrans, Michelia alba, and Rosa rugosa), gas chromatography–ion mobility spectrometry (GC–IMS) and gas chromatography–mass spectrometry (GC–MS) were employed to detect and identify the volatile compounds in the four types of scented teas. GC–IMS and GC–MS identified 108 and 101 volatile compounds, respectively. The key characteristic volatile compounds, namely indole, linalool, β-myrcene, benzyl acetate, and ethyl benzoate (jasmine tea); cedrol, (E)-β-ionone, γ-decalactone, and dihydro-β-ionol (osmanthus tea); geraniol, phenylethyl alcohol, jasmone, methyl jasmonate, hexadecanoic acid, 4-ethyl-benzaldehyde, 2-methylbutyl hexanoate, and indole (michelia tea); and 3,5-dimethoxytoluene, (E)-β-ionone, and 2-methylbutyl hexanoate (rose tea), were identified through chemometric analysis combined with relative odor activity values (ROAVs) and sensory evaluation. This study provides new insights into the formation of aroma molecular fingerprints during green tea scenting with flowers, providing theoretical guidance for infusing distinct aroma characteristics into green tea during scented tea processing. Full article

Osmanthus fragrans Lour. has been cultivated for more than 2500 years because of the fragrance and color of the flowers. The flowers and roots have been used in tea, liquors, foods, and traditional Chinese medicine. The species contains more than 180 compounds including terpenoids, phenylpropanoids, polyphenols, flavonoids, and sterols. However, there has been limited information available on the allelopathic properties and allelopathic substances of O. fragrans. We investigated the allelopathy and allelopathic substances of O. fragrans and Osmanthus heterophyllus (G.Don) P.S. Green, as well as Osmanthus × fortunei Carrière, which is the hybrid species between O. fragrans and O. heterophyllus. The leaf extracts of O. fragrans, O. heterophyllus, and O. × fortunei suppressed the growth of cress (Lepidium sativum L.), alfalfa (Medicago sativa L.), Lolium multiflorum Lam., and Vulpia myuros (L.) C.C.Gmel with the extract concentration dependently. The extract of the hybrid species O. × fortune was the most active among the extracts. The main allelopathic substances of O. × fortunei and O. fragrans were isolated and identified as (+)-pinoresinol and 10-acetoxyligustroside, respectively. (+)-Pinoresinol was also found in the fallen leaves of O. × fortunei. Both compounds showed an allelopathic activity on the growth of cress and L. multiflorum. On the other hand, several allelopathic substances including (+)-pinoresinol may be involved in the allelopathy of O. heterophyllus. O. fragrans, O. heterophyllus, and O. × fortunei are evergreen trees. but their senescent leaves fall and cover the soil under the trees. It is possible that those allelopathic substances are liberated through the decomposition process of the leaves into their rhizosphere soil, and that they accumulate in the soil and provide a competitive advantage to the species through the inhibition of the growth of the neighboring competing plants. Therefore, the leaves of these Osmanthus species are allelopathic and potentially useful for weed management options in some agriculture settings to reduce commercial herbicide dependency for the developing sustainable agriculture systems. Full article

Osmanthus fragrans flowers have long been used as raw materials in food, tea, beverage, and perfume industries due to their attractive and strong fragrance. The P450 superfamily proteins have been reported to widely participate in the synthesis of plant floral volatile organic compounds (VOCs). To investigate the potential functions of P450 superfamily proteins in the fragrance synthesis of O. fragrans, we investigated the P450 superfamily genome wide. A total of 276 P450 genes were identified belonging to 40 families. The RNA-seq data suggested that many OfCYP genes were preferentially expressed in the flower or other organs, and some were also induced by multiple abiotic stresses. The expression patterns of seven flower-preferentially expressed OfCYPs during the five different flower aroma content stages were further explored using quantitative real-time PCR, showing that the CYP94C subfamily member OfCYP142 had the highest positive correlation with linalool synthesis gene OfTPS2. The transient expression of OfCYP142 in O. fragrans petals suggested that OfCYP142 can increase the content of linalool, an important VOC of the O. fragrans floral aroma, and a similar result was also obtained in flowers of OfCYP142 transgenic tobacco. Combined with RNA-seq data of the transiently transformed O. fragrans petals, we found that the biosynthesis pathway of secondary metabolites was significantly enriched, and many 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway genes were also upregulated. This evidence indicated that the OfCYP proteins may play critical roles in the flower development and abiotic response of O. fragrans, and that OfCYP142 can participate in linalool synthesis. This study provides valuable information about the functions of P450 genes and a valuable guide for studying further functions of OfCYPs in promoting fragrance biosynthesis of ornamental plants. Full article

The essential oils of the Osmanthus fragrans tea (OFT), Osmanthus fragrans (OF) and green tea (GT) had been extracted by steam distillation and analyzed by gas chromatography-mass spectrometry (GC-MS) with the help of heuristic evolving latent projections (HELP), an effective chemometric resolution method (CRM). The overlapping peak clusters were resolved into pure chromatograms and pure mass spectra with HELP. The qualitative analysis was performed by similarity searches in the National Institute of Standards and Technology (NIST) mass spectra database with the obtained pure mass spectrum of each component. Identification of some compounds was also assisted by comparison of temperature-programmed retention indices (PTRI) with authentic standards included in our own laboratory database under construction. The quantitative results were obtained by overall volume integration (OVI) method. A total of 67, 73 and 53 components in essential oils of the OFT, OF and GT were identified, accounting for 90.83%, 93.65% and 89.97% total contents of the essential oil of OFT, OF and GT, respectively. Full article