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The columnar cacti Cereus peruvianus and C. jamacaru are being evaluated as potential new exotic fruit crops suitable for cultivation in arid zones. Sensory tests of fruits of two accessions of C. peruvianus (G2 and Q9) and two accessions of C. jamacaru (B3 and B6) indicated that the fruits of the two C. peruvianus cultivars are more palatable than those of the C. jamacaru clones. The study showed that analyses of volatiles and polysaccharides were good indicators of fruit quality (aroma and texture, respectively). However, sensory evaluations were found to be better indicators of quality than physico-chemical criteria that are conventionally in use for quality determination, such as titratable acidity, pH, sugars, and total soluble solids. The results obtained showed that sensory evaluations are of essential value as research tools capable of delineating sensory and quality profiles of fresh Cereus fruits.
Khat (Catha edulis Forsk., Celastraceae) is a perennial shrub that was introduced to Israel by Yemenite immigrants. Its young leaves are chewed for their psycho-stimulating properties. Young khat leaves contain the phenylpropylamino alkaloids (-)-cathinone [(S)-α-aminopropiophenone], (+)-cathine [(1S)(2S)-norpseudoephedrine], and (-)-norephedrine [(1R)(2S)-norephedrine] as the main active principles. A novel GC-MS analysis method for the quantitative determination of phenylpropylamino alkaloids and their putative biosynthetic precursor 1-phenylpropane-1,2- dione in khat leaves was developed. We utilized an alkaline-organic extraction, coupled with gas chromatography and a chiral permethylated beta cyclodextrin phase, to allow a full separation between the two diastereoisomers (1S)(2S)-cathine and (1R)(2 S)-norephedrine. We found a marked diversity in the phenylpropylamino alkaloid content and composition in three different locally grown accessions and the commercial cultivar ‘Mahanaim’.
The potential to produce and accumulate mono- and sesquiterpenes in lemon mint (Mentha aquatica var. citrata) glandular trichomes was evaluated. Volatiles were extracted using methyl-tert-butyl ether or solid phase micro extraction and determined by gas chromatography-mass spectrometry. The main components of the essential oil of lemon mint are the monoterpene alcohol linalool and its ester linalyl acetate. Sesquiterpenes, such as elemol, (E)-caryophyllene, and germacrene D, as well as the monoterpenes 1,8-cineole, β-myrcene, and β-(E)-ocimene, are also prominent. Most of the essential oil is localized in the glands, as leaves devoid of trichomes had very low essential oil levels. The quantities of all these components per leaf increased during leaf development until reaching the third whorl, and then the levels remained steady. Conversely, the essential oil content per gram fresh weight decreased with leaf development, but the decrease was not statistically significant at p = 0.05. Desalted cell-free extracts derived from isolated glandular trichomes were able to convert geranyl diphosphate into linalool. Lower amounts of geranyl diphosphate were also converted to other monoterpenes such as myrcene, α-pinene, β-pinene, limonene, β-(E)-ocimene, and nerol. Furthermore, the extracts were able to convert farnesyl diphosphate into the sesquiterpene (E)-caryophyllene and lesser amounts of other sesquiterpenes such as δ-cadinene, α-humulene, β-(E)-farnesene, and α-gurjunene. These cell-free extracts also efficiently catalyzed the formation of linalyl acetate from linalool and acetyl-coenzyme A. Our findings indicate that glandular trichomes of lemon mint, similar to other members of the Lamiaceae, contain unique enzymatic activities capable of the synthesis of mono- and sesquiterpene components of its essential oil.
Bitter fennel (Foeniculum vulgare Mill. var. vulgare, Apiaceae) is a common perennial hemicryptophyte, used since antiquity as a medicinal and aromatic herb in the Mediterranean basin. We describe the anatomical specialization and some of the factors that affect phenylpropene accumulation in the fruits of a t-anethole-rich chemotype during development. Histological examination of fruits by longitudinal sections indicated that each oil duct is an elongated cavity with a series of internal septa at 200-400 μm intervals. Oleoresin accumulation is accompanied by an increase in the oil duct area, as observed in transversal cross sections in early stages of development (from the yellow bud stage to the open flower stage). Upon maturation, oleoresin is further accumulated due to increased duct volume as a result of duct elongation. The main component of the oleoresin, t-anethole, is synthesized during flowering and in the early stages of fruit development, as monitored by the levels of S-adenosine methionine: t-anol O-methyltransferase activity. Upon transition from the waxy fruit stage (28 days after the yellow bud stage) to fully ripe fruit (42 days after the yellow bud stage) O-methyltransferase activity apparently ceases, indicating the cessation of de novo biosynthesis, while oleoresin levels remain constant, likely due to a lack of further metabolism and minimal volatilization, as indicated by apparent high lignification of the cells lining the oil ducts.
Petals of 11 rose cultivars were analyzed by solvent extraction for the presence of key scent volatiles. Two different cultivars--'Fragrant Cloud', a very fragrant cultivar, and 'Golden Gate', a non-fragrant cultivar--were further analyzed by the headspace technique during flower opening. The 'Fragrant Cloud' headspace is composed of a variety of volatiles, including monoterpene alcohols, acetates, and terpene hydrocarbons, while the 'Golden Gate' headspace is composed mainly of orcinol dimethylether, a compound that is scentless to the human nose but that is perceived by honeybees, as judged by proboscis extension experiments. In both cultivars, the level of volatiles increased during flower development, while the ratio of different major volatiles remained constant.