Volatile constituents in leaves of parsley

Volatile chemicals obtained from the leaves of parsley, Petroselinum sativum by steam distillation, isopentane extraction, and head-space analysis were identified by GLC-MS. The presence in leaf oil of α-pinene, β-pinene, myrcene, β-phellandrene, trans-β-ocimene, γ-terpinene, 1-methyl-4-isopropenyl benzene, and 1,3,8-p-menthatriene as shown by earlier investigators was confirmed. In the present studies, the number of volatile chemicals detected in the leaves was extended by an additional 42. Sniffing tests of effluent from a gas chromatograph of a concentrate from parsley leaves showed that 1,3,8-p-menthatriene was only one of several compounds that gave a parsley-like aroma.     

Volatile aroma constituents of Sri Lankan ginger

Two types of Sri Lankan ginger were examined (Sidda and Chinese varieties) and essential oils of both fresh and dried samples were prepared by standard procedures. Both varieties yielded relatively high percentages of oil (between 1.8 and 4.3%) and total aroma volatiles (ca 5 mg/g for dried samples). Analysis by GC and GC/MS showed terpenes to be the main aroma components (ca 99% for all samples). A number of the identified compounds have not previously been reported as ginger volatiles, including trans-β-ocimene, thujyl alcohol, terpinen-4-ol, myrtenal, guaiene, α-cubebene, δ-cadinene and farnesol. On drying, both varieties of Sri Lankan ginger showed considerable decrease in monoterpene content and very high increase in sesquiterpene concentration. Comparing the aroma volatiles of Sri Lankan dried ginger with those previously reported for dried ginger from some other countries, it was concluded that Sri Lankan ginger was as good as, if not superior to, other types. In particular, SriLankan dried ginger showed high levels of ar-curcumene together with reasonable levels of citral isomers and all other constituents previously claimed to be important to ginger aroma. Sri Lankan ginger would appear to be unusual in containing very low amounts of zingiberene but very high amounts of β-bisabolene.     

The coumarin heraclenol as a growth inhibitor in parsley seeds

By the aid of germination assay with lettuce seeds, the germination inhibitors in the parsley seeds were investigated. One of the inhibitors was revealed to be heraclenol.     

Volatile flavour components of guava

An essence of fresh guava fruit obtained by well-established procedures possessed the characteristic aroma of the fruit. It was analysed by GC/MS using     

Volatile flavour components of mango fruit

An essence of fresh Venezuelan mango fruit obtained by well-established procedures possessed the characteristic aroma of the fruit. It was analysed by GC/MS using both EI and Cl. The fruit produced a relatively small quantity of aroma volatiles (ca 60 μg/kg fresh fruit), less than that obtained from many similar tropical fruits. Terpene hydrocarbons comprised ca 68% of the sample, eight monoterpenes contributing ca 54% and four sesquiterpenes contributing ca 14%. Important constituents included α-pinene, car-3-ene, limonene, γ-terpinene, α-humulene, β-selinene, acetophenone, benzaldehyde and a dimethylstyrene. Car-3-ene (26%) was the major constituent, and on odour evaluation of separated components at an odour port during GC, the peak due to this compound was described as having an aroma of mango leaves. This compound has not previously been detected among mango volatiles. The only other component providing mango aroma was a dimethylstyrene, and this too is a new mango volatile.     

Volatile flavour components of mangosteen, Garcinia mangostana

A representative sample of the aroma volatiles of mangosteen, a tropical fruit, was obtained using previously devised procedures. Components of the sam     

Volatile components of cocoa with particular reference to glucosinolate products

The aroma volatiles of raw, fermented and roasted cocoa beans were extracted and concentrated to valid essences using well-established techniques. Analysis by GC and GC/MS showed at least 84 components of which 13 were identified for the first time as cocoa volatiles. In total, ca 5,66 and 65 μg of aroma components were obtained per g of raw, fermented and roasted cocoa beans, respectively. The most abundant groups of volatiles from fermented beans were alcohols (ca40%w/w of the total volatiles) and esters (ca 32%), whilst those from roasted beans were pyrazines (ca 40%) and aldehydes (ca 23%). Trimethyl- and tetramethylpyrazine were also detected in fermented beans, and it is suggested that they contribute to the noticeable cocoa/chocolate aroma of fermented unroasted beans. Phenylacetonitrile, benzyl isothiocyanate and benzyl thiocyanate were all identified amongst cocoa volatiles, together showing the presence of precursor benzylglucosinolate in cocoa. Glucosinolate products were detected in roasted beans, and it seems likely that the enzyme thioglucoside glucohydrolase survived the conditions of roasting. Benzyl thiocyanate was detected only in raw beans, showing that the glucosinolate ‘thiocyanate–forming factor’ did not withstand conditions of fermentation     

Fate of Listeria spp. on parsley leaves grown in laboratory and field cultures

AIMS: To investigate the population dynamics of Listeria monocytogenes and Listeria innocua on the aerial surfaces of parsley. METHODS AND RESULTS: Under 100% relative humidity (RH) in laboratory and regardless of the inoculum tested (10(3)-10(8) CFU per leaf), counts of L. monocytogenes EGDe, LO28, LmP60 and L. innocua CIP 80-12 tended towards approx. 10(5) CFU per leaf. Under low RH, Listeria spp. populations declined regardless to the inoculum size (10(4)-10(8) CFU per leaf). L. innocua CIP 80-12 survived slightly better than L. monocytogenes in the laboratory and was used in field cultures. Under field cultures, counts of L. innocua decreased more rapidly than in the laboratory, representing a decrease of 9 log(10) in 2 days in field conditions compared to a decrease of 4.5 log(10) in 8 days in the laboratory. Counts of L. innocua on tunnel parsley cultures were always higher (at least by 100 times) than those on unprotected parsley culture. CONCLUSIONS: Even with a high inoculum and under protected conditions (i.e. plastic tunnels), population of L. monocytogenes on the surface of parsley on the field would decrease by several log(10) scales within 2 days. SIGNIFICANCE AND IMPACT OF THE STUDY: Direct contamination of aerial surfaces of parsley with L. monocytogenes (i.e. through contaminated irrigation water) will not lead to contaminated produce unless it occurs very shortly before harvest.     

西芹挥发物对黄瓜枯萎病菌的化感作用

将定量的西芹种子、8～10叶期的叶片、叶柄、鲜根分别置于玻璃真空干燥器的下部,将在PDA培养基上接种黄瓜枯萎病菌的培养皿置于干燥器的上部,密封,利用生长速率法研究了不同西芹离体材料挥发物对黄瓜枯萎病菌的化感作用(各处理材料重量分别为50、100、150、200g)。结果表明:西芹挥发物对黄瓜枯萎病菌有化感抑制作用,且化感效果随着浓度的增加而增加;重量为200g的西芹种子、叶片、叶柄、鲜根挥发物处理黄瓜枯萎病菌144h后,化感效果分别为9.3%、10.9%、12.2%、18.7%;西芹鲜根挥发物的化感作用最强,其次为叶柄,叶片和种子最弱。对共培养后接种黄瓜枯萎病菌的黄瓜幼苗进行病害调查,处理为200株的西芹挥发物化感抑制效果最好,至接菌11d其发病株数为64株,化感效果为15.8%;西芹挥发物浓度越高,其抑制发病的效果越好,抑病效果随着时间的延长而减弱。     

Viable but non-culturable Listeria monocytogenes on parsley leaves and absence of recovery to a culturable state

AIMS: To investigate the presence of viable but non-culturable Listeria monocytogenes during survival on parsley leaves under low relative humidity (RH) and to evaluate the ability of L. monocytogenes to recover from VBNC to culturable state under satured humidity. METHODS AND RESULTS: Under low RH (47-69%) on parsley leaves, the initial number of L. monocytogenes populations counted on non selective media (10(9) L. monocytogenes per leaf on TSA) was reduced by 6 log10 scales in 15 days, whereas number of viable L. monocytogenes counted under the microscope was reduced by 3-4 log10 scales, indicating the presence of VBNC cells. This was demonstrated on three L. monocytogenes strains (EGDe, Bug 1995 and LmP60). Changing from low to 100% RH permitted an increase of the culturable counts of L. monocytogenes and this growth was observed only when residual culturable cells were present. Moreover, VBNC L. monocytogenes inoculated on parsley leaves did not become culturable after incubation under 100% RH. CONCLUSIONS: Dry conditions induced VBNC L. monocytogenes on parsley leaves but these VBNC were likely unable to recover culturability after transfer to satured humidity. SIGNIFICANCE AND IMPACT OF STUDY: Enumeration on culture media presumably under-estimates the number of viable L. monocytogenes on fresh produce after exposure to low RH.     

Coumarin constituents of Selinum tenuifolium

Three furocoumarins, bergapten, heraclenin and heraclenol have been isolated from the roots of Selinum tenuifolium (Umbelliferae). Another coumarin, m.p. 85–86°, isolated from the same source and provisionally designated as ST-1, has been proved to be mixture of imperatorin, and 8-geranyloxypsolaren by analyses of various reaction products and separation by preparative TLC on silica gel G impregnated with silver nitrate.     

Volatile polysulphides of asafoetida

By means of steam distillation, adsorption chromatography and GC/MS analysis, seven sulphur components (di-, tri- and tetra-sulphides) have been characterised in addition to those previously reported from Ferula asafoetida of Afghan origin. The identity of some of the components has been confirmed by synthesis and comparison of GC retentions. The quantitative composition of the constituents in the volatile oil has also been determined.     

Volatile metabolites from suspension cultures of Taraxacum officinale

A suspension culture of T. officinale (dandelion) was developed and maintained on modified Gamborg's B5 and Murashige and Skoog's media. Volatile metabolites, which collectively had an ‘apple-like’ odour, were released into the head-space air above the cultures. Analysis by GC-MS indicated the presence of acetic acid butyl ester, 2-methyl-1-propanol, n-butyl alcohol, 4-phenyl-1-butanol, 4-hydroxy-4-methyl-2-pentanone, acetic acid, 4-terpineol, β-terpineol and -terpineol.     

Volatile constituents from cauliflower and other crucifers

Vapour emanating from intact turnip and radish plants contained small amounts of only one component, probably hexenyl acetate, distinguishable from background vapours. From disrupted leaf tissues of cauliflower, turnip, radish and wallflower at 30°, the predominant vapour component was cis-hex-3-enyl acetate, whereas allyl isothiocyanate was the chief component from Brassica juncea. Other minor components were also identified. Apart from isothiocyanates, the only sulphur-containing component identified from these crucifers was dimethyl disulphide which was detected only from cauliflower, particularly in vapour from disrupted curd tissue.     

Volatile constituents of alphonso mango (mangifera indica)

Concentrates of fresh, ripe Indian Alphonso mango fruit were analysed by HRGC and HRGC/MS. In total, 152 aroma substances were identified, of which 70 are reported for the first time as mango fruit constituent. Quantitative HRGC revealed a considerable quantity of aroma compounds (ca 57 mg/kg fresh fruit pulp) of which 90% consisted of mono- and sesqui-terpene hydrocarbons. Major constituents included (Z)-(44 mg/kg) and (E)-ocimene (3 mg/kg) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (2 mg/kg)     

Comparison of the volatile components of some mango cultivars

Three cultivars of mango from Sri Lanka (Jaffna, Willard and Parrot) were analysed for their volatile aroma components. The total concentrations of volatiles obtained were ca 251, 422 and 628 μg per kg of fresh fruit, respectively. Terpenes were the main volatiles of all three cultivars, with monoterpene hydrocarbons contributing 50–63 % w/w of the total volatiles and sesquiterpene hydrocarbons 14–19 %. Whilst the major volatile of Jaffna mango was cis-β-ocimene (38 %), α-terpinolene was the major volatile of the other two cultivars (32 % and 35 %). Esters were produced by all cultivars (2–16 %), Jaffna yielding most, the majority being unsaturated (12 %). Willard mango gave particularly high levels of non-terpene hydrocarbons (19 %), including a range of six long-chain alkanes (8 %), not detected in the other cultivars.     

Aroma volatiles of aubergine (Solanum melongena)

Samples of the aroma volatiles of aubergine were obtained by well-established methods and were analysed by routine GC and GC/MS. Hydrocarbons comprised over 70 % of the samples and included 20 acyclic alkanes. A very low concentration of total volatiles (ca 2.4 μg/kg) was produced.     

Volatile compounds of Soumbala, a fermented African locust bean (Parkia biglobosa) food condiment

AIMS: To determine the profile of volatile compounds responsible for the aroma of Soumbala produced spontaneously and with pure and mixed cultures of Bacillus subtilis and Bacillus pumilus. METHODS AND RESULTS: Traditional and controlled fermentation trials of African locust bean with pure and mixed starter cultures of B. subtilis (B7, B9 and B15) and B. pumilus (B10) were performed. Aroma volatiles were analysed using Likens-Nikerson method coupled with gas chromatography and mass spectrophotometry. Sensory analysis of Soumbala as well as rice dishes prepared with each type of Soumbala were carried out by 10 panellists. In total 116 compounds were identified. They included pyrazines, aldehydes, ketones, esters, alcohols, acids, alkanes, alkenes, amines, pyridines, benzenes, phenols, sulphurs, furans and other compounds. Using principal component analysis for comparison, the aroma profiles of the Soumbala samples could be separated into three groups. The sensory evaluation showed variable acceptability. However, it was noticed that Soumbala samples produced with starter cultures were scored higher than traditionally prepared Soumbala. CONCLUSIONS: Aroma volatiles and organoleptic properties of Soumbala vary according to the Bacillus isolates involved in the fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to the selection of Bacillus starter cultures for controlled production of Soumbala.     

Regulation of phytochrome A mRNA abundance in parsley seedlings and cell-suspension cultures

A cDNA clone encoding the apoprotein of a parsley phytochrome was isolated and classified as parsley PHYA phytochrome, on the basis of a sequence homology comparison with all available phytochrome sequences. Red light pulses led to a phytochrome-dependent down-regulation of PHYA mRNA abundance in etiolated parsley seedlings to a level of 10–20% compared with the dark control. The PHYA mRNA abundance in a parsley cell suspension culture was also down-regulated by light pulses. Transient expression assays in parsley protoplasts showed light regulation of a chimeric pea PHYA promoter uidA-gene construct.