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PubMedDate not supplied

[Microbiological study of dehydrated garlic (Allium sativum L.) and onion (Allium cepa L.)].

A microbiological study during the process and the storage of garlic (Allium sativum L.) and onion (Allium cepa L.) dehydrated, with the additional barriers of blanching or brine immersion, was made. In all raw materials the average counts of aerobic mesophilic bacteria expressed in CFU/g ranged from 1.2 x 10(2) to 1.6 x 10(3), molds and yeasts from 60 to 1.6 x 10(3), Lactobacillus spp. and Leuconostoc mesenteroides subsp. mesenteroides between 10 and 50. Microorganisms identified were Penicillium spp., Monilia spp., Lactobacillus brevis, Leuconostoc mesenteroides subsp. mesenteroides and yeasts in garlic; Mucor spp., Penicillium spp., Monilia spp., Lactobacillus brevis and yeasts in both types of onions. Leuconostoc mesenteroides subsp. mesenteroides was detected in only kind of onion. In dehydrated garlic storage, Penicillium spp., Monilia spp., Lactobacillus brevis and yeasts were detected. In garlic, when a blanching step was carried out no microflora was detected. Mucor spp., Penicillium spp., Monilia spp. and Lactobacillus brevis were identified in both types of dehydrated onions. When brine immersion was included the microflora detected was significantly lower and only Penicillium spp. were found. The use of additional barriers such as blanching or brine immersion produces an important effect on the microbiological stability in these products.

Bacteria↗
PubMed1989

Immunolocalization of DNA at nucleolar structural components in onion cells.

Intranucleolar DNA, including ribosomal DNA (rDNA), was localized in situ in proliferating onion cells under the electron microscope using an anti-DNA monoclonal antibody and a postembedding indirect immunogold procedure. In the interphase nucleolus of this species, characterized by a very high amount of rRNA genes, we found DNA concentrated mostly in fibrillar centres (FCs) and in the region of the dense fibrillar component (DFC) immediately surrounding them. Clusters of gold particles were frequently seen covering both of these structural components of the nucleolus at the same time. Moreover, the same technique, applied to transcriptionally arrested quiescent onion cells, showed the nucleolar DFC devoid of DNA. Also, in mitotic cells at telophase, the prenucleolar material, which has the same morphological and cytochemical features as the DFC, does not contain DNA. These data suggest the existence of at least two subcomponents of the DFC in the onion cell nucleolus, one associated with pre-rRNA synthesis, and the other, with further processing of transcripts, already released from the rDNA template. We conclude that the first subcomponent forms part of the "transition between FC and DFC", which is the in situ structural counterpart of pre-rRNA synthesis. This transition is morphologicaly sizeable in onion cells, because of their high number of rRNA genes and the large size of the DFC mass; however, it would be largely detectable in situ in other cell systems, where the whole DFC comprises only a thin layer and the amount of rDNA is considerably reduced.

Allium↗
PubMed1994

Intraspecific metabolic diversity among strains of Burkholderia cepacia isolated from decayed onions, soils, and the clinical environment.

A collection of 218 strains of Burkholderia cepacia (including 18% strain replicates) was assembled from organic soils, decayed onions, and clinical sources. Each strain was characterized for virulence to onion, catabolic ability using the Biolog GN microtiter plate, and several other behaviors. Overall test reproducibility was estimated at 98%. The results obtained using the Biolog GN system corresponded well to those obtained using standard methods. Three coefficients of resemblance (Gower similarity, pattern difference, and Jaccard similarity) were calculated and clustered by the group-average method. The sorted matrices and phenograms, while giving evidence of an underlying phenetic structure to the B. cepacia nomenspecies, gave little evidence of sorting by broad source of isolation. Strains isolated from within fields or samples were frequently found to be similar, however, strains isolated from fields with similar cropping histories were not. The Gower-transformed centroids of ordained clusters were projected in a principal coordinate system and estimates of disjunction were calculated. Strains of B. cepacia were shown to be non-uniformly distributed in taxonomic space. Strains isolated by serial dilution on onion slices formed a tight phenetic cluster which includes the type strain of the nomenspecies and that of a synonymous group (Pseudomonas multivorans); the strains in this phenon were generally virulent to onion and were partially differentiated from others by pectolytic behavior and by the production of diffusible pigment on King's medium A. Further characterization should better resolve the taxonomy of the nomenspecies.

Allium↗
PubMed1984

Antiasthmatic effects of onion extracts--detection of benzyl- and other isothiocyanates (mustard oils) as antiasthmatic compounds of plant origin.

Previous studies showed the inhibitory effects of crude ethanolic onion extracts (COE) on allergic skin reactions in man as well as on allergen-induced bronchial asthma in man and guinea-pigs. Work is in progress in order to identify both the mode of action of COE and the active substance(s). The present study describes asthma-protective effects of isothiocyanates. Groups of at least 5 guinea-pigs sensitized to ovalbumin were challenged twice (time 0 and 10 min) by the inhalation of ovalbumin 30 min after oral treatment with increasing doses of the agent tested or control solutions. Bronchial obstruction (BO) was measured by whole body plethysmography. Chloroform extracts of onions showed similar protective effects on BO as COE. The water-soluble fraction of COE was inactive. Benzyl-isothiocyanate (BITC) was identified as one component of onion lipids by combined gas chromatography/mass spectrometry. BITC inhibited BO in a dose-dependent fashion: 150 mg/kg: 89%; 75 mg/kg: 76%; 30 mg/kg: 66%; 15 mg/kg: 49%. Ethyl-isothiocyanate and allyl-isothiocyanate showed similar effects; p-hydroxy-benzyl-isothiocyanate, a very unstable mustard oil, was ineffective. Additional experiments showed no antagonistic effects of COE on histamine- or acetylcholine-induced BO. The antiasthmatic effects of onions and - perhaps - other plants may be mediated at least in part by isothiocyanates.

Administration, Oral↗
PubMed1979

Effects of onion (Allium cepa) extract on platelet aggregation and thromboxane synthesis.

Oral administration of onion and garlic reportedly decreases platelet aggregation in both human and animal subjects. An oily chloroform extract of onion (Allium Cepa) was prepared and separated by column chromatography on silicic acid into six fractions by elution with solvents of increasing polarity. The least polar fraction contained most of the inhibitory activity towards platelet aggregation induced by either ADP or arachidonic acid. Further purification was afforded by thin-layer chromatography. The specific activity of this major active fraction (I50 per ml of PRP) was approximately 7 units per milligram. Platelets incubated in the presence of onion inhibitor and (1-14C)-arachidonic acid showed striking changes in the pattern of arachidonic acid metabolites formed. Thromboxane B2 synthesis was almost completely suppressed without significant decreases in total hydroxy fatty acid formation. It was concluded that the observed antiplatelet activity of onion relates to the presence of a non-polar, heat stable inhibitor of thromboxane synthesis. This appears to be the first demonstration of this type of inhibitor present in significant quantities in a common foodstuff.

Adenosine Diphosphate↗
PubMed1989

Effect of onion and ginger consumption on platelet thromboxane production in humans.

The effects of onion and ginger consumption on platelet thromboxane production were examined. Volunteers, all Danish women, consumed either 70 g raw onion or 5 g raw ginger daily for a period of 7 days. Each participant in each (onion or ginger) group served as her own control. TxB2 determination was made in serum obtained after blood clotting. The following are the results. TxB2 (pmol/ml serum): (i) onion group--before consumption 910 +/- 327, after consumption 1005 +/- 713 (Mean +/- SD, N = 5); (ii) ginger consumption 782 +/- 482, after consumption 498 +/- 164 (Mean +/- SD, N = 7).

Adult↗
PubMed2000

Improvement of in vitro gynogenesis induction in onion (Allium cepa L.) using polyamines.

The effects of polyamines on gynogenetic embryogenesis and regeneration of plantlets in onion were studied. Whole flowers from two onion genotypes, 'Valcatorce INTA' cultivar and 'Torrentina' population, were used as initial explants. Embryo induction was greatest with a combined treatment of 2 mM putrescine and 0.1 mM spermidine. Addition of putrescine alone, with a few exceptions, did not have any significant effect on either embryo induction or haploid plantlet production for both onion genotypes. 'Torrentina' showed a higher embryo generation capacity (9.5%) than 'Valcatorce INTA' (2.8%). Fast regeneration of embryos was achieved (from 60 to 90 days) as compared to a previously reported time of 46-152 days. The use of spermidine (0.1 mM) after 15 days of culture promoted further embryo maturation and plantlet formation. 'Torrentina' produced more haploid plants (1.90%). This is the first report of successful use of polyamines for induction of gynogenic embryos and regeneration of onion plantlets.

Journal Article↗
PubMed1999

Renal lesions in streptozotocin-induced diabetic rats maintained on onion and capsaicin containing diets.

Onion (Allium cepa) powder and capsaicin, the pungent principle of red pepper (Capsicum annum) were added in the amounts of 3 g% and 15 mg%, respectively, to the diet of streptozotocin-induced diabetic Wistar rats for 8 weeks. The presence of renal lesions was assessed by the extent and quality of proteinuria and by the leaching of renal tubular enzymes into the urine. Renal integrity was assessed by measuring the activities in the kidney tissue of several key enzymes of carbohydrate metabolism and of polyol pathway, transaminases, and ATPases. Data on enzymuria and proteinuria, activities of kidney ATPases present in diabetic patients, suggested that dietary onion caused significant beneficial modulation of the progression of renal lesions in the diabetic rats. These findings were also corroborated by histologic examination of kidney sections. Dietary capsaicin did not have any favorable influence on renal pathology in diabetes. It is inferred that this beneficial ameliorating influence of dietary onion on diabetic nephropathy may be mediated through onion's ability to lower blood cholesterol levels and to reduce lipid peroxidation.

Journal Article↗
PubMed1998

Protective Effect of Broccoli, Onion, Carrot, and Licorice Extracts against Cytotoxicity of N-Nitrosamines Evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium Bromide Assay.

The protective effect of nine fruit and vegetable aqueous (H(2)O) and ethanolic (EtOH) extracts against the cytotoxicity of N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrosodibutylamine (NDBA), and N-nitrosopiperidine (NPIP) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The fruit extracts under investigation did not show a protective effect against any N-nitrosamines tested. Four vegetable extracts exhibited a protective effect (to 100% of survival) and a stimulation of cellular proliferation (>100% of survival) in decreasing order against NDMA and NPYR: broccoli(EtOH) > onion(H2O) > carrot(EtOH) > onion(EtOH) > licorice(H2O). Decreasing orders against NDBA and NPIP were, respectively, broccoli(EtOH) > licorice(H2O) > carrot(EtOH) > onion(EtOH) and broccoli(EtOH) > carrot(EtOH) > licorice(H2O) > onion(EtOH). Thus, broccoli(EtOH) extract (19-20 mg/mL) showed greater protective effect and stimulation of cellular proliferation (160% of survival) against all N-nitrosamines studied than the other vegetable extracts tested.

Journal Article↗
PubMed1981

Pectic Enzyme Activities of Bacteria Associated with Rotted Onions (Allium cepa).

The aerobic bacteria associated with soft rot in onions (Allium cepa) were isolated and identified as a Vibrio sp., Micrococcus epidermidis, Pseudomonas cepacia, an Acinetobacter sp., a Xanthomonas sp., Bacillus polymyxa, and Bacillus megaterium. With the cup-plate assay method, no pectin hydrolase could be detected from any of these isolates when they were cultured in pectin medium, but lyase and pectinesterases were detectable. Onion tissue cultures showed pectin hydrolase activity for P. cepacia and B. polymyxa and lyase and pectinesterase activities for all of the isolates, usually at higher levels of activity than those of the pectin medium culture filtrates. In both culture media, Vibrio sp. showed the highest lyase and pectinesterase activities. In the viscometric test, all of the isolates achieved at least a 50% decrease in viscosity for lyase enzyme, with M. epidermidis and Vibrio sp. recording viscosity decreases as high as 83%. The ability to cause soft rot in onion bulbs was demonstrated by P. cepacia and Xanthomonas sp. Benzoic acid at a concentration of 0.8 mg/ml caused total suppression of enzyme production, whereas sodium benzoate at this concentration reduced pectinesterase production by 71% and lyase production by 72%. The possible use of these preservatives in the control of soft rot in onions is noted.

Journal Article↗
PubMed1969

Death of Salmonella typhimurium and Escherichia coli in the presence of freshly reconstituted dehydrated garlic and onion.

The kinetics of the decline of populations of Salmonella typhimurium inoculated into freshly reconstituted dehydrated onion and garlic powders was studied. Measurable bactericidal activity was observed for onion and garlic concentrations of 1 and 5% (w/v), respectively, with maximal death rates occurring for concentrations of 5 and 10%. At these concentrations, the decimal reduction times were 1.1 and 1.2 hr, respectively, for resting cell cultures and 1.8 and 2.1 hr, respectively, for growing cultures. Of the major volatile aliphatic disulfide compounds of onions, n-propyl allyl and di-n-propyl, at concentrations of 0.1%, showed a comparable activity against resting cells but only a bacteriostatic effect toward actively growing cultures, which overcame this effect in 2 to 6 hr. At comparable concentrations, growing cultures of Escherichia coli were as susceptible to garlic, but apparently more resistant to onion, than were those of S. typhimurium.

Escherichia coli↗
PubMed2006

Vorticity banding during the lamellar-to-onion transition in a lyotropic surfactant solution in shear flow.

We report on the rheology of a lyotropic lamellar surfactant solution (SDS/dodecane/pentanol/ water), and identify a discontinuous transition between two shear thinning regimes which correspond to the low-stress lamellar phase and the more viscous shear-induced multilamellar vesicle, or "onion" phase. We study in detail the flow curve, stress as a function of shear rate, during the transition region, and present evidence that the region consists of a shear-banded phase where the material has macroscopically separated into bands of lamellae and onions stacked in the vorticity direction. We infer very slow and irregular transformations from lamellae to onions as the stress is increased through the two-phase region, and identify distinct events consistent with the nucleation of small fractions of onions that coexist with sheared lamellae.

Alkanes↗
PubMed1997

Cysteine-S-conjugate beta-lyase activity and pyridoxal phosphate binding site of onion alliin lyase.

Purification of onion alliin lyase gave two fractions by cation exchange chromatography. Both fractions showed the comparable high catalytic activity of cysteine-S-conjugate beta-lyase with that of alliin lyase using S-(2-chloro-6-nitrophenyl)-L-cysteine and alliin, S-allyl-L-cysteine sulfoxide as substrates. All the active substrates tested with onion alliin lyase were also active to the cysteine-S-conjugate beta-lyase of Mucor javanicus, but the catalytic activity of the Mucor enzyme was lower for all the substrates. The pyridoxal phosphate binding site of the onion alliin lyase was identified as Lys 285 in the amino acid sequence deduced from cDNA which has been reported. This lysine was conserved in all the sequences from the alliin lyase cDNAs, while similarity was not found between the sequences around pyridoxal phosphate binding sites of both the onion alliin lyase and the Mucor cysteine-S-conjugate beta-lyase.

Allium↗
PubMed1979

Onion, garlic, and experimental atherosclerosis.

Forty-two healthy male albino rabbits weighing around 1 Kg were divided into 4 groups. Group I (8)- fed on normal stock diet, Group II (8)- fed on stock diet plus cholesterol (0.5 gm in 5 ml of olive oil). Group III (15)- received stock diet plus cholesterol plus garlic (0.25 gm) juice. Group IV (11)- received stock diet plus cholesterol plus onion (2.5 gm) juice. The animals were closely observed and followed for 16 weeks. Approximately every 4 weeks, blood samples were collected for estimation of various parameters (S. cholesterol, S. triglycerides, S. lipoproteins, S. phospolipids, and fibrinolytic activity). At the end of experiment, animals were sacrificed and degree of aortic atherosclerosis was graded (grade 0 to 4) in different groups and compared. Experimental study revealed that both garlic and onion (garlic more than onion) had significant effect in inhibiting the rise in S. cholesterol, S. triglycerides, S. beta lipoproteins, and S. phospolipids and significant effect in enhancing the fibrinolytic activity. The beta: alpha ratio was altered favourably and the ratio was kept close to normal. As regards the degree of aortic atherosclerosis as seen on post mortem, it was significantly less in garlic and onion group when compared with pure cholesterol group.

Animals↗
PubMed2004

Chemometric techniques on inorganic elements composition for the determination of the geographic origin of Welsh onions.

Techniques to determine the producing country of Welsh onions (Allium fistulosum L.) were developed by using 216 samples from Japan and from Anchu Shandgon, Shanghai and Amoy Fjian in China. Twelve elements (Na, P, K, Ca, Mg. Mn, Fe, Cu, Zn, Sr, Ba, Al, Co, Ni, Rb, Mo, Cd, Cs, La, Ce, Tl and Pb) contained in Welsh onions were determined. In order to determining whether Welsh onions originate in Japan or in China, linear discriminant analysis (LDA) and soft independent modeling of class analogy (SIMCA) were performed, using concentrations of 20 elements excluding Al and Pb in 22 elements. In LDA for two-group discrimination modeled on Welsh onions from Japan and China, 103 samples used for modeling were classified 95% correctly, and 89 other samples were predicted 94% correctly. As the average of predictions by SIMCA modeled on samples selected by 10 times of random selections, 192 samples, including the 103 samples used for modeling, were predicted 96% correctly. In discriminations by combined LDA and SIMCA, all 81 samples produced in Japan were correctly judged to be Japanese ones, and only 8 samples out of 111 samples produced in China were not correctly judged to be Chinese ones.

Journal Article↗
PubMed1999

Inhibition of aflatoxin-producing fungi by Welsh onion extracts.

Welsh onion ethanol extracts were tested for their inhibitory activity against the growth and aflatoxin production of Aspergillus flavus and A. parasiticus. The survival of spores of A. flavus and A. parasiticus depended on both the extract concentration and the exposure time of the spores to the Welsh onion extracts. The mycelial growth of two tested fungi cultured on yeast extract-sucrose broth was completely inhibited in the presence of the Welsh onion ethanol extract at a concentration of 10 mg/ml during 30 days of incubation at 25 degrees C. The extracts added to the cultures also inhibited aflatoxin production at a concentration of 10 mg/ml or permitted only a small amount of aflatoxin production with extract concentration of 5 mg/ml after 2 weeks of incubation. Welsh onion ethanol extracts showed more pronounced inhibitory effects against the two tested aflatoxin-producing fungi than did the same added levels of the preservatives sorbate and propionate at pH values near 6.5.

Aflatoxins↗
PubMed2004

Inhibitory activity of essential oils of garlic and onion against bacteria and yeasts.

The essential oils of garlic and onion and their constituent sulfides with three or more sulfur atoms were potent inhibitors of yeast growth. The minimum inhibitory concentrations of garlic oil, onion oil, diallyl trisulfide, diallyl tetrasulfide, and dimethyl trisulfide for all the yeasts tested ranged between 2 and 45 ppm. The oils and their constituent sulfides, however, were only very weakly antibacterial, showing minimum inhibitory concentrations of greater than 300 ppm for most of the bacteria tested. The antiyeast activity of garlic oil and onion oil was storage stable and was not influenced by pH. Film formation on soy sauce by Zygosaccharomyces rouxii SS1 was completely prevented for 30 days by the addition of 30 and 40 ppm of garlic oil and onion oil, respectively.

Allyl Compounds↗
PubMed2004

The onion skin sign: a specific sonographic marker of appendiceal mucocele.

OBJECTIVE: To evaluate the association of the onion skin sign as a sonographic marker for appendiceal mucocele. METHODS: The sonographic onion skin sign was considered specific for the preoperative diagnosis of appendiceal mucocele. Therefore, detection of this sign in a mass located in the right lower abdomen, unrelated to the female reproductive organs, indicated surgical intervention with a presumptive diagnosis of appendiceal mucocele. From 1998 through 2001, female patients who were found to have atypical cysts containing this sign underwent surgery. The cases were closely followed, and intraoperative findings and final histologic diagnoses were recorded. RESULTS: Appendiceal mucocele was the final diagnosis in all 7 patients in whom the onion skin sign was observed. One additional patient had an appendiceal mucocele with a sonographic picture of a clear tubular cystic structure. CONCLUSIONS: A sonographically layered cystic mass in the right lower quadrant of the abdomen in the presence of a normal ovary strongly suggests the diagnosis of appendiceal mucocele. Recognition of the sonographic onion skin sign in a cystic mass in the right lower quadrant may facilitate the accurate preoperative diagnosis of appendiceal mucocele.

Adult↗