Onion Bulbs (onion + bulb)

Distribution by Scientific Domains


Selected Abstracts


KINETICS AND HYDROLYSIS PARAMETERS OF TOTAL FRUCTOOLIGOSACCHARIDES OF ONION BULBS: EFFECTS OF TEMPERATURE REGIMES AND CULTIVARS

JOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2007
NOUREDDINE BENKEBLIA
ABSTRACT This work studied the percentage of hydrolysis, observed hydrolysis rate constant (kobs), half-life time (t1/2) and kinetics of degradation of the total fructooligosaccharides (FOS) of three different onion bulb cultivars (Yellow Spanish, Red Amposta and Tenshin) kept during 6 months under three temperature regimes, 10, 15 and 20C. The percentage of hydrolysis of FOS was higher at 20C than at 10C and ranged from 47 to 58% at 10C, from 63 to 68% at 15C and from 74 to 83% at 20C. The kobs ranged from 27 × 10,3 to 36 × 10,3/week at 10C and from 41 × 10,3/week to 47 × 10,3/week at 15C, while at 20C, it was high and was about kobs 56 × 10,3/week.. The t1/2 decreased when temperature increased, and varied from 19.5 to 26.0 weeks at 10C, from 14.6 to 16.8 weeks at 15C and from 9.4 to 12.3 weeks at 20C, indicating that high degree of polymerization (DP) FOS have shorter lives than low DP FOS. Linear regression and kinetics of hydrolysis have shown that FOS hydrolysis is higher at 20C, with a coefficient of regression ranging between 0.87 and 0.99. Apparently, FOS hydrolysis is temperature independent, and storage time had more effect on the higher DP FOS than on the lower DP FOS. [source]


Variation of Fructooligosaccharides and their Metabolizing Enzymes in Onion Bulb (Allium cepa L. cv. Tenshin) During Long-term Storage

JOURNAL OF FOOD SCIENCE, Issue 3 2005
Noureddine Benkeblia
ABSTRACT: The objective of this study was to assess the status of fructooligosaccharides (FOS) in onion bulbs (Allium cepa L. cv. Tenshin) and their metabolizing-enzymes,1-fructoexohydrolase (1-FEH), 1-kestose hydrolyzing enzyme (1-KH), fructan:fructan 1F -fructosyltransferase (1-FFT) and fructan:fructan 6G -fructosyltransferase (6G-FFT),during storage at 15°C. Fructose varies slightly, whereas 1-kestose peaked after 6 wk and then decreased progressively during the last 18 wk of storage. Lower degree of polymerization (DP) 3 to 6) FOS, higher (DP 7 to 12) FOS, total FOS, and total carbohydrates showed similar and close patterns during 24 wk. They varied slightly at the beginning of the storage period; afterward they decreased progressively and regularly during the last 20 wk of storage. 1-FEH and 1-KH activities were low but peaked abruptly after 12 and 16 wk, respectively, after which they decreased to levels higher (1-FEH) or similar (1-KH) to those observed at the beginning of the storage. Surprisingly, 1-FFT activity showed similar pattern to the variation of 1-KH hydrolyzing activity; on the other hand, 6G-FFT, although higher, was stable during 16 wk but decreased after that. The results allowed us to associate FOS to the dormancy and sprouting states, and the peaks of the degrading enzymes were shown to signal the release of dormancy of onion bulb. [source]


Cover Picture: (Adv. Eng.

ADVANCED ENGINEERING MATERIALS, Issue 5 2010
Mater.
The INM - Leibniz Institute for New Materials in Saarbruecken engages in fundamental and applied materials research-from a chemical, physical and biological perspective. The cover highlights examples of INM's research which is presented in this special issue. The front cover shows biomineralization using the example of crystals embedded in the outer tissue of onion bulbs (courtesy of Birgit Heiland, INM). The back side demonstrates an in situ adhesion experiment in a scanning electron microscope (courtesy of Andreas S. Schneider/Anika Weber, INM). [source]


Variation of Fructooligosaccharides and their Metabolizing Enzymes in Onion Bulb (Allium cepa L. cv. Tenshin) During Long-term Storage

JOURNAL OF FOOD SCIENCE, Issue 3 2005
Noureddine Benkeblia
ABSTRACT: The objective of this study was to assess the status of fructooligosaccharides (FOS) in onion bulbs (Allium cepa L. cv. Tenshin) and their metabolizing-enzymes,1-fructoexohydrolase (1-FEH), 1-kestose hydrolyzing enzyme (1-KH), fructan:fructan 1F -fructosyltransferase (1-FFT) and fructan:fructan 6G -fructosyltransferase (6G-FFT),during storage at 15°C. Fructose varies slightly, whereas 1-kestose peaked after 6 wk and then decreased progressively during the last 18 wk of storage. Lower degree of polymerization (DP) 3 to 6) FOS, higher (DP 7 to 12) FOS, total FOS, and total carbohydrates showed similar and close patterns during 24 wk. They varied slightly at the beginning of the storage period; afterward they decreased progressively and regularly during the last 20 wk of storage. 1-FEH and 1-KH activities were low but peaked abruptly after 12 and 16 wk, respectively, after which they decreased to levels higher (1-FEH) or similar (1-KH) to those observed at the beginning of the storage. Surprisingly, 1-FFT activity showed similar pattern to the variation of 1-KH hydrolyzing activity; on the other hand, 6G-FFT, although higher, was stable during 16 wk but decreased after that. The results allowed us to associate FOS to the dormancy and sprouting states, and the peaks of the degrading enzymes were shown to signal the release of dormancy of onion bulb. [source]


Novel MPZ Mutation In A Sporadic CMT Patient

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2001
E Bellone
Mutations in the gene for the major structural protein component of peripheral nerve myelin, myelin protein zero (MPZ), are associated with some forms of hereditary neuropathies such as Charcot-Marie-Tooth disease type 1B (CMT1B), Dejerine-Sottas syndrome (DSS) and congenital hypomyelinating neuropathy (CHN). The common pathological characteristics of these allelic disorders are severe demyelination and remyelination of peripheral nerves. Recently, MPZ mutations were also found in patients with the axonal form of CMT neuropathy (CMT2). We studied a patient with negative familiar history and clinical and electrophysiological features of Charcot-Marie-Tooth disease: distal muscle weakness and atrophy, foot deformities (pes cavus), and severely reduced nerve conduction velocities in the motor and sensory nerves. The sural nerve biopsy showed marked loss of myelinated fibers, few onion bulbs, and a high percentage of fibers showing excessive myelin outfoldings. DNA analysis excluded CMT1A duplication by Southern blot and by pulsed field gel electrophoresis methods. SSCP analysis of all six exons of MPZ revealed a shift band in exon 2 in the patient's DNA. No such difference was detected in normal controls. Direct sequencing disclosed a G , A transition at nucleotide position 181. This base substitution predicts the replacement of aspartic acid with asparagine at codon 61. A mutation at the same codon (but different amino acid replacement) was recently identified in a family with the axonal type of CMT, in which the disease was autosomal dominantly inherited. This finding provides further confirmation of the role of MPZ gene in peripheral neuropathies and suggests that MPZ coding region mutations may account for a considerable number of CMT cases which do not involve DNA duplication on 17p11.2-p12. This research was partially supported by a MURST and an Ateneo grant to FA, by a Ministero della Sanità grant to PM. Our laboratory is a member of the European Charcot-Marie-Tooth Consortium co-ordinated by Prof. Christine Van Broeckhoven. [source]


Plant photonics: application of optical coherence tomography to monitor defects and rots in onion

LASER PHYSICS LETTERS, Issue 4 2010
I.V. Meglinski
Abstract The incidence of physiological and/or pathological defects in many fresh produce types is still unacceptably high and accounts for a large proportion of waste. With increasing interest in food security their remains strong demand in developing reliable and cost effective technologies for non-destructive screening of internal defects and rots, these being deemed unacceptable by consumers. It is well recognized that the internal defects and structure of turbid scattering media can be effectively visualized by using optical coherence tomography (OCT). In the present study, the high spatial resolution and advantages of OCT have been demonstrated for imaging the skins and outer laminae (concentric tissue layers) of intact whole onion bulbs with a view to non-invasively visualizing potential incidence/severity of internal defects. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]


Acclimation of photosynthesis to elevated CO2 in onion (Allium cepa) grown at a range of temperatures

ANNALS OF APPLIED BIOLOGY, Issue 1 2004
T R WHEELER
Summary Onion (Allium cepa) was grown in the field within temperature gradient tunnels (providing about -2.5°C to +2.5°C from outside temperatures) maintained at either 374 or 532 ,mol mol,1 CO2. Plant leaf area was determined non-destructively at 7 day intervals until the time of bulbing in 12 combinations of temperature and CO2 concentration. Gas exchange was measured in each plot at the time of bulbing, and the carbohydrate content of the leaf (source) and bulb (sink) was determined. Maximum rate of leaf area expansion increased with mean temperature. Leaf area duration and maximum rate of leaf area expansion were not significantly affected by CO2. The light-saturated rates of leaf photosynthesis (Asat) were greater in plants grown at normal than at elevated CO2 concentrations at the same measurement CO2 concentration. Acclimation of photosynthesis decreased with an increase in growth temperature, and with an increase in leaf nitrogen content at elevated CO2. The ratio of intercellular to atmospheric CO2 (C1/C3 ratio) was 7.4% less for plants grown at elevated compared with normal CO2. Asat in plants grown at elevated CO2 was less than in plants grown at normal CO2 when compared at the same C1. Hence, acclimation of photosynthesis was due both to stomatal acclimation and to limitations to biochemical CO2 fixation. Carbohydrate content of the onion bulbs was greater at elevated than at normal CO2. In contrast, carbohydrate content was less at elevated compared with normal CO2 in the leaf sections in which CO2 exchange was measured at the same developmental stage. Therefore, acclimation of photosynthesis in fully expanded onion leaves was detected despite the absence of localised carbohydrate accumulation in these field-grown crops. [source]