Volume 8, No. 4 (2007)
Articles
SYNTHESIS AND PHYSICOCHEMICAL CHARACTERISATION OF (Si,Ga)-MCM-22 ZEOLITE. TOLUENE DISPROPORTIONATION REACTION
I. FECHETE(1)AND(2)*, E. DUMITRIU(1), P. CAULLET(2), D. LUTIC(3), H. KESSLER(2) *CORRESPONDING AUTHOR: IOANA.FECHETE@ECPM.U-STRASBG.FR
Three samples of (Si,Ga)-MCM-22 zeolites (IZA code MWW) with Si/Ga ratios of 18, 71 and 89 were synthesized hydrothermally under static conditions, using hexamethyleneimine as a structural directing agent (SDA). The pure phase of zeolite was obtained only for Si/Ga = 18, while for the other ratios one unknown phase was detected. SEM, XRD, TG-ATD, BET, 71Ga and 29Si NMR MAS spectroscopies were performed, confirming the isomorphous substitution of gallium into the zeolite structure. The acidic properties were studied by TPD of ammonia, showing that the acid character depends on the gallium concentration. The catalytic performances of (Si,Ga)-MCM-22 zeolite with various Ga contents were studied in the toluene disproportionation reaction in the temperature range 573-673 K. We showed that the fraction of p-xylene increases with the isomorphous substitution degree and decreases with the temperature and also that the catalytic performances are correlated with the structure and the acidic properties of the (Si,Ga)-MCM-22 zeolite.
CADMIUM ELECTRODEPOSITION FROM AN AQUEOUS 0.1 M CdSO4 SOLUTION PART 1: ELECTROCHEMICAL AND IN SITU AFM STUDIES IN THE CASE OF n-Si(100)
BOUBIÉ GUEL
Electrochemical and in situ AFM studies of cadmium electrodeposition from an aqueous 0.1 M CdSO4 solution have been carried out in the case of (100) n-type silicon single crystal. The mechanisms related to the initial stages of the nucleation and growth mechanism of cadmium have been studied as a function of different potential steps. Within appropriate potential ranges the initial deposition kinetics corresponded to a model including progressive nucleation and diffusion controlled cluster growth. Nucleation rate and the number of atoms in the critical nucleus were determined from the analysis of current transients at different overpotentials. A Ncrit-value of 14 ± 1 atoms was determined in the following potential range: –9 mV = ? = –11 mV. The response of the system at different waiting times at the equilibrium potential was also investigated.
HOW STARTER CULTURES AFFECT THE SENSORIAL CHARACTERISTICS AND THE MICROBIOTA EVOLUTION OF DRY SAUSAGES
MARGARETA ZARA*, AURELIA IONESCU, AIDA VASILE, IULIANA APRODU, IOANA MANOLIU
The use of the culture starter in the processing of the meat products is of a crucial importance in order to improve sensorial and preservation characteristics of the final product. The aim of this study was to establish the influence of different starter cultures made of Staphylococcus carnosus and a mix between Pediococcus acidilactici and Lactobacillus plantarum, on the sensorial characteristics and microbiota evolution of the home-made dry sausages, comparing with a control batch. Our results showed an improvement of safety and quality of the fermented meat products with started cultures and confirm other similar experimental studies.
DEVELOPMENT AND EVALUATION OF AN HPLC-DAD METHOD FOR DETERMINATION OF INDIGOTINE IN SOFT DRINKS
ION TRANDAFIR(1)*, VIOLETA NOUR(2), MIRA ELENA IONICA(2)
According to the Directive 94/36/EC of the European Union (EU), quantities of synthetic colorants added to foods are restricted by upper limits and, therefore, reliable methods for their quantification have to be established. Indigotine is the common name for uncertified FD&C Blue No. 2 and it is a blue food color, water soluble. In this paper, the operational parameters that shall lead to the development of a new analysis method of indigotine in soft drinks have been studied; the technique used is the liquid chromatography together with diode array detection. It has been tried to validate the analysis method settled, in terms of sensitivity, linearity range, reproducibility, repeatability, and robustness. The indigotine in the sample is separated on a C18 reversed phase chromatography column, diode array detected at 608 nm and quantified with a calibration graph. The method provides stable retention times and a detection limit of 0.03 mg/L indigotine at a signal to noise ratio of 3.
DEVELOPMENT AND VALIDATION OF AN HPLC METHOD FOR THE DETERMINATION OF ACESULFAME K AND SACCHARIN IN CONFECTIONERY WITH NO ADDED SUGAR
VIOLETA NOUR(1)*, ION TRANDAFIR(2), MIRA ELENA IONICA(1)
A simple, selective, and precise reverse phase high performance liquid chromatographic method has been developed for the simultaneous determination of acesulfame K and saccharin in the confectionery with no added sugar (Solano candies). For analysis, the sample is extracted or diluted with water, and the solution of the sample with the two sweeteners is purified by an extraction with Carrez reagents. The chromatographic separation was achieved with potassium dihydrogen orthophosphate buffer (pH = 4.3) and acetonitrile (98:2, v/v) as mobile phase, a DS HYPERSIL C18 5 ?m column (250 mm ? 4.6 mm) and diode array detection at 220 nm. The analysis time was less than 20 min. The calibration curves showed good linearity over the concentration range of 0-40 mg/L. The correlation coefficients were > 0.999914 in each case. The method was validated with respect to sensitivity, linearity range, reproducibility, repeatability, recovery and robustness. There have been obtained average recovery values of 93.0325% for acesulfame K and 93.7067% for saccharin for an addition level of 5 mg/L in the sample solution (the final concentration in sample 227 mg/kg acesulfame K and 234 mg/kg saccharin). The method proved high fidelity and stability, and the detection limit was 1 mg/kg for acesulfame K and 0.4 mg/kg for saccharin for a signal to noise ratio of 3.
LE LAIT – MATIÈRE PRÉMIÈRE DANS LE CONTEXTE DE L’INTÉGRATION EUROPÉENNE. MILK – RAW MATERIAL IN THE CONTEXT OF EUROPEAN INTEGRATION
IULIANA SION(1)*, ADRIANA DABIJA(1), MIHAELA TITA(2), OVIDIU TITA(2)
Among considerations connected to agriculture and agricultural production adapted to the European standards, it is, of course, the modern and fast evaluation of milk and the dairy products. These have to keep into account the need, always actual, to determinate the deviations in the composition of food and also deviations of technological process. We have checked milk and dairy products coming from four major producers from Bacau area, Romania. These producers have their own harvesting centers for milk from farmers, and also they have their own farms for milk production. For a fast and accurate control, some of them acquired milk analyzers of Lactoscope or Milkoscan type.
DES ASPECTS SUR CONTAMINATION MICOTOXICOLOGIQUE DE L’ORGE – MATIÈRE PRÉMIÈRE DANS L’INDUSTRIE DE LA BIÈRE. ASPECTS OF MYCOTOXICOLOGIC CONTAMINATION OF BARLEY – RAW MATERIAL IN BREWING
ADRIANA DABIJA(1), IULIANA SION(1)*, MIHAELA TITA(2), OVIDIU TITA(2)
The paper presents original researches on the microbiological contamination of barley used as raw material in brewing industry. The subject subscribes to the general effort done for production improvement and trying to solve the main problems faced by the Romanian producers in order to meet EU criteria and standards.
INVESTIGATIONS CONCERNANT L’ACTIVITE ET LE SPECTRE DE QUELQUES ENZYMES SUR DES REGENERANTS DE BRASSICA OLERACEA VAR. CAPITATA EN PROVENANT DES ANTHERES ET OVAIRES
DANIELA NICUTA(1)*, GOGU GHIORGHITA(1), ECATERINA T. TOTH(2), DIANA E. MAFTEI(1)
Cathalase and peroxidase activity was effected on cabbage leaves (Brassica oleracea) from in vitro regenerants. The study of cathalase and peroxidase specific activity on vitroclones provided by anthers and ovaries pointed out major differences due to genotype, explant type and hormonic balance within the nutritive media. Cathalase activity in most investigated regenerants was higher compared to control plants. Seed-grown plantlets (the same ontogenetic stage as the in vitro plants) were referred to as control plants. Cathalase activity was determined by iodometric method, and peroxidase activity – by spectrophotometry. To evince the isoenzyme spectrum of estherase and peroxidase, enzyme preparations were accomplished in Tris-HCl 0.1M, pH=7.2. Wrigley method was used for electrofocussing. Peroxidasic isoenzymes were evinced by means of McDonald and Smith method, 1972. Cathalase specific activity in most investigated vitroclones was higher related to control plants. In case of ovary-provided regenerants (Z2-12 genotype) cathalase activity is higher on media supplemented with BAP (benzylaminopurine) and IAA (indole acetic acid): 7.745 mg H2O2/mg proteins, superior to control plants: 1.196 mg H2O2/mg proteins. Peroxidase specific activity in vitroclones was higher than in control plants (0.763 – 1.709 mg H2O2/mg proteins in anther-provided regenerants, and of 1.429 – 4.326 mg H2O2/mg proteins in ovary-provided regenerants, compared to 0.432 mg H2O2/mg proteins in control). Isoenzymatic spectra of cathalase and of peroxidase evinced some major differences among the regenerants of Brassica oleracea var. capitata provided by anthers and ovaries. Isoestherase spectrum was broad, comprising 9 to 17 electroforetic bands. There was a narrow isoperoxidase spectrum in vitroclones. There were 1 to 4 bands in case of regenerants compared to control (5 bands).
INVESTIGATIONS MORPHOGENETIQUES ET BIOCHIMIQUES EN CULTURES IN VITRO ET SUR DES REGENERANTS DE MENTHA VIRIDIS L.
DIANA E. MAFTEI(1)*, GOGU GHIORGHITA(1), ELVIRA GILLE(2), DANIELA NICUTA(1)
In vitro cultures were initiated using plants of Mentha viridis L. originating from Greece. The shoots tips were sterilised with chloramine-T (5% solution) for 25 minutes. The initiation medium was Murashige-Skoog (1962) (MS) enriched with various combinations of cytokinins and auxins. The main morphogenetic reaction of the inoculated explants (shoot tips and nodes) was neoplantlet regeneration. Shoot and root formation was inhibited only on medium formula comprising 2,4-D, that provided a cream-green friable callus, deprived of organogenetic capacity. MS medium with benzylaminopurine (BAP) and giberellic acid (GA) stimulated multiple shooting and (seldom) root formation. In vitro regenerants were transfered to septic medium and subsequently to experimental fields during 2004 and 2005. The regenerants (first and second year of vegetation) were submitted to biochemical tests in 2005. The best output for polyphenols and flavons was registered for the ethanolic extractions (both warm and cold, 70% ethanol). The quantities of this biologically active principles are similar to those of control plants. There are higher amounts of flavons and lower amounts of polyphenols compared to control. TLC qualitative analysis for triterpenes and phytosteroles (in warm ethanolic extractions) evinced the presence of ? sitosterole and of ursolic acid. The amount of volatile oils in control plants reaches 0.7% and was exceeded in case of vitroclones (3.33% for the first year regenerants and 4.00% in case of the second year regenerants). In vitro regenerants displayed a narrower range of volatile oil compounds. The amount of carvone was much higher (59.11 – 59.16%) compared to control (34.46%). The quantity of 2-cyclohexene-1-one is much lower in regenerants (0 – 1.65%) than in control plants (25.10%).
A NEW RESEARCH ON BIOLOGICAL ACTIVITY OF (2S,3S)-1,4-BIS-SULFANYLBUTANE-2,3-DIOL
CORINA TOADER(1), IRINA ZARAFU(2)*, ION BACIU(2)
One of the key points in tuberculosis control programs is the early confirmation of the diagnostic through Koch bacilli detection. Therefore, this study is trying to highlight the role of digestion-decontamination agents in microscopic detection of M-Tuberculosis, in order to determine the ability of a smear made from respiratory sample to identify which specimens would be culture positive for M. tuberculosis. The research methodology has been based on comparison of three types of smears processed by standard technique and by NALC treatment respiratory specimens, respectively by a new tested mucolitic reagent, dithiothreitol. During each stage of preparation process, AFB microscopic sensitivity has been assessed by Ziehl-Neelsen and auramine-rhodamine staining methods.
CONDENSING REACTION BETWEEN ARYLALDEHYDES AND HYDRAZINE DERIVATIVED FROM AMINOSULPHONYL PHENOXYACETYLHYDRAZIDES
ANCA M. MOCANU*, CORINA CERNATESCU
By taking into account the important biological activity of the aminosulphonyl-phenoxyacetic acids, we considered useful to capitalize a series of seven previously syntetised hydrazides by their condensation with arylaldehydes. The reaction was carried out in ethanol medium using acetic acid as a catalyst. The obtained products were purified by recrystallisation in organic solvents (ethanol especially) and characterised by elemental analysis data, IR spectral measurements and melting points.
INFLUENCE DU SECHAGE SUR LA COMPOSITION CHIMIQUE DE DIFFERENTES VARIETES DE POMMES. INFLUENCE OF DRYING ON THE COMPOSITION OF SEVERAL APPLE VARIETIES
SIMONA CRISTINA SPATARIU, IRINA-CLAUDIA ALEXA*, ADRIANA LUMINITA FÎNARU
In this paper we report the preliminary results of our study concerning the drying of different varieties of apples and the influence of this process to the chemical composition of these fruits. Three varieties of apples imported from Holland (Golden Delicious, Jonagold, Royal) and one Romanian variety of apples (Bot Iepure) were studied. We have determined the percentage in residual water, the sugar concentration and the acidity of the apples before and after the drying process. An evaluation of sensorial properties was completed. Significant differences between the four varieties were observed. Additional studies in this area are underway.