Volume 10, No. 2 (2009)
Articles
STUDY OF THE INTERACTION BETWEEN CATIONIC SURFACTANTS AND POLYMERS<br/> ETUDE DE L’INTERACTION PARMI LES SURFACTANTS CATIONIQUES ET LES POLYMERES
ELENA IRINA MOATER(*), CRISTIANA RADULESCU, IONICA IONITA
The aggregation of surfactants in aqueous solution is governed by equilibrium of hydrophilic, hydrophobic or ionic interactions but similarly the solubility of some polymer in water is realized by equilibrium between their hydrophilic and hydrophobic parts. The studies showed the fact that the aqueous solutions witch contain as surfactant as polymers present the complex models of interaction and their interaction diversities equalize apparent itself number of systems. The surfactant-polymer systems have a special importance, with a variety of applications witch include: pharmaceutical preparations, foods, and cosmetics, fluids for the extraction of oil, detergents, and the interest concerning the research of these systems continuously increases. Also, the understanding of these systems is very important for many biological processes and systems witch included bio-membranes, vesicles and also, in the binding of small molecules into bio-polymers. The interaction between polymers and cationic surfactants in aqueous solutions was studied using different techniques as: superficial tension, electric conductivity, viscosity, the precipitation and solubility, adsorption, calorimetry, electroscopy, fluorescence, magnetic resonance, circular dichroism, etc. Goddard has centralized many results obtained by these techniques. The studies shown the fact that the interactions between ionic surfactants and poly-ions with contrary signs are strong, but the interactions between ionic surfactants and neutral polymers are relatively weak. Non-ionic surfactants don’t react strong with non-ionic polymers witch are soluble in water or with poly-electrolytes, but they can play an important role in the phenomena of binding in systems which contain mixtures of polymers and surfactants.
KINETIC STUDIES ON THE ESTERIFICATION REACTION OF FATTY ACIDS WITH EPICHLOROHYDRIN<br/> ETUDES CINETIQUES SUR LA REACTION D’ESTERIFICATION DES ACIDES GRAS AVEC L’EPICHLOROHYDRINE
EMIL IOAN MURESAN(*1), SPIRIDON OPREA(1), EUGEN HOROBA(1), ANA IRINA ECSNER(2)
The esters of the fatty-acids with oxidants present a particular interest like surfactant soluble out of oil with various uses in the field of food industry, cosmetic and pharmaceutical industries. Taking into account the advantages present by heterogeneous catalysts, in this work was studied the catalytic activity of some anionic exchange resins in the addition reaction of fatty acids to epichlorohydrin.
A CONVENIENT SYNTHESIS OF CONSTITUTIONALLY DIVERSE N-HYDROXYPHENYLETHYL-ISOINDOLINONES<br/> UNE TECHNIQUE SOUPLE ET EFFICACE D'ASSEMBLAGE D'UNE VARIETE DE N-HYDROXYPHENYLETHYL-ISOINDOLINONES
MAGALI LORION, ÉRIC DENIAU, AXEL COUTURE, PIERRE GRANDCLAUDON(*)
A variety of polyalkoxylated N-hydroxyphenethyl-isoindolinones has been assembled by an anionic cyclization process applied to suitably substituted N-(ortho-bromobenzyl)-4-phenyloxazolidinone derivatives.
DIELS-ALDER AND RETRO-DIELS-ALDER REACTIONS SUPPORTED ON GRAPHITE UNDER MICROWAVES
S. DAHMANI(1), Y. KANDRI RODI(1), K. MISBAHI(1), E.M. ESSASSI(2), BERNARD GARRIGUES(3*)
The coupling of graphite (as a support) with microwaves (as an energy source), a new type of « dry reaction », was studied for some Diels-Alder and Hetero-Diels-Alder reactions. It was also possible to achieve in a few minutes, at atmospheric pressure and without solvent, retro-Diels-Alder reactions. All these synthesis have been realized in very short times, without any thermal decomposition products and even in presence of volatile reagents.
DIFFERENCES BETWEEN THE DOUBLE AND SINGLE STRANDED DNA THROUGH THE RAYLEIGH LIGHT DISPERSION PHENOMENON<br/> DIFFÉRENCES ENTRE L’ADN DOUBLE ET MONOCATÉNAIRE VUES A TRAVERS DU PHÉNOMENE RAYLEIGH DE DISPERSION DE LA LUMIERE
MIHAELA ILIE(1*), DANIELA COLTUC(2)
The paper presents the results of a chemometric analysis with the aim of highlighting the differences between the double- and single stranded DNA by using Rayleigh Light Scattering (RLS) spectra. The spectra were obtained by exciting the aqueous solutions of calf thymus DNA in the presence of a molecular probe (the Terbium chelate of the diethylenetriaminopentaacetic acid – Tb-DTPA). Each spectrum consisted in 400 points representing the measured intensities in the range 200-400 nm, with a 0.5 nm step. The paper presents two kinds of chemometric analysis: Principal Component Analysis (PCA) and Independent Component Analysis (ICA). PCA is well known for its ability in confining the information in a reduced number of uncorrelated coefficients, whilst ACI – lesser used in chemometrics – refines the analysis by imposing the condition of statistically independent components. Both PCA and ICA were used to reduce the dimension of each spectrum to two components. The two-dimensional representation of these components puts a into evidence a clusterisation of the spectra following the excitation wavelength and, for the same excitation wavelength, a separation tendency between spectra belonging to a different kind of DNA (single-stranded and double-stranded).
AMINO ACIDS RECUPERATION BY LIQUID-LIQUID EXTRACTION AND SUPPORTED LIQUID MEMBRANE EXTRACTION. OPTIMIZATION OF THE PROCESSES
AMEL DIDI, MOHAMED AMINE DIDI(*)
The amino acids constitute a significant class in biochemical sciences. Of this importance, their extraction and purification do not cease developing with the sight of research in progress. Our work concerns a comparative study by two techniques liquid-liquid extraction (ELL) and supported liquid membrane (SLM), of phenylalanine (phe) and tyrosine (tyr). Several extractants were the subject of this study, the di 2-ethylhexyl phosphoric acid (D2EHPA), the tri-octy phosphine oxide (TOPO), the tri-butyl phosphate (TBP) and the quaternary ammonium salt Aliquat 336 and “D2EHPA+TBP” mixture. The results showed that the D2EHPA, is high performance in ELL of phe (82%) and tyr (23.4%). Mixture “D2EHPA+TBP”, produced a synergistic effect on phe (73.5%) by ELL. The extraction by SLM of phe (feed solution 36.4%, stripping 100%) and of tyr (feed solution 2,4%; stripping 5.6%) by TBP, shows that this technique is powerful, to separate the mixture from these two amino acids in one extraction stage. The effects of solvents and salt were also tested; however the optimization of these processes remains to be perfected.
RESEARCHES CONCERNING THE OBTAINING OF LACTO-FERMENTED CABBAGE JUICE – FUNCTIONAL FOOD
IULIANA MANEA(*), LAVINIA BURULEANU, DANIELA AVRAM, MAGDA BRATU
The purpose of this study is to emphasize the evolution of the most important components of the cabbage juice during the lactic acid fermentation: reducing sugars, ascorbic acid, amino acids. The cabbage juice was obtained from white cabbage, thermally treated at 80°C for 5 minutes and inoculated with a brine inoculum with 105 cells/mL lactic bacteria mixture. The lactic acid fermentation was performed in a thermostat at 25°C during 5 days. During this time were accomplished analytical determinations for pH, titrable acidity, lactic acid, total sugar, reducing sugar, vitamin C and amino acids. Important changes were established referring to the reducing sugar content (which decreased from 4.63 g/100 g to 1.3 g/100 g) and lactic acid (which increased from 0.121 g/100 g to 1.02 g/100 g). The ascorbic acid has had a slowly involution from 23.58 mg/100 g to 19.81 mg/100 g. The amino acids content has had a tangible quantitative increasing during lactic acid fermentation.
STUDY ON THE POSSIBILITIES OF DIVERSIFYING THE ASSORTMENTS OF LACTIC ACID FERMENTED JUICES
LAVINIA BURULEANU(*), DANIELA AVRAM, IULIANA MANEA, MAGDA G. BRATU
The suitability of carrots and red beet for the preparation of vegetable juices processed by lactic acid fermentation was tested. The influence of glucose addition on the final acidity of the juices and the evolution of some chemical parameters during the lactic acid fermentation of cocktails obtained from carrot and red beet were tested. The following analytical parameters were studied during fermentation: pH, titrable acidity, reducing sugars and amino acids content. The substratum amount of the batches was varied between 1.4 g/100 g (cocktail carrot-beet 1:3) and 3.6 g/100 g (beet juice with glucose added). Before the fermentation starting the pH values of the juices ranged between 5.88 (cocktail carrot-beet 1:3) and 6.15 (carrot juice), while after 96 hours the limits of the same parameter were 3.99 (carrot juice with glucose added) and 4.27 (cocktail carrot-beet 1:1). The largest reduction of the content of reducing sugars was registered in the case of the cocktail carrot-red beet (1:3), which retained about 30% of the initial amounts after 96 hours of fermentation. The lactic acid content was varied between 0.14 and 1.25 g/100 g. No significant differences were determined through the analysis of the amino acids content of the juices, but the dynamics of this parameter was correlated with the stability of the final products. This way it was possible to compare the course of fermentation of different vegetable juices and to recommend the optimum variant from the sensory and shelf-stable point of view. The correlation between some analytical parameters was also realized, with a view to systematize the experimental data.
STUDIES CONCERNING THE QUALITY OF BREAD WHEAT VARIETIES FROM ROMANIA
IULIANA BANU(1), GEORGETA STOENESCU(2), VIOLETA SORINA IONESCU(2), IULIANA APRODU(1), INA VASILEAN(1)
Nine bread wheat varieties from Romania were analyzed (2007 and 2008, summer crops, 65 samples). Thousand kernel weight, test weight, ash content, gluten content, gluten index, falling number, gluten swelling index, and rheological properties with Mixolab and Alveograph were investigated. The characteristics were influenced by climatic growing conditions and genetic factors. A characteristic for Romanian wheat for 2008 crop was the poor gluten content because the crop practices and environmental conditions. Other characteristic of the 2007 and 2008 crops was the very high falling number value. In fact, in Romania this characteristic it is maintained in the last years. The flour obtained from milling of the wheat, crops 2007 and 2008, is necessary to be supplied with vital gluten and exogenous α-amylases. The extensibility and the dough strength were very lower, from 12 to 26 mm, respectively 87.3×10-4J. The values for C3, C4 and C5, registered at Mixolab, were low for all varieties.
THE PHYSICAL-CHEMICAL MECHANISM OF THE EDIBLE OILS DEEP REFINING
IULIANA VINTILĂ
Deep or soft degumming mechanism was treated in the present research paper. Deep degumming is a physical-chemical refining process, which involves the complete removing of total oil phosphatides by using a chelating agent (EDTA) in the presence of an emulsifying additive (sodium dodecyl sulfate – SDS). The direct hydratable phosphatides are, in the first stage, separated from the crude oil by water classic degumming process and, in the second stage, a chelating treatment is applied in order to remove the heavy metals which imposed the non-hydratable phosphatides to separate from the partial degummed oil.
DEVELOPMENT AND VALIDATION OF AN HPLC METHOD FOR SIMULTANEOUS QUANTIFICATION OF ACESULFAME-K, SACCHARIN, ASPARTAME, CAFFEINE AND BENZOIC ACID IN COLA SOFT DRINKS
ION TRANDAFIR(*1), VIOLETA NOUR(2), MIRA ELENA IONICA(2)
A simple, selective, and precise reversed-phase HPLC method has been developed for the simultaneous quantification of acesulfame-K, saccharin, aspartame, caffeine and benzoic acid in no-added sugar cola soft drinks. The chromatographic separation was performed by using potassium dihydrogen orthophosphate buffer (pH = 4.3) and acetonitrile (88:12, v/v) as mobile phase, a DS Hypersil C 18.5 μm column (250 mm ± 4.6 mm) and "diode array" detection at λ= 227 nm for acesulfame-K, λ= 265 nm for saccharin and λ= 217 nm for aspartame, caffeine and benzoic acid. The analysis time was less than 40 min. The calibration curves showed good linearity over the concentration range of 0-100 mg/L. The validation of the analysis method was attempted in terms of sensitivity, linearity range, reproducibility, repeatability, analytical recovery and robustness.