Valorisation of low quality edible oil with tomato peel waste

The aim of this study is to enrich edible oils with carotenoids and lycopene from tomato purée or tomato peel, an industrial tomato waste. These tomato derivatives were incorporated in refined olive oil, extra virgin olive oil and refined sunflower oil. The incorporation of peel enhanced the concentration of β-carotene and lycopene more than tomato purée. Furthermore, the incorporation of both tomato purée and peel induced better thermal stability of the refined olive oil compared to extra virgin oil and sunflower oil. A decrease on total phenols as well as some prooxidant activity account for this, when tomato purée was incorporated. In our oil preparations, rutin and naringenin, as flavonoids coming exclusively from tomato purée or peel, were detected. The enrichment of oils with tomato carotenoids and lycopene, in particular low quality oils like refined olive oils, might be an alternative approach to elaborate new functional foods.     

Magnetic force microscopy on nanocrystalline Co films

Pioneer works in ultrathin magnetic films have shown perpendicular magnetic domains in the demagnetized state. The source of this perpendicular anisotropy is the interface anisotropy developed at the interface. Similar domains could be observed in tetragonally distorted ultrathin films due to the magnetoelastic anisotropy. On the other hand, single-crystalline hexagonal close packed (hcp) Co films when grown epitaxially with the c-axis oriented perpendicular to the film plane may show perpendicular stripe magnetic domains even up to a thickness of about 500 nm. In that case the source of perpendicular anisotropy was the magnetocrystalline anisotropy of bulk Co, which favors the c-axis. In this work, we have grown by radio frequency magnetron sputtering Co films in the thickness range 15-4500 nm. We have used various substrates, such as Corning glass, silicon and Al-foil. The substrate temperature was about 350 K. The films have been found by X-ray diffraction experiments to present various structures and textures depending on the preparation conditions, mainly the Ar-pressure and deposition rate. Stripe- and labyrinth-like domain configurations are observed in films textured along the c-axis, and in films with a mixture of hcp and fcc grains, repectively. Films which show mainly fcc or amorphous structure do not form perpendicular domains. The results are discussed with respect to magnetization loops.     

Photocatalytic degradation of 2-phenethyl-2-chloroethyl sulfide in liquid and gas phases

This work explores the ability of photocatalysis to decontaminate water and air from chemical warfare agent mustard using its simulant 2-phenethyl 2-chloroethyl sulfide (PECES). PECES like mustard slowly dissolves in water with hydrolysis, forming 2-phenethyl 2-hydroxyethyl sulfide (PEHES). Irradiation of TiO2 suspension containing PECES with the unfiltered light of a mercury lamp (lambda > or = 254 nm) decomposed all PECES mostly via photolysis. Reaction under filtered light (lambda > 300 nm) proceeds mainly photocatalytically and requires longer time. Sulfur from starting PECES is completely transformed into sulfuric acid at the end of the reaction. Detected volatile, nonvolatile, surface products, and the suggested scheme of degradation are reported. The main volatile products are styrene and benzaldehyde, nonvolatile--hydroxylated PEHES, surface--2-phenethyl disulfide. Photolysis of PECES produced the same set of volatile products as photocatalysis. Photocatalytic degradation of gaseous PECES in air results in its mineralization but is accompanied by TiO2 deactivation. The highest rate of mineralization with minimum deactivation was observed at about room temperature and a water concentration of 27,500 ppm. No gaseous products except CO2 were detected. The main extracted surface product was styrene. It was concluded that PECES photocatalytic degradation proceeds mainly via C-S bond cleavage and further oxidation of the products. Hydrolysis of the C-S bond was detected only in gas-phase photocatalytic degradation. The quantum efficiency of gas-phase degradation (0.28%) was much higher than that of liquid-phase degradation (0.008%). The results demonstrate the ability of photocatalysis to decontaminate an aqueous and especially an air environment     

Study of water sorption of egg powders by inverse gas chromatography

Summary Inverse gas chromatography was used to study the water sorption properties of two spray-dried egg powders as a function of water activity, temperature and food composition. A considerably higher water uptake was observed in the defatted egg powder than in the whole-egg powder. Sorption isotherms at different temperatures were determined in order to obtain the thermodynamic parameters of sorption. The thermodynamic parameter values were less negative for the whole-egg powder than for the defatted powder. The reduction in water-binding capacity in the whole-egg powder is explained by the masking of the sorption sites by the non-hygroscopic fat. Both the BET and Freundlich equations were applied to the sorption isotherms, and the BET monolayer as well as the sorptive capacity values were calculated.

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Untersuchung der Wassersorption von Eipulver durch Invers-Gaschromatographie

Zusammenfassung Für die Untersuchung der Wassersorption zweier sprühgetrockneter Eipulver als Funktion der Wasseraktivität, Temperatur und Lebensmittelzusammensetzung wurde die Invers-Gaschromatographie verwendet. Im entfetteten Eipulver wurde eine beträchtlich höhere Wasseraufnahme beobachtet als im Volleipulver. Um die thermodynamischen Parameter zu erhalten, wurden die Sorptionsisothermen bei verschiedenen Temperaturen bestimmt. Die Werte der thermodynamischen Parameter waren für das Volleipulver weniger negativ als für das entfettete Eipulver. Die Verminderung der Wasserbindungskapazität im Volleipulver erklärt sich durch die Belegung der Sorptionsstellen durch das nicht-hygroskopische Fett. Sowohl die BET-Methode¹ als auch die Freundlichsche Gleichung wurden für die Sorptionsisotherme angewandt und die Werte der nach BET monomolekularen Schicht wie auch die Sorptionskapazität wurden berechnet.

     

Water sorption and water vapour diffusion in food-grade plastics packaging materials: Effect of a polymeric plasticizer

It is recognized that packaging has a profound effect on the ultimate quality of food products reaching the consumer. So, the selection of proper packaging materials has become one of the major problems of the food technologist. In the field of flexible packaging one of the most important properties is water vapour/package interaction. Inverse gas chromatography has been used to study water sorption of polyvinylchlor-ide and poly(vinylidene chloride-vinylchloride) plasticized with different amounts of a polymeric plasticizer (poly(adipate ester)) at temperatures between 25°C and 50°C. It was found that the specific retention volume of water increases with decreasing temperature and increasing amount of plasticizer into the polymeric mixtures. The effect of temperature on water sorption behaviour is more pronounced compared with that of plasticizer addition. The thermodynamic parameters of water/polymer interaction, namely free energy, entropy, enthalpy and activity coefficient were calculated. Values were interpreted on the basis of an active-site absorption model. The Van Deemter equation was found to be applicable to these systems and was used to determine diffusion coefficients and activation energies for diffusion. Diffusion coefficient values increase with increasing amounts of plasticizer and this increase is accompanied by a decrease in the activation energy for diffusion.     

Fractal Nature of Fluorescence Quenching and its Relation to Percolative Conduction in Water-in-Oil Microemulsions

Results of fluorescence quenching and electrical conductivity measurements in water-in-oil microemulsions were analyzed in terms of fractal models. It was found that for SDS/water/pentanol/alkane microemulsions there exists a connection between the fractal nature of the reaction domain and the magnitude of electrical conductivity. Conductivity values increase as the domain becomes less fractal.     

Safety and quality of plastic food packaging materials: validation of a modified chemical inertness test method for refillable poly(ethylene terephthalate) bottles

The increased use of refillable poly(ethylene terephthalate) (PET) bottles as packaging for soft drinks has prompted us to investigate the effect of sorption of artificially introduced chemical contaminants into refillable PET bottles in order to establish a practical and easy-to-apply test procedure to evaluate their chemical inertness. For this evaluation, quick laboratory procedures, which focus on the interaction of PET bottle wall strips in place of actual bottles with a selection of model contaminants representing the myriad of chemicals, are proposed. The first objective of this study was to validate a modified quick chemical inertness test method for refillable bottles by comparing the results of sorption into PET strips with those of tests using actual PET bottles. A further objective was to investigate the stability of refillable PET bottles which were stored under unfavorable conditions, in relation to the chemical inertness behavior of the material. The results indicate the suitability of the modified quick test as it satisfactorily simulates contamination of refillable PET bottles. Moreover, storage of these bottles under unfavorable conditions does not have an adverse effect on the chemical inertness behavior of the plastic material.     

Zeolites-catalyzed Alkylation of Isobutane with 2-butene: Influence of Acidic Properties

Mixed-conducting SrFe_0.7Al_0.3O_3- (SFA) exhibits substantial catalytic activity towards partial oxidation of methane and can thus be considered as a component of monolithic ceramic reactors for synthesis gas generation, where the dense membrane and porous catalyst at the permeate-side surface are made of similar compositions. Surface modification of SFA powder and membranes with Pt has no essential effect on the performance of a model reactor, suggesting that the catalytic behavior of SFA is mainly determined by the surface states of iron and oxygen ions in the catalyst. The Mössbauer spectroscopy shows that reduction of SrFe_0.7Al_0.3O_3-, having cubic perovskite lattice in air, leads to the co-existence of perovskite- and brownmillerite-like domains, whilst the concentrations of metallic Fe and even Fe²⁺ under typical operation conditions are lower than the detection limits. The amount of vacancy-ordered phase increases with decreasing oxygen content, the estimations of which were confirmed by coulometric titration data. The catalytic activity of ferrite-based materials may thus be associated with lattice instability characteristic of morphotropic phase transformations.     

Author Index

Authors Index

Author Index     

Fuzzy Logic Decision Mechanism Combined with a Neuro-Controller for Fabric Tension in Robotized Sewing Process

A new approach for flexible automated handling of fabrics in the sewing process is described, which focuses to control the cloth tension applied by a robot. The proposed hierarchical robot control system includes a Fuzzy decision mechanism combined with a Neuro-controller. The expert's actions during the sewing process are investigated and this human behavior is interpreted in order to design the controller. The Fuzzy Logic decision mechanism utilizes only qualitative knowledge concerning the properties of the fabrics, in order to determine the desired tensional force and the location of the robot hand on the fabric. A Neural Network controller regulates the fabric tension to achieve the desired value by determining the robot end effector velocity. The simulation results demonstrate the efficiency of the system as well as the robustness of the controller performance since the effects of the noise are negligible. The system capabilities are more evident when the controller uses its previously acquired experience.