Modified-atmosphere packaging of minimally processed “Lollo Rosso” (Lactuca sativa) Phenolic metabolites and quality changes

 The effect of modified-atmosphere packaging (MAP) on the amount of soluble phenolics in, and the visual appearance of, white, green and red tissues of minimally processed “Lollo Rosso” lettuce were evaluated. Minimal processing induced a two-fold increase in the amount of soluble phenylpropanoids in the midribs during storage in air at 5°C. When the lettuce was stored in the presence of 2–3% O₂ and 12–14% CO₂, this increase was not induced and no browning was observed. A particularly marked decrease in the amount of phenylpropanoids was observed in MAP-stored green and red tissues. The concentrations of flavonoids and anthocyanins did not change much in midribs and green tissues, while they were significantly degraded in red tissues under MAP conditions. MAP storage proved useful in the prevention of browning, the main cause of quality loss in minimally processed “Lollo Rosso” lettuce. However, MAP storage was not so beneficial for the preservation of the quality of red tissues and, in fact, their overall visual quality, texture, aroma and macroscopic breakdown under MAP conditions were worse than those of air-stored tissues. Received: 5 November 1997     

Differentiation between Pseudocubic and Cubic Phases in Y–ZrO2 Using Rietveld Analysis

The precise microstructural characterization of the yttriapartially stabilized zirconia (Y-PSZ) system by means of X-ray diffractometry (XRD) experiments faces a serious challenge: the discrimination beween the cubic, c , and pseudocubic, t', phases. We show how the confusion between the two phases goes beyond a simple qualitative problem, because the relative abundances for all the present polymorphs can be substantially modified. This is particularly true for the amount of transformable tetragonal phase, which is of paramount importance for the design of zirconia-based tough ceramics. Similarly, we show that a conclusive discrimination between c and I' phases is possible on the basis of XRD experiments by a careful application of the Rietveld method and by emphasizing some subtle details around the angular domain close to the {200} planes. The procedure is applied to samples of Y-PSZ (4.7 mol%).     

Analysis of phenolic compounds in Spanish red wines by capillary zone electrophoresis

A simple technique for the routine capillary electrophoretic analysis of phenolic compounds in red wines from different Spanish regions, is described. Separation was achieved using a fused-silica capillary column with a borate buffer at pH 9.5, and UV detection at 280 nm. The compounds identified were: (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, syringic acid, vanillic acid, gallic acid, 3,4 dihydroxybenzoic acid, p-coumaric acid, caffeic acid and the hydroxycinnamic tartaric acid esterscis- andtrans-coumamyl tartaric acid andcis-caffeoyl tartaric acid. Different wines showed very similar electrophoretic profiles, but significant quantitative differences were observed.     

Cinnamic ester of D‐sorbitol for immobilization of mushroom tyrosinase

Mushroom tyrosinase was immobilized by adsorption onto the totally cinnamoylated derivative of D ‐sorbitol. The polymerization and cross‐linking of the derivative initially obtained was achieved by irradiation in the ultraviolet region, where this prepolymer shows maximum sensitivity. Immobilization of tyrosinase on this support involves a process of physical adsorption and intense hydrophobic interactions between the cinnamoyl groups of the support and related groups of the enzyme. The pH value, enzyme concentration and immobilization time were all important parameters affecting immobilization efficiency; also, enzyme immobilization efficiency correlated well with the tyrosinase isoelectric point. The immobilized enzyme showed an optimum measuring pH of 3.5 and greater activity at acid and neutral pH values than the soluble enzyme. The optimal reaction temperature was 35 °C and the temperature profile was broader than that of the free enzyme or of the enzyme immobilized on other supports. The apparent Michaelis constant of mushroom tyrosinase immobilized on the SOTCN derivative acting on 4‐tert‐butylcatechol (TBC) was 0.40 ± 0.02 mmol dm^?3, which was lower than for the soluble enzyme, suggesting that the affinity of this enzyme for this substrate was greater when immobilized than when in solution. Immobilization stabilized the enzyme and made it less susceptible to activity loss during storage at pH values in the range 4–5.5, and the suicide inactivation of the immobilized tyrosinase was null or negligible in a reaction medium with 4‐tert‐butylcatechol at a concentration of 0.4 mmol dm^?3. The results show that cinnamic carbohydrate esters of D ‐sorbitol are an appropriate support for tyrosinase immobilization and could be of use for several tyrosinase applications. Copyright © 2005 Society of Chemical Industry     

Wheelchair for physically disabled people with voice,ultrasonic and infrared sensor control

This paper describes a wheelchair for physically disabled people developed within the UMIDAM Project. A dependent-user recognition voice system and ultrasonic and infrared sensor systems has been integrated in this wheelchair. In this way we have obtained a wheelchair which can be driven with using voice commands and with the possibility of avoiding obstacles and downstairs or hole detection. The wheelchair has also been developed to allow autonomous driving (for example, following walls). The project, in which two prototypes have been produced, has been carried out totally in the Electronics Department of the University of Alcalá (Spain). It has been financed by the ONCE. Electronic system configuration, a sensor system, a mechanical model, control (low level control, control by voice commands), voice recognition and autonomous control are considered. The results of the experiments carried out on the two prototypes are also given.     

Effect of lipids and surfactants on extracellular lipase production by Yarrowia lipolytica

The production of extracellular lipase in submerged cultures of Yarrowia lipolytica CECT 1240 has been investigated. Several compounds have been added to the culture medium, in order to assess their efficiency as inducers of lipase production. First, the effect of triglycerides (olive oil, sunflower oil, tributyrin) and fatty acids (oleic acid) has been studied. The highest activity level was obtained with sunflower oil (58 U cm^?3), followed by olive oil (49 U cm^?3). The cultures with tributyrin and oleic acid attained similar activities (33 U cm^?3). Then, several surfactants (Tween 80, Triton X‐100, gum arabic, polyethylene glycol 200) were added to the cultures with sunflower oil, in an attempt to increase the levels of extracellular lipase activity. The obtained activities were slightly lower than those achieved without surfactants. The assay of a wide range of surfactant concentrations in the case of PEG‐200 (with which the highest activity levels had been attained) did not improve the results. This strain secreted lipase concentrations two‐fold higher and showed significantly different behaviour towards the presence of surfactants in the culture medium, compared with other wild‐type Yarrowia lipolytica strains. Copyright © 2003 Society of Chemical Industry     

Agonistic activity of a CD40-specific single-chain Fv constructed from the variable regions of mAb G28-5

A single-chain Fv (sFv) was expressed from the variable regions of the CD40-specific mAb G28-5. The molecule bound CD40 with a high affinity (2.2 nM) and was a monomer in solution. Surprisingly, G28-5 sFv was a potent CD40 agonist that rapidly crosslinked CD40 on the cell surface but did not crosslink CD40-Ig in solution. G28-5 sFv was a more potent agonist than G28-5 IgG and was able to stimulate CD40 responses by B cells and monocytes. G28-5 IgG partially blocked, whereas G28-5 sFv augmented CD40 responses during stimulation with natural ligand (gp39-CD8 fusion protein). These results indicate that the functional activity of ligands built from the binding site of G28-5 is highly dependent upon the size and physical properties of the molecule both in solution and on the cell surfaces.