Effect of Dipping and Vacuum Impregnation Pretreatments on the Quality of Frozen Apples: A Comparative Study on Organic and Conventional Fruits

The effect of dipping and vacuum impregnation (VI) pretreatments with lemon juice solution on the quality and stability of organic and conventional frozen apples was investigated. Fresh apples were characterized; organic apples showed, at equal starch and ripeness index, a lower sugar content, and higher acidity than conventional ones. The polyphenol content was slightly higher in organic apples than in conventional ones while polyphenoloxidase activity was similar. No differences in color and firmness were evidenced. Dipping affected organic and conventional apples’ color by determining an increase of lightness (ΔL^* ≈ 4) and h° (Δh° ≈ 6) parameters. VI reduced the lightness of apples (ΔL^* ≈ ?3) but the addition of lemon juice counterbalanced the lightness reduction by increasing ΔL^* from 3 to 1.5 ca. Pretreatments did not affect the firmness of organic fruits while impaired that of the conventional ones ( 26% on average), likely due to different fruit matrix porosity and cell wall composition. Freezing (?40 °C) and frozen storage (up to 300 days) dramatically reduced the firmness of organic (42%) and conventional products (58%). At equal pretreatment and storage time (that is, 15, 30, 300 days), higher firmness retention was evidenced in organic apples than in conventional ones. All through frozen storage, VI was shown to better preserve the mechanical properties of organic apples than that of conventional ones. Both freezing and frozen storage reduced the hue of frozen apple products by up to 8% due to browning reactions. Lemon juice addition increased the hue of both frozen samples and thawed samples by about 2% all through storage time.     

Biofunctional Silk/Neuron Interfaces

Silk fibroin (SF) is a biocompatible and slowly biodegradable material with excellent mechanical properties and huge potential for use as biofunctional interface in electronic devices that aim to stimulate and control neural network activity and peripheral nerve repair. It is shown that SF films act as material interfaces that support the adherence and neurite outgrowth of dorsal root ganglion (DRG) neurons and preserve neuronal functions. Silk films preserve the capability of neuronal cells to fire and DRG neurons on silk films retain the intracellular free Ca²⁺ concentration ([Ca²⁺]_i) response to capsaicin, a typical noxious stimulus for this neuronal culture model. It is also demonstrated that nerve growth factor (NGF)‐functionalized silk films promote neurite outgrowth and modulate functional properties of DRG neurons. The results show that silk preserves DRG neuronal physiology and is a promising biomaterial platform for the future development of devices with goals including functional recovery of injured neurons, neurite functional outgrowth in vitro, or functional electrostimulation in vivo.     

Thermal analysis of the Dehydration process of cross-linked Polyvinylpyrrolidone and its mixtures with Naproxen

Ways of finding kinetic parameters useful for pharmaceutical formulators from thermal analytical methods (TGA, DSC) under both isothermal and non-isothermal conditions are suggested. We considered as an example those followed to determine the first-order kinetics of dehydration of cross-linked polyvinylpyrrolidone (PVP XL). PVP XL samples differing in particle size (granulometric fractions in the 250 μm to 63 μm range) and/or equilibrium moisture content (12 to 32 gH₂o/100 g) show activation energy values in the 43 to 54 kJ mol^-1 (non-isothermal TGA) and 48 to 61 kJ mol^-1 (non-isothermal DSC) ranges. The weight fraction of water present may influence the activation energy of the dehydration process whilst the particle size of PVP XL seems not to affect this parameter. The low interaction energy between PVP XL and water suggests that the interaction mainly occurs within the porous agglomerates of the polymer particles, at the intraparticulate surface level (surface-type interaction). The influence of an admixed drug (naproxen) on the thermodynamic and kinetic parameters of PVP XL dehydration suggests that analogous surface phenomena are probably involved in the solid-state interaction between the amorphous polymer and the crystalline drug.     

Practical variable selection for generalized additive models

The problem of variable selection within the class of generalized additive models, when there are many covariates to choose from but the number of predictors is still somewhat smaller than the number of observations, is considered. Two very simple but effective shrinkage methods and an extension of the nonnegative garrote estimator are introduced. The proposals avoid having to use nonparametric testing methods for which there is no general reliable distributional theory. Moreover, component selection is carried out in one single step as opposed to many selection procedures which involve an exhaustive search of all possible models. The empirical performance of the proposed methods is compared to that of some available techniques via an extensive simulation study. The results show under which conditions one method can be preferred over another, hence providing applied researchers with some practical guidelines. The procedures are also illustrated analysing data on plasma beta-carotene levels from a cross-sectional study conducted in the United States.     

Analysis of diffraction from the occulter edges of a giant externally occulted solar coronagraph

A technique is described for the calculation of the intensity of the light diffracted by the occulter of an externally occulted solar coronagraph. This technique can be applied to an occulter of generic shape, but the attention is here focused on a specific application; that is, the case of a giant space solar coronagraph, in which the occulter is located at 100 m from the telescope aperture. By means of the code developed, it has been possible to simulate the effects of various shapes of the occulter edge with the aim of analyzing in detail the best apodization for the coronagraph. The results obtained show that an occulter with a circular serrated edge allows a remarkable reduction of the amount of diffracted light on the coronagraph's entrance aperture with respect to a simpler circular disk case.     

Public–private contribution to biopharmaceutical discoveries: a bibliometric analysis of biomedical research in UK

Scientometrics - Basic research creates new knowledge that fuels technological advances. However, budgetary concerns and escalating R&D prices are challenging organizations to show returns...     

Volatility spillovers, interdependence and comovements: A Markov Switching approach

The transmission mechanisms of volatility between markets can be characterized within a new Markov Switching bivariate model where the state of one variable feeds into the transition probability of the state of the other. A number of model restrictions and hypotheses can be tested to stress the role of one market relative to another (spillover, interdependence, comovement, independence, Granger noncausality). The model is estimated on the weekly high-low range of five Asian markets, assuming a central (but not necessarily dominant) role for Hong Kong. The results show plausible market characterizations over the long run with a spillover from Hong Kong to Korea and Thailand, interdependence with Malaysia and comovement with Singapore.     

Surface characterization of Ba-β-alumina

The surface properties of a Ba-β-alumina sample (Ba ∶ Al ratio 1∶ 12) very stable to sintering (15 m²/g after calcination at 1670 K for 10 h) have been investigated by FT-IR spectroscopy of adsorbed probe molecules (water, pyridine and CO₂) and by measuring the isoelectric point. The surface has a medium-strong basic character, justified by the preferential exposition of Ba-O-containing “mirror planes”, parallel to 0001 planes, on the surface of plate-like particles. This behavior has been associated to the resistance to sintering, typical of this material, possibly originated by the difficulty of the very big Ba²⁺ ions to migrate into the spinel-type alumina blocks. This should imply the blocking of the crystal growth along the crystallographicc axis.     

Ecuadorian stingless bee (Meliponinae) honey: A chemical and functional profile of an ancient health product

Stingless bee honey samples from west Amazonian Ecuador were studied for their physiochemical, chemical and functional properties. Reducing sugars (44.9 ± 5.72 g/100 g), water (34.1 ± 4.34 g/100 g), free acidity (31.8 ± 4.05 meq/100 g), diastase activity (1.60 ± 0.20 u.d./g), hydroxymethylfurfural (15.0 ± 1.91 mg/kg), electrical conductivity (0.48 ± 0.06 mS/cm), ash (0.28 ± 0.04 g/100 g), colour (150 mm Pfund) were determined as physicochemical parameters. Melissopalynological analyses were processed evidencing pollen belonging to 14 plant families. Glucose (25.5 ± 3.41 g/100 g), fructose (25.2 ± 3.37 g/100 g) and sucrose (3.72 ± 0.49 g/100 g) contents were determined by HPLC, evidencing equal concentrations between fructose and glucose. Coumarins and flavonoids were determined by densitometric HPTLC: fraxin and bergamotin (0.065 ± 0.009; 0.035 ± 0.005 μg/g) among coumarins; luteolin (0.045 ± 0.006 μg/g), quercitrin (0.020 ± 0.003 μg/g), isoramnetin (0.015 ± 0.002 μg/g) among flavonoids. Among the vitamin E isomers, evaluated by HPLC, the occurrence of the only β-tocopherol (1.12 ± 0.15 μg/g) was noted. All these results were compared with those acquired for two multifloral Apis mellifera honeys. DPPH and β-carotene bleaching tests were performed, showing interesting values for Ecuadorian honey samples, higher than those shown by multifloral A. mellifera honeys (88.1 ± 11.1 DPPH inhibition%; 70.8 ± 8.90 β-carotene inhibition%). Antibacterial activity, against both Gram positive and Gram negative bacteria, revealed MIC values (10–50 μg/ml) always lower than those of A. mellifera honeys. Ecuadorian Meliponinae honey samples also showed anti-mutagenic activity assayed with Saccharomyces cerevisiae D7 strain, inhibiting back mutation over the entire range of concentrations.