Soy protein cold-set hydrogels as controlled delivery devices for nutraceutical compounds

The release of riboflavin from soy protein hydrogels of filamentous or particulate microstructure was investigated under gastric and intestinal conditions in the presence or absence of digestive proteases. Microscopic examination showed riboflavin arranged into crystals dispersed randomly throughout the gels. Rheological analysis revealed that the riboflavin load weakened the gel networks, which led to gel disintegration during hydro-swelling tests at pH 7.5. Dissolution tests showed that riboflavin release was faster at pH 7.5 than at pH 1.2 for both gels. Initial release was faster from particulate gels, due to their higher porosity and eroding granular texture. The release mechanisms involved in riboflavin release were diffusion and matrix degradation for both gels at pH 1.2 and pH 7.5. In the presence of pepsin at pH 1.2, both gel types provided good protection of riboflavin for at least 6 h, while both were digested in the presence of pancreatin at pH 7.5. These results suggest that both gels might be useful for transporting bioactive molecules through the gastrointestinal tract and delivering them in the small intestine. Considering their non-synthetic nature, they should be of great interest to developers of innovative functional foods.     

Quantification of the compactibility of several protein isolates: Relationship between isolate physical–chemical properties and compaction properties

Despite their growing interest in the conception of several nutraceutical delivery systems including tablets, no work seem to deal with the tabletability of proteins. In this study, seven commercial isolates have been selected (soy and whey proteins) and the influence of their primary properties (protein type, protein content, humidity, and ash content) and secondary properties (particle size, shape and tap density) on their compactibility and compressibility were studied. Whey proteins seemed to show a better tabletability than soy proteins. Isolate density and humidity strongly affected proteins compactibility: powders with high density showed very low compactibility and a decrease of isolate water content strongly lowered powder compactibility, suggesting that liquid bridges may increase protein-protein interactions during compaction. Laser diffraction measurements/ microscopic observations showed that isolate particles would have the same size/shape, consequently, these properties did not show any influence on protein tabletability. At last, surprisingly, no clear relationship between compactibility and compressibility has been showed.     

Sterol content in sunflower seeds (Helianthus annuus L.) as affected by genotypes and environmental conditions

Phytosterols play essential roles in many plant cell mechanisms. They are of industrial interest since, as part of the diet, they can reduce low density lipoprotein cholesterol. An increase in plant sterol contents, by improved crop varieties or crop management, could help to answer industrial demands and also to develop environmentally friendly extraction methods. The aim of this study was to evaluate genotypic variability of sterol content in cultivated sunflower and, in particular, effects of sowing date. Results showed large variability among a collection of sixteen sunflower inbred lines and hybrids. Total sterols varied almost twofold between extreme genotypes. A delay of sowing, giving higher temperatures during seed formation, induced a general increase in total sterol concentration by up to 35%, as well as variation in sterol composition according to genotype. These results are considered with an aim of improving sterol content by sunflower breeding programmes.     

Comparative oxidation and net emissions of methane and selected non-methane organic compounds in landfill cover soils

The surface emissions of methane (CH4) and non-methane organic compounds (NMOCs) were determined at two different areas at a French landfill: a permanently covered and fully vegetated area (40 cm coarse sand + 80 cm of loam) and a temporarily covered area (40 cm of coarse sand). The 37 NMOCs quantified in the landfill gas samples included alkanes (C1-C10), alkenes (C1-C4), halogenated hydrocarbons (including (H)CFCs), and aromatic hydrocarbons. Both positive and negative CH4 fluxes ranging from -0.01 to 0.008 g m(-2) d(-1) were measured from the permanently covered cell. However, high spatial variation was observed, and a hot spot with a high flux (10 g m(-2) d(-1)) was identified. A higher CH4 emission occurred from the temporarily covered cell (CH4 flux of 49.9 g m(-2) d(-1)) as compared to the permanently covered cell. The NMOC fluxes from the permanently covered zone were all very small with both positive and negative fluxes in the order of 10(-7) to 10(-5) g m(-2) d(-1). Higher and mainly positive NMOC fluxes in the order of 10(-5) to 10(-4) g m(-2) d(-1) were obtained from the temporarily covered zone. The lower emission from the permanently covered and fully vegetated cell was attributable to the thicker soil layer, which functions as microbial habitat for methanotrophic bacteria. The NMOC oxidation capacity was investigated in soil microcosms incubated with CH4. Maximal oxidation rates for the halogenated aliphatic compounds varied between 0.06 and 8.56 microg (g of soil)(-1) d(-1). Fully substituted hydrocarbons (tetrachloromethane, perchloroethylene, CFC-11, CFC-12, and CFC-113) were not degraded in the presence of CH4 and O2. Benzene and toluene were rapidly degraded, giving very high maximal oxidation rates (28 and 39 microg (g of soil)(-1) d(-1)). On the basis of the emission measurements and the batch experiments conducted, a general pattern was observed between emissions and biodegradability of various NMOCs. The emissions mainly consisted of compounds that were not degradable or slowly degradable, while an uptake of easily degradable compounds was registered. As an example, perchloroethylene, trichloromethane, CFC-11, and CFC-12 were emitted, while atmospheric consumption of aromatic hydrocarbons and lower chlorinated hydrocarbons such as vinyl chloride, dichloromethane, and chloromethane was observed. This study demonstrates that landfill soil covers show a significant potential for CH4 oxidation and co-oxidation of NMOCs. Under certain conditions, landfills may even function as sinks for CH4 and selected NMOCs, like aromatic hydrocarbons and lower chlorinated compounds.     

Tabletted soy protein cold-set hydrogels as carriers of nutraceutical substances

The swelling of soy protein filamentous hydrogels and tablets thereof and the release of riboflavin from these drug delivery devices were investigated under simulated gastrointestinal conditions in the presence or absence of digestive proteases. Microscopic examination showed riboflavin arranged into crystals dispersed randomly throughout the hydrogel and the tablet powder. Swelling experiments showed a comparable behavior of water uptake for hydrogel and tablet at pH 1.2 as well as tablet at pH 7.5, featuring a low swelling rate. Hydrogel at intestinal pH began to shrink after 1 h, which coincided with a loss its structure. Riboflavin release was faster at pH 7.5 than at pH 1.2 for both devices. Swelling was the principal mechanism of riboflavin release from tablets at pH 7.5, while drug-polymer interactions slowed this release at pH 1.2. In the presence of pepsin at pH 1.2, both devices showed slow zero-order release of riboflavin for 6 h, while both were digested completely in the presence of pancreatin at pH 7.5. These results suggest that these tabletted hydrogels and the hydrogels themselves might both be useful for transporting bioactive molecules through the gastrointestinal tract and delivering them in the small intestine. Considering their non-synthetic nature, they should be of great interest for the development of innovative functional foods.     

An investigation of hydrogen storage in a magnesium-based alloy processed by equal-channel angular pressing

Equal-Channel Angular Pressing (ECAP) can be successfully used to process Mg and Mg-based hydrides to produce bulk samples with enhanced hydrogen sorption properties. The primary advantages associated with ECAP processing are the shorter processing time, lower cost and the production of safer and more air-resistant bulk material by comparison with powders produced by high-energy ball milling. ECAP can produce special features for hydrogen absorption such as preferential textures, an increased density of defects and submicrometer grain sizes. In this research, ECAP was used to process a commercial AZ31 extruded alloy in order to evaluate its use as a hydrogen storage material. The ECAP was conducted under conditions of temperature and number of passes in order to avoid grain growth. Additional experiments were conducted on commercial coarse-grained magnesium to evaluate the effect of sample thickness on the sorption properties. The ECAP sample was evaluated in two different orientations and it is shown that better hydrogen properties are related to a refined microstructure allied to the (0001) texture.     

In vitro release of α-tocopherol from emulsion-loaded β-lactoglobulin gels

Cold-set oil-loaded protein gels based on an emulsifying step followed by Ca²⁺-induced gelation of pre-denatured β-lactoglobulin (β-LG) have been recently developed. In vitro release and stability of a fat-soluble compound (α-tocopherol) therein were investigated in this work. Release of α-tocopherol was found to be controlled mainly by matrix erosion due to protein degradation. Compound release and matrix erosion were almost complete after incubation under gastric or intestinal conditions for 6.5 h. However, both processes were basically inhibited upon changing the dissolution medium from the gastric to the intestinal type, possibly due to β-LG partial hydrolysis products with greater emulsifying capacity anchoring to the surface of gel oil droplets. The stability of released α-tocopherol was apparently improved by binding to protein and/or hydrolysis products thereof.     

Inhibitory tagging in inhibition of return is affected in schizophrenia: Evidence from the Stroop task.

L. J. Fuentes, A. B. Vivas, and G. W. Humphreys (see record 1999-10305-007) showed that stimulus processing is affected when stimuli are presented to locations subject to inhibition of return. They argued that activated representations of stimuli presented at inhibited locations are disconnected from their associated responses through an "inhibitory tagging" mechanism occurring in inhibition of return. In the present research, the authors asked whether such a mechanism is affected in people with schizophrenia. Healthy adults and patients with schizophrenia performed a Stroop task in an inhibition of return paradigm. Healthy adults showed a reduction in the Stroop interference when stimuli were presented at inhibited locations, a result that agrees with the inhibitory tagging mechanism hypothesis and replicates previous findings. However, patients with schizophrenia did not show such a reduction, a result suggesting that they have a deficit in inhibitory processing occurring in inhibition of return. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microcystin ecotypes in a perennial Planktothrix agardhii bloom

The dynamics and microcystins (MC) concentrations of a perennial Planktothrix agardhii bloom were investigated in a eutrophic lake (Viry-Chatillon, France). A weak relationship was observed between P. agardhii population biomass and the MC concentrations in a 1-year survey. To further investigate the causes of MC concentration changes, we concurrently conducted experiments on 41 strains isolated from this lake. We first checked the clonal diversity of P. agardhii population (i) by molecular techniques, to assess the presence of MC synthetase gene (mcyB), (ii) by biochemical assay (PP2A inhibition assay), for MC production, and (iii) by mass spectrometry (MS), to identify the MC chemotypes. Our results illustrated the diversity of genotype and MC chemotypes within a P. agardhii natural population. Eleven chemotypes among the 16 possible ones were found by MS. Furthermore, we noticed major differences in the MC content of isolated strains (from 0.02 to 1.86 microg equiv. MC-LR mg DW(-1), n=25). Growth and MC production of one MC-producing strain and one non-MC-producing strain were also assessed at two temperatures (10 and 20 degrees C). We showed that growth capacities of these strains were similar at the two tested temperatures, and that the MC production rate was correlated to the growth rate for the MC-producing strain. On the basis of these results, several hypotheses are discussed to explain the weakness of relationships between natural P. agardhii biomass and MC concentration. One of the main reasons could lie in the proportion of MC-producing clones and non-MC-producing clones that may change during the sampling period. Also, the MC-producing clones may present different intracellular MC content due to (i) MC chemotypes diversity, (ii) changes in MC variants proportions within a strain, and (iii) changes in MC rate production depending on the physiological state of cells. Finally, we concluded that various biological organization levels have to be considered (population, cellular and molecular), through an integrative approach, in order to provide a better understanding of P. agardhii in situ MC production.