Effect of Saccharomyces and non-Saccharomyces native yeasts on beer aroma compounds.

Recently, the increase in microbreweries and the consequent production of craft beers have reached exponential growth. The interest in non-conventional yeasts for innovation and a unique selling feature in beer fermentation is increasing. This work studied the autochthonous Saccharomyces and non-Saccharomyces yeasts, isolated from various food sources, with the ability to modify and improve the fermentative and aromatic profiles during alcoholic fermentation. The ability to ferment maltose and produce desirable aroma compounds were considered as the key characters for the screening selection. A synthetic beer wort was developed for this purpose, to simulate beer wort composition. A total of forty-seven yeast strains belonging to different genera were analysed according to their fermentation profile, volatile compounds production and sensory analysis. Three native strains of Saccharomyces cerevisiae, Zygoascus meyerae and Pichia anomala were selected to evaluate their aromatic profile in single and mixed fermentations. The strains produced 4-vinylguaiacol, ß-phenylethyl alcohol, and isoamyl alcohol at levels significantly above the sensory threshold, making them interesting for wheat and blond craft beer styles. The native Hanseniaspora vineae was also included in a co-fermentation treatment, resulting in a promising yeast to produce fruity beers.

Assessment of in vitro dermal absorption of the kaurenic acid from Coespeletia moriziana extracts.

Espeletiinae are plants which grow above 3000 m of altitude in the Northern Andes and kaurenic acid was extracted from the leaves of Coespeletia moritziana. This compound has shown a wide range of biological activities, including cytotoxicity which is efficient in cancer therapy. The percutaneous penetration of this compound was measured in vitro using Franz cells. At appropriate intervals for up to 24h, diffusion samples were analyzed using HPLC. At the end of the test period, the amount of kaurenic acid was determined in each compartment and approximately 10% of kaurenic acid had been absorbed and was found in the skin layers.

Mechanisms underlying Andersen's syndrome pathology in skeletal muscle are revealed in human myotubes.

Andersen's syndrome is a rare disorder that has been defined with a triad: periodic paralysis, cardiac arrhythmia, and development anomalies. Muscle weakness has been reported in two-thirds of the patients. KCNJ2 remains the only gene linked to Andersen's syndrome; this gene encodes for the alpha-subunit of the strong inward-rectifier K+ channel Kir2.1. Several studies have shown that Andersen's syndrome mutations lead to a loss of function of the K+ channel activity in vitro. However, ex vivo studies on isolated patient muscle tissue have not been reported. We have performed muscle biopsies of controls and patients presenting with clinically and genetically defined Andersen's syndrome disorder. Myoblasts were cultured and characterized morphologically and functionally using the whole cell patch-clamp technique. No morphological difference was observed between Andersen's syndrome and control myoblasts at each passage of the cell culture. Cellular proliferation and viability were quantified in parallel with direct cell counts and showed no difference between control and Andersen's syndrome patients. Moreover, our data show no significant difference in myoblast fusion index among Andersen's syndrome and control patients. Current recordings carried out on myotubes revealed the absence of an inwardly rectifying Ba2+-sensitive current in affected patient cells. One consequence of the Ik1 current loss in Andersen's syndrome myotubes is a shift of the resting membrane potential toward depolarizing potentials. Our data describe for the first time the functional consequences of Andersen's syndrome mutations ex vivo and provide clues to the K+ channel pathophysiology in skeletal muscle.

Effects of spinosad and Bacillus thuringiensis israelensis on a natural population of Daphnia pulex in field microcosms.

Spinosad, a candidate biological larvicide for mosquito control, was evaluated for its effects on a field population of Daphnia pulex, using Bacillus thuringiensis serovar israelensis (Bti) as a reference larvicide. Microcosms (125L enclosures) were placed in a shallow temporary oligohaline marsh where D. pulex was present. Three concentrations of spinosad (8, 17 and 33 microg L(-1)) and two concentrations of Bti (0.16 and 0.50 microL L(-1)) were applied (5 replicates per concentration, including the controls). Effects of larvicides on D. pulex were evaluated after 2, 4, 7, 14 and 21d of exposure, through measurements of abundance and individual size. Dissipation of spinosad from the water phase was rapid. Four days after treatment, residue concentration represented 11.8%, 3.9% and 12.7% of the initial exposure level for the nominal concentrations of 8, 17 and 33 microg L(-1), respectively. Spinosyns A and D dissipated at similar rates. Analysis of abundance and size structure of the D. pulex population showed an impact of spinosad. Both survival and size structure were affected. However, at the lowest concentration (8 microg L(-1)), population recovered after the first week. In microcosms treated with Bti, the abundance of D. pulex was not affected but the size structure of the population changed after 21d. As compared to laboratory tests, the use of in situ microcosms improved the environmental risk assessment of larvicides, taking into account the influence of environmental factors (e.g., temperature, light, salinity) and intrinsic capacity of recovery of D. pulex under field conditions.

Novel variant of the P2X2 ATP receptor from the guinea pig organ of Corti.

ATP functions as a neurotransmitter and a neuromodulator in various tissues by acting on metabotropic (P2Y) and ionotropic (P2X) receptors. Evidence suggests that ATP activates P2X receptors on several cell types in the organ of Corti of guinea pig including outer hair cells (OHCs), Deiters' cells, Hensen's cells, pillar cells and inner hair cells (IHCs). Determining the sequence and structure of P2X receptors in guinea pig organ of Corti is important for understanding the function of ATP in the cochlea. We screened a guinea pig organ of Corti cDNA library for P2X2 ATP receptors using rat P2X2 cDNA as a probe. We sequenced three P2X2 variants which were found to be abundant in this library. One is a novel P2X2 isoform (P2X2-3) created by a retained intron coding for an additional 27 amino acids (81 bp) in the putative extracellular domain. We have also sequenced a variant (P2X2-2) that lacks both the 81-bp sequence and a 192-bp sequence in the 3' intracellular domain. A third variant (P2X2-1) contains the intracellular 192-bp sequence but not the extracellular 81-bp sequence found in P2X2-3. The multiple transcripts arise from alternative intron and exon splicing events. In situ hybridization with a probe common to the three variants localized P2X2 to many of the cells of the organ of Corti.

Food-contact epoxy resin: co-variation between migration and degree of cross-linking. Part II.

The study of epoxy resin composed of bisphenol A diglycidylether (BADGE), bisphenol F diglycidylether (BFDGE) (base), and primary aliphatic polyamines (hardener), has confirmed the interest of measuring certain physical parameters in order to evaluate the density of cross-linking of the network and thus predict the risks of resin molecules migrating into foodstuffs. This suggestion had been made in a preceding study on an epoxy resin composed of bisphenol A diglycidylether (BADGE) and primary aromatic polyamines. Samples with different densities of cross-linking, obtained by subjecting the resin to different curing temperatures (5, 20, 50 and 90 degrees C) for 7 days, were studied. The density of cross-linking increased with curing temperature, as indicated by the increase in glass transition temperature, the increased stability of the rubber storage modulus E'rub (increase in cross-link nodes), the fall in relaxation enthalpies (reduction in physical ageing) and the decreased amplitude of the loss-factor tan delta (reduction in chain mobility). Maximum cross-linking was obtained in the resin cured at 90 degrees C (temperature above Tg infinity). Concurrently, tests of migration into different liquid food simultants (distilled water, distilled water/ethanol/acetic acid, distilled water/ethanol) revealed a considerable reduction in specific migrations of BADGE and BFDGE, and of unidentified peaks.

Chromatographic analysis of water and wine samples for phenolic compounds released from food-contact epoxy resins.

Food-contact epoxy resins can release phenolic compounds such as phenol, m-cresol, bisphenol F, bisphenol A, 4-tert-butylphenol, bisphenol F diglycidyl ether (BFDGE), and bisphenol A diglycidyl ether (BADGE) into foodstuffs. A validated high-performance liquid chromatographic method with fluorometric detection is described for the simultaneous analysis of these compounds in wine and mineral water. Sample preparation by solid-liquid extraction enables detection limits of 2.5 micrograms/L in wine and 0.25 microgram/L in mineral water to be achieved. Recovery rates are close to 100%, except for BFDGE and BADGE (around 60% in wine and 75% in mineral water).

Food-contact epoxy resin: co-variation between migration and degree of cross-linking.

In order to predict the behaviour towards foodstuffs of an epoxy resin composed of bisphenol A diglycidyl ether (BADGE), 4,4'-methylenedianiline (MDA) and additives (plasticizers: dibutylphthalate (DBP), dioctylphthalate (DOP); accelerator: salicylic acid; inorganic fillers), a co-variation was established between the parameters evaluating the degree of cross-linking of the three-dimensional network and the migration of constituent molecules into various food simulants (distilled water, distilled water/ethanol/acetic acid, distilled water/ethanol). Varied degrees of cross-linking were obtained by subjecting the resin to different curing temperatures: respectively, 5 degrees C, 20 degrees C, 50 degrees C and 90 degrees C for 7 days. Irrespective of the food stimulant tested, specific migrations (DBP, DOP, salicylic acid, primary aromatic amines) diminished greatly as the curing temperature increased. At the same time, the degree of cross-linking increased with curing temperature, as indicated by the increase in glass transition temperature, the decrease in residual reaction exotherms and increased stability of the rubber storage modulus E'rub (increase in cross-link nodes), the fall in relaxation enthalpies (reduction in physical ageing) and the decreased amplitude of the loss-factor, tan delta (reduction in chain mobility). Maximum cross-linking was obtained in the resin cured at 90 degrees C (temperature above Tg infinity). In contrast to the degree of cross-linking, evaporation contributed little to the reduction of migration due to the elevation of curing temperature.

[Determination of residual monomers of epoxy resins in wine simulants]. / Méthodes de dosage des monomères résiduels des résines époxydiques dans des simulants du vin.

Wine is widely stocked in epoxy resin vats. These bisphenol A epoxy resins are cured with methylenedianiline hardener. The residual monomers are able to migrate through the polymer matrix into the wine. So, migration studies were undertaken in order to prevent human health hazard. In this paper specific chromatographic methods for the determination of the residual monomers in simulants of wine are described. Liquid chromatographic methods were developed for the determination of methylenedianiline and bisphenol A, and a gas chromatographic method for the determination of epichlorhydrin. The procedures described proved to be sensitive, reproducible and efficient.