Assessment of cell damage in high-pressure-shift frozen broccoli: comparison with market samples

Pressure-shift freezing (PSF) is one of the most promising methods for obtaining high-quality frozen products. The aim of this work was to analyse the differences between broccoli that was frozen using two different PSF processes. In one of the processes, all the freezing was done inside the high-pressure vessel tempered at −20.5 °C. In the other process, the sample was taken out of the vessel after expansion, and freezing was completed using liquid N₂. Colour, texture, electrical conductivity, microstructure and drip losses after centrifugation were analysed and a sensory test was performed. The results were compared with those for conventionally frozen broccoli purchased at the market. PSF broccoli presented less cell damage, lower drip losses and better texture than the market samples. The two different PSF processes assayed produced no significant differences in the final quality of the samples.     

Production of lactic acid from vine‐trimming wastes and viticulture lees using a simultaneous saccharification fermentation method

An effective process for the chemical–biotechnological utilization of trimming wastes of vineshoots, an agricultural waste with little use, is reported. Initial treatment with sulfuric acid (prehydrolysis) allowed the solubilization of hemicelluloses to give xylose and glucose‐containing liquors (suitable to make fermentation media for lactic acid production with Lactobacillus pentosus) and a solid phase containing cellulose and lignin. The solid residues from prehydrolysis were treated with NaOH in order to increase their cellulase digestibility. In the alkaline treatments, the effects of temperature (in the range, 50–130 °C), reaction time (30–120 min) and NaOH concentration (4–12 wt% of solution) on the composition and susceptibility to enzymatic hydrolysis of solid residues were assessed by means of an experimental plan with factorial structure. The lignin content decreased, whereas the susceptibility towards the enzymatic hydrolysis increased with temperature, reaction time and NaOH concentration within the tested range. Using the cellulosic residues achieved under the harsher conditions, favorable fermentation kinetics during simultaneous saccharification and fermentation carried out by L rhamnosus for lactic acid production were observed. The nutrients employed were the complete MRS broth and a cheaper medium developed using viticulture lees coming from the white wine making technology. In all cases the final lactic acid concentration achieved was similar, although the volumetric productivity was lower when using lees due to inhibitory effects over the enzymatic hydrolysis. Copyright © 2004 Society of Chemical Industry     

Review of the environmental policy instruments in the standardization of H2 for the decarbonization of Mexico

The objective of this work is to review the environmental and ecological policy instruments that Mexican legislation for existence of an Official Mexican Hydrogen Standard according to the premises motivates decarbonization. There is a worldwide interest in hydrogen (H₂) and its incorporation into legal systems. In Mexico there are large legal gaps that question the legality of H₂, because it is not recognized in a federal law and is only considered in technical standards of voluntary application. Also, Mexico has forest, agricultural, and livestock waste that, if properly used, can cover the energy demand of communities. The main findings of this study refer to the fact that, according to international standards for the management of H₂ and taking into account the regulatory limitations in Mexico, it is possible to promote, an Official Mexican Standard exclusively aimed at establishing the minimum requirements for the design, construction, operation and maintenance of H₂ storage, considering the areas of the opportunity offered by foreign experiences, according to the Mexican context. It is concluded that the parameters of legality exist in the instruments of environmental policy, to support the existence of an Official Mexican Standard of H₂.     

Influence of the gasket materials on the clamping pressure distribution in a PEM water electrolyzer: Bolt torques and operation mode in pre-conditioning

To keep optimally connected, all electrolysis cell elements is one of the most important design criteria. The optimal distribution of the clamping points is crucial to increasing cell performance. In this work, the compression pressure distribution inside of a 25 cm² PEM electrolysis cell was evaluated, using different materials: Teflon®, Viton®, ethylene propylene diene monomer rubber (EPDM), and nitrile rubber. Sealing material evaluation was performed taking as performance indicators: total compressed area (%) and compression pressure, for different torques applied. Pressure distribution was obtained by using pressure-sensitive films, analyzing the distribution of pressure points from three-dimensional plots (3D), and quantifying intensities of the images obtained. Results showed that pressure points distribution depends on the stiffness and thickness of the gasket materials. For a tightening torque of 3.70 N m, a pressure of 2.23 MPa is obtained with 85% of the membrane area compressed using nitrile rubber-EPDM gaskets.     

Non-digestible fraction of cooked bean (Phaseolus vulgaris L.) cultivar Bayo Madero suppresses colonic aberrant crypt foci in azoxymethane-induced rats

The non-digestible fraction (NDF) of common bean (Phaseolus vulgaris L.) cultivar Bayo Madero was evaluated for its chemopreventive effect on azoxymethane (AOM) induced aberrant crypt foci (ACF) in rats. Diets containing cooked beans (CB) or its non-digestible fraction (NDF) were fed to 72 male rats after 2 azoxymethane injections (15 mg kg(-1) of body weight once a week for 2 weeks). ACF number, short chain fatty acids (SCFA) and β-glucuronidase activity were measured in colon sections from rats sacrificed 7 weeks after the last AOM injection. Food intake and weight gain of rats were unaffected by CB and NDF. CB and NDF suppressed the AOM-induced formation of ACF (0.8 and 1.5 ACF/distal zone, respectively vs. 6.6 ACF/distal zone based on methylene blue stain) and lowered β-glucuronidase activity in cecal, colonic and fecal content compared to AOM group. SCFA production was not significantly different among fecal, cecal and colonic content. These results indicate that CB and NDF from Bayo Madero provide direct chemoprotection against early stage of azoxymethane (AOM)-induced colon cancer in rats.     

Genome-wide effect of tetracycline,doxycycline and 4-epidoxycycline on gene expression in Saccharomyces cerevisiae

Tetracycline (Tet) and derivative chemicals (e.g., doxycycline or Dox) have gained widespread recognition for their antibiotic properties since their introduction in the late 1970s, but recent work with these chemicals in the lab has shifted to include multiple techniques in all genetic model systems for the precise control of gene expression. The most widely used Tet-modulated methodology is the Tet-On/Tet-Off gene expression system. Tet is generally considered to have effects specific to bacteria; therefore, it should have few off-target effects when used in eukaryotic systems, and a previous study in the yeast Saccharomyces cerevisiae found that Dox had no effect on genome-wide gene expression as measured by microarray. In contrast, another study found that the use of Dox in common cell lines and several model organisms led to mitonuclear protein imbalance, suggesting an inhibitory role of Dox in eukaryotic mitochondria. Recently, a new Dox derivative, 4-epidoxycycline (4-ED) was developed that was shown to have less off-target consequences on mitochondrial health. To determine the best tetracycline family chemical to use for gene expression control in S. cerevisiae, we performed RNA sequencing (RNA-seq) on yeast grown on standard medium compared with growth on media supplemented with Tet, Dox or 4-ED. We found each caused dozens of genes to change expression, with Dox eliciting the greatest expression responses, suggesting that the specific tetracycline used in experiments should be tailored to the specific gene(s) of interest when using the Tet-On/Tet-Off system to reduce the consequences of confounding off-target responses.     

Phenolic composition of Tempranillo wines following early defoliation of the vines

BACKGROUND: Early defoliation is a viticultural practice aimed at crop control. So far, the impact of early leaf removal on the monomeric phenolic composition of wines has not been explored. This study examines the effects of early defoliation on the phenolic profile and content in Tempranillo wines. The influence of the defoliation method (manual vs mechanical) and the timing of leaf removal (pre‐bloom vs fruit set) was investigated. RESULTS: Over two consecutive seasons, 2007 and 2008, the monomeric phenolic composition in Tempranillo wines was studied by high‐performance liquid chromatography with photodiode array detection, and 22 compounds were identified and quantified. Overall, early defoliation led to wines more intensely coloured, of higher alcohol content and with larger concentrations of hydroxycinnamic acids, flavonols and anthocyanins (in 2008 only for mechanical treatments). In the absence of fungal infection, resveratrol was found to increase in wines corresponding to early defoliation treatments. The method of leaf removal seemed to be more critical than the timing of intervention, and larger effects on wine phenolic composition were observed for mechanical treatments. CONCLUSION: Early defoliation proved to be an effective technique for improving the phenolic composition of Tempranillo wines, by favouring the accumulation of hydroxycinnamics, flavonols and anthocyanins. This is an important achievement, as wine quality is often described by its colour and phenolic attributes. Copyright © 2011 Society of Chemical Industry