Entity

Time filter

Source Type


Peralta Pelaez L.A.,Technological Institute of Veracruz | Moreno-Casasola P.,Institute of Ecology AC | Lopez Rosas H.,National Autonomous University of Mexico
Marine and Freshwater Research | Year: 2014

Coastal dunes include several habitats, including dune lakes. These habitats are valuable environmental assets. We analysed the impact of the surrounding land use on plant species composition, vegetation structure and water quality of 15 dune lakes in the coast of Veracruz in the Gulf of Mexico. The physical and chemical characteristics were determined for water during both the dry and rainy seasons, and vegetation was sampled once. Ammonium, nitrate, orthophosphate and total phosphorus varied between seasons and among lakes. Multivariate analysis revealed a gradient from lakes in a good state (water and wetland vegetation) to degraded lakes. These lakes fall into two groups: the first one has five lakes with a higher nutrient content, and surrounded by land where livestock is pastured and sugarcane is grown. The vegetation of these lakes consists of a combination of aquatic plants and flood-tolerant grasses introduced to feed cattle (Cynodon dactylon, Pennisetum purpureum, Setaria geniculata). Oligotrophic and mildly eutrophic lakes are characterised by little human activity, and aquatic species predominate (Cabomba palaeformis, Nymphaea ampla, Acrostichum aureum). Rural activities such as sugarcane cultivation and cattle rearing are likely the main factors causing changes in water enrichment and affecting the composition and structure of wetland vegetation. Management measures should be implemented to recover these areas and prevent further deterioration. © CSIRO 2014. Source


Brito-de la Fuente E.,Kabi Innovation Center | Torrestiana-Sanchez B.,Technological Institute of Veracruz | Martinez-Gonzalez E.,Kabi Innovation Center | Mainou-Sierra J.M.,Kabi Innovation Center
Chemical Engineering Research and Design | Year: 2010

The impact of high-frequency cross-flow back-pulsing on microsieves permeation performance during the microfiltration of whole milk is described in this work. Silicon nitride microsieves (0.8μm rectangular) combined with a dynamic permeate cross-flow back-pulsing technique to control fouling were used. Results showed that the transmembrane pressure (TMPpos) and the back-pulsing frequency were the process variables that most influenced microsieves performance. Permeation rates in the range of 5000 up to 27,000Lh-1m-2 which are one order of magnitude higher than those reported for skim milk microfiltration were obtained depending on the process conditions selected. It was concluded that higher permeation rates are obtained when the back-pulse pressure, i.e., the negative TMP is set equal to the positive TMP, both at 150mBar and the back-pulsing frequency at 15Hz. © 2009 The Institution of Chemical Engineers. Source


Ledesma-Escobar C.A.,University of Cordoba, Spain | Feliciano Priego-Capote,University of Cordoba, Spain | Feliciano Priego-Capote,Technological Institute of Veracruz | De Castro M.D.L.,University of Cordoba, Spain
PLoS ONE | Year: 2016

Background Flavonoids have shown to exert multiple beneficial effects on human health, being also appreciated by both food and pharmaceutical industries. Citrus fruits are a key source of flavonoids, thus promoting studies to obtain them. Characteristics of these studies are the discrepancies among sample pretreatments and among extraction methods, and also the scant number of comparative studies developed so far. Objective Evaluate the effect of both the sample pretreatment and the extraction method on the profile of flavonoids isolated from lemon. Results Extracts from fresh, lyophilized and air-dried samples obtained by shaking extraction (SE), ultrasound-Assisted extraction (USAE), microwave-Assisted extraction (MAE) and superheated liquid extraction (SHLE) were analyzed by LC-QTOF MS/MS, and 32 flavonoids were tentatively identified using MS/MS information. ANOVA applied to the data from fresh and dehydrated samples and from extraction by the different methods revealed that 26 and 32 flavonoids, respectively, were significant (p<0.01). The pairwise comparison (Tukey HSD; p<0.01) showed that lyophilized samples are more different from fresh samples than from air-dried samples; also, principal component analysis (PCA) showed a clear discrimination among sample pretreatment strategies and suggested that such differences are mainly created by the abundance of major flavonoids. On the other hand, pairwise comparison of extraction methods revealed that USAE and MAE provided quite similar extracts, being SHLE extracts different from the other two. In this case, PCA showed a clear discrimination among extraction methods, and their position in the scores plot suggests a lower abundance of flavonoids in the extracts from SHLE. In the two PCA the loadings plots revealed a trend to forming groups according to flavonoid aglycones. Conclusions The present study shows clear discrimination caused by both sample pretreatments and extraction methods. Under the studied conditions, liophilization provides extracts with higher amounts of flavonoids, and USAE is the best method for isolation of these compounds, followed by MAE and SE. On the contrary, the SHLE method was the less favorable to extract flavonoids from citrus owing to degradation. © 2016 Ledesma-Escobar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in anymedium, provided the original author and source are credited. Source


Ledesma-Escobar C.A.,University of Cordoba, Spain | Ledesma-Escobar C.A.,Technological Institute of Veracruz | Priego-Capote F.,University of Cordoba, Spain | Luque De Castro M.D.,University of Cordoba, Spain
Journal of Mass Spectrometry | Year: 2015

Eighty four metabolites (32 flavonoids, 15 amino acids, nine carboxylic acids, six coumarins, six sugars, five phenolic acids and 11 unclassified compounds) have been tentatively identified in a polar extract from lemon, without reference standards, based on their liquid chromatography-quadrupole-time-of-flight MS/MS spectra and the comparison with databases. Despite information in databases for some families of plant compounds is poor, tentative identification based on MS/MS information (mass of the precursor ion and their fragments, together with neutral mass loss) was possible with the help of known fragmentation patterns for the given families of compounds. Both positive and negative ionization modes and at least two collision energies were always applied to obtain as much information as possible from each molecular entity, thus helping for identification. As the tentatively identified metabolites are the same regardless of the organism they belong, their fragmentation patterns are useful for identification with independence of the sample nature. Copyright © 2015 John Wiley & Sons, Ltd. Source


Ledesma-Escobar C.A.,University of Cordoba, Spain | Ledesma-Escobar C.A.,Technological Institute of Veracruz | Priego-Capote F.,University of Cordoba, Spain | Luque De Castro M.D.,University of Cordoba, Spain
Talanta | Year: 2015

Abstarct A comparative study of methods for ultrasound-assisted extraction (USAE), microwave-assisted extraction (MAE) and superheated liquid extraction (SHLE) of compounds from citrus has been performed. The suited conditions for each method were evaluated to maximize the concentration of 10 representative compounds (sugars, carboxylic acids, phenolic acids and flavonoids) by a desirability function approach based on the chromatographic peaks obtained by LC-DAD. Extracts obtained under the suited conditions were analyzed by LC-QTOF MS/MS. The ANOVA on the molecular entities showed 232 significant entities (p<0.01), and pairwise comparison revealed that USAE and MAE methods are the most similar (50 different entities), and USAE and SHLE the most dissimilar (224 different entities). A discrimination test by PCA showed a clear discrimination among the extraction methods, explaining 78.51% of the total variability. Similarities in the abundance of the monitored compounds was tested by ANOVA showing that the extraction of carboxylic acids (malic and citric acids) was equal by all methods; while for each of the other eight compounds, at least one extraction method is different from the others. Under the evaluated conditions the SHLE method is the less favorable to extract metabolites from citrus, being the best the USAE method. © 2015 Elsevier B.V. Source

Discover hidden collaborations