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Raposo F.,Campus Universitario Pablo Of Olavide
TrAC - Trends in Analytical Chemistry | Year: 2016

The analytical calibration of an instrumental method is very important, being considered as a key point in method validation. There are different validation guidelines; showing that analytical calibration process variety prevails in terms of nomenclature, methodology employed and acceptance criteria. Very common mistakes in the analytical calibration process are the use of correlation and/or determination coefficients as a test for linearity, the negligence in the heteroscedasticity of the experimental data and selection of appropriate weighting factor, misunderstanding about the regression through the origin and using zero-point calibration. Once the calibration function is established, their linearity can be confirmed by using different procedures such as graphical plots, statistical significance tests and numerical parameters. In particular, deviation from back-calculated concentrations expressed in the form of percentage of relative error (%RE) can be considered very useful for unambiguous linearity evaluation. Some case studies were included to explain the linearity assessment from a practical viewpoint. © 2015 Elsevier B.V. Source

Vergara-Dominguez H.,Pablo De Olavide University | Rios J.J.,Campus Universitario Pablo Of Olavide | Gandul-Rojas B.,Pablo De Olavide University | Roca M.,Pablo De Olavide University
Food Chemistry | Year: 2016

The central reaction of chlorophyll (chl) breakdown pathway occurring during olive fruits maturation is the cleavage of the macrocycle pheophorbide a to a primary fluorescent chl catabolite (pFCC) and it is catalyzed by two enzymes: pheophorbide a oxygenase (PaO) and red chl catabolite reductase (RCCR). In subsequent steps, pFCC is converted to different fluorescent chlorophyll catabolites (FCCs) and nonfluorescent chlorophyll catabolites (NCCs). This work demonstrated that RCCR activity of olive fruits is type II. During the study of evolution of PaO and RCCR activities through the olive fruits maturation in two varieties: Hojiblanca and Arbequina, a significant increase in PaO and RCCR activity was found in ripening stage. In addition, the profile and structure of NCCs present in epicarp of this fruit was studied using HPLC/ESI-TOF-MS. Five different NCCs were defined and for the first time the enzymatic reactions implied in chlorophyll degradations in olive fruits elucidated. © 2016 Elsevier Ltd. All rights reserved. Source

Lourenco A.B.,Pablo De Olavide University | Munoz-Jimenez C.,Pablo De Olavide University | Venegas-Caleron M.,Campus Universitario Pablo Of Olavide | Artal-Sanz M.,Pablo De Olavide University
Biochimica et Biophysica Acta - Bioenergetics | Year: 2015

The mitochondrial prohibitin complex, composed of two proteins, PHB-1 and PHB-2, is a context-dependent modulator of longevity. Specifically, prohibitin deficiency shortens the lifespan of otherwise wild type worms, while it dramatically extends the lifespan under compromised metabolic conditions. This extremely intriguingly phenotype has been linked to alterations in mitochondrial function and in fat metabolism. However, the true function of the mitochondrial prohibitin complex remains elusive. Here, we used gas chromatography coupled to a flame ionization detector (GC/FID) and 1H NMR spectroscopy to gain molecular insights into the effect of prohibitin depletion on the Caenorhabditis elegans metabolome. We analysed the effect of prohibitin deficiency in two different developmental stages and under two different conditions, which result in opposing longevity phenotypes, namely wild type worms and daf-2(e1370) insulin signalling deficient mutants. Prohibitin depletion was shown to alter the fatty acid (GC/FID) and 1H NMR metabolic profiles of wild type animals both at the fourth larval stage of development (L4) and at the young adult (YA) stage, while being more pronounced at the later stage. Furthermore, wild type and the diapause mutant daf-2(e1370), either expressing or not prohibitin, were clearly distinguishable based on their metabolic profiles, revealing changes in fatty acid composition, as well as in carbohydrate and amino acid metabolism. Moreover, the metabolic data indicate that daf-2(e1370) mutants are more robust than the wild type animals to changes induced by prohibitin depletion. The impact of prohibitin depletion on the C. elegans metabolome will be discussed herein in the scope of its effect on longevity. This article is part of a Special Issue entitled: Mitochondrial Dysfunction in Aging. Guest Editor: Aleksandra Trifunovic © 2015 The Authors. Published by Elsevier B.V. Source

Lucena-Padros H.,Campus Universitario Pablo Of Olavide | Ruiz-Barba J.L.,Campus Universitario Pablo Of Olavide
Food Microbiology | Year: 2016

The presence and enumeration of halophilic and alkaliphilic bacteria in Spanish-style table-olive fermentations was studied. Twenty 10-tonne fermenters at two large manufacturing companies in Spain, previously studied through both culture dependent and independent (PCR-DGGE) methodologies, were selected. Virtually all this microbiota was isolated during the initial fermentation stage. A total of 203 isolates were obtained and identified based on 16S rRNA gene sequences. They belonged to 13 bacterial species, included in 11 genera. It was noticeable the abundance of halophilic and alkaliphilic lactic acid bacteria (HALAB). These HALAB belonged to the three genera of this group: Alkalibacterium, Marinilactibacillus and Halolactibacillus. Ten bacterial species were isolated for the first time from table olive fermentations, including the genera Amphibacillus, Natronobacillus, Catenococcus and Streptohalobacillus. The isolates were genotyped through RAPD and clustered in a dendrogram where 65 distinct strains were identified. Biodiversity indexes found statistically significant differences between both patios regarding genotype richness, diversity and dominance. However, Jaccard similarity index suggested that the halophilic/alkaliphilic microbiota in both patios was more similar than the overall microbiota at the initial fermentation stage. Thus, up to 7 genotypes of 6 different species were shared, suggesting adaptation of some strains to this fermentation stage. Morisita-Horn similarity index indicated a high level of codominance of the same species in both patios. Halophilic and alkaliphilic bacteria, especially HALAB, appeared to be part of the characteristic microbiota at the initial stage of this table-olive fermentation, and they could contribute to the conditioning of the fermenting brines in readiness for growth of common lactic acid bacteria. © 2015 Elsevier Ltd. Source

Romero-Gil V.,Campus Universitario Pablo Of Olavide | Rejano-Zapata L.,AgroSevilla SCA | Garrido-Fernandez A.,Campus Universitario Pablo Of Olavide | Arroyo-Lopez F.N.,Campus Universitario Pablo Of Olavide
Food Microbiology | Year: 2016

This study uses a mathematical approach to assessing the inhibitory effect of Zn2 +(0-10 mM, obtained from ZnCl2 and ZnSO4) in presence of NaCl (0-8%) and hydroxytyrosol (0-2588 mg/L), on a yeast cocktail formed by species Pichia galeiformis, Pichia kudriavzevii, Pichia manshurica and Candida thaimueangensis obtained from spoilt green olive packages. The logistic/probabilistic models were built in laboratory medium using a total of 1980 responses (1188 for NaCl and 792 for hydroxytyrosol). ZnCl2 showed significantly higher inhibitory effect than ZnSO4 in the presence of both NaCl (p < 0.033) and hydroxytyrosol (p < 0.009). NaCl did not interfere the effect of Zn2 +while hydroxytyrosol, at high levels, had a slight antagonistic effect. According to models, Zn2 +inhibits (p = 0.01) the yeast cocktail in the range 4.5-5.0 mM for ZnCl2, or 8.5-9.5 mM for ZnSO4. Therefore, this work confirms the fungicidal activity of zinc compounds (mainly ZnCl2) in synthetic medium, and also shows that the loss of zinc effectiveness in real green Spanish-style olive packaging is not due to the presence of NaCl or hydroxytyrosol, two of the most abundant chemical compounds in the product. © 2016 Elsevier Ltd. Source

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