Enrichment of gamma‐linolenic acid from fungal oil by lipases

Abstract

Two microbial lipases from Geotrichum spp and Rhizopus spp isolated previously in this laboratory and a commercial lipase from Candida cylindracea were evaluated as biocatalysts for the enrichment of gamma‐linolenic acid (GLA, 18:3 n‐6) from a fungal oil derived from Mucor spp. Lipase from Geotrichum spp, as compared to lipases from Candida cylindracea and Rhizopus spp was found to be most effective in the enrichment of GLA in unesterified fatty acids upon esterification of the fungal oil fatty acids with n‐butanol. The level of GLA in the unesterified fatty acid could be raised from 10.9 % in the starting material to about 30 % in the unesterified fatty acids after a reaction period of 4 h. Selective hydrolysis of the fungal oil using lipase from Rhizopus spp resulted in about 1.5‐fold enrichment of gamma‐linolenic acid in the unhydrolysed acylglycerols. The other Upases tested were ineffective in the enrichment of GLA by selective hydrolysis of the fungal oil triacylglycerols.     

Chemical characterisation of Nephrops norvegicus from Portuguese coast

BACKGROUND: Among seafood products, crustaceans are an important group owing to their nutritional benefits and high market value. The aim of this study was to evaluate the proximate composition as well as essential and non‐essential elements in the edible muscle of Nephrops norvegicus (Norway lobster). RESULTS: The studied crustacean showed a high protein level of about 210 g kg^?1 and a mineral level of about 24 g kg^?1. The pattern for the elements studied was Cl > Na > K > P > S > Ca > Mg > Br > Fe > Sr ≈ Zn > Cu > Mn > Rb > Se > Ni > Cr. Regarding non‐essential elements, the average total Hg content was 0.40 mg kg^?1, but two samples exceeded the legal limit set by the European Union (EU) for Hg in crustaceans (0.50 mg kg^?1). The levels of Pb and Cd found in all samples were below the EU limits (0.50 mg kg^?1 for both metals). CONCLUSION: Nephrops norvegicus is a good source of protein and contains most minerals at levels sufficient to satisfy the dietary reference intake. The amounts of Pb and Cd are not a concern. Hg levels indicate some contamination; however, taking into account the type of consumption of this species, it can be concluded that this does not represent a risk in terms of the human diet. Copyright © 2009 Society of Chemical Industry     

Study of molybdenum electrodes for hydrogen evolution reaction

The molybdenum electrode, Mo, has been investigated for hydrogen production via water electrolysis in 10 vol.% aqueous solutions of 1-butyl-3-methylimidazolium tetrafluoroborate (BMI·BF₄) using electrochemical impedance spectroscopy (EIS). The EIS measurements show that the Mo system has much higher interfacial capacitance, and correspondently the electrical double layer formed on this electrode is thicker than those formed on nickel or platinum. The positive displacement of potential of zero charge (PZC) values indicates the specific adsorption of the imidazolium cation on the Mo surface. This study provides an elegant explanation for the better performance of Mo electrodes in the hydrogen evolution reaction (HER): the BMI cation acts as an intermediate for the proton transfer from water to the electrode surface, thereby decreasing the overpotential of HER. This model explains the synergism between Mo and the BMI cation in the HER process.     

Comparing machine learning classifiers in potential distribution modelling

Species’ potential distribution modelling consists of building a representation of the fundamental ecological requirements of a species from biotic and abiotic conditions where the species is known to occur. Such models can be valuable tools to understand the biogeography of species and to support the prediction of its presence/absence considering a particular environment scenario. This paper investigates the use of different supervised machine learning techniques to model the potential distribution of 35 plant species from Latin America. Each technique was able to extract a different representation of the relations between the environmental conditions and the distribution profile of the species. The experimental results highlight the good performance of random trees classifiers, indicating this particular technique as a promising candidate for modelling species’ potential distribution.     

Fast assessment of diene values in pyrolysis gasoline by UV-visible spectroscopy and multivariate calibration

Conjugated dienes in pyrolysis gasoline samples were assayed by spectrophotometry. The calibrations were carried out by partial least squares regression using spectrophotometric data and the reference method UOP-326. The maximum deviation observed for an independent set of samples was 12% compared with the reference method. Spectral data preprocessing and weighting were investigated for the modeling. Values of root mean square error of calibration and prediction, and normalized root mean squared error were used as criteria to define the best calibration condition. 26 non-hydrogenated and 21 hydrogenated pyrolysis gasoline samples were used to model the spectral data by PLS regression.     

UV–Vis spectrometric classification of coffees by SPA–LDA

UV–Vis spectrometry and chemometric techniques were used to classify aqueous extracts of Brazilian ground roast coffee with respect to type (caffeinated/decaffeinated) and conservation state (expired and non-expired shelf-life). Two classification methods were compared: soft independent modelling of class analogy (SIMCA) and linear discriminant analysis (LDA) with wavelength selection by the successive projections algorithm (SPA). The best results were obtained by SPA–LDA, which correctly classified all test samples. The classification accuracy of this model remained high (96%) even after the introduction of artificial spectral noise. These results suggest that UV–Vis spectrometry and SPA–LDA modelling provide a promising alternative for assessment of conservation state and decaffeination condition of coffee samples.     

Electrocardiographic signal compression using multiscale recurrent patterns

In this paper, we use the multidimensional multiscale parser (MMP) algorithm, a recently developed universal lossy compression method, to compress data from electrocardiogram (ECG) signals. The MMP is based on approximate multiscale pattern matching , encoding segments of an input signal using expanded and contracted versions of patterns stored in a dictionary. The dictionary is updated using concatenated and displaced versions of previously encoded segments, therefore MMP builds its own dictionary while the input data is being encoded. The MMP can be easily adapted to compress signals of any number of dimensions, and has been successfully applied to compress two-dimensional (2-D) image data. The quasi-periodic nature of ECG signals makes them suitable for compression using recurrent patterns, like MMP does. However, in order for MMP to be able to efficiently compress ECG signals, several adaptations had to be performed, such as the use of a continuity criterion among segments and the adoption of a prune-join strategy for segmentation. The rate-distortion performance achieved was very good. We show simulation results were MMP performs as well as some of the best encoders in the literature, although at the expense of a high computational complexity.     

Physicochemical,technological and sensory characteristics of a rice (Oryza sativa L.) and bean (Phaseolus vulgaris L.) soup prepared by extrusion

The aim of this work was to prepare and evaluate an instant soup formulated with broken rice and beans processed by thermoplastic extrusion using a pilot‐scale, single‐screw extruder. The final product was characterised regarding its physicochemical composition, amino acid profile, functional–technological properties and sensory performance. The extrusion parameters were set using three extrusion zone temperatures (30, 40 and 70 °C), a screw speed of 177 rpm, feed rate of 260 g min^?1. and circular matrix of 3.85 mm. The final product contained considerable levels of protein (12.91 g per 100 g) and dietary fibre (8.07 g per 100 g). Amino acid profile analysis showed that only sulphur‐containing amino acids and tryptophan were limiting with the remaining present in adequate concentrations to meet children's requirements. Regarding functional and technological properties, the instant soup powder showed appropriate water solubility and water absorption indexes as expected. The soup sensory analysis indicated good acceptability, with a purchase intent index of 71%.     

A modal multidimensional kinetics method using pseudo-harmonics

This work proposes to use the pseudo-harmonics technique as a modal method in spatial kinetics. The pseudo-harmonics are the eigenfunctions associated with the leakage + removal operators in the multigroup steady-state diffusion equation. In this work, the pseudo-harmonics are obtained from the diffusion equation discretized with the Coarse Mesh Finite Difference Method (CMFD) coupled to the Nodal Expansion Method (NEM).     

Typological classification of clayey raw materials for ceramics manufacture, in the Tábua region (central Portugal)

Mapping of clay resources in the Cenozoic deposits of the Tábua region (central Portugal) has been carried out, together with the chemical, mineralogical and technological characterization of seventeen clay samples. The study was undertaken to relate the lithostratigraphic units and the typology of raw materials with regard to the manufacture of ceramics. The sedimentary succession comprises two units with different suitability for the manufacture of ceramics: an upper unit, with clays that present technological restrictions; and a lower unit with a much greater potential. A small set of parameters has been identified which differentiate the typological units. These parameters allow a realistic estimation to be made of the ceramic properties of any clay layer sampled in the study area. It is anticipated that with minor field work and sampling, the typological column can also be used in adjacent areas.