Antioxidant and antimicrobial activity and potential of heather (Erica spp.) extracts in the control of Listeria monocytogenes

In this work, heather and its flowers were studied regarding their antioxidant and antimicrobial activities. Plants were subjected to ultrasound-assisted methanolic extraction followed by fractionation. A phytochemical characterisation of extracts content in total phenols and flavonoids, and their antioxidant activity was performed. The antimicrobial activity was evaluated through the determination of minimum inhibitory concentration and by bioautography. Following, studies on the antilisterial potential were carried out by: time-kill curves, inhibition of biofilm formation and tolerance of Listeria monocytogenes to adverse conditions. The results evidenced the antioxidant activity in both extracts, as well as, the antimicrobial activity against Gram-positive bacteria. Concerning the evaluation of the antilisterial potential, a bacteriostatic behaviour and inhibition of biofilms formation ability were observed. Listeria monocytogenes showed an increased susceptibility to adverse conditions when preincubated with extracts. Thus, heather and its flowers may be a source of new compounds with antilisterial activity potential.     

Electrochemical behavior of Ni?P?SiC composite coatings: Effect of heat treatment and SiC particle incorporation

This paper describes the effects of heat treatment and of SiC particle incorporation on the electrochemical behavior and physical structure of Ni? P (17 at% P) composite coatings. The deposits were obtained by electrodeposition with various contents of SiC particles in the plating bath and heat treated at 420 °C. The physical structure was investigated by inductively coupled plasma atomic emission spectrometry (ICP‐AES), X‐ray diffraction (XRD), and scanning electron microscopy (SEM – image analysis). The electrochemical behavior of the resultant composite coatings was determined by chronopotentiometry, electrochemical impedance spectroscopy, and potentiodynamic measurements in 0.6 M NaCl solution at pH 6. Heat treatment showed a positive effect on the electrochemical behavior of Ni? P coatings, shifting the open circuit potential toward less active potentials. The incorporation of SiC particles inhibited pit nucleation on the Ni? P composite coating, with or without post‐heat treatment. However, heat treatment in the Ni? P? SiC seemed to induce cracks in the metallic matrix, initiating at the SiC particles, possibly caused by the contraction in the metallic matrix. The cracked structure promoted localized corrosion, while coatings without heat treatment resulted in a general and uniform corrosion.     

Validation of Gamma and Electron Beam Irradiation as Alternative Conservation Technology for European Chestnuts

Chestnuts are widely consumed around the world, especially in China, which is the major producer. Portugal is the fifth biggest producer, reaching an income of 17 M €, with particular relevance for Trás-os-Montes region, which is responsible for 81 % of Portuguese production. During postharvest storage, a number of pests tend to attack chestnuts, contributing to high economic losses. Since 2010, the most effective postharvest treatment, i.e., fumigation with methyl bromide, was banned in the European Union, urging producers to seek effective and reasonable alternatives. One alternative could be irradiation with gamma rays or electron beam, which is used in food commodities, legally regulated and allows outstanding results. Our research group has tested both irradiation types in chestnuts and studied the nutritional, antioxidant, and other chemical parameters, obtaining promising results. Herein, we extended these studies to selected cultivars from Portugal and Italy in order to validate this technique as a viable alternative to fumigation. The selected irradiation dose (1 kGy) was chosen following previous results where it proved to be effective without causing remarkable changes in chemical or antioxidant profiles. To obtain a global knowledge about how each cultivar reacts to irradiation, principal component analysis was performed using all the measured parameters. Despite the detected differences among cultivars, which differentiated particularly Palummina and Cota, it was verified that irradiation did not cause changes in chemical and antioxidant parameters that could enable defining distinctive features among irradiated and non-irradiated chestnuts. Hence, the results herein reported might be seen as a new step toward the completion of irradiation as feasible conservation technology, independently of chestnuts origin.     

Mapping inland water carbon content with Landsat 8 data

Landsat 8 is the first Earth observation satellite with sufficient radiometric and spatial resolution to allow global mapping of lake CDOM and DOC (coloured dissolved organic matter and dissolved organic carbon, respectively) content. Landsat 8 is a multispectral sensor however, the number of potentially usable band ratios, or more sophisticated indices, is limited. In order to test the suitability of the ratio most commonly used in lake carbon content mapping, the green–red band ratio, we carried out fieldwork in Estonian and Brazilian lakes. Several atmospheric correction methods were also tested in order to use image data where the image-to-image variability due to illumination conditions would be minimal. None of the four atmospheric correction methods tested, produced reflectance spectra that matched well with in situ measured reflectance. Nevertheless, the green–red band ratio calculated from the reflectance data was in correlation with measured CDOM values. In situ data show that there is a strong correlation between CDOM and DOC concentrations in Estonian and Brazilian lakes. Thus, mapping the global CDOM and DOC content from Landsat 8 is plausible but more data from different parts of the world are needed before decisions can be made about the accuracy of such global estimation.     

Development of a special geometry carbide tool for the optimization of vertical turning of martensitic gray cast iron piston rings

The machining process for vertical turning martensitic gray cast iron is of great importance to the automotive industry, mainly in the manufacturing process of piston rings. The aim of this paper is to demonstrate the process of development of coated carbide tools to maximize the productivity of the process, considering the maximum life of the cutting tool and the minimum machining cost per part. Using full-factorial design of experiments, we tested two different geometries: a square tool with special geometry—formed by two edges and two ends simultaneously cutting—and a hexagonal tool. Considering that the special square geometry provided maximum life, full quadratic models for responses of interest were constructed using a central composite design for feed (f) and rotation (n). Applying the generalized reduced gradient algorithm, the proposed optimization goals were achieved with feed f?=?0.37?mm/v and rotation of 264?rpm for the use of the special square tool. Confirmation experiments prove the effectiveness of this solution.     

Pasting,thermal, gel texture,resistant starch and colour properties of unripe banana flour from 10 desert banana varieties cultivated in South Africa

Unripe banana flour is a potential commercial ingredient in various food products for increased resistant starch and reduced gluten contents. In the present study, the pasting (rapid visco-analysis), gel texture (penetration test), thermal (differential scanning calorimetry), colour (tri-stimulus colour indices) and the resistant starch properties of unripe banana flour produced from different dessert banana varieties (n?=?10) cultivated in South Africa, were analysed and juxtaposed to wheat and maize flour. The functional properties varied significantly (p?≤?0.05) between banana varieties, and from wheat and maize flours, to various extents. Selected functional property ranges of unripe banana, wheat and maize flours, respectively included; flour colour index (63.16–76.42, 77.34 and 80.96), paste viscosity (405.5–556.6, 124.7 and 115.6 RVU), gelatinization temperature (64.67–71.21, 71.11 and 69.95?°C), gel firmness (7.24–11.44?×?10^??2 N, 3.49?×?10^??2 N and 6.56?×?10^??2 N) and resistant starch content (19.9–47.4, 2.8 and 2.2% w/w). Multivariate analysis (principle component analysis) showed that the unripe banana flours from different varieties were distinguished from each other based on the pasting temperature. The unripe banana flours were distinguished from both wheat and maize flour based on breakdown and peak paste viscosities. The breakdown viscosity was the most positively related measure to the resistant starch content with a linear regression R-squared value of 0.898, indicating a significant role played by granule structure in resistance to enzymatic hydrolysis. The present research demonstrates that selection of appropriate dessert banana variety is important when replacing staple flours (wheat and maize) with unripe dessert banana flour as a functional ingredient.     

Fuzzy methodology for frequency response estimation of uncertain dynamic systems

Fuzzy frequency response: definition and analysis for uncertain dynamic systems is proposed in this paper. In terms of transfer function, the uncertain dynamic system is partitioned into several linear sub‐models and organized according to Takagi–Sugeno fuzzy representation. The main contribution of this paper is to demonstrate through the proposal of a Theorem that fuzzy frequency response is a boundary in the magnitude and phase Bode plots. Low‐ and high‐frequency analysis of fuzzy dynamic model is obtained by varying the frequency ω from zero to infinity. Copyright © 2011 John Wiley & Sons, Ltd.     

Different ratios of carbon sources in the fermentation of cheese whey and glucose as substrates for hydrogen and ethanol production in continuous reactors

The fermentation of glucose, cheese whey and the mixture of glucose and cheese whey were evaluated in this study from two inocula sources (sludge from a UASB reactor for swine wastewater treatment and poultry slaughterhouse) for hydrogen production in continuous anaerobic fluidized bed reactors (AFBR). For all fermentations, a hydraulic retention time (HRT) of 6 h and a substrate concentration of 5 g COD L⁻¹ were used. In glucose fermentation, the maximum hydrogen yield (HY) was 1.37 mmol H₂ g⁻¹ COD. The co-fermentation of the cheese whey and glucose mixture was favorable for the concomitant production of hydrogen and ethanol, with yields of up to 1.7 mmol H₂ g⁻¹ COD and 3.45 mol EtOH g⁻¹ COD in AFBR2. The utilization of cheese whey as a sole substrate resulted in an HY of 1.9 mmol H₂ g⁻¹ COD. Throughout the study, ethanol fermentation was evident.