Extraction optimization and profile analysis of oligosaccharides in banana pulp and peel

This study evaluated the effect of ethanol concentration (EC, 0–70%) and temperature (25–75 °C) on the oligosaccharides extraction from ripe banana pulp, as well as the profile of mono‐, di‐, galacto‐, fructo‐, malto‐ and xylooligosaccharides in ripe banana pulp and peel. According to response surface plots, EC of 52% (vol/vol) and 75 °C provided the maximum oligosaccharides extraction from banana pulp. High‐performance anion exchange chromatography coupled to pulsed amperometric detection showed the presence of glucose, fructose, sucrose, maltose, arabinose, 1‐kestose, xylopentaose, and xylohexaose in banana pulp and glucose, fructose, sucrose, 1‐kestose, maltotriose, xylopentaose, and xylohexaose in banana peel. Banana pulp and peel showed 6.47 and 1.42 mg/g dw of total oligosaccharides, respectively. The chromatographic analysis showed fructo‐ and xylooligosaccharides as the main banana oligosaccharides. Finally, banana can contribute to the intake of sugars and prebiotic oligosaccharides.

Practical applications

The extraction is the first step in the evaluation of the plant composition and several factors influence the recovery of the target compound. Oligosaccharides present a wide variety of applications in food science and industry and they are extensively studied in fruits metabolism. Methods with extraction conditions optimized and chromatography conditions well‐defined are very important to obtain reliable results. Furthermore, banana is one of the most consumed and processed fruits around the world and, consequently, the extraction procedure and analytical technique showed in this study can be helpful for quality control of banana and their products.     

Heavy metal tolerance in the psychrotolerant Cryptococcus sp. isolated from deep‐sea sediments of the Central Indian Basin

A deep‐sea isolate of the psychrotolerant yeast Cryptococcus sp. (NIOCC#PY13) obtained from polymetallic nodule‐bearing sediments of the Central Indian Basin was examined for its capacity to grow in the presence of various concentrations of the heavy metal salts i.e., ZnSO₄, CuSO₄, Pb(CH₃COO)₂ and CdCl₂. It demonstrated considerable growth in the presence of 100 mg/l concentrations of the above‐mentioned four heavy metal salts both at 30°C and 15°C. This strain tolerated comparatively higher levels of these four metal salts than other deep‐sea and terrestrial yeast isolates belonging to Cryptococcus, Rhodotorula, Rhodosporidium and Sporidiobolus spp. Optimum pH for growth of this isolate was in the range of 6–8 in the presence of heavy metal salts at these two temperatures. Scanning electron microscopic (SEM) studies exhibited altered cell surface morphology of the cells under the influence of heavy metals compared to that with control. The adsorption of heavy metals to the cells was demonstrated by FTIR and EDAX analysis. As evidenced by atomic absorption spectrophotometric (AAS) analysis, about 30–90% of the heavy metals were removed from the culture supernatant after 4 days of growth at 30°C. This deep‐sea yeast isolate appears to be a potential candidate for bioremediation of metal‐contaminated sites. Moreover, its metal tolerance properties provide a significant insight into its ecological role and adaptations to growth in such extreme conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of the feeding system on intramuscular fatty acids and conjugated linoleic acid isomers of beef cattle,with emphasis on their nutritional value and discriminatory ability

Thirty two Alentejano purebred bulls were used to investigate the effect of four feeding systems (pasture only, pasture feeding followed by 2 or 4 months of finishing on concentrate, and concentrate only) on meat fatty acid composition (GC-FID), including conjugated linoleic acid (CLA) isomeric distribution (Ag[+]–HPLC–DAD). In addition, meat fatty acids and CLA isomers were used to elucidate the impact of the different feeding regimens on the nutritional value of intramuscular fat and their usefulness as chemical discriminators of meat origin. The diet had a major impact on the fatty acid composition of beef (affected 27 of 36 fatty acids and 10 of 14 CLA isomers), which was independent of the fatty acid concentration. Beef fat from pasture-fed animals had a higher nutritional quality relative to that from concentrate-fed bulls. Finally, meat fatty acid composition was an effective parameter to discriminate between ruminant feeding systems, including different finishing periods on concentrate.     

Characterization for enterotoxin production,virulence factors,and antibiotic susceptibility of Staphylococcus aureus isolates from various foods in Portugal

Staphylococcus aureus represents a public health challenge worldwide. The aim of this study was the characterization of different food isolates of S. aureus on the basis of their production of enterotoxins, hemolysins and resistance to antibiotics. A total of 148 coagulase-positive staphylococcal strains isolated from different food origins were identified to the species level. By multiplex PCR, 69% of the isolates were shown to be enterotoxigenic (SEs); the most common were sea seg, sea seg sei and seg sei. According to CLSI [CLSI, Clinical and Laboratory Standards Institute, 2007. Performance Standards for Antimicrobial Susceptibility Testing; Fifteenth Informational Supplement. CLSI document M100-S15. Clinical and Laboratory Standards Institute, Wayne, PA], 38% of the isolates were resistant to oxacillin (≥6 μg/mL; MRSA positives) but only 0.68% showed the presence of mecA gene. 70 and 73% of the S. aureus strains were resistant to β-lactams, ampicillin and penicillin, respectively. The virulence pattern was demonstrated to be origin and strain dependent. These findings emphasise the need to prevent the presence of S. aureus strains and SEs production in foods.     

Synthesis of telechelic monodispersed dithiols

Summary The synthesis of novel telechelic monodispersed dithiols from a nonconjugated diene and an , -dithiol is presented. The batch reaction produced a polydispersed mixture of dithiols separable with difficulty whereas a dropwise addition of diene onto an excess of dithiol in the presence of peroxide led selectively and quantitatively to the addition product: dithiol-diene-dithiol.     

Effect of the degree of clay delamination on the phase morphology,surface chemical aspects,and properties of hydrolyzable polyurethanes for periodontal regeneration

In recent years, there has been increased interest in biodegradable polyurethanes for use in regenerative medicine because of their versatility and biocompatibility. Nevertheless, these polymers are usually produced using organic solvents that can lead to the release of toxic components. In this work, polyurethane/montmorillonite nanocomposites were designed to work as guided tissue regeneration membranes to treat periodontal diseases. Polyurethanes were synthesized in an aqueous environment. The composition, morphology, and mechanical properties of the biomaterials were evaluated. The cellular viability, proliferation, and morphology changes of rat culture cementoblasts were also investigated using a montmorillonite assay. Small‐angle X‐ray scattering, X‐ray diffraction, and infrared spectroscopy results showed that the degree of clay delamination within the polymer was able to tailor the phase morphology of the polymer, the chemical aspects of the surface, the mechanical properties, and the kinetics of hydrolysis of the materials. The produced scaffolds provided a good environment for the adhesion and proliferation of cementoblasts and thus can be considered suitable biomaterials for participating in procedures associated with periodontal regeneration. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Annealing Ni nanocrystalline on WC–Co

The effects of annealing temperature on nanocrystalline sputter-deposited Ni thin films (500 nm) deposited on WC–Co (4 wt.%) were investigated. Special attention was focused on quantitative evaluation of residual stress and Ni diffusion into the WC–Co, after heat treatment, from 873 to 1273 K. The estimated level of residual stress, as measured by X-ray diffraction, is around −1.3 ± 0.1 GPa for the as-deposited film, whereas after annealing at 1273 K it decreases significantly.Atomic force microscopy shows that high annealing temperature results into an exponential increase of the roughness. An intermixing between the nanocrystalline Ni and the Co from WC substrate occurs, as it is revealed by quantitative depth-resolved Rutherford backscattering spectrometry analysis and also supported by X-ray photoelectron spectroscopy. We ascribe a significant stress relief with the increasing annealing temperature to the diffusion process. The understanding of this process is particularly important in WC–Co parts with the surface treated with Ni in order to improve the maximum surface service temperature.     

Topological instability,average electronegativity difference and glass forming ability of amorphous alloys

In this paper, we report the remarkable agreement of the glass forming ability of binary alloys with a new criterion that combines the topological instability parameter (λ) and the average electronegativity difference among the elements of an alloy, assuming both exert a synergetic effect. The best glass forming compositions for Zr–Cu and Ti–Ni systems are well predicted by this new approach. Although the new criterion needs further refinement, it is concluded that the proposed approach is a promising and simple tool to guide and reduce the tedious and labour intensive work to find good glass former compositions in metallic systems.     

Magnetic domain morphologies and wall energy in YFe11Ti crystals

Magnetic domain configurations in YFe₁₁Ti aggregates have been investigated by magnetic force microscopy. Single domain behaviour, stripe/maze domains, wavy domain structures and reverse spike domains have been observed. Domain wall energy of 6 mJ/m² has been estimated based on the scale of the micromagnetic configurations.