High-resolution Orbitrap™-based mass spectrometry for rapid detection of peanuts in nuts

Peanut represents one of the most harmful allergenic foods capable of triggering severe and sometimes lethal reactions in allergic consumers upon ingestion of even small amounts. Several proteins capable of inducing allergic reactions that have been recognised by patients’ IgE antibodies have been identified from this nut source. Methods mainly based on ELISA assays have been developed in order to detect peanuts in several food commodities. In addition LC-MS/MS methods based on different mass analysers have also been devised for tracing peanut contamination in different foods achieving low limits of detection. The applicability of a benchtop high-resolution Exactive? mass spectrometer has never been investigated for the rapid screening of peanut contamination in complex food matrices like mixtures of nuts. We report in this paper the design of suitable peanut markers and the development of an high-resolution Orbitrap? mass spectrometer-based method for peanut detection in a mixture of nuts species. With this aim, different types of samples were prepared: (1) nuts-based powder made up of a mixture of hazelnuts, pistachios, almonds and walnuts; and (2) nuts powder fortified with peanuts. Different levels of fortifications were produced and the applicability of the method was tested. Finally, a subset of six peptides fulfilling specific analytical requirements was chosen to check the suitability of the method tailored to the detection of peanuts in nuts-based products, and two of them, peptides VYD and WLG, were selected as quantitative markers. The method proved to be a suitable screening tool to assess the presence of traces of peanuts in other tree nuts with a limit of detection as low as 4 µg of peanuts proteins or 26 µg of peanuts in 1 g of matrix.     

Bioinspired Tunable Lens with Muscle‐Like Electroactive Elastomers

Optical lenses with tunable focus are needed in several fields of application, such as consumer electronics, medical diagnostics and optical communications. To address this need, lenses made of smart materials able to respond to mechanical, magnetic, optical, thermal, chemical, electrical or electrochemical stimuli are intensively studied. Here, we report on an electrically tunable lens made of dielectric elastomers, an emerging class of “artificial muscle” materials for actuation. The optical device is inspired by the architecture of the crystalline lens and ciliary muscle of the human eye. It consists of a fluid‐filled elastomeric lens integrated with an annular elastomeric actuator working as an artificial muscle. Upon electrical activation, the artificial muscle deforms the lens, so that a relative variation of focal length comparable to that of the human lens is demonstrated. The device combined optical performance with compact size, low weight, fast and silent operation, shock tolerance, no overheating, low power consumption, and possibility of implementation with inexpensive off‐the‐shelf elastomers. Results show that combing bioinspired design with the unique properties of dielectric elastomers as artificial muscle transducers has the potential to open new perspectives on tunable optics.     

Hydrophobin as a Nanolayer Primer That Enables the Fluorinated Coating of Poorly Reactive Polymer Surfaces

A new and simple method is presented to fluorinate the surfaces of poorly reactive hydrophobic polymers in a more environmentally friendly way using the protein hydrophobin (HFBII) as a nanosized primer layer. In particular, HFBII, via electrostatic interactions, enables the otherwise inefficient binding of a phosphate‐terminated perfluoropolyether onto polystyrene, polypropylene, and low‐density polyethylene surfaces. The binding between HFBII and the perfluoropolyether depends significantly on the environmental pH, reaching the maximum stability at pH 4. Upon treatment, the polymeric surfaces mostly retain their hydrophobic character but also acquire remarkable oil repellency, which is not observed in the absence of the protein primer. The functionalization proceeds rapidly and spontaneously at room temperature in aqueous solutions without requiring energy‐intensive procedures, such as plasma or irradiation treatments.     

Considerations on CDMA–OFDM System Performances in Different Channel Environments for Different Modulation and Coding Scenarios

This paper presents a number of results obtained based on a CDMA–OFDM simulator developed in Matlab. The simulator has been extended to accommodate in a flexible manner to different modulation schemes, multiple access techniques, spreading codes types and lengths, convolutional codes rates, number of users and types of channels. The performances are evaluated and compared based on the Bit Error Rate (BER) as a function of the Signal to Noise Ratio (SNR) results achieved in different scenarios. In this paper are presented the results obtained by the developed simulator for two types of spreading codes—perfectly orthogonal Walsh type codes versus pseudo-orthogonal Gold type codes. The performances are evaluated in different channel environments the classical AWGN, pedestrian, vehicular and indoor ITU-R M.1225 models, for BPSK and QPSK modulations and 1/2 respectively 3/4 rate channel coding. Furthermore, since the results shown that the Gold spreading codes, QPSK modulation and 1/2 rate coding achieves the best performances in all type of channels analyzed, the authors investigate the effect of the code length and of the number of users on these results.     

Genipin‐cross‐linked chitosan‐based hydrogels: Reaction kinetics and structure‐related characteristics

The main aim of this work is the synthesis and characterization of cross‐linked chitosan systems. Chitosan hydrogels can be prepared by physical or chemical cross‐linking of polymer chains. Chemical cross‐linking, leading to the creation of hydrogel networks possessing improved mechanical properties and chemical stability, can be achieved using either synthetic agents or natural‐based agents. In this work, the cross‐linker Genipin, a naturally derived compound, was selected because of the lower acute toxicity compared to many other commonly used synthetic cross‐linking reagents. In particular, the chemical stabilization of chitosan through genipin cross‐linking molecules was performed and characterized by calorimetric analyses (differential scanning calorimetry), swelling measurements in different pHs, and ionic strength. The reaction kinetics was carried out by means of rheological measurements, and both the activation energy (E_a) and the reaction order (m) were calculated. The hydrogel analyses were carried out at different concentrations of genipin (GN1 and GN2). The results were used to evaluate the possibility to use the chemical cross‐linked chitosan–genipin hydrogel for biomedical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42256.     

Biodegradable antimicrobial films based on poly(lactic acid) matrices and active azo compounds

Using solvent casting and melt compounding methods, we realized antibacterial and antifungal poly(lactic acid)‐based films by introducing different percentages of antimicrobial azo dyes into polymer matrices. Concentration up to 0.01% (w/w) of azo compounds permitted the preparation of antimicrobial and transparent films. The thin films retained the properties of the pure PLA matrices, such as glass transition temperature, flexibility, and amorphous nature. The films exhibited antimicrobial activity and the capability to inhibit biofilms formation of Staphylococcus aureus and Candida albicans. Spectrophotometric investigation of azo compounds release from the polymer matrices confirmed that the materials might have applications in fields where an intrinsic antimicrobial ability of the material is required, such as biomedical tools, biodegradable antibacterial coatings, and films for active packaging. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42357.     

Study of Linkage between Glutathione Pathway and the Antibiotic Resistance of Escherichia coli from Patients’ Swabs

In this work, we focused on the differences between bacterial cultures of E. coli obtained from swabs of infectious wounds of patients compared to laboratory E. coli. In addition, blocking of the protein responsible for the synthesis of glutathione (γ-glutamylcysteine synthase—GCL) using 10 mM buthionine sulfoximine was investigated. Each E. coli showed significant differences in resistance to antibiotics. According to the determined resistance, E. coli were divided into experimental groups based on a statistical evaluation of their properties as more resistant and more sensitive. These groups were also used for finding the differences in a dependence of the glutathione pathway on resistance to antibiotics. More sensitive E. coli showed the same kinetics of glutathione synthesis while blocking GCL (K_m 0.1 µM), as compared to non-blocking. In addition, the most frequent mutations in genes of glutathione synthetase, glutathione peroxidase and glutathione reductase were observed in this group compared to laboratory E.coli. The group of “more resistant” E. coli exhibited differences in K_m between 0.3 and 0.8 µM. The number of mutations compared to the laboratory E. coli was substantially lower compared to the other group.     

Dry matter content and fruit size affect flavour and texture of novel Actinidia deliciosa genotypes

BACKGROUND: Previous studies with commercial kiwifruit cultivars have demonstrated that the taste of fruit with higher dry matter content (DM) is more liked by consumers. A unique replicated trial of kiwifruit genotypes (10 high/low DM × small/large‐fruited genotypes) has provided an opportunity to consider how the genetic propensity for a kiwifruit to accumulate DM affects fruit flavour and texture. In the present study, eating‐ripe fruit from each of the genotypes were assessed using a trained sensory panel and the relationships between these sensory attributes and fresh weight, DM, flesh firmness and soluble solids content (SSC) were explored. RESULTS: The genotypes provided a diversity of flavour and texture attributes, each of which varied in perceived intensity of the sensory experience. High‐DM genotypes had higher SSC and were perceived as sweeter than low‐DM genotypes. Sweet taste was closely associated with the perception of the tropical flavour and high‐DM genotypes were found to have more tropical notes. Fruit size was associated with fruit texture, and small fruit were characterised by a firmer and more fibrous core. Large high‐DM fruit were perceived as juicier than those of all other genotypes. CONCLUSIONS: Genotypes were perceived differently from one another, and differences in fruit size and DM content were reflected in fruit sensorial properties. This study is unique in demonstrating interactions between fruit size, DM and sensory properties. These findings could be relevant not only to kiwifruit but to fruiting crop breeders in general, because of the demonstrated potential for effects of fruit size and DM content on sweetness, flavour and fruit texture. Copyright © 2010 Society of Chemical Industry     

Evaluation of the oxidation state and metal concentration in the adipose tissue of Parma ham

The effect of different dietary fat supplements: A, no added fat; B, 3% added lard and C, 3% added partially hydrogenated lard (PHL), were evaluated in dry cured Parma ham fat by determination of the lipid oxidation indices, R1 and R2, on a total of 30 Italian Landrace×Italian Large White pigs. Furthermore, correlations between lipid oxidation and calcium, magnesium, iron, zinc, copper and nickel concentrations, determined in Parma ham fat, was also investigated. Results highlighted a correlation between the oxidative state of Parma ham fat and the pigs' diet; in particular the addition of 3% PHL led to a more stable depot fat towards lipid oxidation compared to the addition of lard. Finally, Parma ham fat from treatment C showed higher concentrations of Ca (p<0.01) and Mg (p<0.05) compared to those from control, A, and treatment B groups. On the contrary, no significant differences were found for Fe, Zn, Cu and Ni.     

Stabilisation of sunflower oil and reduction of acrylamide formation of potato with rosemary extract during deep-fat frying

The aim of this study was to evaluate the effects of rosemary extract on the stabilisation of sunflower oil and the reduction of acrylamide formation in potato during deep-fat frying. The synthetic antioxidants butylated hydroxyanisole, tertiary butylhydroquinone, and tocopherols served as positive controls. Thermo-oxidative alterations were measured according to various physical and chemical parameters. Total polar compounds, free fatty acids, conjugated dienes, conjugated trienes, and colour (L*, b*) were evaluated for effectiveness of the antioxidants to stabilise the sunflower oil. The acrylamide concentration was evaluated for effectiveness of the antioxidants to reduce the acrylamide content in the deep-fried potato. Except for the decreased L* value (darkness of oil colour), these parameters all increased with the number of frying cycles. The order of effectiveness for inhibition of sunflower oil degradation and reduction of acrylamide formation in deep-fried potato was: rosemary extract > tocopherols > tertiary butylhydroquinone > butylated hydroxyanisole > control (P < 0.05). Total polar compounds, free fatty acid and acrylamide levels were significantly correlated with frying time (P < 0.05). The acrylamide formation in fried potatoes was significantly correlated with the formation of total polar compounds (P < 0.05) in the frying oil during the frying process.