Listeria monocytogenes in Gorgonzola: subtypes, diversity and persistence over time

L. monocytogenes represents a primary concern in the production of Gorgonzola, a Protected Designation of Origin (PDO) Italian blue-veined cheese produced only in the Piedmont and Lombardy regions. L. monocytogenes isolates (N=95) obtained from Gorgonzola rinds, paste, and production/ripening environments were serotyped and then genotyped using Pulsed Field Gel Electrophoresis (PFGE). The goal of this study was to investigate the variability of L. monocytogenes PFGE-types across different PDO Gorgonzola manufacturers (N=22). The majority of the strains (88%) were serotyped as 1/2a. PFGE identified 2 major pulse-types grouping 62 strains, detected from different plants and years, suggesting the presence of persistent and niche-adapted L. monocytogenes. In 9 plants, environmental strains shared the same pulse-types with strains from rinds or paste, suggesting a possible transmission pathway. Encouragingly, L. monocytogenes was retrieved from only 1 paste, indicating that production processes were under control in 21 plants. In the remaining plant, un-effective pasteurization or cross-contamination during production processes could be the cause of the contamination. Consequently, it is imperative that producers operate under the total respect of the Good Manufacturing Practices and following the principles of the Hazard Analysis Critical Control Point plans, in order to contain contamination throughout the whole processing.     

Inactivation of Spoiling Yeasts of Fruit Juices by Pulsed Ultrasound

This paper reports on the use of ultrasound (US) as a suitable strategy to control the growth of spoiling yeasts in fruit juices. In a first phase, US technique was tested towards Saccharomyces cerevisiae inoculated in different juices (strawberry, orange, apple, pineapple and red-fruits): the treatment was performed by modulating the level of the power (20–60 %), the duration of the treatment (2–6 min) and the pulse (2–6 s), according to a fractional design. Then, the best treatment was applied against some other spoiling yeasts (Pichia membranifaciens, Wickerhamomyces anomalus, Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Candida norvegica). Finally, a challenge test for a commercial beverage (red-fruit juice), inoculated with Z. bailii and containing a citrus extract, was conducted evaluating the effect of US on the sensory scores of the beverage. The results showed that the effect of US was mainly influenced by the power and the duration of the treatment; on the other hand, the effect of pulse was less significant and slight. The highest reduction of S. cerevisiae was found in the following combination of the design: power 60 %/time 4 min/pulse 2 s and power 60 %/time 6 min/pulse 6 s; this result was confirmed for the other spoiling yeasts. US and citrus extract could be combined to prolong the shelf life of the red-fruit juice and control the growth of Z. bailii. The two hurdles exerted a different role and acted in different times: US reduced the initial contamination, whilst citrus extract controlled the yeast within the storage.     

Buccal tablets containing cysteine and chlorhexidine for the reduction of acetaldehyde levels in the oral cavity

There is growing evidence that a large proportion of upper digestive tract tumors are ascribable to heavy alcohol drinking and tobacco consumption. The cancer-promoting action of ethanol is mediated by acetaldehyde, its first metabolite, also derived from the bacterial oxidation of alcohol by the oral microflora, classified by the International Agency for the Research on Cancer as a carcinogen. Acetaldehyde is also one of the major components of tobacco smoke. These findings suggest two different strategies to decrease the risk of alcohol-related oral cancers: the reduction of the levels of alcohol-derived acetaldehyde in saliva and the reduction of oral bacterial flora. Therefore, the aim of our study was to develop and characterize some buccal tablet formulations containing both 20 mg L-cysteine hydrochloride (able to chemically neutralize acetaldehyde) and 10 mg chlorhexidine diacetate (well-known antiseptic compound active against a large spectrum of oral microbes). One of these formulations, chosen on the basis of its favourable delivery kinetics of the active principles, was demonstrated to be able to reduce acetaldehyde concentration in an in vitro system and to lower its salivary levels in volunteers after ethanol contact. Our findings support the hypothesis that the application of buccal devices containing cysteine and chlorhexidine could reduce salivary acetaldehyde levels and thus the incidence of upper gastrointestinal cancer in drinkers and smokers.     

Sketched oxide single-electron transistor

Devices that confine and process single electrons represent an important scaling limit of electronics. Such devices have been realized in a variety of materials and exhibit remarkable electronic, optical and spintronic properties. Here, we use an atomic force microscope tip to reversibly 'sketch' single-electron transistors by controlling a metal-insulator transition at the interface of two oxides. In these devices, single electrons tunnel resonantly between source and drain electrodes through a conducting oxide island with a diameter of ～1.5 nm. We demonstrate control over the number of electrons on the island using bottom- and side-gate electrodes, and observe hysteresis in electron occupation that is attributed to ferroelectricity within the oxide heterostructure. These single-electron devices may find use as ultradense non-volatile memories, nanoscale hybrid piezoelectric and charge sensors, as well as building blocks in quantum information processing and simulation platforms.     

Direct electrospray ionization mass spectrometry quantitative analysis of sebacic and terephthalic acids in biodegradable polymers

A direct, rapid, and easy electrospray ionization mass spectrometry (ESI-MS) method to determine concentrations of sebacic acid (SA) and terephthalic acid (TA) residues in biodegradable copolymers was developed. Copolyester samples were synthesized from 1,4-butanediol and sebacic and terephthalic acids by melt polymerization. Extraction of monomers was performed in methanol. Their concentrations were determined by direct infusion ESI-MS, without chromatographic separation, using 1,12-dodecanedioic acid (DDA) as an internal standard. Calibration curves were obtained by plotting the ratio of the areas of the peaks relative to monomers and DDA standard as a function of their concentration ratio. We validated the method by determining the concentration of TA residue using both the ESI-MS protocol and high-performance liquid chromatography (HPLC) analysis with UV detection. The linearity range and the detection limit of this assay were 0.1-5.0 and 0.01 ppm for SA and 0.1-6.0 and 0.03 ppm for TA. This assay represents a useful alternative to conventional methods currently employed for acid quantification, resulting advantageous for its speed and high sensitivity.     

Polymer nanocomposites based on epoxy resin and ATH as a new flame retardant for CFRP: preparation and thermal characterisation

Nanoscale aluminium trihydroxide (ATH) is examined to its suitability for carbon fibre reinforced plastics (CFRP) as a novel flame retardant. In particular the influence of particle size and concentration of ATH to the fire behaviour of epoxy polymer matrices is determined. The particle size is adjusted by means of different dispersing techniques. By SEM images and viscosity measurements the homogeneity of the produced ATH dispersions for the liquid ones and of cured epoxy–ATH nanocomposites is determined. Based on these pre-results, selected ATH dispersions are used for the manufacturing of CFRP which are produced by the proved injection technology. The thermal stability of the ATH nanocomposite plates and the corresponding CFRP plates are analyzed by means of quantitative single difference thermoanalysis (QSDTA). The fire behaviour is characterised by using the OSU chamber test. Both tests indicate a reduced heat release rate by decreasing the ATH particle size, i.e. the thermal load decreases. A combined fire protection mechanism is discussed for the improved fire protection through ATH nanoparticles.     

trans Fatty Acids in Colostrum,Mature Milk and Diet of Lactating Adolescents

The purpose of this study was to investigate the trans fatty acids (TFA) content and distribution in colostrum, mature milk, and diet of adolescent mothers, after TFA declaration in food labels became mandatory in Brazil. Participants were healthy adolescents (n 54, 15–19 years, 1–90 days postpartum) practicing exclusive breastfeeding. Milk samples were collected 3 days after delivery (colostrum) and in the third month postpartum (mature milk) by hand expression. The fatty acid composition of the milk samples was determined by gas chromatography. TFA intake corresponded to 1.23 % of total energy value. Total 18:2 TFA accounted for less than 0.5 % of the energy intake. The amount of total 18:1 TFA (mean ± SEM) was 1.9 % ± 0.14 in colostrum and 1.5 % ± 0.2 in mature milk. The total content of n‐3 PUFA was inversely correlated with the total content of 18:1 TFA in colostrum. Both in colostrum and in mature milk, vaccenic acid (11t‐18:1) was found to be the most abundant 18:1 trans isomer, followed by elaidic acid (9t‐18:1), whereas rumenic acid (9c,11t‐18:2 CLA) was the predominant 18:2 trans isomer. In conclusion, the levels of TFA of industrial sources found in the mother's diet and breast milk (colostrum and mature milk) showed a decrease in relation to those observed in studies conducted prior to the TFA labeling resolution in Brazil. However, the current low intake levels of n‐3 LCPUFA and DHA content in the milk of lactating adolescents may be insufficient for supporting adequate neurological development of the infants.