Colony-blot assay with anti-p60 antibodies as a method for quick identification of Listeria in food

The present study evaluated the ability to isolate Listeria from foods, using shortened procedure of sample enrichment followed by immunomagnetic separation or filtration methods, and serological identification of isolated bacteria by colony-blot and Western blot methods with anti-p60 antibodies. By these rapid methods, identification of Listeria was achieved in much shorter time (40-48 h) than with standard cultivation and biochemical identification procedures. The rapid methods used are easy to perform and, what is most important, their specificity is very high and fulfills the expectations. The possibility to select Listeria colonies growing on non-selective media by blotting with anti-p60 antiserum seems to be particularly valuable in examination of food samples containing/not too many Listeria (1-10 CFU/25 g). However, the blot method using anti-PepD mAb specific to unique region of L. monocytogenes p60 is necessary to distinguish L. monocytogenes from other Listeria species.     

Effects of the methods of pre-treatment before freezing on the retention of chlorophylls in frozen leaf vegetables prepared for consumption

The investigation included kale, New Zealand spinach and spinach. The evaluation covered the raw material; the raw material after blanching; the raw material after cooking; and frozen products prepared for consumption after 0, 4, 8 and 12 months of refrigerated storage. Both the traditional method of freezing (blanching before freezing) and the modified method of freezing (cooked before freezing) were used in the experiment, as well as two storage temperatures, T = −20 °C and T = −30 °C. The content of chlorophylls in fresh kale was four times that in New Zealand spinach and 1.5 times that in spinach. With the exception of New Zealand spinach, blanching and cooking significantly reduced the content of chlorophylls. In kale products prepared for consumption, the content of chlorophylls decreased in each successive stage of the investigation. In products of New Zealand spinach and spinach, the losses were usually not significant. After 12 months of refrigerated storage, frozen kale products prepared for consumption retained 52–65% of total chlorophylls compared with the content in the raw material; products of New Zealand spinach and spinach retained 66–71%. In kale and New Zealand spinach, the content of chlorophyll a decreased more rapidly than that of chlorophyll b, while in spinach the converse was true. The kale products obtained using the modified method contained more chlorophylls, while in the two spinach species their content was lower. The lower storage temperature resulted in a higher retention of chlorophylls in vegetables.     

Effect of phytic acid degradation by soaking and exogenous phytase on the bioavailability of magnesium and zinc from Pisum sativum, L.

The effect of dephytinization of Pisum sativum, L. flour on the bioavailability of Mg and Zn was evaluated in growing rats. Processing of legume flours under optimal conditions for phytase activity (pH 5.5, 37 °C, 60 min) and subsequent removal of the soaking solution led to a 42 and 61% reduction in the content of Mg and Zn, respectively. Treatment with phytase led to an additional reduction in the concentration of the above-mentioned seed flour components, compared to the raw pea flour (69% and 74% for Mg and Zn, respectively). The considerable reduction in the content of inositol phosphates with high degree of phosphorylation attained under both processing conditions did not affect the digestive utilization of Mg, whereas the metabolic utilization of this mineral increased significantly. The digestive and metabolic utilization of Zn increased significantly in response to both processes assayed, reaching the highest values in the experimental group that was fed the phytase-treated pea flour diet. The amount of Mg retained by the experimental animals was reflected in the content of this mineral in the different tissues studied (femur, sternum, kidney, and heart), whereas no correlation was found in the case of Zn.     

金属针布钢丝的球化退火工艺

介绍纺织行业金属针布的现状及针布钢丝生产的工艺流程。详细分析金属针布钢丝球化退火的目的、种类、机制及其影响因素,介绍国内外球化退火的设备,并对球化退火钢丝的质量进行评价,对针布钢丝的生产提出几点建议。     

Stiffness alterations of single cells induced by UV in the presence of nanoTiO2

Nanocrystalline titanium dioxide (nanoTiO2) has been reported to generate reactive oxygen species (ROS) under UV illumination. In our studies, changes in mechanical properties of human skin fibroblasts, exposed to the oxidative stress induced in the presence of nanoTiO2 and UV light, were studied using atomic force microscopy (AFM). The exposure of cells to the action of ROS was performed at low TiO2 concentration (4 microg/mL) and under illumination with low-intensity UVA (8 and 20 mW/cm2) or UVC (0.1 mW/ cm2). AFM measurements of the cell stiffness were carried out immediately after exposure of cells to the oxidative stress. The data suggest that under illumination with low-intensity UVA nanoTiO2 generates ROS, which, in turn, damage cellular and subcellular structures. This process was detected by AFM as a marked drop in the cellular stiffness of ca. 30-75%, which occurred rapidly, in the time frame of 1 min. The photo-oxidative stress inducing the decrease of cell stiffness was cancelled in the presence of a well-established antioxidant, beta-carotene. The results highlight the sensitivity of AFM to detect early changes in mechanical properties of cells exposed to oxidative stress.     

Evaluation of the phenolic content,antioxidant activity and colour of Slovenian honey

Honey samples from the seven most common honey types in Slovenia were screened for total phenolic content by the modified Folin–Ciocalteu method, for potential antioxidant activity using the ferric reducing antioxidant power (FRAP) assay and by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method for antiradical activity. In addition the colour characteristics of honey samples were analysed. The results of the study showed that total phenolic content, antioxidant activity and colour parameters differ widely among different honey types. Phenolic content expressed as gallic acid equivalent ranged from 44.8 mg/kg in acacia honey to 241.4 mg/kg in fir honey. Antioxidant activity was the lowest in the brightest acacia and lime honeys and the highest in darker honeys, namely fir, spruce and forest. The colour of the Slovenian honeys, analysed in this study was very variable and ranged from pale yellow to dark brown. Correlations between the parameters analysed were found to be statistically significant (p < 0.05).     

Organotin compounds in the liver tissue of marine mammals from the Polish coast of the Baltic Sea

Butyltins (BTs) and phenyltins (PhTs) were determined in the livers of marine mammals found by-caught or stranded along the Polish coast of the Baltic Sea. During the investigation an original analytical method was developed. Butyltin compounds were detected in all the liver samples, whereas phenyltins were not detected in any of the samples. The total concentrations of BTs ranged from 43.9 to 7698 ng(Sn) x g(-1) dry weight. Age-related trends to accumulate BTs in immature porpoises were found. At the same time there were no male-female differences in BTs concentrations observed. No statistically significant spatial distribution differences were found between the locations corresponding to the open Baltic Sea waters and inside the Gulf of Gdańsk, which is characterized by high maritime activity. In comparison to butyltin levels in marine mammals from other geographic regions, the samples analyzed indicate a significant degree of tributyltin pollution along the Polish coast of the Baltic Sea. On the basis of a literature review, higher BT levels are usually found in waters close to highly industrialized areas, such as Japan, Hong Kong, and the United States.     

Pesticide Residue Determination by Gas Chromatography-Tandem Mass Spectrometry as Applied to Food Safety Assessment on the Example of Some Fruiting Vegetables

A multiresidue method for the analysis of over 140 multiclass pesticides in fruiting vegetables, based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation procedure followed by gas chromatography-tandem mass spectrometry (GC-MS/MS), was established. In the validation study, the overall recoveries from spiked samples were 102?±?7, 95?±?7, and 95?±?7 % with RSD values of 7?±?3, 7?±?4, and 7?±?3 % at the spiking levels of 0.01, 0.05, and 0.5 mg kg^?1, respectively, demonstrating fitness for purpose of the method. The limit of quantification (LOQ) was 0.01 mg kg^?1 for more than 90 % of the target compounds. The analysis of over 300 samples of tomatoes, sweet peppers, and cucumbers was carried out in 2006–2014. Of these samples, 52 % contained pesticide residues but the results of the assessment of dietary exposure supported the conclusion that the presence of pesticide residues was unlikely to have a negative effect on the health of consumers. Although some of the pesticides detected in years 2006–2009 are no longer approved in the European Union member countries (namely endosulfan, oxadixyl, procymidone, propargite, and tolylfluanid), the consumer dietary exposure was low and did not exceed 12 % of the acceptable daily intake (ADI) considering both adults’ and children’s diet. Regarding short-term exposure (acute), in only one case of procymidone in sweet pepper, the acute reference dose (ARfD) for children was exceeded by 139.6 % of the ARfD.