Use of Lactoperoxidase Inhibitory Effects to Extend the Shelf Life of Meat and Meat Products.

Lactoperoxidase (LP) is an important enzyme of the salivary and mammary glands. It has been proven to increase the shelf life of raw milk by inhibiting the growth of bacteria, especially Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Pseudomonas spp. The aim of this work was to verify the use of LP to extend the shelf life of meat products. In vitro experiments showed inhibitory effects on the selected bacteria (Listeria innocua (ATCC 33090), Staphylococcus saprophyticus (CP054440.1), and Pseudomonas fluorescens (ATCC 13525) due to a prolongation of the lag phase of growth curves. A lower increase in viable counts (p < 0.05) was also found by testing pork cubes' surface treated with LP solution (5%) + L. innocua and stored for 7 days at 15 °C. LP has also been studied at concentrations of 0.25 and 0.50% in meat products (pork ham and pâté) during refrigerated storage (4 °C for 28 days). Lower viable counts were observed throughout the storage experiment, especially for 0.50% LP (p < 0.05). Meat products containing LP also showed lower levels of oxidation (MAD) (p < 0.05). According to these results, LP could extend the shelf life of a wider range of products.

Field Use of Protective Bacteriophages against Pectinolytic Bacteria of Potato.

The pectinolytic Dickeya solani bacterium is an important pathogen found in potatoes. We conducted laboratory and field experiments mimicking severe and mild Dickeya spp. infection and investigated the application of a mixture of two lytic bacteriophages before and after bacterial infection to protect the plants. Application of the phage solution to tuber disks and wounded tubers did not completely eliminate the infection but reduced the development of soft rot symptoms by 59.5-91.4%, depending on the phage concentration. In the field trial, plants treated with bacteriophages after severe Dickeya infection had 5-33% greater leaf cover and 4-16% greater tuber yield compared to untreated plants. When simulating a mild infection, leaf cover was 11-42% greater, and tuber yield was 25-31% greater compared to untreated plants. We conclude that the phage mixture has the potential to protect potatoes ecologically from D. solani.

Bacteriophages as a Strategy to Protect Potato Tubers against Dickeya dianthicola and Pectobacterium carotovorum Soft Rot.

The protective effect of bacteriophage suspensions (Ds3CZ + Ds20CZ and PcCB7V + PcCB251) on phytopathogenic bacteria causing soft rot of potato tubers, namely Dickeya dianthicola (D50, D200) and Pectobacterium carotovorum (P87, P224), was observed in ex vivo and in vitro experiments. Ex vivo tests were performed (with air access) on potato slices, on cylindrical cuts from the center of the tubers, and directly in whole potato tubers. In vitro experiments were carried out in a liquid medium using RTS-8 bioreactors, where bacterial growth was monitored as optical density. In particular, the inhibitory effects of phages were confirmed in experiments on potato slices, where suppression of rot development was evident at first glance. Phage treatment against selected bacteria positively affected potato hardness. Hardness of samples treated with bacteria only was statistically significantly reduced (p < 0.05 for D50 and p < 0.001 for D200 and P87). Ex vivo experiments confirmed significant inhibition of P87 symptom development, partial inhibition of D200 and D50 in phage-treated tubers, and no effect was observed for P224. The inhibitory effect of phages against bacteria was not observed in the in vitro experiment.

Modelling desorption isotherm for durable meat products.

The desorption isotherms of two durable meat products (sample 1 - durable fermented meat product and sample 2 - unheated durable meat product) by Dynamic Dewpoint Isotherm (DDI) at 20, 25, and 30 °C and Saturated Salt Slurry (SSS) method at 20 °C has been studied. The data acquired from these measurements for 7 models (GAB, DLP, Henderson, Chin, Smith, Oswin, Halsey) were used and statistically evaluated. Based on our collected data, the most suitable model for these types of durable meat products is the DLP model. For the DDI method, DLP model (20-30 °C) reached the R2 = 0.999, P value 3.48-4.22 of sample 1 and R2 = 0.999, P value 1.51-3.24 of sample 2. For SSS method DLP model (20 °C) reached R2 = 0.999, P value 4.23 of sample 1 and R2 = 0.998, P value 3.68 of sample 2. The most commonly used GAB model according to statistical treatment was very accurate only for the DDI method, GAB model (20-30 °C) reached R2 ≥ 0.994, P value 1.93-7.12 of sample 1 and R2 = 0.999, P value 1.76-5.54 of sample 2. In general, for DDI method for both samples have models (DLP, GAB, Halsey, Henderson, and Oswin) a P value of less than 10% for all three measured temperatures. For the SSS method, only the DLP and Henderson models are below 10% for both samples. It has been verified that the DDI method is a suitable and accurate method for measuring desorption isotherms for durable meat products.

Comparison of the Automatic and Manual Broiler Pre-Slaughter Chain Based on Trailer Microclimate during Transportation and Its Effect on m. pectoralis major.

This study aims to compare two broiler pre-slaughter chain methods: (i) the automatic pre-slaughter chain (APC) and (ii) manual pre-slaughter chain (MPC). The comparison is based on the evaluation of the trailer microclimate, number of injuries, and breast muscle (m. pectoralis major) quality. Transportation lasts 3.5 h, unloading 1 h. The selection of two hundred 39-day-old broilers (Ross 308 and Cobb 500 breeds) is random for each type of method. After slaughter, the pH value, electrical conductivity (EC), and color (lightness) of breast muscle tissues are determined at different post-mortem intervals. The MPC negatively affects the microclimate (p < 0.001), meat qualitative characteristics (p < 0.001), and places a greater strain on the body of chickens compared with APC. The average pH15min value of MPC broiler breast muscle tissue, generally used as the main meat quality parameter, is 5.97 ± 0.12, in contrast to 6.36 ± 0.16 for APC. Higher pH15min value of APC indicates better welfare and pre-slaughter handling. Values of EC and L* of breast tissues also confirms a difference between the methods of broiler handling (p < 0.001). No difference is found between the breed lines (p > 0.05).

Complete genome sequences of novel Berlinvirus and novel Certrevirus lytic for Pectobacterium sp. causing soft rot and black leg disease of potato.

Two novel dsDNA bacteriophages named Pectobacterium virus CB251 (PcCB251) and Pectobacterium virus CB7V (PcCB7V) targeting plant pathogen Pectobacterium parmentieri have been isolated and sequenced. The PcCB251 genome consists of 40,557 bp with G+C content of 48.6% and contains 47 predicted genes on a single strand. The phage is classified in genus Berlinvirus, family Autographiviridae. The PcCB7V phage has a circular dsDNA genome of 146,054 bp with G+C content of 50.4% and contains 269 predicted protein genes on both strands and 13 tRNA genes. The PcCB7V phage can be classified in genus Certrevirus, subfamily Vequintavirinae. Both novel bacteriophages have narrow host ranges, but they extend the list of candidates for phage-based control of pectolytic bacteria causing soft rot disease of potato.

Diversity of limestone bacteriophages infecting Dickeya solani isolated in the Czech Republic.

Seven novel tailed lytic viruses (Ds3CZ, Ds5CZ, Ds9CZ, Ds16CZ, Ds20CZ, Ds23CZ, Ds25CZ) infecting the bacterium Dickeya solani were isolated in the Czech Republic. Genomes of these viruses are dsDNA, 149,364 to 155,285 bp in length, and the genome arrangement is very similar to that of the type virus Dickeya virus LIMEstone 1. All but the Ds25CZ virus should be regarded as strains of a single species. Most of the sequence differences are due to the presence or absence of homing endonuclease (HE) genes, with 23 HEs found in Ds3CZ, Ds5CZ, and Ds20CZ, 22 in Ds9CZ, 19 in Ds16CZ, 18 in Ds25CZ, and 15 in Ds23CZ.

Measuring citrate synthase activity as an enzymatic approach to the differentiation of chilled and frozen/thawed meat.

Citrate synthase belongs between mitochondrial enzymes which are released from the meat tissue after cell membrane damage caused by ice crystal formation. The presence of this enzyme can indicate a previous freezing process. In this study, we determined citrate synthase activity for chilled and frozen/thawed meats (chicken, pork, beef, and salmon). As an additional factor, we examined a potential connection between microbial spoilage and increased enzyme activity. UV spectrophotometry was used for the evaluation of the citrate synthase activity. The effect of microbial spoilage on the enzyme activity was established through microbial analysis, which was carried out for two weeks for chilled and five months for frozen/thawed meats. The citrate synthase activity in the frozen/thawed samples was significantly higher than in the chilled samples. Dependence of microbial contamination and the increased activity of the citrate synthase was not observed. Our results suggest that there could be designed specific limits of citrate synthase activity for the resolution of chilled and frozen/thawed meats.

[Lead poisoning. A surprising cause of constipation, abdominal pain and anemia]. / Otrava olovem - prekvapivá prícina bolestí bricha, obstipace a anémie.

This article reports on patient that has been presented with sudden onset of constipation, abdominal pain and normocytic anemia. Gastroscopy and colonoscopy ruled out an organic diseases. In peripheral blood and bone marrow aspirates mears, coarse basophilic stippling of erythrocyte (and erythroblasts) point out a possibility of heavy metal poisoning. The level of plumbemia exceeded 8.4 times the maximal permitted value for common (non-professional) population. A source of poisoning was indentified from a glaze on a ceramic jug, from which the patient had drank tea with lemon for three months. A lead concentration in the tea extract was 227 mg/kg. In developed countries, lead poisoning is a rare diagnosis. As the symptoms are nonspecific, missed diagnoses could occur, especially in sporadic, non-occupational exposure. However, a microscopic evaluation of the peripheral bloods mear with finding of predominantly coarse basophilic stippling of erythrocyte mayle ad to suspicion of lead poisoning.

Evaluation of ice-tea quality by DART-TOF/MS.

DART (Direct Analysis in Real Time) coupled with Time-of-Flight Mass Spectrometry (TOF/MS) has been used for analyses of ice-teas. The article focuses on quality and authenticity of ice-teas as one of the most important tea-based products on the market. Twenty-one samples of ice-teas (black and green) were analysed. Selected compounds of ice-teas were determined: theobromine, caffeine, total phenolic compounds, total soluble solids, total amino acid concentration, preservatives and saccharides were determined. Fingerprints of DART-TOF/MS spectra were used for comprehensive assessment of the ice-tea samples. The DART-TOF/MS method was used for monitoring the following compounds: citric acid, caffeine, saccharides, artificial sweeteners (saccharin, acesulphame K), and preservatives (sorbic and benzoic acid), phosphoric acid and phenolic compounds. The measured data were subjected to a principal components analysis. The HPLC and DART-TOF/MS methods were compared in terms of determination of selected compounds (caffeine, benzoic acid, sorbic acid and saccharides) in the ice-teas. The DART-TOF/MS technique seems to be a suitable method for fast screening, testing quality and authenticity of tea-based products.

Characterization of mustard seeds and paste by DART ionization with time-of-flight mass spectrometry.

Direct analysis in real time (DART) is a novel technique with great potential for rapid screening analysis. The DART ionization method coupled with high-resolution time-of-flight mass spectrometry (TOF-MS) has been used for characterization of mustard seeds and table mustard. The possibility to use DART to analyse glucosinolates was confirmed on determination of sinalbin (4-hydroxybenzyl glucosinolate). The DART-TOF-MS method was optimized and validated. A set of samples of mustard seeds and mustard products was analyzed. High-performance liquid chromatography and DART-TOF-MS were used to determine glucosinolates in mustard seeds and compared. The correlation equation between these methods was DART = 0.797*HPLC + 6.987, R(2) = 0.972. The DART technique seems to be a suitable method for evaluation of the quality of mustard seeds and mustard products.

DART mass spectrometry for rapid screening and quantitative determination of cholesterol in egg pasta.

To ensure that egg-containing products, such as dried eggs and egg pasta, conform to the technological and legislative requirements for egg content, methods are needed to determine the amount of cholesterol in such products. The conventional approach, direct saponification and hexane extraction followed by cholesterol determination by gas chromatography coupled to a flame ionization detector, is very time consuming. Therefore, we developed a rapid method on the basis of direct analysis in real time coupled to time-of-flight mass spectrometry. Samples were prepared simply by solvent extraction followed by extract filtration. The optimization of certain parameters, including the solvent used and direct analysis in real time ionization gas temperature, had a pronounced effect on the intensities of the produced ions, in particular, the molecular and dehydrated ions of cholesterol and its deuterated analog, cholesterol 2,2,3,4,4,6-d(6) which was used as an internal standard. For the developed method, limits of detection and quantification were 0.03 and 0.05 mg g(-1) respectively. The results of the real samples were compared with those obtained using the conventional approach [limit of detection = 0.002 mg g(-1) and limit of quantification = 0.05 mg g(-1)], and it was found that, although the results obtained using the conventional approach were more accurate, our developed method is much simpler and faster, where the time was dramatically reduced by 87% for executing a screening analysis.

Rapid determination of 5-hydroxymethylfurfural by DART ionization with time-of-flight mass spectrometry.

DART (direct analysis in real time), a novel technique with wide potential for rapid screening analysis, coupled with high-resolution time-of-flight mass spectrometry (TOF-MS) has been used for quantitative analysis of 5-hydroxymethylfurfural (5-HMF), a typical temperature marker of food. The DART/TOF-MS method was optimised and validated. Quantification of 5-HMF was achieved by use of a stable isotope-labelled 5-HMF standard prepared from glucose. Formation of 5-HMF from saccharides, a potential source of overestimation of results, was evaluated. Forty-four real samples (honey and caramelised condensed sweetened milk) and 50 model samples of heated honey were analysed. The possibility of using DART for analysis of heated samples of honey was confirmed. HPLC and DART/TOF-MS methods for determination of 5-HMF were compared. The correlation equation between these methods was DART = 1.0287HPLC + 0.21340, R(2) = 0.9557. The DART/TOF-MS method has been proved to enable efficient and rapid determination of 5-HMF in a variety of food matrices, for example honey and caramel.

The effects of new Alibernet red wine extract on nitric oxide and reactive oxygen species production in spontaneously hypertensive rats.

We aimed to perform a chemical analysis of both Alibernet red wine and an alcohol-free Alibernet red wine extract (AWE) and to investigate the effects of AWE on nitric oxide and reactive oxygen species production as well as blood pressure development in normotensive Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHRs). Total antioxidant capacity together with total phenolic and selected mineral content was measured in wine and AWE. Young 6-week-old male WKY and SHR were treated with AWE (24,2 mg/kg/day) for 3 weeks. Total NOS and SOD activities, eNOS and SOD1 protein expressions, and superoxide production were determined in the tissues. Both antioxidant capacity and phenolic content were significantly higher in AWE compared to wine. The AWE increased NOS activity in the left ventricle, aorta, and kidney of SHR, while it did not change NOS activity in WKY rats. Similarly, increased SOD activity in the plasma and left ventricle was observed in SHR only. There were no changes in eNOS and SOD1 expressions. In conclusion, phenolics and minerals included in AWE may contribute directly to increased NOS and SOD activities of SHR. Nevertheless, 3 weeks of AWE treatment failed to affect blood pressure of SHR.

Determination of phytic acid and inositolphosphates in barley.

Phytic acid (PA) and lower inositolphosphates (InsP(n) ) is the main storage form of phosphorus in grains or seeds. The content of PA and InsP(n) in different varieties of barley was analyzed by capillary isotachophoresis and online-coupled capillary isotachophoresis with CZE. The electrolytes (in demineralized water) for the isotachophoretic analysis consisted of 10 mM HCl, 14 mM glycylglycine, and 0.1% 2-hydroxyethylcellulose (leading) and 10 mM citric acid (terminating). The optimized electrolytes for the online coupling isotachophoresis with zone electrophoresis analysis were mixtures of 5 mM HCl, 7 mM glycylglycine, and 0.1% 2-hydroxyethylcellulose (leading), 20 mM citric acid, 10 mM glycylglycine, and 0.1% 2-hydroxyethylcellulose (background) and 10 mM citric acid (terminating). PA and all studied InsP(n) were separated within 25 min and detected by a conductivity detector. Simple sample preparation (acidic extraction), sufficient sensitivity, speed of analysis, and low running cost are important attributes of the electrophoretic methods. The method was used for the determination of PA and InsP(n) in barley varieties within an ongoing research project.

Electrophoretic determination of calystegines A3 and B2 in potato.

Potatoes, members of the Solanaceae plant family, contain calystegines, water-soluble nortropane alkaloids, which are biologically active as glycosidase inhibitors. The content of calystegines A(3) and B(2) in different varieties of potato and in various parts of the tubers (whole potato, peel, flesh, and sprouts) were analysed by new capillary zone electrophoresis and capillary isotachophoresis methods and by the routine GC method. The optimized background electrolyte for capillary zone electrophoretic analysis was mixture of 20 mM histidine, 20 mM N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid and 20% (v/v) methanol in demineralized water. Calystegines were detected by indirect UV detection at 210 nm. A clear separation of calystegines from other components of the methanolic sample extract was achieved within 4 min. The electrolytes for isotachophoretic analysis consisted of 5 mM NH(4)OH, 10 mM N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, 0.1% hydroxyethylcellulose and 20% (v/v) methanol in demineralized water (leading) and 5 mM histidine+10 mM acetic acid+20% (v/v) methanol in demineralized water (terminating). Calystegines were separated within 20 min and detected by a conductimeter. Method characteristics of both zone electrophoresis and isotachophoresis, i.e., linearity (10-100 ng/microl and 1-10 ng/microl), accuracy (recovery 96+/-5% and 98+/-4%), intra-assay repeatability (4.2% and 3.5%), and detection limit (3 and 0.4 ng/microl) were evaluated. Simple sample preparation, sufficient sensitivity, speed of analysis, and low running cost are important attributes of the electrophoretic methods. The overall results of electrophoretic methods were comparable with GC.

Determination of domoic acid by on-line coupled capillary isotachophoresis with capillary zone electrophoresis.

An on-line coupled capillary isotachophoresis--capillary zone electrophoresis (cITP-CZE) method for the determination of domoic acid in shellfish and algae is described. The optimised cITP-CZE electrolyte system was 10 mM HCl + 20 mM beta-alanine (BALA) + 0.05% hydroxyethylcellulose (leading electrolyte), 5 mM caproic acid (terminating electrolyte) and 20 mM caproic acid + 20 mM BALA + 0.1% HPMC (background electrolyte). A clear separation of the domoic acid from the other components of methanolic sample extract was achieved within 25 min. Method characteristics, i.e., linearity (0-200 microg/l), accuracy (recovery 101+/-3%), intra-assay repeatability (2.4%) and detection limit (1.5 microg/l) were determined. Speed of analysis, low laboriousness, high sensitivity and low running cost are the typical attributes of the cITP-CZE method. Developed method was successfully applied to analysis of shellfish samples and food supplements containing algae extract.

Capillary electrophoresis determination of carnitine in food supplements.

L-Carnitine is a substance natural for human body which transfers fatty acids to the place of burning-mitochondria and aids the transformation of fats into energy and this way supports overweight reduction and immediate physical performance, increases resistance from physical load and protect heart from overload. In this study are described newly developed electrophoretic methods (ITP, CZE with direct and/or indirect UV detection) for carnitine determination in various samples. The results were compared with results obtained by validated HPLC method. All of these methods gave comparable results. The detection limits of the electrophoretic methods were between 2.4 and 4.7 microg/ml, reproducibility (relative standard deviation, RSD%) was between 1.2 and 4.4% and recoveries were between 91 and 113% in different samples. The shorter analysis and low running cost are the main advantages of CE methods.