Lucia Zeleňáková

Detection of Listeria monocytogenes in ready-to-eat food by Step One real-time polymerase chain reaction

The aim of this study was to follow contamination of ready-to-eat food with Listeria monocytogenes by using the Step One real time polymerase chain reaction (PCR). We used the PrepSEQ Rapid Spin Sample Preparation Kit for isolation of DNA and MicroSEQ® Listeria monocytogenes Detection Kit for the real-time PCR performance. In 30 samples of ready-to-eat milk and meat products without incubation we detected strains of Listeria monocytogenes in five samples (swabs). Internal positive control (IPC) was positive in all samples. Our results indicated that the real-time PCR assay developed in this study could sensitively detect Listeria monocytogenes in ready-to-eat food without incubation.

Identification of sweet chesnut pollen in bee pollen pellet using using molecular analysis.

Castanea sativa posses many characteristics that are used by human for different purposes, not only as a part of the food. One of them is the utilization of the sweet chesnut pollen for its pharmacological benefits. Actually, no information about the DNA based identification of the sweet chesnut exist. Here, an identification of Castanea sativa based on the specific DNA fragment amplification is described for the first time. Sweet chesnut identification was performed in the very complex sample of bee pollen pellets that were identified as to contain sweet chesnut pollen grains by morphological analysis. First, bioinformatic analysis was performed to find a Castanea sativa conservative part of galactol synthase gene. BLAST alignment of the CDS of GolS1 gene was performed by BLASTtn against plants nucleotide sequences in the NCBI database to ensure for the specifity or existing nucleotide differences. Then, specific primers were subsequently designed and PCR amplification was performed. All the PCRs have run in duplicates for pollen pellet sample and two independent samples of Castanea sativa pure pollen. Restriction cleavage of the PCR amplified fragment was performed to confirm the specifity of the obtained PCR product with the positive confirmation as the predicted three restriction fragments were obtained that fully correspond by the length to those from virtual clevage. Restriction endonuclease Hpy166II was used in restriction cleavage analysis. Castanea sativa pollen grains were confirmed reliable in multifloral pollen pellet by PCR and this approach has the potential to be used effectively for the authentication purposes of sweet chesnut.

COMPARISON OF THE QUALITY OF VEGETABLE OILS DESIGNED FOR THE FRYING FOOD

The object of the research was to investigate the quality of vegetable oils for cooking food. The analysis used two types of oils - oil Fritol and Promienna. Both oils were purchased commercially. Oil changes were observed at frying French fries. At the same changes were observed oil stored at room temperature and the temperature in the refrigerator. The determined parameters included the measurement of polar materials in oil with electronic device Testo 265 for measuring the quality of cooking oil. Determination of change in the texture of oil during the oil deterioration by device Texturometer TA.XT Plus and determination the peroxide value by STN EN ISO 3960:2007. The work is also evaluating the results of the studied parameters. In all compared cases based on the content of the TPM showed higher heat resistance oil Fritol and sample of oil stored in the refrigerator. doi:10.5219/210

Effect of different reverse transcription aproaches in Pru p 3 transcripts semiquantitative amplification

Normal 0 21 false false false MicrosoftInternetExplorer4 Reverse transcriptase transcribes the cDNA based on its previous extraction and standardization. Reverse transcription step is considered to be critical in the workflow of quantification of transcribed genes. The aim of the study was to extract total RNA by different methods and to analyse the results of the subsequent reverse transcription reaction when different commercial RT kits were used to process RNA extracted from pulp of matured peach fruit. Mature peach pulp was used in the study. The fruit of variety Vistarich was collected in summer 2017 in the orchard of Dvory nad Žitavou. Two RNA extraction methods, TRIzol® Reagent and GeneJET Plant RNA Purification Kit, were tested in to determine the suitable method for peach fruit RNA extraction. Three different cDNA reagent sets were used to transcribe 115 ng/500 ng total RNA or 11 ng/115 ng, respectively. Both variants of the primers, random hexamers as well as oligo (dT) 18, were used to anneal the target mRNA of Pru p 3 allergen following the manufacturer instructions. No specific effect was obtained in the case of peach fruit when using ethanol-extracted tissue treatment and the effect of the used extraction method was more significant. The A260/230 ratios were similar for three from four tested methods. In the case of these three methods, the A260/A230 ratios for all the extracted samples were higher than 1.9 which indicates high purity without contamination by polyphenols and polysaccharides. The specificity of obtained amplicons was proved by restriction cleavage using Tse I restriction endonuclease. This provided the cleavage of the 179 bp long product in all amplicons. Working with mature fruit meet a specific situation in the field of RNA extraction and subsequently all the downstream applications. That is, why choosing the most fitting methods and kits is a crucial step. Here, the method for the semi-quantitative analysis of the Pru p 3 allergen expressions was set up in the way that will be directly applicable for Pru p 3 expression analyses.

Authentication of caprine milk and cheese by commercial qPCR assay

The objective of the study was to investigate potential adulteration of commercial caprine milks and cheeses with bovine milk using commercial qPCR assay. The assay comprised of bovine-, ovine- and caprine-specific primers and TaqMan probe and mammalian internal control. Specificity, sensitivity, linearity, reproducibility and efficiency of the bovine assay were tested as well. Specificity was verified by running reaction on the DNA of other milk-producing species (caprine and ovine) and made-up bovine-caprine (v/v) milk mixes. In both experiments, a bovine DNA fragment was amplified whereas no amplification was obtained from the other species. Sensitivity, linearity, reproducibility and efficiency were tested on 10-fold dilution series of 10 ng bovine DNA. The assay has shown good linearity (R 2 = 0.983) within whole range, with efficiency of 86% and excellent reproducibility (SD around the C T for the technical replicates <0.5). The sensitivity was adequate, as calculated LOD and LOQ were 1.44 pg and 2.94 pg of bovine DNA, respectively. Finally, the assay was used to authenticate 5 caprine milk samples and 5 caprine cheese samples, purchased from local supermarkets. Totally, 1 milk sample has shown the fluorescence signal, which exceeded baseline in cycle 39.01 ±0.69. However, the signal was above LOD and LOQ suggesting that there could not be unambiguously declared any adulteration with bovine milk. Amplification of bovine-specific DNA was not observed in the other samples indicating products were not adulterated. The commercial qPCR assay has proved that real-time PCR assays, as well as DNA-based techniques in a general, are the excellent and reliable tools for fighting with frauds in the food industry and protecting the public health. Normal 0 21 false false false SK X-NONE X-NONE

Selected parameters of quality and safety of herbal tea.

The aim of this work was to assess the heavy metal presence and possible microbiological contamination in herbal teas. Evaluation of selected tea products was performed from Nitra locality during years 2009 - 2013. Microscopic filamentous fungi detection, bacteria such as Escherichia coli and Salmonella spp . were compared to requirements given in the Codex Alimentarius of Slovakia. The highest permissible limit for microscopic filamentous fungi was not exceeded (in 32 observed herbal tea samples). For incidence of Escherichia coli, 93 samples were investigated and for Salmonella spp ., 91 herbal tea samples. No sample showed the presence of Salmonella spp., and at E. coli maximum permitted presence was detected below limit. Among chemical parameters, cadmium, lead and mercury content were monitored. The highest amount of lead and mercury was found in year 2012. In 2009, the highest cadmium content was found. The average content of lead in all 100 inspected herbal tea samples was 0.784 mg.kg -1 so all the samples met requirements defined in the legislation. The mean content of mercury (98 investigated herbal tea samples) was 0.0161 mg.kg -1 so all samples met the requirements as well. Average cadmium content was 0.1702 mg.kg -1 while the highest permitted limit for cadmium is 1.0 mg.kg -1 . All herbal tea samples were in accordance with the legislation except one (white willow bark tea) with a very high content of cadmium (4.36 mg.kg -1 ).

ANALYSIS OF SELECTED DETERMINANTS OF ALIMENTATION HYGIENE OF SCHOOL CHILDREN

The aim of the work was an analysis of nutriotion and hygienic habits of students while staying at school as well as analysis of catering hygiene in the school catering establishment. Method for obtaining information, a questionnaire was developed for this purpose (355 respondents, aged 7 – 15 years). We have focused on the awareness of the issues of healthy nutrition, the observance of the principles of personal hygiene, prioritising certain dishes and drinks, the food, the overall level of quality of the knowledge of the risk and the overall level of hygiene of catering in the school meals catering establishment. The results have shown that it is necessary to increase the awareness and education in the areas of healthy eating and hygiene principles and achieve the mutual cooperation of students, families, and schools. doi:10.5219/211

EXAMINATION OF FACTORS INFLUENCING THE VARIABILITY OF YEAST AMOUNT IN THE CONTEXT OF PH CHANGES IN BOTTLED WINES

Aim of this paper was to examine of factors ( manufacturer, temperature and storage time ) influencing the variability of yeast amount and pH changes in bottled white wines. It was confirmed that wine coming f rom the business network was better quality in contract to domestic wine. We have assumed that domestic wine was contaminated during the manufacturing process, while the most probable reason was imperfect filtration of wine, or its contamination during the bottling. The results showed that the way of storage wine in the room , resp. cooler temperature did not significant effect on changes in the amount of yeast (p-hodnota=0.2080). Regarding the period of storage of wine , the conclusions are identical to the previous factor , ie . storage time not significantly impacted amount of yeast in wine ( p - value =0.5507 ). doi:10.5219/151

VERIFICATION OF THE FOOD SAFETY MANAGEMENT SYSTEM IN DEEP FROZEN FOOD PRODUCTION PLANT

In work is presented verification of food safety management system of deep frozen food. Main emphasis is on creating set of verification questions within articles of standard STN EN ISO 22000:2006 and on searching of effectiveness in food safety management system. Information were acquired from scientific literature sources and they pointed out importance of implementation and upkeep of effective food safety management system. doi:10.5219/28