Microbiological evaluation of poultry sausages stored at different temperatures

The aim of our study was to evaluate the microbiological quality of poultry sausages, which were stored at different temperatures (4 °C, 15 °C). Total count of bacteria, coliform bacteria, yeasts and filamentous microscopic fungi were detected in poultry sausages. Microbiological quality was evaluated using the horizontal method for the determination number of microorganisms. Total count of bacteria in sausages stored at 4 °C ranged from 1 × 101 CFU.g-1 in sample 1 (after opening) to 4.35 × 104 CFU.g-1  in sample 1 (7th day of storage). Total count of bacteria in sausages stored at 15 °C ranged from 3.25 × 103 CFU.g-1 in sample 1 (after opening) to 3.12 × 106 CFU.g-1 in sample 1 to 3.12 × 106  CFU.g-1 in sample 1 (7th day of storage).  Coliform bacteria in sausages stored at 4 °C ranged from 1 × 101 CFU.g-1 to 3.15 × 105 CFU.g-1. Coliform bacteria in sausages stored at 15 °C ranged from 1.54 × 103 CFU.g-1 to 1.40 × 106 CFU.g-1.  Yeasts and microscopic filamentous fungi in sausages stored at 4 °C ranged from 2.75 × 104 CFU.g-1 to 1.40 × 106 CFU.g-1.  Yeasts and microscopic filamentous fungi in sausages stored at 15 °C ranged from 1.30 × 104 CFU.g-1 to 1.44 × 106  CFU.g-1. Total count of bacteria, coliform bacteria, yeast and microscopic fungi were not in accordance with Codex Alimentarius of Slovak Republic on 3rd day in samples stored at 15 °C

Evaluation of microbiological quality of selected cheeses during storage

The aim of this article was to evaluate and compare the microbiological quality of selected types of cheeses immediately after opening and after 5 days storage in the refrigerator. Total viable counts (TVC), coliform bacteria (CB) and microscopic filamentous fungi (MFF) were determined by microbiological analysis. We analyzed 8 samples of cheese of Slovak origin. Plate dilution method was used for microbiological analysis. The Codex Alimentarius of Slovak republic (2006) just indicates number of coliforms bacteria (102) and microscopic fungi (5 × 102). The TVC values after opening of cheeses ranged from 1.68 × 103 CFU.g-1 (3.22 log CFU.g-1) in the sample no. 1 to 1.71 × 105 KTJ.g-1 (5.23 log CFU.g-1) in the sample no. 4 after storage in the refrigerator. All samples were negative for the presence of coliform bacteria after opening. The values of CB were 1.18 × 102 CFU.g-1 (2.07 log CFU.g-1) in sample no. 7 and 1.90 × 102 CFU.g-1 (2.27 log CFU.g-1) in the sample no. 8 after storage in refrigerator. These values are not in accordance with Codex Alimentarius of Slovak Republic (2006). Other samples were negative for presence of CB after storage at 4 °C. The values of MFF in samplesranged from 1.81 × 101 CFU.g-1 (1.25 log CFU.g-1) in the sample no. 1 after opening to 1.68 × 102 CFU.g-1 (2.22 log CFU.g-1) in sample no. 7 after storage of samples. All analysed samples were in accordance with Codex Alimentarius of Slovak republic (2006).

Influence of meat maturation to the presence of coliform bacteria

The aim of our study was detection of coliforms bacteria and pH changes in the process of beef maturation. The number of coliforms bacteria were lower as 1 log cfu.g-1 in four samples and the highest coliforms bacteria count was 3.1 log cfu.g-1 after 1-st week of meat maturation. Average number of coliforms bacteria was lower as 1.43 log cfu.g-1.  The pH values of meat varied from 5.5 to 6.1 after 1-st week. Average value of pH was 5.75.  The number of coliforms bacteria were from 2.61 log cfu.g-1 to 3.35 log cfu.g-1after 2-nd week of meat maturation. Average number of coliforms bacteria was 3.17 log cfu.g-1. The pH values of meat were from 6.0 to 6.2 after 2-nd week of meat maturation. Average value of pH was 6.05.

The prevalence of Salmonella infections in laying hen flocks producing eggs and their impact on the public health

Since 2008, Slovakia has implemented the National control program of Salmonella infections in laying hen flocks. This program requires the farm operators to monitor and investigate the invasive types of Salmonella (S. Enteritidis and S. Typhimurium) according to STN ISO 6579. The aim of this study was to perform a microbiological examination of dust and chicken droppings samples of laying hens in the Trenčín region for the presence of Salmonella by Horizontal method according to STN ISO 6579: 2002, to compare results with the statistics across Slovakia and selected EU countries and to evaluate the impact of official controls of salmonellosis in animals and humans.  In the years 2009 - 2013 in the Trenčín region, 730 samples of dust from the conveyor belts and droppings of laying hens were taken to determine the prevalence of Salmonella in individual rearings. In these years, the incidence of positive samples was found from 0% to 29.17%. For the period from 2009 till 2013 was reported 22833 salmonellosis cases in human population of Slovakia, while in the Trenčín region it was 2636. Five-year EU-trend (2009 - 2013) showed a statistically significant decrease of salmonellosis occurence (with a mean reduction of 12% per year). The Wilcoxon signed-rank test was performed in order to provide in-depth epidemiological assessment of salmonellosis cases in Trenčin region in relation to selected characters: etiological agens, transmission mechanism, age, location as well as seasonality of infection

Microbiological quality of fresh and heat treated cow's milk during storage

The aim of the present study was to evaluate the microbiological quality of raw milk from milk vending machine and heat treated milk during storage. There were analyzed 120 samples of milk (30 samples of fresh milk, 30 samples of raw milk stored 4 day at 4 °C, 30 samples of heat treated milk - 70 °C  stored 4 day at 4 °C and 30 samples of heat treated milk - 100 °C stored 4 day at 4 °C). Total viable counts (TVC), coliform bacteria (CB) and microscopic filamentous fungi (MFF) were determined by microbiological analysis. Plate dilution method were used for microbiological analysis. The number of total viable counts (TVC) in fresh milk ranged from 4.08 log KTJ.mL-1 to 4.89 CFU.mL-1. TVC in raw milk after storage ranged from 5.31 log CFU.mL-1 to 6.81 log CFU.mL-1. TVC in heat treated milk with temperature 70 °C after storage ranged from 3.89 log CFU.mL-1 to 4.45 log CFU.mL-1 and TVC in heat treated milk with temperature 100 °C after storage ranged from 2.96 log KTJ.mL-1 to 3.91 log KTJ.mL-1 in heat treated milk with temperature 100 °C after storage. The number of CB were in range from 1.49 log CFU.mL-1 to 1.89 log CFU.mL-1 in fresh milk, from 1.99 log CFU.mL-1 to 2.61 log CFU.mL-1 in raw stored milk. Coliform bacteria were not present in heat-treated milk samples. The values of MFF ranged from 0 log CFU.mL-1 to 2.01 log CFU.mL-1 in fresh milk, from 1.43 log CFU.mL-1 to 3.98 log CFU.mL-1 in raw milk after storage, from 1.33 log CFU.mL-1 to 3.41 log CFU.mL-1 in heat treated milk with temperature 70 °C after storage and from 1.30 log CFU.mL-1 to 3.32 log CFU.mL-1 in heat treated milk with temperature 100 °C after storage

Microbiological quality of chicken breast meat after application of thyme and caraway essential oils

The aim of the present study was to evaluate the effect of selected types of antimicrobial essential oils to the various groups of microorganisms during storage of chicken meat. The samples of chicken breast meat were used in the experiment. The number of lactobacilli, Pseudomonas spp., anaerobic plate count and Enterobacteriaceae after application of caraway and thyme essential oils (EO) at concentration 1% v/w in a combination with the ethylenediaminetetraacetate (EDTA) solution 1.5% w/w and vacuum packaging were evaluated. The samples were analyzed at 0, 4th, 8th, 12th and 16th day of storage of chicken meat at temperature 4 °C. Another aim was to determine the species of isolated microorganisms from samples of chicken meat by MALDI-TOF MS Biotyper (matrix assisted laser desorption ionization-time of flight mass spectrometry). The number of Lactobalillus spp. ranged from 1.35 log CFU.g-1 in all groups to 3.04 log CFU.g-1 on 0th day to 3.04 log CFU.g-1 on 4th day in control group stored in air. The Pseudomonas spp. was not found in all tested samples at the start of the experiment, the highest number of Pseudomonas spp. was in the control group on 16th day (2.68 log CFU.g-1). Presence of Pseudomonas spp. were not found during storage in groups after treatment with caraway and thyme EO. The values of anaerobic plate count ranged from 2.81 log CFU.g-1 on 4th day in control group with vacuum packaging to 5.19 log CFU.g-1 on 16th day in control group in air condition. The Enterobacteriaceae was not found in all tested samples on 0th day and ranged to 4.46 log CFU.g-1 on 12th day in control group in air condition. From Lactobacillus spp., the most often identified species was Lactobacillus paracasei, from genus Pseudomonas, there were identified Pseudomonas fluorescens in two cases. From anaerobic plate count, there were isolated Staphylococcus warneri from control goup stored in air condition, Kocuria rhizophila from control group with vacuum packaging, Staphylococcus warneri, Aeromonas salmonicida and Aeromonas popoffii from control group treated with EDTA, Staphylococcus hominis and Staphylococcus epidermidis from group treated with caraway essential oil.  From Enterobacteriaceae, the most bacteria were isolated from control group in air condition and from control group treated with EDTA

Thermo-degradative changes of rapeseed and sunflower oils during deep-frying French fries

The purpose of this study was to investigate changes in TPCs, acid value and peroxide value as well as fatty acids composition in edible oils during french fries production. Lower TPCs content was found in rapeseed oil (3.3%) and the threshold (24%) was achieved on the fourth day. The total time for the deterioration of deep-frying rapeseed oil was 23½ hours. On the contrary, in fresh sunflower oil at the first day was TPCs content 5.5% and the limit of 24% was reached on the third day. The total time for the deterioration of deep-frying sunflower oil was 17½ hours. The results indicated significant differences (<0.05) in TPCs content between rapeseed and sunflower oils during deep-frying process. At the beginning of deep-frying French fries in rapeseed oil, the acid number was 0.374 mg KOH.g-1 and 1.271 mg KOH.g-1 at the fourth day of deep-frying. The measured peroxide value was 4.3 mEq O2.kg-1 at the beginning and at the end of deep-frying 10.5 mEq O2.kg-1. The initial peroxide and acid values were higher in sunflower oil compared with rapeseed oil, respectively. It should be note, then the acid values and peroxide values, respectively, in the two fresh oils used in this study were below the limit of refined oil according to Slovak legislation (peroxide value - not more than 10 mEq O2.kg-1, acid value - not more than 0.6 mg KOH.g-1). However, detected values varied during deep-frying process. Monounsaturated fatty acids were predominantly observed in fresh rapeseed oil (61.22%) wherever in sunflower oil they were much lower (29.77%). A slight increase of MUFA was found in both oils. The initial content of saturated fatty acids in rapeseed oil was 6.94%, in fresh sunflower oil was observed slightly higher content of SFA (10.37%). The major groups of fatty acids in fresh sunflower oil were polyunsaturated fatty acids (PUFA) which have in principle a significant effect on oil deterioration. A slight decrease of PUFA was observed in both oils throughout the frying period. The content of PUFA was reduced by about 9.42% in rapeseed oil and by 10.8% in sunflower oil. The initial content was 28.14% and 58.91%, respectively

The extension of shelf-life of chicken meat after application of caraway and anise essential oils and vacuum packaging

The effect of caraway (CEO) and anise (AEO) essential oils as well as vacuum packaging (VP) in extending of the shelf life of fresh chicken breast meat stored at 4 °C was investigated. CEO and AEO were used at concentrations 0.2% v/w with and without VP. Microbiological properties of chicken breast meat were monitored over a 16 day period. The microbiological parameters as the anaerobic plate count (AC), Enterobacteraceae, lactic acid bacteria and Pseudomonas spp. counts were detected. The anaerobic plate counts ranged from 2.77 log cfu.g-1 in all tested group on 0 day to 5.45 log cfu.g-1 on 16 day in control group stored in air condition. The number of lactic acid bacteria ranged from 3.20 log cfu.g-1 in all tested group on 0 day to 4.75 log cfu.g-1 on 16 day in control group stored in air condition. Enterobacteriaceae counts ranged from 0.00 to 4.25 log cfu.g-1on 16 day in control group stored in air condition. The number of Pseudomonas spp. ranged from 0.00 log cfu.g-1 in all tested group on 0 day to 2.65 log cfu.g-1 on 16 day in control group stored in air condition. Statistically significant differences (P≤0.001) were found among tested group in all tested microorganisms. Among the antimicrobial combination treatments were examined in the study, the as application of vacuum packaging, EDTA, and essential oils were the most effective against the growth of lactic acid bacteria and Enterobactericeae and to a less extent on anaerobic plate count. The results of this present study suggest the possibility of using the essential oil of caraway and anise as natural food preservatives and potential source of antimicrobial ingredients for chicken breast meat

Application of lavender and rosemary essential oils improvement of the microbiological quality of chicken quarters

The aim of the present work was monitoring of chicken quarters microbiological indicators after treatment by ethylenediaminetetraacetate (EDTA), lavender (Lavandula angustifolia L.) and rosemary (Rosmarinus officinalis L.) essential oil, stored under vacuum packaging, at 4 ±0.5°C for a period of 16 days. The following treatments of chicken quarters were used: Air-packaging control samples, control vacuum-packaging samples, vacuum-packaging with EDTA solution 1.50% w/w, control samples, vacuum-packaging with Lavandula angustifolia essential oil at concentrations 0.2% v/w and vacuum-packaging with Rosmarinus officinalis essential oil at concentration 0.2% v/w. The quality assessment of all samples was established by microbiological analysis. Sampling was carried out after certain time intervals: 0, 4, 8, 12 and 16 days. Chicken quarters were stored under vacuum packaging, at 4 ±0.5°C during experiment. Microbiological analyses were conducted by using standard microbiological methods. Anaerobic plate count were determined using Plate Count Agar, after incubation for 2 days at 35°C under anaerobic condition. Pseudomonas spp. were determined on Pseudomonas Isolation agar after incubation at 48 h at 25°C. For lactic acid bacteria were inoculated into Rogosa and Sharpe agar after incubation 48-78 h at 37°C in an aerobic atmosphere supplemented with carbon dioxide (5% CO2). For members of the family Enterobacteriaceae violet red bile glucose agar were used and samples were incubated at 37°C for 24 h. The initial APC value of chicken quarter was 3.00 log CFU.g-1 on 0 day. The number of anaerobic plate count ranged from 3.00 log CFU.g-1 in all tested group on 0 day to 6.11 log CFU.g-1 on 16 day in control group stored in air condition. The initial LAC value of chicken quarter was 3.00 log CFU.g-1 on 0 day. The number of lactic acid bacteria ranged from 3.00 log CFU.g-1 in all tested group on 0 day to 3.58 log CFU.g-1 on 16 day in control group stored in air condition. The initial Enterobacteriacea genera value of chicken quarter was 2.00 log CFU.g-1 on 0 day. Presences of these bacteria were found on all groups at 16 days. The results of this present study suggest the possibility of application the Lavandula angustifolia and Rosmarinus officinalis essential oil as natural food preservatives and potential sources of antimicrobial ingredients for food industry.

Identification of the Slovak traditional cheese “Parenica” microflora

Numerous studies have demonstrated the higher accuracy, faster time-to-results and lower costs provided by MALDI Biotyper systems compared to classical methods. In this study, the culturable population of total count of bacteria, enterococci, coliforms bacteria, lactic acid bacteria (LAB) and microscopic fungi and yeasts from cow’s dairy products was identified using the MALDI-TOF MS Biotyper. Altogether, 50 samples of the Slovak cheese “Parenica” were examined. Total numbers of bacteria were cultured on Plate count agar at 37 °C for 24–48 h, aerobically; enterococci were cultured on Enterococcus selective agar at 37 °C for 24–48 h, aerobically; coliforms bacteria were cultured on Violet Red Bile lactose agar at 37 °C for 24–48 h, aerobically. The LAB were cultured on MRS (Main Rogosa agar), MSE and APT agar at 30 °C in microaerophilic conditions. The microscopic fungi and yeasts were cultured on Malt extract agar at 25 °C for 5 days, aerobically. Isolated strains (total 669) were subjected to identification by the MALDI-TOF MS. Among total count the identified bacteria mostly were Acinetobacter baumannii, Bacillus cereus, Micrococcus luteus and Staphylococcus warneri. Escherichia coli and Enterobacter cloacae were the most abundant coliform bacteria representatives identified. Coliform bacteria included Citrobacter, Hafnia and Klebsiella. Altogether three genera belonged to the LAB – Lactobacillus, Lactococcus and Leuconostoc were identified with Lactococcus lactis, Lactobacillus plantarum, Lactobacillus coryniformis, L. fructivorans and Leuconostoc mesenteroides were considered as the dominated LAB species in dairy products. Among yeasts, Kluyveromyces lactis, Candida zeylanoides and Yarrowia lipolytica were among the most isolated