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Yersiniosis, one of the leading foodborne infections in the European Union, is caused by Yersinia enterocolitica. In this study, the antibacterial and antibiofilm effects of cinnamon (Cinnamomum zeylanicum Nees), clove (Syzygium aromaticum L.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and winter savory (Satureja montana L.) essential oils were investigated against Y. enterocolitica strains belonging to the bioserotype 4/O:3. Cinnamon essential oil showed the highest antibacterial activity, with an MIC value 0.09 µL/mL, followed by oregano and thyme essential oils, with MIC values from 0.09 to 0.18 µL/mL, and from 0.18 to 0.23 µL/mL, respectively. Thyme essential oil at 0.23 µL/g (MIC) and at 0.46 µL/g (2MIC) significantly (p < 0.05) reduced the number of Y. enterocolitica by 0.38 log CFU/g and 0.64 log CFU/g, respectively, in minced pork meat during storage at 4 °C for 4 days. The Y. enterocolitica strains formed biofilms at 15 °C and 37 °C in tryptic soy broth and Luria–Bertani broth, while no biofilms were obtained at 5 °C, and in meat broth nutrient media. Applying the minimum bactericidal concentrations of cinnamon, clove, oregano, rosemary, thyme, and winter savory essential oils on preformed biofilms led to significant reductions being observed in the range from 45.34% to 78.89%. A scanning electron microscopy assay showed the devastating impact of oregano and thyme essential oils on the morphology of Y. enterocolitica bacterial cells. In conclusion, the results of this study show that essential oils possess high anti-Yersinia and antibiofilm effects. [ABSTRACT FROM AUTHOR]

The composition of 18 essential oils was determined using gas chromatography–mass spectrometry, and their antilisterial activity was evaluated by the disk diffusion method, followed by the determination of the minimum inhibitory and minimum bactericidal concentrations. The most active essential oils were oregano, thyme, cinnamon, winter savory, and clove, with MIC values ranging from 0.09 to 1.78 µL/mL. We investigated the biofilm-forming potential of Listeria monocytogenes on polystyrene at 5 °C, 15 °C, and 37 °C in three different media. The formation of biofilm was found to be dependent on the temperature and the availability of nutrients. After treatment with selected essential oils, the reduction in biofilm biomass was in the range of 32.61% and 78.62%. Micromorphological changes in the L. monocytogenes treated by oregano and thyme essential oils were observed in the form of impaired cell integrity and cell lyses by using scanning electron microscope. Oregano and thyme essential oils (MIC and 2MIC) significantly (p < 0.05) reduced the population of L. monocytogenes in minced pork meat during storage at 4 °C. In conclusion, the obtained results indicated the good activity of some selected essential oils on L. monocytogenes, with bacteriostatic, bactericidal, and antibiofilm effects at very low concentrations. [ABSTRACT FROM AUTHOR]

Yersiniosis, one of the leading foodborne infections in the European Union, is caused by Yersinia enterocolitica. In this study, the antibacterial and antibiofilm effects of cinnamon (Cinnamomum zeylanicum Nees), clove (Syzygium aromaticum L.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and winter savory (Satureja montana L.) essential oils were investigated against Y. enterocolitica strains belonging to the bioserotype 4/O:3. Cinnamon essential oil showed the highest antibacterial activity, with an MIC value 0.09 µL/mL, followed by oregano and thyme essential oils, with MIC values from 0.09 to 0.18 µL/mL, and from 0.18 to 0.23 µL/mL, respectively. Thyme essential oil at 0.23 µL/g (MIC) and at 0.46 µL/g (2MIC) significantly (p < 0.05) reduced the number of Y. enterocolitica by 0.38 log CFU/g and 0.64 log CFU/g, respectively, in minced pork meat during storage at 4 °C for 4 days. The Y. enterocolitica strains formed biofilms at 15 °C and 37 °C in tryptic soy broth and Luria–Bertani broth, while no biofilms were obtained at 5 °C, and in meat broth nutrient media. Applying the minimum bactericidal concentrations of cinnamon, clove, oregano, rosemary, thyme, and winter savory essential oils on preformed biofilms led to significant reductions being observed in the range from 45.34% to 78.89%. A scanning electron microscopy assay showed the devastating impact of oregano and thyme essential oils on the morphology of Y. enterocolitica bacterial cells. In conclusion, the results of this study show that essential oils possess high anti-Yersinia and antibiofilm effects.

The composition of 18 essential oils was determined using gas chromatography–mass spectrometry, and their antilisterial activity was evaluated by the disk diffusion method, followed by the determination of the minimum inhibitory and minimum bactericidal concentrations. The most active essential oils were oregano, thyme, cinnamon, winter savory, and clove, with MIC values ranging from 0.09 to 1.78 µL/mL. We investigated the biofilm-forming potential of Listeria monocytogenes on polystyrene at 5 °C, 15 °C, and 37 °C in three different media. The formation of biofilm was found to be dependent on the temperature and the availability of nutrients. After treatment with selected essential oils, the reduction in biofilm biomass was in the range of 32.61% and 78.62%. Micromorphological changes in the L. monocytogenes treated by oregano and thyme essential oils were observed in the form of impaired cell integrity and cell lyses by using scanning electron microscope. Oregano and thyme essential oils (MIC and 2MIC) significantly (p < 0.05) reduced the population of L. monocytogenes in minced pork meat during storage at 4 °C. In conclusion, the obtained results indicated the good activity of some selected essential oils on L. monocytogenes, with bacteriostatic, bactericidal, and antibiofilm effects at very low concentrations.

Hepatitis E virus (HEV) is a causative agent of acute hepatitis throughout the world. HEV genotypes 1 through 4 infect humans, whereas genotypes 3 and 4 (Gt3 and Gt4) also infect other animals. In developed countries, the main HEV infection route is by foodborne transmission, resulting from the consumption of undercooked meat. It is important to know the criteria for HEV control in daily cooking. In this study, we assessed the heat conditions required to inactivate HEV Gt3 and Gt4 in culture supernatants and spiked minced pork meat. HEV inactivation was determined by measuring viral RNA amplification in PLC/PRF/5 cell culture. In our cell culture assay, an inoculum containing HEV titer that is equivalent to >105 genome RNA copies can be determined as infectious. The internal temperature of pork during heating was measured to represent that achieved during cooking. Both HEV Gt3 and Gt4 were inactivated in culture supernatants heated at >65°C for 5 min and at >80°C for 1 min and in minced meat at 70°C for 5 min. Inoculated culture supernatant contained 108 HEV genome RNA copies (103 infectious units [IU]); therefore, it was indicated that HEV titer decreased >3 log IU after heating. In a comparison of Gt3 and Gt4, Gt4 showed slightly greater heat stability than Gt3. Boiling showed superior heating efficacy compared with roasting, and pork liver was slightly easier to heat than pork loin. Heating for 5 min by both boiling and roasting increased the internal temperature of pork products to more than 70°C. Although our data revealed that HEV Gt4 was slightly more heat stable than Gt3, both genotypes were inactivated by the appropriate heating conditions. Therefore, the risk of HEV foodborne infection could be mitigated by the appropriate cooking of pork meat. It is also important that both the supplier and the consumer are cognizant of the risk of HEV foodborne infection from livestock products. [ABSTRACT FROM AUTHOR]

In this study, the infl uence of lactic acid fermentation on the quality of tomato powder was evaluated. The eff ect of adding fermented tomato powder to ready-to-cook minced pork meat to improve its nutritional value and sensory characteristics was also analysed. The cell growth of Lactobacillus sakei (7.53 log CFU/g) was more intense in the medium containing tomato powder, compared to the growth of Pediococcus pentosaceus (6.35 log CFU/g) during 24 h of fermentation; however, higher acidity (pH=4.1) was observed in the tomato powder samples fermented with Pediococcus pentosaceus. The spontaneous fermentation of tomato powder reduced cell growth by 38 % and pH values slightly increased to 4.17, compared to the fermentation with pure LAB. The lactofermentation of tomato powder increased the average β-carotene and lycopene mass fractions by 43.9 and 50.2 %, respectively, compared with the nonfermented samples. Lycopene and β-carotene contents in the ready-to-cook minced pork meat were proportional to the added tomato powder (10 and 30 %). Aft er cooking, β-carotene and lycopene contents decreased, on average, by 24.2 and 41.2 %, respectively. The highest loss (up to 49.2 %) of carotenoids was found in samples with 30 % nonfermented tomato powder. Tomato powder fermented with 10 % Lactobacillus sakei KTU05-6 can be recommended as both a colouring agent and a source of lycopene in the preparation of ready-to-cook minced pork meat.

The aim of this study was to evaluate the effectiveness of different packaging conditions (vacuum and modified atmosphere) on the microbiological status (total viable count, lactic acid bacteria and Enterobacteriaceae), total volatile basic nitrogen (TVB-N) and pH in minced pork meat. Pork mince was packaged in vacuum, modified atmosphere with 20% O2, 50% CO2 and 30% N2 (MAP 1) or modified atmosphere with 20% O2, 30% CO2 and 50% N2 (MAP 2), refrigerated at 3±1°C and examined on the days 0, 3, 6, 9 and 12 of storage. The average total viable counts and total Enterobacteriaceae counts in vacuum packaged mince were statistically significantly higher (p<0.01; p<0.05) than in modified atmosphere packaged mince with both combinations of gases, on different days of storage. The largest decrease of total viable count and Enterobacteriaceae count was noted in modified atmosphere packaged mince with the higher concentration (50%) of CO2. [ABSTRACT FROM AUTHOR]

In this study, the antioxidant activity of edible polysaccharides such as alginic acid, chitosan and pectin were estimated using four antioxidant assay systems: 2,2-diphenyl-l-picrylhydrazyl (DPPH) free radical scavenging, ferric ion reducing activity power (FRAP), oxygen radical absorbance capacity (ORAC) assays, in minced pork meat as the storage test. Alginic acid had the strongest antioxidant ability to scavenge free radicals and reduce ferrous ion among all polysaccharides tested. Alginic acid inhibited the production of hydroperoxides and secondary oxidation products of lipids in minced pork meats during storage. [ABSTRACT FROM AUTHOR]

The nutritional strategies to improve the quality of food products of animal origin are relatively new approach. In this work the solid state fermentation (SSF) and traditional submerged fermentation (TF) with bacteriocin-like inhibitory substances (BLIS) producing lactic acid bacteria was applied for treatment of Satureja montana L. plants (SMP). The effect of fermented SMP additives on ready-to-cook minced pork (RCMP) quality and safety was studied. Viability of LAB in SMP medium significantly ( p < 0.05) depended on type of fermentation (TF and SSF). Supplementation of RCMP with SSF SMP reduced the growth of mesophilic bacteria up to 34 % during 120 h storage, while TF SMP additives had lower effect (up to 17.4 %) compared to control sample. The highest antimicrobial activity against pathogens showed SSF SMP additives fermented with P. acidilactici. Sensory analysis indicated the significant ( p < 0.05) acceptability increase of RCMP prepared with 3 % SSF SMP additives. The addition of SMP increased tenderness and water holding capacity and enriched the RCMP with biologically active compounds such as ρ-cimene, γ-terpinene and carvacrol. Both types of SMP fermented with tested LAB strains influenced the significant ( p < 0.05) reduction of total biogenic amines in the RCMP (to 0.3 mg/kg d.w.) compared to control sample (43.96 mg/kg d.w.). SMP fermented with BLIS producing LAB could be a good alternative for RCMP processing to prevent meat decolouration and microbial spoilage, thus increasing acceptability and shelf-life of meat products. [ABSTRACT FROM AUTHOR]

In this study, the influence of lactic acid fermentation on the quality of tomato powder was evaluated. The effect of adding fermented tomato powder to ready-to-cook minced pork meat to improve its nutritional value and sensory characteristics was also analysed. The cell growth of Lactobacillus sakei (7.53 log CFU/g) was more intense in the medium containing tomato powder, compared to the growth of Pediococcus pentosaceus (6.35 log CFU/g) during 24 h of fermentation; however, higher acidity (pH=4.1) was observed in the tomato powder samples fermented with Pediococcus pentosaceus. The spontaneous fermentation of tomato powder reduced cell growth by 38 % and pH values slightly increased to 4.17, compared to the fermentation with pure LAB. The lactofermentation of tomato powder increased the average β-carotene and lycopene mass fractions by 43.9 and 50.2 %, respectively, compared with the nonfermented samples. Lycopene and β-carotene contents in the ready-to-cook minced pork meat were proportional to the added tomato powder (10 and 30 %). After cooking, β-carotene and lycopene contents decreased, on average, by 24.2 and 41.2 %, respectively. The highest loss (up to 49.2 %) of carotenoids was found in samples with 30 % nonfermented tomato powder. Tomato powder fermented with 10 % Lactobacillus sakei KTU05-6 can be recommended as both a colouring agent and a source of lycopene in the preparation of ready-to-cook minced pork meat. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work was to investigate the feasibility of Fourier transform infrared (FTIR) spectroscopy to quantify biochemical changes occurring in fresh minced pork meat in the attempt to monitor spoilage. For this reason, partial least squares (PLS) models were constructed to correlate spectral data from FTIR with minced pork meat spoilage during aerobic storage of meat samples at different storage temperatures (0, 5, 10, and 15°C). Spectral data were collected from the surface of meat samples in parallel with microbiological analysis to enumerate the population of total viable counts, Pseudomonas spp., Brochothrix thermosphacta, lactic acid bacteria and Enterobacteriaceae. Qualitative interpretation of spectral data was based on sensory evaluation, using a three point hedonic scale, discriminating meat samples in three quality classes, namely fresh, semi-fresh and spoiled. The purpose of the developed models was to classify minced pork samples in the respective quality class, and also to correlate the population dynamics of the microbial association with FTIR spectra. The obtained results demonstrated good performance in classifying meat samples in one of the three pre-defined sensory classes. The overall correct classification rate for the three sensory classes was 94.0% and 88.1% during model calibration and validation, respectively. Furthermore, PLS regression models were also employed to provide quantitative estimations of microbial counts during meat storage. The performance was based on graphical plots and statistical indices (bias factor, accuracy factor, standard error of calibration, standard error of prediction, and correlation coefficient). The values of the bias factor were close to unity for all microbial groups indicating no systematic bias of the models. Moreover, the calculated values of the accuracy factor showed that the average deviation between predictions and observations was 7.5% and 7.9% for total viable counts and Pseudomonas spp. and 10.7% and 11.3% for lactic acid bacteria and B. thermosphacta. Finally, correlations above 0.80 between observed and estimated counts were observed for both training and test data sets. [Copyright &y& Elsevier]