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The effect of high pressure processing (300 and 600 MPa) combined with mild heat treatment (55 and 75 °C) on the colour parameters, anthocyanin content, and sensory characteristics of strawberry puree were examined after the treatments and 2 weeks of cold storage at 2 and 15 °C. As on an industrial scale the simultaneous implementation of these treatments remains a challenge, the HHP and heat treatments were carried out consecutively in different sequences. The colour parameters and the anthocyanin content did not change significantly due to the treatments, but decreased during cold storage, at 15 °C storage the changes were more intensive than at 2 °C. Regarding the sensory test results, the different sequence of the 600 MPa-75 °C combined treatments is not detectable even after 2 weeks of storage at 15 °C, but in case of 300 MPa-55 °C, the enzyme inactivation is probably not sufficient enough as differences between the samples were detected.

Micro-organisms can attach to food surfaces and develop biofilms which present a concern in food and environmental safety. The main goal of the current study was to investigate the biofilm formation of six non-pathogenic Listeria strains under different stress conditions using a microplate assay. The effect of the weak biofilm-forming non-pathogenic Listeria strains on the biofilm formation of a strong biofilm-forming pathogenic Listeria strain (Listeria monocytogenes #8) was also examined. Listeria innocua CCM4030, Listeria innocua 2885 and Listeria seeligeri/welshimeri 292 showed the same patterns of biofilm formation with increasing NaCl concentrations from 0.05 to 15%, but all the other strains showed a continuously decreasing trend of OD595 in the same conditions. This study showed that in the case of non-pathogenic Listeria strains, higher concentrations of NaCl do not present a stress condition that enhances biofilm formation. Decrease in pH inhibited biofilm formation for all the non-pathogenic Listeria strains. The weak biofilm forming non-pathogenic Listeria strains (Listeria innocua 2885 and Listeria innocua CCM4030) overgrew the strong biofilm-forming Listeria strain (Listeria monocytogenes #8) during biofilm formation. This phenomenon could be beneficial and potentially be used as a novel control strategy to prevent the colonization of the pathogenic Listeria at food processing facilities such as in meat industry.

This work aimed to study the antimicrobial activity of eight various components of plant origin on the growth of Pseudomonas lundensis and Listeria monocytogenes. Different in vitro methods were used: agar plate diffusion, micro atmosphere, agar hole diffusion, micro-dilution, and gradient-plate method. In the first agar plate assay, p-cymene and γ-terpinene did not inhibit the growth of the tested bacteria therefore they were not used in further experiments. Both α-pinene and limonene were only partially effective, but these were screened only for their partial inhibition. The other four components completely inhibited the growth of the tested bacteria. Using the agar-well diffusion method showed that carvacrol and thymol were found to be the most effective active components, thymol had minimum inhibitory concentration (MIC) at 1.563 mg/mL, however, in the case of carvacrol, MIC was 7.813 μL/mL. Additionally, eugenol and camphor show the same results but in higher concentrations. Gradient plate method was used to determine MIC values, in which it has been proved that carvacrol and thymol possess strong antimicrobial activity, no growth of tested bacteria was observed with carvacrol (100 μL/mL), while thymol exhibited MIC of 1.887 mg/mL against P. lundensis and 0.943 mg/mL needed to show complete inhibition of Listeria monocytogenes. Further experiments are needed to determine the optimum concentrations of the active components against P. lundensis and L. monocytogenes.

Recently, bioactive peptides as a health-promoting agent have come to the forefront of health research, however, industrial production is limited, possibly due to the lack of the required technological knowledge. The objective of the investigation was to prepare bioactive peptides with hypoallergenic properties from liquid milk protein concentrate (LMPC), through sequential enzymatic and microbial hydrolysis. LMPC was produced from ultra-heat-treated (UHT) skimmed cow’s milk using a nanofiltration membrane. The effect of the concentration of trypsin (0.008–0.032 g·L−1) on the hydrolysis of LMPC was studied. Subsequently, the hydrolysis of tryptic-hydrolyzed LMPC (LMPC-T) with lactic acid bacteria was performed, and the effect of glucose in microbial hydrolysis was studied. Aquaphotomic analysis of the hydrolysis of LMPC was performed using the spectral range of 1300–1600 nm (near-infrared spectra). Changes in antioxidant capacity, anti-angiotensin-converting enzyme activity, and antibacterial activity against Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes were noted after the sequential tryptic and microbial hydrolysis of LMPC. Allergenicity in LMPC was reduced, due to sequential hydrolysis with 0.016 g·L−1 of trypsin and lacteal acid bacteria. According to the aquaphotomic analysis result, there was a dissociation of hydrogen bonds in compounds during the initial period of fermentation and, subsequently, the formation of compounds with hydrogen bonds. The formation of compounds with a hydrogen bond was more noticeable when microbial hydrolysis was performed with glucose. This may support the belief that the results of the present investigation will be useful to scale up the process in the food and biopharmaceutical industries.

The stochastic growth of homogeneous bacterial populations in the wells of a microtiter plate was studied as a function of the random initial cell number and their random individual lag times. These significantly affected the population growth in the well, while the maximum specific growth rate of the population was constant (or its variance was negligible) for each well. We showed the advantages of the mathematical assumption that a transformation of the single cell lag time, called the single cell physiological state (or, more accurately, that of the sub-population generated by the single cell) follow the Beta distribution. Simulations demonstrated what patterns would such assumption generate for the distribution of the detection times observed in the wells. An estimation procedure was developed, based on the beta-assumption, that resulted in an explicit expression for the expected value of the single cell physiological state as a function of measured "time to detection" values using turbidity experiments. The method was illustrated using laboratory data with Escherichia coli, Salmonella enterica subsp. enterica strains. The results gave a basis to quantify the difference between the studied organisms in terms of their single-cell kinetics.

Heat resistant thermophilic spore-forming bacteria, such as Aeribacillus (A.) pallidus, may contaminate the surfaces in food facilities resulting food spoilage of the products. The aim of this work was to determine the heat and disinfectant resistance of an A. pallidus strain that was isolated from a canning factory environment. Compared to other heat-resistant spore-forming bacteria, it did not prove to be very resistant to heat with a D10-values of A. pallidus from 12.2 min to 2.4 min (at 102 °C and at 110 °C), with a calculated z-value of 11.6 °C. Not only spores but vegetative cells showed resistance against all investigated disinfectants.

This study was conducted to evaluate the effect of bioactive compounds (BACs): linalool (LIN) and piperine (PIP) on chicken meat characteristics. The meat was treated with 500, 1000 ppm of BACs, vacuum packaged and stored at 4 °C for 8 days. Physicochemical characteristics, lipid oxidation (thiobarbituric acid reactive substances, TBARS), microbiological status, and sensorial (electronic-nose based) properties were investigated. Both BACs significantly increased the redness (a*) and chroma (C*) values in meat compared to increased lightness (L*) and higher TBARS in control. Although both BACs showed overlapping aroma profile, the E-nose was able to distinguish between the different meat groups. LIN with various dilution ratios, particularly 1:10 (v:v), showed in vitro growth inhibition against Escherichia coli, Staphylococcus aureus, Salmonella Typhimurium, and Bacillus cereus, concomitantly Listeria monocytogenes required 1:80 (v:v) to be inhibited, and no inhibition was detected for Pseudomonas lundensis. In contrast, PIP at different dilutions did not exhibit inhibitory activity. Regarding aerobic mesophilic counts (AMC), less than 7 log CFU g⁻¹ were recorded except for control showing higher log. Both BACs have potential to improve quality characteristics and increase the shelf life of meat and meat products.

Due to its biological composition, poultry meat is perishable by nature and susceptible to quality deterioration such as microbial spoilage and oxidation changes. Meat and meat products with healthy, extended shelf-life and good organoleptic properties are highly demanded by consumers. In current study, the antimicrobial and antioxidant effects of allyl-isothiocyanate (AITC) as a natural additive on raw chicken meat during chilling storage were determined. For this purpose, samples of minced were treated with different concentrations of AITC (100, 200, 300 and 500 ppm) and control no AITC added, the samples packaged and stored for 8 days at 4 °C. Fluctuations with no significant effect were noticed in TBARS values during the storage period. Simultaneously, AITC with higher concentration showed lower mesophilic aerobic counts compared to control and meat containing a low concentration of AITC. Moreover, compared to the beginning of storage, AITC decreased water holding capacity (WHC) of meat this can affect other physicochemical properties of meat. Further study needed to determine the effect of AITC on the physicochemical properties of meat and food products.

Liquid milk protein concentrate with different beneficial values was prepared by membrane filtration and enzymatic modification of proteins in a sequential way. In the first step, milk protein concentrate was produced from ultra-heat-treated skimmed milk by removing milk serum as permeate. A tubular ceramic-made membrane with filtration area 5 &times, 10&minus, 3 m2 and pore size 5 nm, placed in a cross-flow membrane house, was adopted. Superior operational strategy in filtration process was herein: trans-membrane pressure 3 bar, retention flow rate 100 L&middot, h&minus, 1, and implementation of a static turbulence promoter within the tubular membrane. Milk with concentrated proteins from retentate side was treated with the different concentrations of trypsin, ranging from 0.008&ndash, 0.064 g&middot, L&minus, 1 in individual batch-mode operations at temperature 40 &deg, C for 10 min. Subsequently, inactivation of trypsin in reaction was done at a temperature of 70 &deg, C for 30 min of incubation. Antioxidant capacity in enzyme-treated liquid milk protein concentrate was measured with the Ferric reducing ability of plasma assay. The reduction of angiotensin converting enzyme activity by enzyme-treated liquid milk protein concentrate was measured with substrate (Abz-FRK(Dnp)-P) and recombinant angiotensin converting enzyme. The antibacterial activity of enzyme-treated liquid milk protein concentrate towards Bacillus cereus and Staphylococcus aureus was tested. Antioxidant capacity, anti-angiotensin converting enzyme activity, and antibacterial activity were increased with the increase of trypsin concentration in proteolytic reaction. Immune-reactive proteins in enzyme-treated liquid milk protein concentrate were identified with clinically proved milk positive pooled human serum and peroxidase-labelled anti-human Immunoglobulin E. The reduction of allergenicity in milk protein concentrate was enzyme dose-dependent.

Antibiotic resistance containment strategies at wastewater treatment plants need to be supported by a firm knowledge on the behavior of resistant bacteria within a diverse microbial population in the presence of trace amount of antibiotics. In this study via investigating the population dynamics of resistant/sensitive Staphylococcus aureus co-cultures in several model wastewater matrix systems, valuable insights were obtained into the effect of trace amount of antibiotics (piperacillin and erythromycin) on bacteria, and into the suitability of advanced oxidation treatment (electron beam irradiation) as a remediation measure. It appears that environmentally relevant concentration levels of the antibiotic present in a wastewater matrix leads to a shift in the population in favor of the sensitive subtype, presumably on account of triggering protective biochemical processes in the resistant mutant, which confer no selective advantage since the sensitive strain remains unaffected in this concentration range. The impact of these conditions on the population dynamics can be diminished by using advanced oxidation treatment, considering that degradation products from the wastewater matrix constituents (such as humic acid) might also have an effect. Furthermore, it became also apparent that the presence of trace amount of antibiotics while triggers biological processes in the resistant subtype, concomitantly makes the bacteria more sensitive towards the attack of free radicals during advanced oxidation treatment. The behavior of resistant bacteria under environmental conditions at the cellular and population level clearly merits more attention.

Predictive microbiology methods were used to study the effect of carvacrol on the bacterial resistance to antimicrobials. Our objective was to estimate the optimum dose of carvacrol at concentrations below its MIC value (Minimum Inhibitory Concentration). As a fluorescent marker, ethidium bromide (EtBr) was applied to Escherichia coli to acquire raw data. The accumulation of EtBr was measured by its fluorescence signal (Fs), in the unit of RFU (Relative Fluorescence Unit). The temporal change of the fluorescence values, at a constant concentration of carvacrol, was described by a saturation curve (primary model). The difference, within the observation interval, between the fitted initial and maximum fluorescent values was chosen as the primary parameter to be fitted in the secondary model: a convex, asymmetric, bi-linear function of the carvacrol concentration changing between 0 and 0.5 MIC. Its breakpoint is the optimum value of the carvacrol, a cardinal parameter of the secondary model, where the chosen primary parameter assumes its highest value. This optimum was estimated with high uncertainty for individual experiments, but F-test showed that, with appropriate experimental and numerical procedure, its existence and value can be claimed with confidence. Our results demonstrate that the estimation of the optimum of the secondary model can be robust even if the full secondary model is uncertain.

In Hungary, dried pasta products are very popular amongst all groups of society. In recent years the demand for not only dried pasta made from hen eggs (Gallus gallus domesticus) but from alternative types of ingredients has increased. However, according to the literature the chemical and microbiological characteristics of this type of pasta have yet to be studied in depth. The effects of the use of quail eggs and heat treatments at different temperatures were studied by chemical and microbiological measurements. The activity of oxidative enzymes and nutritional characteristics (water-soluble total polyphenol content, water-soluble antioxidant capacity, peroxidase enzymatic activity, water-soluble protein content and yellow pigment content) was tested during our experiments. The data were evaluated by relevant statistical methods. Significant differences were found both between heat treatments and between the egg content of the dried pasta samples. The peroxidase enzymatic activity and yellow pigment content increased with temperature. However, the usage of quail eggs provides a higher water-soluble protein content and water-soluble antioxidant capacity. The presence of microorganisms is decreased by increasing the drying temperature. The number of all the examined microorganisms was within limits.

Nigella sativa L. (black cumin) is well known for its benefits in the field of traditional medicine. The aim of this study was to determine the chemical composition and investigate the antimicrobial activity of cold pressed oil (CO) and essential oil (EO) of Nigella sativa L. on food-borne pathogenic and spoilage bacteria. The microdilution method was used to determine the minimal inhibitory concentration (MIC) of Nigella sativa crude oil (CO) and essential oil (EO) against 4 Gram-positive (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, and Listeria monocytogenes) and 3 Gram-negative (Salmonella Hartford, Pseudomonas aeruginosa, and Escherichia coli) foodborne pathogenic and spoilage bacteria occurring in food products. Total fatty acid composition of CO was analysed by GLC, while the EO was analysed by GC-MS to detect its active compounds. The results showed that the major fatty acid of CO was palmitic acid (C16:0), as saturated fatty acid, however, linoleic acid (C18:2) was the main unsatura...

The aim of our study was to examine the combined effect of NaCl and low temperature on antilisterial bacteriocin production of L. plantarum. Traditionally, the activity of the bacteriocin (arbitrary unit/ml) is determined as an adaptation of the critical dilution method. With that methodology, the value of AU/ml is a discrete variable, which may cause information loss. Therefore, redox potential measurement technique was applied. Bacteriocin producer L. plantarum and a bacteriocin sensitive L. monocytogenes strain were selected for this study. The measure of the inhibition activity of bacteriocin was expressed in ΔTTD terms which means the difference between the detection times of L. monocytogenes in inhibited and non-inhibited culture media. During the L. plantarum fermentations the antilisterial activity proved to be the highest in the transient section between the late linear and stationer phase of the logarithmic growth curves. Multiple regression model was established to describe the combined effect of temperature and NaCl concentration on the bacteriocin production of L. plantarum.

Effluents of wastewater treatment plants represent critical control points for antibiotic resistance management. To meet strict regulations coming into effect in the future advanced technologies need to be implemented that can remove the factors contributing to the development of resistance in receiving natural environments. By performing microbiological assays we show that electron beam treatment of a complex synthetic effluent wastewater matrix is able to eliminate one of these factors, the antimicrobial activity of the β-lactam antibiotic piperacillin present at environmentally relevant concentration. Since OH governs the antibacterial inactivation the technology needs to be designed to the stoichiometric presence of OH.

BACKGROUND/AIM N. sativa essential oil (EO) and its compounds (thymoquinone, carvacrol and p-cymene) have a broad antimicrobial spectrum. The aim of this study was to investigate the antimicrobial and resistance modifying activity of N. sativa EO, thymoquinone, carvacrol and p-cymene against Listeria monocytogenes. MATERIALS AND METHODS N. sativa EO, thymoquinone, carvacrol and p-cymene was assessed for its antimicrobial activity, modulation of antimicrobial resistance, inhibition of antimicrobial efflux and membrane integrity by broth microdilution, ethidium bromide accumulation and LIVE/DEAD BacLight™ assays. RESULTS L. monocytogenes showed substantial susceptibility toward N. sativa EO, thymoquinone, and carvacrol. A significant reduction in MIC's of EtBr and ciprofloxacin was noticed when tested in combination with N. sativa EO, thymoquinone, carvacrol and reserpine. In the presence of each compound the membrane integrity was disintegrated, and the EtBr accumulation increased which was comparable to positive control reserpine. CONCLUSION N. sativa EO might have a potential for controlling the antibiotic resistance in Listeria.

Among Fusarium mycotoxins, deoxynivalenol (DON) is the most common contaminant in case of cereals and cereal-based foods in Hungary. In this study, Hungarian wheat (n = 305), maize (n = 108), wheat flour (n = 179) and pasta (n = 226) samples were analysed (N = 818). The samples were collected during 2008-2015 in Hungary. Applied methods of analysis were enzyme-linked immunosorbent assay and liquid-chromatography coupled with a mass spectrometer. Results were compared and evaluated with Hungarian weather data. Among cereal samples, in 2011, wheat was contaminated with DON (overall average ± standard deviation was 2159 ± 2818 µg kg-1), which was above the maximum limit (ML). In case of wheat flour and pasta, no average values above ML were found during 2008-2015, but higher DON contamination could be observed in 2011 as well (wheat flour: 537 ± 573 µg kg-1; pasta: 511 ± 175 µg kg-1).

Subinhibitory levels of antibiotics in reservoirs highly affected by anthropogenic activity, e.g., wastewater treatment plants, have a profound impact on the development and spread of resistant bacteria in the biosphere. As an aid, advanced oxidation processes (AOPs) have been suggested to eliminate the antibacterial activity of several antibiotics, and this activity has been followed using conventional antibiotic susceptibility tests. While the antibacterial activity can hardly be monitored below the minimum inhibitory concentration (MIC) with these assays, the selective pressure on a bacterial population might remain in this concentration range. To assess the applicability of an AOP for eliminating the subinhibitory effects of antibiotics on selection of resistant bacteria, a microbiological assay is introduced. The test is based on the dynamics of a mixed bacterial population in response to the presence of antibiotics in a concentration range well below the MIC in a synthetic wastewater matrix. Sensiti...

Enzymatic hydrolysis of soybean milk proteins with cysteine protease papain was performed in an advanced bioreactor, operated with batch mode. In soybean milk protein hydrolysis reaction, enzyme and substrate ratio and reaction temperature were varied, ranging from 0.029:100&ndash, 0.457:100 and 30&ndash, 60 &deg, C, respectively. The degree of hydrolysis of soybean milk proteins was increased with increase of enzyme and substrate (soybean milk protein) ratio. However, the degree of hydrolysis was increased due to change of reaction temperature from 30 &deg, C to 60 &deg, C with enzyme and substrate ratio 0.229:100 and was reduced when hydrolysis reaction was performed with enzyme and substrate ratio 0.11:100 at hydrolysis temperature 60 &deg, C. Antioxidant capacity of enzyme-treated milk had a similar trend with degree of hydrolysis. In a later exercise, a membrane bioreactor was adopted for continuous production of antioxidant and antibacterial peptides from soybean milk. The membrane bioreactor was operated for 12 h with constant feeding. Ceramic-made tubular membrane with a pore size 20 nm was used. Application of static turbulence promoter in a membrane separation process was investigated and its positive effects, with respect to higher permeate flux and lower energy consumption in filtration process, were proven. Antioxidant capacity and antibacterial activity against Bacillus cereus of enzyme-hydrolyzed milk and permeate from membrane were confirmed.

Published data suggest that detection of Listeria monocytogenes is affected by presence of other Listeria species in matrix. In this study efficacy for traditional standard detection method (ISO 11290-1) of L. monocytogenes was investigated, focussing on the growth in Fraser broth (FB). The multiplication ability of different mixtures of L. monocytogenes strains and Listeria innocua strain was investigated in half FB (hFB) and FB. Growth parameters were determined by DMFit software using the Baranyi-model. When initial cell concentration of L. innocua was higher than that of L. monocytogenes inhibition of the latter was observed. Based on the results it was concluded that the strain of L. monocytogenes was overgrown by L. innocua in Fraser broth. When their growth was monitored during co-culturing in hFB the lag phase of L. monocytogenes was prolonged by 3.4 h. When L. monocytogenes grew in the presence of L. innocua in 1:1 ratio a three log cycle difference was observed at the end of Fraser culturing step. Testing the suitability of ALOA plates for detection of L. monocytogenes it was determined that halo formation has to be checked after 24, 34 and 48 h incubation. All these difficulties might lead to false negative results.

Nigella sativa essential oil (EO) and its compounds (thymoquinone, carvacrol, and p-cymene) have a broad antimicrobial spectrum. The aim of this study was to investigate the antimicrobial and resistance modifying activity of N. sativa EO, thymoquinone, carvacrol, and p-cymene against one methicillin susceptible and one methicillin resistant Staphylococcus aureus strain. N. sativa EO, thymoquinone, carvacrol, and p-cymene were assessed for antimicrobial activity and modulation of antimicrobial resistance (by broth microdilution), inhibition of antimicrobial efflux (by ethidium bromide [EtBr] accumulation assay), relative expression of mepA gene (by real-time reverse transcriptase quantitative polymerase chain reaction), membrane disrupting effect (by LIVE/DEAD BacLight™ Kit), and finally antibiofilm activity (by the crystal violet assay). Both strains of S. aureus were susceptible to N. sativa EO, thymoquinone, and carvacrol. N. sativa EO and carvacrol induced the increase of EtBr accumulated by both S. aureus strains. Membrane integrity of ATCC strain was disrupted by carvacrol and p-cymene, whereas for the methicillin resistant S. aureus (MRSA) strain the membrane integrity was disrupted by each compound. N. sativa EO and its bioactive compounds such as carvacrol and p-cymene could be applied as resistance modifiers in MRSA strains.

Background/Aim: N. sativa essential oil (EO) and its compounds (thymoquinone, carvacrol and p-cymene) have a broad antimicrobial spectrum. The aim of this study was to investigate the antimicrobial and resistance modifying activity of N. sativa EO, thymoquinone, carvacrol and p-cymene against Listeria monocytogenes. Materials and Methods: N. sativa EO, thymoquinone, carvacrol and p-cymene was assessed for its antimicrobial activity, modulation of antimicrobial resistance, inhibition of antimicrobial efflux and membrane integrity by broth microdilution, ethidium bromide accumulation and LIVE/DEAD BacLight™ assays. Results: L. monocytogenes showed substantial susceptibility toward N. sativa EO, thymoquinone, and carvacrol. A significant reduction in MIC’s of EtBr and ciprofloxacin was noticed when tested in combination with N. sativa EO, thymoquinone, carvacrol and reserpine. In the presence of each compound the membrane integrity was disintegrated, and the EtBr accumulation increased which was comparable to positive control reserpine. Conclusion: N. sativa EO might have a potential for controlling the antibiotic resistance in Listeria.

Bacteriocin producing lactic acid bacteria (LAB) cultures can be used as biopreservatives in fermented food products; thus the food industry is interested in stable cultures that produce bacteriocins consistently. Inhibtion of Listeria spp. by bacteriocinogenic Pediococcus acidilactici and Lactobacillus plantarum (both isolated from fermented meats) was investigated under conditions of stress induced by low pH and high salt concentrations. Listeria monocytogenes serogroup IIb (from cheese), L. monocytogenes serogroup IVb (from cheese), L. monocytogenes serogroup IIb (from ground beef) and Listeria innocua NCTC 11288 were used as target strains. P. acidilactici and Lb. plantarum demonstrated antilisterial activity under the stress conditions investigated (pH 3.5; pH 8.5; 7.5% NaCl). However, activity was dependent on the stress conditions applied and on the target organism. L. monocytogenes serogroup IIb (from ground beef) and L. innocua C 11288 were, respectively the most sensitive and the most resistant to the cell-free supernatants produced by the LAB investigated.

Hipoalergeni antibakterijski peptidi male molekularne mase proizvedeni su iz nemasne sojine sačme u membranskom bioreaktoru. U prvom su koraku proteini sojine sačme razgrađeni pomoću tripsina u šaržnom bioreaktoru. Optimalni uvjeti za razgradnju tripsinom bili su: koncentracija sojine sačme od 75 g/L, temperatura od 40 °C i pH=9. Nakon toga su peptidi male molekularne mase pročišćeni pomoću „cross-flow“ membrane (veličina pora 100 μm), a zatim pomoću keramičke cjevaste membrane (veličine pora koja ne propušta molekule veće od 5 kDa). Ispitan je utjecaj transmembranskog pritiska i primjene statičkih promotera turbulencije na smanjenje koncentracijske polarizacije blizu površine ultrafiltracijske membrane, te je potvrđen njihov pozitivan učinak. Transmembranski pritisak od 3•105 Pa i diskontinuirana dijafiltracija provedena u tri koraka bili su optimalni za filtraciju pomoću ultrafiltracijske membrane. Distribucija molekularne mase peptida pročišćenih pomoću ultrafiltracijske membrane utvrđena je pomoću metode LC-ESI-Q-TOF-MS. Više od 96 % peptida (izraženih kao relativna frekvencija) iz permeata ultrafiltracijske membrane imalo je molekularnu masu manju od 1,7 kDa, a najveća je molekularna masa bila 3,1 kDa. Smanjenje alergenih svojstava proteina za više od 99,9 % nakon obrade tripsinom i membranske filtracije utvrđeno je imunoenzimskim testom. Također je zaključeno da peptidi pročišćeni pomoću ultrafiltracijske membrane pozitivno djeluju na rast bakterije Pediococcus acidilactici HA6111-2, te sprečavaju rast bakterije Bacillus cereus., Hypoallergenic antibacterial low-molecular-mass peptides were produced from defatted soybean meal in a membrane bioreactor. In the first step, soybean meal proteins were digested with trypsin in the bioreactor, operated in batch mode. For the tryptic digestion of soybean meal protein, optimum initial soybean meal concentration of 75 g/L, temperature of 40 °C and pH=9.0 were determined. After enzymatic digestion, low-molecular-mass peptides were purified with cross-flow flat sheet membrane (pore size 100 μm) and then with tubular ceramic ultrafiltration membrane (molecular mass cut-off 5 kDa). Effects of transmembrane pressure and the use of a static turbulence promoter to reduce the concentration polarization near the ultrafiltration membrane surface were examined and their positive effects were proven. For the filtration with ultrafiltration membrane, transmembrane pressure of 3·10^5 Pa with 3-stage discontinuous diafiltration was found optimal. The molecular mass distribution of purified peptides using ultrafiltration membrane was determined by a liquid chromatography–electrospray ionization quadrupole time-of-flight mass spectrometry setup. More than 96 % of the peptides (calculated as relative frequency) from the ultrafiltration membrane permeate had the molecular mass M≤1.7 kDa and the highest molecular mass was found to be 3.1 kDa. The decrease of allergenic property due to the tryptic digestion and membrane filtration was determined by an enzyme-linked immunosorbent assay and it was found to exceed 99.9 %. It was also found that the peptides purifi d in the ultrafi tration membrane promoted the growth of Pediococcus acidilactici HA6111-2 and they possessed antibacterial activity against Bacillus cereus.

Urogenital tract infection caused by obligate intracellular bacterium Chlamydia trachomatis D (CtrD) is a leading cause of sexually transmitted diseases. Essential oil (EO) of Nigella sativa has a broad antimicrobial spectrum. The aim of this study was to evaluate the antimicrobial activity of the bioactive compounds (p-cymene, thymoquinone, carvacrol, and thymol) of N. sativa EO against CtrD. The cytotoxic effects of the compounds were determined by MTT assay. In order to quantify the anti-chlamydial activity of the compounds, HeLa cells were infected with CtrD or CtrD treated previously with the compounds. The titer of the infectious CtrD was determined by indirect immunofluorescence assay. The minimum inhibitory concentrations of the compounds were evaluated by direct quantitative PCR. None of the compounds showed a cytotoxic effect on HeLa cells in the concentrations tested. According to the immunofluorescence assay, all of the compounds significantly inhibited the growth of CtrD. The quantitative PCR revealed that the minimum concentration that exerted anti-chlamydial activity was 3.12 µM in the case of thymoquinone and p-cymene, while that of carvacrol and thymol was 6.25 µM. Therefore, it can be concluded that bioactive compounds of N. sativa EO could be used as effective antimicrobial agents against CtrD.

Fusarium genera can produce trichothecenes like deoxynivalenol (DON), zearalenone (ZEN) and T-2 toxin, which can occur in feed cereal grains. Enzyme-linked immunosorbent assays (ELISA) tests of different Hungarian swine feedstuff proved that these mycotoxins were present. In this survey, 45 feed samples from 3 significant Hungarian swine feedstuff manufacturers were tested. ELISA methodology validation showed mean recovery rates in ranges from 85.3% to 98.1%, with intermediate precision of 86.9-96.9% and variation coefficients of 3.4-5.7% and 5.9-7.1%, respectively. The results showed that among Fusarium toxins, generally DON was present in the highest concentration, followed by T-2 and finally ZEN in all tested swine feeds. Each of the mycotoxins was found above the limit of detection in all swine feedstuffs. Boars feed's DON (average ± standard deviation was 872 ± 139 µg kg-1) and ZEN (172 ± 18 µg kg-1) results of one of the manufacturers were above the guidance values. It indicates the necessity for efficient monitoring of DON, ZEN and T-2 mycotoxins in swine feeds.

The Fusarium mycotoxins deoxynivalenol (DON), zearalenone (ZEN) and T-2 frequently contaminate grain crops in Middle and Eastern Europe. In this survey, 116 cereal samples (maize, wheat, barley and oat) were examined for DON, ZEN and T-2 mycotoxins. Samples were collected from different areas in two Hungarian regions (North and South Transdanubia). The method of analysis was indirect competitive ELISA. Maize was the most contaminated grain regarding DON (86%), ZEN (41%) and T-2 (55%) toxins. The average results of the deoxynivalenol and zearalenone tests of maize proved to be significantly higher than those of barley or oat. DON was the most represented Fusarium mycotoxin followed by T-2 and ZEN. The examination of these mycotoxins would be necessary at a larger scale as to re-evaluate permissible levels, so increase of the monitoring programme would be advisable for the future.