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: Outbreaks of food poisoning associated with drinking un-pasteurised apple juice contaminated with enterohaemorrhagic Escherichia coli O157:H7 are a cause of serious illness and occasionally death. Whilst a well-established heat process (pasteurisation) will readily eliminate the pathogen, some consumers are demanding more fresh-like foods that have not been subjected to processing methods that are perceived as severe and may lead to loss of flavour and vitamins. Therefore, alternative methods are being investigated to replace pasteurisation and improve the safety of minimally-processed juices. The addition of natural antimicrobial substances such as the phenolic substances carvacrol and p-cymene (derived from the essential oils of herbs and spices) provides a potential new route to assure safety and extend the shelf-life of raw fruit juices.

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.

Abstract. Background/Aim: N. sativa essential oil (EO) and its compounds (thymoquinone, carvacrol and p-cymene)

Aims: To develop new measures for controlling both spoilage and pathogenic micro-organisms in unpasteurized apple juice using chitosan. Methods and Results: Micro-organisms were isolated and identified from apple juice treated or untreated with chitosan using enrichment, selective media, microscopy, substrate assimilation patterns and ribosomal DNA profiling. Chitosan (0AE05-0AE1%) delayed spoilage by yeasts at 25°C for up to 12 days but the effect was species specific: Kloeckera apiculata and Metschnikowia pulcherrima were inactivated but Saccharomyces cerevisiae and Pichia spp. multiplied slowly. In challenge experiments at 25°C, total yeast counts were 3-5 log CFU ml )1 lower in chitosan-treated juices than in the controls for 4 days but the survival of Escherichia coli O157:H7 was extended from 1 to 2 days; at 4°C, chitosan reduced the yeast counts by 2-3 log CFU ml )1 for up to 10 days but survival of the pathogen was prolonged from 3 to 5 days. The survival of Salmonella enterica serovar Typhimurium was unaffected by chitosan at either temperature.Conclusions: The addition of chitosan to apple juice delayed spoilage by yeasts but enhanced the survival of E. coli O157:H7. Significance and Impact of the Study: The results suggest that the use of chitosan in the treatment of fruit juices may potentially lead to an increased risk of food poisoning from E. coli O157:H7.

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), 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; pasta: 511 ± 175 µg kg).

The effect of active compounds (ACs), allyl-isothiocyanate (AITC) and carvacrol (CARV), as natural additives on the quality of fresh chicken meat was evaluated. The meat was treated with 500 and 1000 ppm of ACs, vacuum packaged and stored at 4°C up to 8 days. Physicochemical characteristics, lipid oxidation, microbiological status, sensorial electronic-nose based properties were examined. AITC, particularly 1000 ppm, showed greater activity than CARV and resulted in colour changes, accumulative odour production, triggered reduction in the growth of Pseudomonas lundensis, Staphylococcus aureus, and Bacillus cereus and 3 log10 CFU/g reduction in aerobic mesophilic counts. However, CARV was more active in increasing chroma properties and reducing the growth of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella typhimurium. Concomitantly, 500 ppm CARV showed greater activity than AITC in controlling lipid oxidation and protecting the colour changes. Therefore, both AITC and CARV possess great potential to extend the shelf life of meat and meat products.

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