Carvacrol and p-cymene inactivate Escherichia coli O157:H7 in apple juice

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 aim of this study was to evaluate the addition of very low concentrations (0.25–1.25 mM) of carvacrol and p-cymene both individually and in combination as a novel means of controlling Escherichia coli O157:H7 in un-pasteurised apple juice. RESULTS: When inoculated at a level of 4 log CFU/ml into un-pasteurised apple juice (pH 3.20 ± 0.06), Escherichia coli O157:H7 survived for up to 3 and 19 days at 25° and 4°C, respectively. Treatment of the juice with 1.25 mM carvacrol or p-cymene reduced the numbers of E. coli O157:H7 to undetectable levels within 1–2 days at both storage temperatures. The effective concentrations of carvacrol could be reduced even further by combining it at 0.5 mM with cymene at 0.25 mM. The phenolic compounds were biocidal against both spoilage yeasts and E. coli O157:H7 thereby increasing the shelf-life and improving the safety of un-pasteurised apple juice, particularly when stored at chill temperatures. CONCLUSION: The results showed that the natural antimicrobial compounds carvacrol and p-cymene could potentially be used to extend the shelf life and improve the safety margins in un-pasteurised chilled fruit juices

Don, F-2 and T-2 mycotoxin assay of plant-based feedstock raw materials using the ELISA method

In our study, plant-based raw materials, used for feeding different animal species, are investigated, using a competitive ELISA method. The raw materials most commonly used for feeding (soy and alfalfa pellets, as well as wheat, barley and maize) were used in the tests. Of Fusarium mycotoxins, deoxynivalenol (DON), zearalenone (F-2) and T-2 toxins were measured. Measurement results were evaluated using the mathematical- statistical program RStudio. In our experiment, we found that all three mycotoxins tested could be detected in all of the samples, but the values were not quantifiable with acceptable precision in each case. The average detected DON toxin result was an order of magnitude greater than the results of the other toxins. It has been shown in our study that the presence of the mycotoxins deoxynivalenol, zearalenone and T-2 poses a serious food and feed safety risk, since they are present in feedstock raw materials, even though only in small amounts. Today, these mycotoxins are present together in more and more cases, greatly increasing the above-mentioned risk

Distribution of bacterial single cell parameters and their estimation from turbidity detection times

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 illus- trated 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

Takarmányozásra használt növényi alapanyagok DON, F-2, T-2 mikotoxin-vizsgálata ELISA-módszerrel

Tanulmányunkban különböző állatfajok etetésére használt növényi alapanyagokat vizsgáltunk kompetitív ELISA-módszerrel. A vizsgálatok során takarmányozáshoz legygyakrabban használt alapanyagokkal (szója- és lucerna-pellet, valamint búza, árpa és kukorica) dolgoztunk. A Fusarium mikotoxinok közül a deoxinivalenol (DON), zearalenon (F-2) és a T-2 toxinokat mértünk. A mérési eredményeinket RStudio matematikai-statisztikai programmal értékeltük. Kísérletünkben megállapítottuk, hogy mindhárom vizsgált mikotoxin detektálható - volt mindegyik mintában, de nem mindegyikben volt mennyiségileg elfogadható pontossággal meghatározható érték. A detektált DON toxin eredmények átlagértéke egy nagyságrenddel nagyobbnak bizonyult a többi toxinnál. Vizsgálatunk során bizonyítást nyert, hogy a deoxinivalenol, zearalenon és T-2 mikotoxinok jelenléte komoly takarmány- és élelmiszer-biztonsági veszélyt jelent, hiszen ha csak kis mennyiségekben is, de jelen vannak már a takarmány-alapanyagokban. Napjainkban egyre több esetben fordul elő ezen mikotoxinok együttes jelenléte, ami nagymértékben sokszorozza az előbb említett kockázatot