Authors:R. Ágoston, Cs. Mohácsi-Farkas, and S. Pillai
The food industry utilizes a variety of stressors such as heat treatment to inactivate or prevent the multiplication of
in foods. The aim of this study was to identify the extent to which pre-exposure to sub-lethal temperatures would induce temperature tolerance to 60 °C and result in increased D values.The D value of an avirulent
strain (4ab No 10) was initially determined in Tryptic Soy Broth at 55 °C, 60 °C and 65 °C. The cells were pre-exposed to sub-lethal heat stress of 46 °C (for 30 and 60 min), 48 °C (for 30 and 60 min) and 50 °C (for 30 and 60 min). Then they were exposed to 60 °C and the D
values were calculated. The pre-treatment at sub-lethal temperatures enhanced the D
value of the strain from 3.03 min to longer times. The D
values increased as a function of pre-treatment time at 46 °C: after 30 min exposure it was 5.24 min, and 16.18 min after exposure to 60 min. Similarly, the D
value after 30 min and 60 min exposure at 48 °C was 6.72 min and 14.83 min, respectively. The D
value after 30 min and 60 min exposure at 50 °C, was 13.88 min and 11.16 min, respectively. Heat injury was found to occur in this
strain under the experimental conditions.
Authors:Á. Vajda, Gy. Kasza, and Cs. Mohácsi-Farkas
While in developed countries research findings are available on the estimation of the realistic number of different diseases and their economic impact at social level, in Central and Eastern European countries these country specific data are neither sufficient nor reliable. This study partially fills the gap and gives a picture of the real number of foodborne salmonellosis in Hungary. In the spring of 2017, a survey about diarrhoeal and foodborne diseases was conducted by interviewing 1001 adults (over the age of 18). Our survey showed that approximately 18 times more individuals are suffering from Salmonella infection than it is assumed under the national and international epidemiological database. Based on our estimation, the annual number of foodborne salmonellosis may range from 91 242 to 105 606 in Hungary. In this paper a methodology has been developed to estimate the true occurrence of this disease. Our results can be used to calculate the costs-benefit ratios of future salmonellosis prevention programmes and inform decision-makers on the effectiveness of Salmonella-related measures in the area of food safety.
Authors:A. Taczman-Brückner, Cs. Mohácsi-Farkas, Cs. Balla, and G. Kiskó
Applying antagonistic yeasts is one of the recent possibilities for controlling postharvest disease caused by blue mould (Penicillium expansum). In this work, antagonistic activity of several Kl. lactisstrains was tested against two strains of P. expansum. Three strains of Kl. lactiswere compared to three biocontrol yeasts: Metschnikowia pulcherrima, Sporobolomyces roseusand Pichia anomala. The investigations were carried out at 25 °C, 15 °C and 5 °C, applying different yeast cell densities and culture media. Statistical analysis showed no significant differences among the three Kl. lactisstrains. The inhibitory effect of the tested yeasts was different according to the applied mould strain temperature, culture medium and cell density. Application of antagonistic yeasts combined with reduced temperature enhanced the inhibitory effect. Direct relationship was observed between increasing cell density and the biocontrol efficiency of Kl. lactis. According to this work, Kl. lactisis a possible biocontrol agent.
Authors:A. Taczman-Brückner, Cs. Mohácsi-Farkas, Cs. Balla, and G. Kiskó
Numerous yeasts are reported as being effective in controlling plant pathogenic moulds. By selecting new biocontrol agents, knowledge about the mode of action of mould inhibition is important. In our study, mode of action of Kluyveromyces lactis - successfully applied against Penicillium expansum in former studies - was investigated. According to the results, volatile compounds are supposed to play a role in restriction of mould growth. Antibiotic substances and killer toxins produced by the tested Kl. lactis strain were not detected.
Authors:Cs. Mohácsi-Farkas, G. Kiskó, L. Mészáros, and J. Farkas
Laboratory batches of fresh tomato juices were treated in several experimental trials by high hydrostatic pressure alone or in combination with various concentrations of oregano, thyme or dill seed oils. Lactic acid bacteria formed the dominating component of the spoilage microbiota during post-processing storage at 15 °C causing spoilage of the untreated samples within 4 days. One tenth of a percent oregano or thyme oils at least doubled the microbiological shelf life, while their respective concentrations of 0.5% alone, or 400 MPa 5-20 min high hydrostatic pressure treatment alone resulted in microbial stability for at least two weeks. Two hundred MPa for 10 min resulted only in an approx. 3 days delay of spoilage, whereas 0.1% thyme oil increased the efficiency of this moderate UHP-treatment, resulting in a microbiologically stable product for at least 3 weeks at the storage temperature applied.
Authors:B. Fekete, G. Kiskó, É. Stefanovits-Bányai, and Cs. Mohácsi-Farkas
Fruits and vegetables are increasingly consumed as a part of healthy diets. They are routinely consumed raw, without any further antimicrobial processing. The aim of our studies was to determine radiation doses improving the microbial safety of fruits without diminishing quality parameters of these produce. Effects of low dose irradiation on the microbiota, antioxidant capacity, total polyphenol contents, firmness and sensory properties of pre-cut apple, orange and banana were investigated. Dose of 2.0 kGy was able to reduce considerably the microbiological contamination of fruits, apple, orange, banana, but microorganisms surviving the irradiation are able to recover and grow during refrigerated storage. Two kGy was an acceptable radiation dose for the treatment of these products, having no significant effect on the mentioned quality parameters.
Authors:Á. Vajda, Cs. Mohácsi-Farkas, L. Ózsvári, and Gy. Kasza
Salmonellosis is a widely known infectious disease in Hungary that played dominant role between 1960 and 1996 and remained one of the top food-borne illnesses to these days with an estimated total number of 96 048 cases (2019). Beside direct costs of treatment, indirect costs are also significant on the level of population. Among indirect costs, consumer well-being losses are difficult to be estimated. For this purpose, the willingness to pay (WTP) method is used most frequently that measures the cost an individual would undertake to avoid a certain harm. For the well-being loss estimation, the data of National Food Chain Safety Authority's annual consumer survey was used, in which 323 respondents gave evaluable answer to the open-ended WTP question. Results indicate that an average respondent would pay 18.6 EUR to avoid salmonellosis. Main factors affecting WTP were size of family and number of children. The numbers indicate that the consumer well-being loss could be about 1 786 060 EUR annually, resulting from the multiplication of the estimated number of annual salmonellosis cases and the average WTP value. It can be concluded that consumer well-being losses alone would call for further interventions in Salmonella eradication, not to mention other – more direct – cost elements.
Authors:Y. Hassan, L. Mészáros, A. Simon, E. Tuboly, Cs. Mohácsi-Farkas, and J. Farkas
The total viable cell count of bacteria in vacuum-packaged chilled minced beef has been decreased equally, by approx. two log-cycles, as an effect of 1.5-2.0 kGy gamma radiation or 200-300 MPa high hydrostatic pressure (UHP) treatment for 20 min. Coliform bacteria could be eliminated to non-detectable levels by the same treatments. The shelf-life of both untreated and non-thermally pasteurised samples were limited mainly by growth of lactic acid bacteria. At about equal bactericidal effect, more drastic changes of texture and colour occurred in UHP-pasteurized minced beef samples than in the radiation-pasteurized ones. Whereas radiation pasteurisation caused minimal changes in appearance, texture and DSC-thermograms of minced beef, UHP-pasteurisation of the raw samples proved to be strongly discolouring by denaturing the muscle pigments and causing extensive denaturation of the myofibrillar proteins. The water holding capacity of irradiated samples decreased, while that of high pressure treated ones increased as compared to the untreated control. Near infrared spectrometry and electronic nose measurements gave promising results to make distinctions non-destructively on changes of various physical-chemical changes and quality parameters as a function of pasteurising treatments and/or storage.