Basic aspects of food preservation by hurdle technology.

Federal Centre for Meat Research, Kulmbach, Germany.
International Journal of Food Microbiology (Impact Factor: 3.16). 05/2000; 55(1-3):181-6. DOI: 10.1016/S0168-1605(00)00161-6
Source: PubMed

ABSTRACT Hurdle technology is used in industrialized as well as in developing countries for the gentle but effective preservation of foods. Previously hurdle technology, i.e., a combination of preservation methods, was used empirically without much knowledge of the governing principles. Since about 20 years the intelligent application of hurdle technology became more prevalent, because the principles of major preservative factors for foods (e.g., temperature, pH, a(w), Eh, competitive flora), and their interactions, became better known. Recently, the influence of food preservation methods on the physiology and behaviour of microorganisms in foods, i.e. their homeostasis, metabolic exhaustion, stress reactions, are taken into account, and the novel concept of multitarget food preservation emerged. In the present contribution a brief introduction is given on the potential hurdles for foods, the hurdle effect, and the hurdle technology. However, emphasis is placed on the homeostasis, metabolic exhaustion, and stress reactions of microorganisms related to hurdle technology, and the prospects of the future goal of a multitarget preservation of foods.

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    ABSTRACT: Ultraviolet (UV) light irradiation at 254 nm is considered as a novel non-thermal method for 24 decontamination of foodborne pathogenic bacteria. However, lower penetration depth of UV light at 254 25 nm in apple juice resulted in higher UV dose consumption during apple juice decontamination. In 26 addition, no studies are available on the reactivation of pathogens following exposure to UV light in 27 drinks and beverages. Two novel monochromatic UV light sources (λ = 222 and 282 nm) have been 28 developed for bacterial disinfection. However, the inactivation of pathogenic E. coli O157:H7 following 29 exposure to these UV wavelengths is still unclear. Therefore, the present study was conducted to 30 determine the inactivation and reactivation potential of pathogenic E. coli O157:H7 in apple juice 31 following exposure to UV light at three monochromatic wavelengths: Far UV (λ = 222 nm), Far UV+ (λ 32 = 282 nm) and UVC light (λ = 254 nm). The results showed that E. coli O157:H7 is acid-resistant, and 33 up to 99.50% of cells survived in apple juice when incubated at 20°C for 24 h. Inactivation of E. coli 34 O157:H7 following exposure to Far UV light (2.81 Log reduction) was higher (P < 0.05) than the 35 inactivation caused by UVC light (1.95 Log reduction) and Far UV+ light (1.83 Log reduction) at the 36 similar levels of UV fluence of 75 mJ/cm2. No any reactivation potential was observed for E. coli 37 O157:H7 in dark incubation phases after exposure to UV light as determined by the regular plating 38 method. In addition, the exposure to Far UV light at 222 nm followed by incubating at 37°C significantly 39 decreased (P < 0.05) the survival of E. coli O157:H7 during dark incubation phase compared to that of 40 UVC and Far UV+ light.
    Food Microbiology 08/2014; · 3.37 Impact Factor
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    ABSTRACT: Formation of mixed-species biofilms constitutes a common adaptation of foodborne pathogens and indigenous microbiota for prolonged survival in their food niche. Nevertheless, the potential role of mixed-species biofilms in food safety remains to be elucidated. The formation of mixed-species biofilms on food and food processing surfaces depends on various physical, chemical, and biological processes including species composition, especially of the indigenous microbiota and nutrients, food types, temperature, quorum sensing, extracellular polymeric substance (EPS) production, biofilms maturation, and dispersal steps. Compared to monospecies, mixed-species are highly resistant to antimicrobials, possibly due to higher EPS production, internalization into food, fitness of species, denser and thicker biofilms maturation, and interspecific protection of 1 species by others, although there are much debate among studies. The fitness of mixed-species biofilms populations is suggested to be of a cooperative, competitive, or neutral nature based on the genetic background of the involved species. Currently, various methods using microarray, confocal microscopy, proteomics, and selective media are being explored for the detection of mixed-species biofilms to resolve the conflict issues. Here, we review recent progress in this emerging field in the context of food safety and propose that novel and alternative techniques like antiquorum sensing, antibiofilms, enzymes, hurdle techniques, and bacteriophages will significantly help to control the formation of mixed-species biofilms for enhanced food safety. The next challenge will be to integrate the fitness and resistance patterns of mixed-species biofilms in the laboratory with those of natural settings.
    Comprehensive Reviews in Food Science and Food Safety 09/2014; 13(5). · 3.54 Impact Factor


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