Resistance of Staphylococcus aureus to UV-C light and combined UV-heat treatments at mild temperatures

International Journal of Food Microbiology
E GayánSantiago Condón

Abstract

In this investigation, the resistance of enterotoxigenic Staphylococcus aureus to short-wave ultraviolet light (UV-C) and to combined UV C-heat (UV-H) treatments in buffers and in liquid foods with different physicochemical characteristics was studied. Microbial resistance to UV-C varied slightly among the S. aureus strains tested. The UV-C resistance of S. aureus increased in the entry of stationary growth phase, which in part was due to the expression of the alternative sigma factor σ(B). The UV-C resistance of S. aureus was independent of the treatment medium's pH and water activity, but it decreased exponentially as the absorption coefficient increased. UV-C bactericidal efficacy in liquids of high absorption coefficients was improved synergistically when combined with a mild heat treatment at temperatures ranging from 50.0 to 57.5 °C. pH of the treatment medium modified the lethality of UV-H treatments and therefore the temperature of maximum synergy. The advantage of combined UV-H treatments was demonstrated in fruit juices and vegetable and chicken broths, inactivating 5 Log₁₀ cycles of S. aureus by applying UV-C treatments of 27.1 mJ/L for 3.6 min at 52.5 °C or 13.6 mJ/L for 1.8 min at 55.0 °C.

References

Oct 6, 2000·International Journal of Food Microbiology·A H GeeraerdJ F Van Impe
Nov 28, 2000·Journal of Bacteriology·S GertzM Hecker
Mar 29, 2003·Photochemical & Photobiological Sciences : Official Journal of the European Photochemistry Association and the European Society for Photobiology·Rajeshwar P Sinha, Donat P Häder
Aug 21, 2003·International Journal of Food Microbiology·Pilar MañasSantiago Condón
Aug 30, 2003·Photochemistry and Photobiology·Ronald O RahnKeith R Lykke
Jul 18, 2006·International Journal of Food Microbiology·Shigenobu Koseki, Kazutaka Yamamoto
Oct 9, 2009·International Journal of Food Microbiology·C ArroyoR Pagán
Sep 20, 2012·Foodborne Pathogens and Disease·Cristina ArroyoSantiago Condón
Jul 6, 2013·International Journal of Food Microbiology·Angeliki BirmpaApostolos Vantarakis

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