Elimination of Listeria monocytogenes in soft and red smear cheeses by irradiation with low energy electrons |
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| Authors: | SAÏD ENNAHAR FLORENT KUNTZ ALAIN STRASSER MARTINE BERGAENTZLE CLAUDE HASSELMANN VALÉRIE STAHL |
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| Affiliation: | AERIAL, 19 rue Saint-Junien, BP 23, 67305 Schiltigheim Cedex, France.;Département des Sciences de l'Aliment, Facultéde Pharmacie, 74 route du Rhin, BP 24, 67401 Illkirch Cedex, France |
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| Abstract: | Soft and red smear cheeses are frequently contaminated by Listeria monocytogenes , sometimes at relatively high concentration (< 105 CFUg-1). This bacterium is radiosensitive (D10 value of approximately 0.45 kGy) but irradiation of the whole cheese by X-rays induced off-flavours when the dose exceeded 1.0 kGy. Irradiation could be effective in eliminating L. monocytogenes only from lightly contaminated cheeses (> 102CFU g-1).
L. monocytogenes appears only in the rind (where the pH is greater than 6.3) and never grows in the core of the cheese. Under these conditions, a specific irradiation of the rind after ripening, with a low-energy electron beam at relatively high doses (up to 3.0 kGy), allows the total elimination of L. monocytogenes in heavily contaminated samples (105-106 CFU g-1) without noticeable modifications of the organoleptic properties of the cheese. |
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| Keywords: | Lactobacilli pigmented flora sensory analysis streptococci surface ionizing treatment X-rays |
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