Tabelle 1: Wachstumsgrenzen pathogener Mirkoorganismen1 Min. pH Min. aw aerob/ anae-rob3 Listeria monocytogenes -0,41 4,3 0,92 fakultativ Bacillus cereus 44 4,55 0,931 fakultativ Campylobacter jejuni 32 4,9 0,99 mikroaerophil Clostridium botulinum 10-121 4,6 0,93 anaerob (mesophil/ proteolytisch 3,3 5,0 0,97 (0,5%NaCl) anaerob Clostridium perfingens 121 5,5-5,81 0,9351 anaerob E.coli 0157:H7 6,5 4,5 0,95 fakultativ Salmonellen 6 4,0 0,94 fakultativ Staphylococcus aureus6 5,27 4,5 0,86 fakultativ Vibrio cholera 10 5,0 0,97 fakultativ Vibrio parahaemolyticus 5 4,8 0,94 fakultativ Yersina entercolitica -1,31 4,2 0,96 fakultativ E.coli (Indikator-Organismus) 7-8 4,4 0,95 fakultativ 1 Mikroorganismen in Lebensmitteln. Vol. 5 Microbiological Specifications of Food Pathogens (1995), ICMSF, Blackie Acade-mic & Professional; ACMSF Report on Verocytoxin-Producing E.coli (1995), HMSO, London, ISBN 0-11-321909-1. 2 Wachstumsgrenzen unter anderweitig gegebenen optimalen Bedingungen. Wachstumskriterien variieren nach Stamm, Temperatur und Säuretyp, gelöster Substanz und anderen Faktoren und sie kommen gewöhnlich in höheren Konzentrationen in Lebensmitteln vor. Allerdings muss die Messvariabilität etc. berücksichtigt werden und eine gewisse Fehlerspanne muss einbezogen werden. 3 Hinweis: Es muss beachtet werden, dass sogar anaerob verarbeitetet Lebensmittel eine Gefahr für das Wachstum von anaeroben Mikroorganismen sein können, weil sie eine anaerobe interne Umgebung haben können. 4 keine emetische Toxinbildung bei einer Temperatur unter 10°C. 5 Der Beweis für diesen Grenzwert wurde erbracht durch LL Prokopova (1970) Multiplication and toxigenicity of Bacillus cereus contained in food products stored under different thermal conditions. Voprosy Pitanila, 29,56-61 and M. Reavuori and C. Gerigeorgis (1975). Effect of pH and sodium chloride on growth of Bacillus cereus in laboratory media and certain foods. Applied Microbiology, 29, 68-73 6 Grenzwerte für Enterotoxinproduktion, kein Wachstum 7 Die meisten Seroytypen geben ihr Wachstum bei <7°C auf. Continued from page 30 Mikroorganismen und Wachstumsgrenzen2 Min.Temp. (°C) Clostridium botulinum (psycho-troph/ nicht-proteolytisch somit quasi „in situ“ schneller und im gesam-ten Produkt erreicht. Dr. rer. nat. und Diplom-Nahrungsmitteltechnologe Bernhard Roth, Consultant für den Be-reich Innovation und beim KIN-Lebensmittelins-titut, Neumünster F The products treated in this way are classified as chilled food due to the required cold storage with temperatures between +3°C – +7°C. The products in this category are very different. A common Berieselungsautoklaven criteria of them, however, is that they have to be absolutely safe with regard to micro-biological aspects at the time of consumption. Inevitable requirements resulting from this are that toxin forming and pathogen micro-organisms have to be reliably controlled and the integrity of the entire production chain must be guaranteed – from primary production of the ingredients through to processing, dispatch, intermediate storage and consumption. Therefore it‘s necessary to test the finished product on pathogens. Of the micro-organisms shown in table 1, the pathogen potential of Listeria monocytogenes and the toxic potential of Clostridium botulinum type B (psychotropic) re-quire special attention. Due to their characteristics, these germs serve as indicator germs for thermal preservation. In addition there are germs with spores that cannot be killed by common heat treat-ment methods, and which are toxin forming. The types of germs mentioned above have in common that they multiply at refrigerator temperatures and thus are able to form toxins and have pathogen effects respectively. The behaviour of indicator germs If thermal treatment methods are applied in order to reduce L. monocytogenes and C. botulinum, it‘s necessary to use a process that ensures a reduction by six logarithmic cycles. In the case of Listeria monocytogenes this means 2 minutes at 70°C or a corresponding equivalent at a different tempera-ture. Listeria are heat-resistant vegetative germs, which are relevant in chilled products with a shelf life of up to ten days. Regarding psychotropic Clostridium botulinum, the ACMSF advices heat treatment at 90°C for a period of 10 minutes in order to achieve a reduction by six logarithmic cycles. Equivalent settings for different temperatures are applicable, if protective gas (MAP) or vacuum is used to package chilled food with shelf lives of >10 days. Spores of mesophilic Clost-ridium botulinum and psychotropic Bacillus cereus are however not killed by this treatment. The first-wird Cascading water autoclaves VOS Schott GmbH • Am Seefeld 3 • 35510 Butzbach • Fon +49 6033 9190-0 • E-Mail info@vos-schott.com • www.vos-schott.com CONVENIENCE FOOD CONCENIENCE-PRODUKTION 2013 33
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