Etude de l'irradiation gamma de poudres alimentaires éffets sur la microflore aérobie de l'amidon

  • J. -M. Delattre
  • J. -M. Fretton
  • R. Fretton
  • F. Poncelet
  • H. Beerens
Food Microbiology

Resume

Cette étude a pour objet d'évaluer l'efficacité des rayons γ pour la désinfection d'une poudre alimentaire: l'amidon. Elle comprend d'une part, l'analyse qualitative et quantitative de la microflore d'amidons industriels, d'autre part, l'établissement de courbes de survie pour les flores totales et certaines souches pures susceptibles de créer des difficultés par leur fréquence, leur pouvoir pathogène ou leur radiorésistance élevée. Un microcoque pigmenté en rose formant des tétrades a été isolé. Il présente une résistance comparable à celle deM. radiodurans. Néanmoins le groupe le plus préoccupant est celui desBacillus. Un barème indicatif tenant compte de leur résistance est proposé pour la radiopasteurisation de l'amidon.

Study of the gamma irradiation of powdered foodstuffs: Effects on the aerobic microflora of starch

Summary

The microbicidal effects of γ-irradiation on the microflora of starch have been investigated. Large variations were observed in the total numbers (up to 7.106 per 1g of mesophilic aerobes) as well as types (1 to 15) of bacteria encountered. The most abundant groups appeared to beBacilli, Micrococci andPenicillia. Enterobacteriaceae were only seldomly isolated. The only pathogen isolated was aStaphylococcus.

Inactivation curves in starch were determined for “total” floras (mesophilic aerobes, mesophilic and thermophilic spore-formers, moulds) and 40 pure cultures. These curves show considerable variation in patterns and levels of resistance. Hypotheses are given to explain the various patterns of inactivation. The established levels of resistance are in agreement with liberature data. A very radioresistantMicrococcus was isolated (LD90=750 Krad). However, the group presenting most problems is that ofBacillus spores, because of their frequency, thermo- and radioresistance, and the possible enterotoxicity of some strains (B. cereus). From survival rates obtained with spore-formers at various No values, a diagram for the radiopasteurisation of starch is derived. It results in over-dosing starch when it is lightly contaminated, owing to a so-called dispersion effect.

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Copyright information

© Springer-Verlag 1975

Authors and Affiliations

  • J. -M. Delattre
    • 1
  • J. -M. Fretton
    • 1
  • R. Fretton
    • 1
  • F. Poncelet
    • 1
  • H. Beerens
    • 1
  1. 1.Laboratoire Détaché au Centre D'Etudes Nucléaires de CadaracheCentre d'Etudes et de Recherches Technologiques des Industries Alimentaires (C.E.R.T.I.A.)Saint-Paul-lez-DuranceFrance

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