The effect of water activity and temperature on the production of some mycotoxins

M.D. Northolt

    Research output: Thesisexternal PhD, WU

    Abstract

    <p/>Preventing mold from growing and producing mycotoxins requires knowledge of the conditions under which each of the toxinogenic molds becomes active. In this investigation the relation between fungal growth and mycotoxin formation and the factors water activity and temperature is studied. Various fungal species known to produce mycotoxin were tested. Optimal substrates for production of the particular mycotoxin were used to determine the lowest possible water activity and temperature at which mycotoxins may be produced.<br/>In article 1 a water activity measurement device is described which has been designed for accurate measurements. The first study encompasses the aflatoxin production by <em>Aspergillus parasiticus</em> at different conditions of water activity and temperature. Experience is gained with both liquid cultures and surface cultures. Because of its reproducibility and resemblance to mold growth in practice, the surface culture is preferred and used in the following investigations.<br/>In article 2 attention is paid to differences between <em>Aspergillus flavus</em> strains in their response to various conditions of water activity and temperature.<br/>In articles 3, 4 and 5 the results of similar investigations with patulin, penicillic acid and ochratoxin A, respectively, are described and discussed. The effect of water activity and temperature on mycotoxin production is studied with semi-synthetic agar media, but also with some natural substrates.<br/>In the last experimental section of the thesis the effect of water activity and temperature on the mycotoxin production rate and mycotoxin production lag<br/>time of the four mycotoxins is described. For this a calculation model is developed to exclude the influence of mycelial weight and growth time on the outcome of the experiments.<br/>In the chapter Discussion the results of articles 1-5 are discussed in the light of the results described in the last experimental section. In a final discussion the practical implications of the results with respect to safeguarding of foods from mycotoxin contamination are considered.<p/>
    Original languageEnglish
    QualificationDoctor of Philosophy
    Awarding Institution
    Supervisors/Advisors
    • Kampelmacher, E.H., Promotor, External person
    Award date7 Dec 1979
    Place of PublicationWageningen
    Publisher
    Publication statusPublished - 1979

    Keywords

    • mycotoxins
    • aflatoxins
    • fungi
    • mycology
    • toxic substances
    • toxins
    • plants

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