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Gewählte Master / Diploma Thesis:

Kathrin Schuller (2016): Methodenvergleich zum Nachweis käsereischädlicher Clostridien.
Master / Diploma Thesis - Institut für Lebensmittelwissenschaften, BOKU-Universität für Bodenkultur, pp 121. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
This master thesis entitled "Method comparison for the detection of cheese-spoiling clostridia" compares a set of MPN-based methods for the detection of butyrate-producing clostridia in raw milk. Clostridium tyrobutyricum is mainly responsible for the so-called late-blowing defect. This effect occurs if the spores are present in the raw milk used for cheese-making. The late-blowing defect is responsible for substantial financial loses of the cheese producer. The relevant group of clostridia is able to produce butyric acid and gas in the cheese matrix. Next to other sources, they can be isolated from silage of poor quality. Originating from the feeds as well as from the environment of dairy cows, they contaminate the raw milk during the milking process. Poor stable and milking hygiene are main reasons for high clostridia spore counts in raw milk. Depending on the cheese type and the corresponding regulation different measures and techniques are applied to remove spores or to prevent their germination. Next to bactofugation the application of lysozyme or nitrate is possible. The strategy in the alpine raw milk cheese producing area (hay milk producing area) is the prevention of contamination. Several restrictions regarding feeds as well as hygiene measures prevent the contamination of the raw cheese milk. For the testing of raw milk for the presence of anaerobic spore-forming clostridia a number of MPN methods are applied. In this master thesis four different MPN methods were compared for their abilities to detect Clostridium tyrobutyricum in different batches of raw milk. The results display a strong influence of the method on the results. Further, molecular identification of isolates displayed a broad variety of other microorganisms. The missing selectivity for clostridia limits the relevance of the results obtained with the traditional MPN-methods applied to detect butyrate producing clostridia in raw milk.

Beurteilende(r): Domig Konrad

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