Hygiene survey in Estonian dairies and pathogen analysis: Master's thesis

Helen Ehavald

Research output: ThesisMaster's thesis


Hygiene survey was performed in three Estonian dairies. Samples were collected from process environment, equipment, packaging material. Liquid and solid samples were taken from raw material, product from the process, final product, wastewater and water. Samples for detecting Bacillus cereus, Listeria monocytogenes, mycobacteria, total bacterial count, Enterobacteriaceae spp., coliforms, 43-glucuronidase positive bacteria, yeast and mould were collected from all dairies and analyzed. Gauze tests, Rida Count and Hygicult tests were used for detecting bacteria from surfaces. Traditional cultivation techniques and DryCult test were used for liquid samples. Results were compared with each other. Equipment samples were both food and non-contact, results showed that food contact samples were less contaminated than non-contact, therefore dairies pay more attention to cleaning process of food contact equipment. Two Listeria monocytogenes positive samples were found from two dairies, both were from raw milk samples, one Listeria seeligeri/ivanovii was found from food-contact equipment sample and 13 mycobacteria were found from all dairies, two of them were identified with DNA sequence method. One was either Mycobacterium porcinum or Mycobacterium fortuitum (both risk group 2), it was found from wastewater. Other was Mycobacterium phlei (risk group 1) and it was found from final product. One final product was "very contaminated" with aerobic bacteria and two raw material samples were "contaminated" according to Finnish law. Amounts of "clean", "contaminated" and "very contaminated" samples for each dairy were similar. As contamination from non-contact places (environmental and equipment) may be carried to food contact places and from there to the process line, dairies should pay more attention to cleaning processes of these places. Carriers can be for example employees hands. Biofilms are problems in food industry, because they are protective barrier for microorganisms against sanitizers, and due to it cleaning can be more complicated.
Original languageEnglish
QualificationMaster Degree
Awarding Institution
  • Tallinn University of Technology
Place of PublicationTallinn
Publication statusPublished - 2004
MoE publication typeG2 Master's thesis, polytechnic Master's thesis


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