Persistence of wild Streptococcus thermophilus strains on wooden vat and during the manufacture of a traditional Caciocavallo type cheese

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Abstract

The present work was undertaken to evaluate the influence of the wooden dairy plant equipment on the microbiologicalcharacteristics of curd to be transformed into Caciocavallo Palermitano cheese. Traditional rawmilk productions were performed concomitantly with standard cheese making trials carried out in stainlesssteel vat inoculated with a commercial starter. Milk from two different farms (A and B) was separately processed.The wooden vat was found to be a reservoir of lactic acid bacteria (LAB), while unwanted (spoilageand/or pathogenic) microorganisms were not hosted or were present at very low levels. All microbial groupswere numerically different in bulk milks, showing higher levels for the farm B. LAB, especially thermophiliccocci, dominated the whole cheese making process of all productions. Undesired microorganisms decreasedin number or disappeared during transformation, particularly after curd stretching. LAB were isolated fromthe wooden vat surface and from all dairy samples, subjected to phenotypic and genetic characterizationand identification. Streptococcus thermophilus was the species found at the highest concentration in all samplesanalyzed and it also dominated the microbial community of the wooden vat. Fourteen other LAB speciesbelonging to six genera (Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus and Weissella)were also detected. All S. thermophilus isolates were genetically differentiated and a consortium of fourstrains persisted during the whole traditional production process. As confirmed by pH and the total acidityafter the acidification step, indigenous S. thermophilus strains acted as a mixed starter culture.
Original languageEnglish
Pages (from-to)73-81
Number of pages9
JournalInternational Journal of Food Microbiology
Volume155
Publication statusPublished - 2012

All Science Journal Classification (ASJC) codes

  • Food Science
  • Microbiology

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