Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese Production
Thermization is a sub-pasteurization heat treatment widely applied in traditional Greek hard cheese technologies. In this study, five bulk milk batches from two native Epirus sheep breeds were analyzed microbiologically before (raw milk; RM) and after thermization at 65 °C for 30 s (TM) followed by...
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2025-01-01
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| author | John Samelis Loulouda Bosnea Athanasia Kakouri |
| author_facet | John Samelis Loulouda Bosnea Athanasia Kakouri |
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| description | Thermization is a sub-pasteurization heat treatment widely applied in traditional Greek hard cheese technologies. In this study, five bulk milk batches from two native Epirus sheep breeds were analyzed microbiologically before (raw milk; RM) and after thermization at 65 °C for 30 s (TM) followed by characterization of 125 presumptive LAB isolates from each of the counterpart RM and TM samples. Psychrotrophic <i>Pseudomonas</i>-like spoilage bacteria and mesophilic LAB, primarily of the genera <i>Leuconostoc</i> (48.4%) and <i>Lactococcus</i>/<i>Streptococcus</i> (32.8%), co-dominated in RM at mean levels 5.7–6.3 log CFU/mL, whereas thermophilic LAB, <i>Enterococcus</i>, <i>Staphylococcus</i>, coliforms, and yeasts were subdominant at mean levels 4.1 to 5.2 log CFU/mL. Coagulase-positive staphylococci were abundant (3–4 log CFU/mL) in all RM batches. <i>Listeria monocytogenes</i> was found in one batch. Both pathogens were diminished by thermization, which reduced all non-LAB contaminants below 100 CFU/mL. Enterococci (68.6%) were highly selected in all TM batches, followed by thermophilic streptococci (8.6%). Only 7.4% of the total RM microbiota survived in the resultant five TM batches. <i>Leuconostoc</i> showed the lowest (1.3%) survival. Thus, thermization improved the quality and safety of raw sheep milk, but reduced mesophilic LAB by ca. 2 log units in favor of enterococci in TM. |
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| spelling | doaj-art-dd9a96d6f67f4d1f88b9b54d9c5c20d32025-08-20T03:43:47ZengMDPI AGApplied Microbiology2673-80072025-01-01511110.3390/applmicrobiol5010011Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese ProductionJohn Samelis0Loulouda Bosnea1Athanasia Kakouri2Dairy Research Department, Institute of Technology of Agricultural Products, Hellenic Agricultural Organization ‘DIMITRA’, Katsikas, 45221 Ioannina, GreeceDairy Research Department, Institute of Technology of Agricultural Products, Hellenic Agricultural Organization ‘DIMITRA’, Katsikas, 45221 Ioannina, GreeceDairy Research Department, Institute of Technology of Agricultural Products, Hellenic Agricultural Organization ‘DIMITRA’, Katsikas, 45221 Ioannina, GreeceThermization is a sub-pasteurization heat treatment widely applied in traditional Greek hard cheese technologies. In this study, five bulk milk batches from two native Epirus sheep breeds were analyzed microbiologically before (raw milk; RM) and after thermization at 65 °C for 30 s (TM) followed by characterization of 125 presumptive LAB isolates from each of the counterpart RM and TM samples. Psychrotrophic <i>Pseudomonas</i>-like spoilage bacteria and mesophilic LAB, primarily of the genera <i>Leuconostoc</i> (48.4%) and <i>Lactococcus</i>/<i>Streptococcus</i> (32.8%), co-dominated in RM at mean levels 5.7–6.3 log CFU/mL, whereas thermophilic LAB, <i>Enterococcus</i>, <i>Staphylococcus</i>, coliforms, and yeasts were subdominant at mean levels 4.1 to 5.2 log CFU/mL. Coagulase-positive staphylococci were abundant (3–4 log CFU/mL) in all RM batches. <i>Listeria monocytogenes</i> was found in one batch. Both pathogens were diminished by thermization, which reduced all non-LAB contaminants below 100 CFU/mL. Enterococci (68.6%) were highly selected in all TM batches, followed by thermophilic streptococci (8.6%). Only 7.4% of the total RM microbiota survived in the resultant five TM batches. <i>Leuconostoc</i> showed the lowest (1.3%) survival. Thus, thermization improved the quality and safety of raw sheep milk, but reduced mesophilic LAB by ca. 2 log units in favor of enterococci in TM.https://www.mdpi.com/2673-8007/5/1/11raw/thermized sheep milknative sheep breedsthermization<i>Listeria monocytogenes</i>RFP+ staphylococcithermoduric enterococci |
| spellingShingle | John Samelis Loulouda Bosnea Athanasia Kakouri Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese Production Applied Microbiology raw/thermized sheep milk native sheep breeds thermization <i>Listeria monocytogenes</i> RFP+ staphylococci thermoduric enterococci |
| title | Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese Production |
| title_full | Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese Production |
| title_fullStr | Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese Production |
| title_full_unstemmed | Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese Production |
| title_short | Microbiological Quality and Safety of Raw Sheep Milks from Native Epirus Breeds: Selective Effects of Thermization on the Microbiota Surviving in Resultant Thermized Milks Intended for Traditional Greek Hard Cheese Production |
| title_sort | microbiological quality and safety of raw sheep milks from native epirus breeds selective effects of thermization on the microbiota surviving in resultant thermized milks intended for traditional greek hard cheese production |
| topic | raw/thermized sheep milk native sheep breeds thermization <i>Listeria monocytogenes</i> RFP+ staphylococci thermoduric enterococci |
| url | https://www.mdpi.com/2673-8007/5/1/11 |
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