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dc.contributor.authorMathusa, Emily Claireen_US
dc.date.accessioned2014-03-14T20:36:59Z
dc.date.available2014-03-14T20:36:59Z
dc.date.issued2007-05-03en_US
dc.identifier.otheretd-05152007-121510en_US
dc.identifier.urihttp://hdl.handle.net/10919/32809
dc.description.abstractBatches of fromage blanc, a soft white cheese were prepared from whole pasteurized cowâ s milk. Processing and formulation methods were used in cheese making to reduce Listeria monocytogenes in artificially contaminated cheese. Treatments implemented included use of additional starter culture in formulation (25% more starter culture than original formulation), use of a higher temperature draining process (at 45oC instead of 22oC), addition of the anti-listerial bacteriocin nisin (Danisco Nisaplin) in formulation at different levels (125 ppm, 250 ppm, 400 ppm), and combinations of these treatments. Characteristics including pH, fat content, protein content, and color were evaluated for each treatment cheese. Statistically significant differences (p<0.0001) were found between the population (log CFU/g) values of L. monocytogenes in the different treatment cheeses and control cheese. Treatments using additional starter culture or higher temperature draining alone were not successful in significantly reducing numbers of L. monocytogenes, but when combined, a 1 log reduction resulted. Of the different concentrations of nisin used in cheese formulation, the level of 250 ppm nisin was used in combination treatments. The treatments using 250 ppm nisin were able to reduce numbers of L. monocytogenes by 2 log 24h after addition. Combination treatments with 250 ppm nisin and additional starter culture in formulation reduced the level of L. monocytogenes by only 1 log, while combination treatments coupling 250 ppm nisin with a higher temperature draining and treatments with 250 ppm nisin, additional starter culture, and a higher temperature draining were able to reduce the pathogen by 2 log. There were statistically significant (p<0.0001) differences found between cheese treatments for values of pH, fat content, and protein content. This soft cheese could be standardized for each of these parameters by the processor before packaging and sale of cheese. There were no statistically significant (p>0.05) differences found between colorimetric values for different cheese treatments.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartthesis_emily_mathusa.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectsoft cheesesen_US
dc.subjectbacteriocinsen_US
dc.subjectnisinen_US
dc.subjectListeria monocytogenesen_US
dc.titleElimination of Listeria monocytogenes in a Soft Cheese, Fromage Blanc, Using Processing Methods, Formulation Changes, and Additive Bacteriocin Nisinen_US
dc.typeThesisen_US
dc.contributor.departmentFood Science and Technologyen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineFood Science and Technologyen_US
dc.contributor.committeechairSumner, Susan S.en_US
dc.contributor.committeememberMarcy, Joseph E.en_US
dc.contributor.committeememberWilliams, Robert C.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05152007-121510/en_US
dc.date.sdate2007-05-15en_US
dc.date.rdate2007-05-24
dc.date.adate2007-05-24en_US


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