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dc.contributor.authorMd Sikin, Adi
dc.identifier.otherbibid: 9596996
dc.description.abstractInactivation of microorganisms with high-pressure carbon dioxide (HP-CO2) is emerging as an innovative process for the sterilization of biological materials. However, its application in milk processing poses a challenge since CO2-induced reduction in pH may lead to casein precipitation. High-pressure nitrous oxide (HP-N2O) has been suggested as an alternate choice for the processing of fluid milk. Agitated supercritical carbon dioxide (Sc-CO2) at 10.3 MPa and 35°C with 100 ppm peracetic acid (PAA) resulted in a complete 8- and 5-log10 inactivation of Escherichia coli and Bacillus atrophaeus spores in thin milk-films after 15 and 40 min, respectively. The treatment also resulted in partial milk-protein coagulation (55%) and thus possible applications of this approach may be in those processes where curd formation from sterile milk is beneficial. The HP-CO2 treatment at 10.3 MPa with 50 ppm PAA resulted in 2.6-, 5.4- and 9.2-log10 reductions of E. coli in agitated bulk milk after 120 min at 5, 15 and 25°C, respectively, whereas a 0.7-log10 reduction of B. atrophaeus spores was obtained at 25°C. The Fermi model was used to describe the inactivation kinetics of E. coli and B. atrophaeus. This strategy should be attractive for low-temperature ([LESS-THAN OR EQUAL TO]25°C) pasteurization of fluid milk. A 20-min treatment of skim milk with added nisin (150 IU/mL) using HP-N2O (15.2 MPa and 65°C) resulted in 8- and 8.6-log10 reductions of E. coli and Listeria innocua, respectively. ! Meanwhile, a 2.5-log10 inactivation of B. atrophaeus spores was obtained when lysozyme (50 [MICRO SIGN]g/mL) was also added and the temperature was increased to 85°C. There were no significant changes in the physico-chemical properties of the treated milk and no sub-lethally injured cells were detected following the treatment. Agitated Sc-CO2 at 9.8 MPa and 35°C with 100 ppm PAA synergistically resulted in the inactivation of major microbial groups in shredded Mozzarella cheese after 30-min of treatment. A >5-log10 reduction in the populations of E. coli, L. innocua, yeasts & molds and the total bacterial counts along with a 4-log10 reduction of Geobacillus stearothermophilus spores was achieved during storage for 21 days at 25°C. !
dc.subjectsupercritical carbon dioxide
dc.subjectperacetic acid
dc.subjectspores inactivation
dc.titleInactivation Of Microorganisms In Skim Milk And Shredded Mozzarella Cheese Using High Pressure Carbon Dioxide And Nitrous Oxide
dc.typedissertation or thesis Science and Technology University of Philosophy D., Food Science and Technology
dc.contributor.chairRizvi,Syed S H
dc.contributor.committeeMemberMoraru,Carmen I
dc.contributor.committeeMemberCaffarella,Rosemary S.

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