Inactivation Of Microorganisms In Skim Milk And Shredded Mozzarella Cheese Using High Pressure Carbon Dioxide And Nitrous Oxide
| dc.contributor.author | Md Sikin, Adi | |
| dc.contributor.chair | Rizvi,Syed S H | |
| dc.contributor.committeeMember | Moraru,Carmen I | |
| dc.contributor.committeeMember | Caffarella,Rosemary S. | |
| dc.date.accessioned | 2016-07-05T15:29:55Z | |
| dc.date.available | 2021-05-30T06:00:21Z | |
| dc.date.issued | 2016-05-29 | |
| dc.description.abstract | Inactivation 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.identifier.doi | https://doi.org/10.7298/X4B56GNP | |
| dc.identifier.other | bibid: 9596996 | |
| dc.identifier.uri | https://hdl.handle.net/1813/44267 | |
| dc.language.iso | en_US | |
| dc.subject | supercritical carbon dioxide | |
| dc.subject | peracetic acid | |
| dc.subject | spores inactivation | |
| dc.title | Inactivation Of Microorganisms In Skim Milk And Shredded Mozzarella Cheese Using High Pressure Carbon Dioxide And Nitrous Oxide | |
| dc.type | dissertation or thesis | |
| thesis.degree.discipline | Food Science and Technology | |
| thesis.degree.grantor | Cornell University | |
| thesis.degree.level | Doctor of Philosophy | |
| thesis.degree.name | Ph. D., Food Science and Technology |
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