Cheese ripening is a costly and lengthy process. Increasing the enzyme pool in the cheese curd has been shown to accelerate the cheese ageing process, enhance flavour and texture. The characteristics of two lactic acid bacteria attenuated by pulsed electric fields were studied in a milk system and in cheese slurry. The potential of accelerating cheese ripening via the addition of starter cultures attenuated by pulsed electric fields (PEF) was studied. / Pulsed electric field treatment was performed in a static treatment chamber using bi-polar waveform with a field intensity of 20 kV and 2 mus pulse width. The number of pulses ranged from 10 to 500. Evaluation of the starter cultures was assessed through the analysis of acidifying abilities, survival fractions, enzymatic activities and proteolysis (RP-HPLC and Cd-ninhydrin) in water soluble nitrogen extracts following the different attenuation treatments. / Pulsed electric fields significantly affected the general viability of the cells through a delayed acidification and an inhibition of enzymatic activity. A study in cheese slurry systems showed that the cultures under investigation were not able to provide an increased proteolysis levels following PEF treatment. The results of this study also suggest that optimal PEF treatment varies for each LAB strain and that the Lactococcus strains do not possess high enough proteinase and peptidase activities to be beneficial for the acceleration of cheese ripening.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.78330 |
| Date | January 2003 |
| Creators | Briggs, Stephanie Sheryl |
| Contributors | Ngadi, M. O. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Agricultural and Biosystems Engineering,) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001985332, proquestno: AAIMQ88165, Theses scanned by UMI/ProQuest. |
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