Mapping the thermo-tolerant proteases in ultra high temperature (UHT) treated milk using molecular approaches

Vithanage, Nuwan R (2017) Mapping the thermo-tolerant proteases in ultra high temperature (UHT) treated milk using molecular approaches. PhD thesis, Victoria University.


Refrigerated storage of raw milk selects for psychrotrophic bacterial genera such as Pseudomonas (mainly Pseudomonas fluorescens), Bacillus, Acinetobacter, Hafnia, Klebsiella, Rahnella, Stenotrophomonas and Aeromonas, Serratia, which are disseminated by means of feed, faeces, bedding material, soil, air, water and milking and processing equipment at the farming and processing environments. These bacteria produce a wide range of extracellular proteases that are resistant to the current heating regimes used in Ultra High Temperature (UHT) processing, typically 135-150 °C for 2-10 s. The residual bacterial proteases can lead to the development of quality defects in UHT milk, including bitterness, increased viscosity, sedimentation and age gelation, all of which, cause spoilage and shelf-life deterioration during ambient storage and transportation of UHT milk and dairy products.

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This thesis includes 1 article for which access is restricted due to copyright (Chapters 4). Details of access to this paper has been inserted in the thesis, replacing the article themselves.

Item type Thesis (PhD thesis)
Subjects Historical > FOR Classification > 0908 Food Sciences
Current > Division/Research > College of Health and Biomedicine
Keywords milk processing; dairy; raw milk; metalloproteases;, proteolytic activities; extended shelf life; storage life; matrix-assisted laser desorption time-of-flight mass spectrometry; MALDI-TOF MS; gram-negative psychotrophic bacteria; thermoduric psychrotrophs; Pseudomonas spp; bacillus cereus growth; isothermal temperature; thesis by publication
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