Abstract
Cold-tolerant bacteria, also known as psychrotrophic bacteria, are notorious contaminants of milk in
the refrigerated dairy food chain. These organisms, especially the pseudomonads, may produce heatresistant
enzymes that are responsible for the breakdown of proteins and lipids in milk and dairy products.
Such reactions result in a variety of defects in the raw or unprocessed milk that may affect the suitability of
such milk for further processing. The enzymes produced may cause defects in long-life dairy products such
as cheese, butter and long-life milk. In the present study, a range of 18 yellow pigmented psychrotrophic
bacteria, collectively known as flavobacteria, were isolated from local dairy products. One aim of this study
was to identify these bacteria to species level using molecular techniques. A second aim was to determine
the spoilage potential of these organisms based on profiles generated by the BIOLOG system (that may relate
to hydrolytic enzymes produced). Of the 18 isolates, 14 belonged to the genus Chryseobacterium while 4
were identified as Empedobacter isolates. The most active spoilage organisms in this group were shown
to be C. bovis, C. shigense and E. brevis. These findings illustrate that enzymatically catalysed defects
in dairy products should not be attributed solely to acknowledged psychrotrophic bacteria such as the
pseudomonads, but that flavobacterial species may also be actively involved.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001999 |
| Date | 01 February 2016 |
| Creators | Jooste, PJ, Tsoeu, LI, Charimba, G, Hugo, CJ |
| Publisher | South African Journal of Science |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Relation | Research Gate |
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