Title page for ETD etd-02092006-160534


Document Type Master's Dissertation
Author Verachia, Wasseela
Email wverachia@yahoo.com
URN etd-02092006-160534
Document Title Application of Pediococcus spp. as adjunct cultures in Gouda cheese
Degree MSc (Food Science)
Department Food Science
Supervisor
Advisor Name Title
Prof E M Buys
Keywords
  • no key words available
Date 2005-06-11
Availability unrestricted
Abstract
The commercial significance of the dairy fermentation industry which incorporates the production of cheeses, is well recognised and ranks second only to the production of alcoholic beverages. Consumers today demand greater choice and variety with improved quality standards. Lactic acid bacteria, in particular the genera Lactococcus, Leuconostoc, Lactobacillus, Streptococcus and Pediococcus play a central role in the production of new and exotic flavoured cheeses.

Gurira & Buys (2005) found that the Pediococcus species crude pediocin extract that were isolated from South African Gouda cheeses was inhibitory against food pathogens, Listeria monocytogenes and Bacillus cereus. Selected Pediococcus species were evaluated in this study for their activity against available mixed strain mesophilic lactic acid Gouda cheese starter cultures. The commercially available starter cultures, Nizostar 500MT, LL 50C and DairysafeTM were evaluated. The starter cultures were evaluated for their sensitivity to the Pediococcus species crude pediocin extract on the basis of their lactic acid production, pH and growth levels. The mesophilic mixed strain lactic acid Gouda cheese starter culture, DairysafeTM was identified as the starter culture that was the least sensitive to the Pediococcus species crude pediocin extract as the lactic acid production and pH level of DairysafeTM was the least affected. Thus, starter culture, DairysafeTM was used in conjunction with live cultures of Pediococcus acidilactici ST 79 and Pediococcus pentosaceus ST 13 as an adjunct culture in the manufacture of Gouda cheese.

Gouda cheese made using DairysafeTM as the starter culture and live cultures of P. acidilactici ST 79 and P. pentosaceus ST 13 as an adjunct culture was found to have a chemical composition comparable to that of the cheese, to which no adjunct culture had been added. The addition of the Pediococcus species as an adjunct culture in Gouda cheese manufacture had no significant effect on the levels of lipolysis or proteolysis of the cheese during the 45 day ripening period.

However, there were significant differences noted in the sensory attributes of the cheese manufactured using Pediococcus species as an adjunct culture and the cheese manufactured without an adjunct culture.

The results of this study indicate that P. acidilactici ST 79 and P. pentosaceus ST 13 can be used as an adjunct culture in conjunction with a pediocin resistant starter culture, such as DairysafeTM to produce a cheese that is physico-chemically comparable to Gouda cheese currently on the market but is clearly differentiable from the homogenous products currently available.

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