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Characterisation of a scum in sport drink and determination of the effects of preservation factors on its development.

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The development of a scum in a commercial sports drink is of concern because the product would be of poor quality, which may result in financial losses due to consumer rejection of the product and hence a decrease in the firm’s market share. The scum could be harmful to health and as such the firm could be litigated. Several factors, including microbial proliferation, may be the cause of the development of a scum in sports drink, but the actual cause seems not to have been established. The aim of this study was to characterise the scum in sports drink and determine the effects of preservation factors (pasteurisation, chemical preservatives and refrigeration) on its development. Samples of the sports drink were taken at different stages of processing to determine the effect of preservatives, pasteurisation and storage temperature on scum development. Some samples were kept at room temperature (approx. 25°C) and others were kept in the refrigerator (approx. 4ºC) during the study. A total of 150 samples were analysed over a period of four months. The structural characteristics of the scum that developed in the sports drink were determined by scanning electron microscopy (SEM) and elemental analysis. The sports drink samples were analysed for their microbial load and microbial types. Consumer acceptability of pasteurised and non-pasteurised drink was compared by conducting sensory evaluation using a consumer panel of 60 panellists. Customer complaints recorded by the sports drink manufacture that were due to scum development in the drink were also reviewed to establish the impact of scum development on consumer acceptability of the drink. The results of the study indicated that scum development was due to microbial contamination of the drink. The causative organism of the scum was identified as Acinetobacter baumanii. Acinetobacter baumanii is a gram negative non-spore forming coccobacilli and does not ferment sucrose. Acinetobacter baumanii forms the scum in sports drink as a means of protection from environmental stresses. The scum was found to be a compound of C, Si and O. The non-pasteurised samples were slightly more acceptable to consumers compared to the pasteurised samples. The consumer acceptability of pasteurised drink samples was negatively affected by the loss of aroma and flavour during pasteurisation. The preservation factors (chemical preservatives, pasteurisation and refrigeration) had no effect on scum development. To prevent post pasteurisation contamination, it is recommended that the pasteurisation process be done at the filling stage instead of at the holding stage. The frequency of changing rubbers and gaskets on the filling line should be at least every two months. The drink is pasteurised at 90ºC for 20 seconds, this needs to be reduced to a level where it will not have an influence on the loss of taste and aroma of the pasteurised drink, but without reducing the effectiveness of pasteurisation.


Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.


Non-alcoholic beverages., Food contamination., Energy drinks., Consumer preferences., Acinetobacter., Theses--Food security.