Effect of Preservatives on the Microbial Keeping Quality of the Burkina Drink

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May, 2018
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Food or the food industry has been a major driving force behind the growth of most economies and the “Burkina” drink which is gradually becoming a popular drink in major cities of this country. This study was carried out to evaluate the effect of sodium benzoate and potassium sorbate on the microbial keeping quality of the Burkina drink as well as to identify pathogens present in the drink during its storage period. The sample was obtained from local vendors within the Ayigya community and treated with varying concentrations of preservatives: sodium benzoate (0.05, 0.1 %) and potassium sorbate (0.1, 0.2 %) with the samples with no added preservatives serving as controls. Samples were stored at room temperature and refrigeration temperature for 15 days and assayed at three days intervals. Total aerobic count, total coliform count and yeast count were determined as stipulated by (ISO 4833-1:2003). The pH of the samples was recorded over the study period with the microbial quality test featuring the aforementioned with the inclusion of Escherichia coli and Staphylococcus aureus. The initial outcome indicated the product to be of low microbial quality with the total aerobic count, total Coliform count and yeast counts of 1.24×106±5.66 cfu/ml, 1.64×104±4.95cfu/ml and 1.23×106±7.07cfu/ml respectively exceeding the safe limits. The pathogenic profile indicated the presence of Escherichia coli (9.4×104 ± 7.07cfu/ml), Staphylococcus aureus (0 cfu/ml) and Enterococci (6.9×104±3.54 cfu/ml). Probing into the identity of the isolated microorganisms revealed a total of five species of which four could be identified fully namely Escherichia coli, Enterococcus faecalis, Bacillus cereus and Alcaligenes faecalis all of which are food pathogens associated with food spoilage. At the end of the study, there was no significant difference (p > 0.05) in the pH of the samples with regards to the treatments and the storage conditions. There was a significant difference (p < 0.05) in the total aerobic count of the samples with regards to the effect of the preservatives though there was no difference (p > 0.05) with the different temperatures. The yeast count in the samples were significantly different (p < 0.05) with regards to both the treatment and storage condition. At the end of the study, 0.2 % of potassium sorbate proved to be more effective against microbial growth compared with the other preservatives and concentrations used.  
A thesis submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Science and Technology.