The microbiology and deterioration of soft drinks subjected to two different marketing

The microbial quality and successional changes in two brands (A and B) of soft drinks held under two marketing conditions (ambient ca 28 ºC and open air ca 34 ºC) were investigated using spread-plate technique. Heterogeneous flora was isolated from the two brands but varied with brand. Pediococcus spp. occurred in brand A but not in brand B. Much higher incidence (30%) of Staphylococcus spp. was observed in brand B as compared with 10% in brand A. Bacillus spp. were the most predominant bacterial group found in both brands while Aspergillus spp. and Cladosporium spp. dominated the two brands. Incidence of Bacillus spp. in samples held in open-air was remarkably increased by approximately 103% in brand A but tended to remain unchanged in brand B. Exposure of samples to the two conditions resulted in about 2-fold increase in Lactobacillus spp. in brand B on day 14 and decreased thereafter but decrease occurred in brand A after initial increase. Initial increase in Staphylococcus spp. occurred in both brands but became non-detectable in samples held under ambient condition as opposed to low incidences in samples subjected to open-air. Dramatic changes also occurred in the mycoflora; Arthrinium spp. were not isolated until day 14 and higher incidences occurred in samples held in open-air. Saccharomyces spp. were undetected in the samples until day 21. Approximately 13- and 9-fold increases in total aerobic bacterial counts were observed in brands A and B samples held in at 34 ºC respectively. Higher fungal populations occurred in both brands subjected to open-air with brand B samples showing the higher population. The diversity of the microbial flora and the phenomenal changes in incidences of Bacillus spp. coupled with prevalence of Aspergillus spp. in the open-air-held samples could pose health risks. Adoption of adequate quality control measures and distribution practices would likely reduce the microbial diversity and deterioration (characterized by sedimentation) due probably to Bacillus spp. and Saccharomyces spp. Consumption of these products is not advised after 14 days of exposure to the marketing conditions studied in this work. Global Journal of Pure and Applied Sciences Volume , No 1 January (2001) pp. 43-48 KEY WORDS: Soft drinks, microbial composition, deterioration, marketing conditions