A survey of the microflora of Hibiscus sabdariffa (Roselle) and the resulting “Zobo” juice

Abstract

The dried calyx of Hibiscus sabdariffa (Roselle) is locally processed into a non alcoholic drink known as ‘Zobo’ in Nigeria. This popular drink is quite cheap compared to other bottled soft drinks but its acceptability is still limited because of its very short shelf life (24 h at room temperature). The composition and numbers of the microflora of the dried calyx of the Roselle plant and its resulting juice (Zobo) were examined using standard microbiological methods. The dried calyx obtained from a retail market was processed into juice that was compared with commercially sold (retail) juice. The microorganisms isolated from the dried calyx and the juices included the fungi, Aspergillus niger, Aspergillus flavus, Rhizopus oligosporus, Penicillium citrinum, Mucor spp., Saccharomyces cerevisiae, and Candida krusei, while Bacillus subtilis, Pseudomonas spp., Staphylococcus aureus, Streptococcus faecalis, Escherichia coli, Proteus mirabilis, Serratia spp., Lactobacillus brevis and Lactobacillus fermentum represented the bacterial isolates. Viable counts ranged from 0.4 x 10⁴ to 3.2 x 10⁴ cfu/ml. Aerobic and anaerobic bacterial counts were higher in the retail juice (1.1 to 2.2 x10⁴ cfu/ml) than in the laboratory-prepared juice (0.8 to 1.4 x10⁴ cfu/ml) while the dried calyx had the highest fungal counts of 3.2 x 10⁴ cfu/ml. pH of the juices ranged between 2.67 and 2.77 while total titratable acidity values were between 0.02 and 0.08.

Keywords: Dried calyx, microflora, viable counts, Zobo juice