Identification and Characterization of Fungi in Hibiscus sabdariffa (zobo) Drink Produced and Hawked in Eket Metropolis, Nigeria

Abstract

Zobo drink is an affordable local soft beverage derived from the calyx of Hibiscus sabdariffa, a herbaceous medicinal plant that thrives in tropical regions. The characterization and identification of fungi present in Zobo drinks produced and sold by vendors in Eket, Akwa Ibom State, was the aim of this study. Hawked Zobo drinks packaged in plastic bottles were purchased from ten different hawkers, two each from five locations. The pH values of the samples were determined and the total fungal count. The pour plate technique, using Sabouraud Dextrose Agar (SDA) was used to determine the total fungal count. Macroscopic and microscopic features were used to characterize the isolates obtained from the samples. The microscopic identification was done by preparing a wet mount of isolated colonies and observing under a microscope. The rate of growth, colony colour, colour changes, colour of reverse colonies, odour and texture of surface were observed and compared with previous work done on fungi. Results showed that the pH of the freshly obtained and stored samples was 3.9 and 2.8 respectively. The average number of colonies for samples stored in the refrigerator ranged from 0.54 x 105 to 0.91 x 105 cfu/ml while that of the freshly obtained samples ranged from 1.26 x 105 to 1.64x105 cfu/ml at 10-3 dilution. A total of 43.6% Aspergillus spp., 29.5% Candida spp. 15.4% Penicillium spp. and 11.5% Rhizopus spp. were identified. With increased acidity in the refrigerated samples, the number reduced to 41.2% Aspergillus spp., 27.4% Candida spp. 15.7% Penicillium spp. and 15.7% Rhizopus spp. The fungi species isolated are known to produce mycotoxins with potential immunosuppressive and cytotoxic effect. These microorganisms could have been introduced to the drinks at various stages of production, during transportation, through the ingredients utilized in the manufacturing process, or even during the cultivation of the Hibiscus sabdariffa plant. This issue can be mitigated by implementing effective manufacturing practices throughout the production process.