Obioma E. Nwafor
The growth inhibitions of Penicillium citrinum, Rhizopus stolonifer and Aspergillus niger isolated from locally prepared zobo drinks using sorbic and benzoic acids at room temperature were investigated for a period of eight weeks (56 days). A concentration of 0.05% (w/v) sorbic acid showed complete growth inhibition of P. citrinum and R. stolonifer on the 35th day and A. niger on the 49th day. The same concentration of benzoic acid inhibited the growth of P. citrinum and R. stolonifer on the 42nd day and A. niger on the 56th day. All combinations of the two preservatives demonstrated enhanced growth inhibitions to the three tested fungi. A combination of 0.05% (w/v) of sorbic and benzoic acids completely inhibited the growth of P. citrinum and R. stolonifer on the 21st day of storage. Similar inhibitory effect was observed for A. niger on the 25th day. The finding is an indication that sorbic acid and benzoic acid can be used to control the growth of these zobo drink spoilage microorganisms during storage.
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