Abstract

Fresh white bread and ‘eba’ (a carbohydrate; > 80% starch, indigenous staple food in southern Nigeria) were purchased from traders in Lagos, Nigeria and stored under aseptic conditions in the laboratory at room temperature (27 ± 2°C) (11 h of darkness and 15 h of daylight) for duration of 144 h, during which samples were analyzed at 48 h intervals for fungal population using the plate count technique. The sensitivity of the spoilage fungi to aqueous and methanol extracts of leaves of Thaumatococcus danielli and Megaphrynium macrostachyum was determined using the broth dilution method. Fungal populations increased with hour of storage. For bread, Penicillium sp was dominant throughout with average populations of 2.0 x 10¹ and 8.01 x 10⁶ cfu/g at 0 and 144 h, respectively, while Mucor sp was dominant in eba with average populations of 1.0 x 10¹ and 9.5 x 10⁶ cfu/g at 0 and 96 h, respectively. For T. danielli, while the methanol extract had greater activity against the spoilage fungi than the aqueous extract, the reverse was observed for M. macrostachyum. The lowest minimum inhibitory concentration (MIC) of T. danielli was 25 mg/ml of the methanol extract against Saccharomyces cerevisiae and Saccharomyces chevalieri and its lowest minimum cidal concentration (MCC) was 50 mg/ml of the methanol extract against S. cerevisiae and Penicillium sp. For M. macrostachyum, the lowest MIC and MCC were 25 and 50 mg/ml of the aqueous extract respectively against S. chevalieri. The results highlight the potential of extracts of T. daniellii and M. macrostachyum as sources of alternative natural preservatives of bread and ‘eba’.

Key words: Thaumatococcus danielli, Megaphrynium macrostachyum, minimum inhibitory concentration, minimum cidal concentration.