Abstract

The quantitative effect of ‘abafe’ (Piliostigma thionnigii) and ‘agehu’ (Khaya ivorensis) leaves (fresh or dried; singly or combined) on the microbial load of dry-yam ‘gbodo’ was studied.  The treated samples had lower microbial loads (>10 to 10⁴ cfu/g) (total plate count, fungal count and staphylococcal count) compared to that of an untreated sample (10⁶ cfu/g).  Also, as the level of inclusion of leaves (especially fresh leaves) increased, the preservative effect of the leaves on dry-yam increased.  Samples F-AB50-Y, F-AG40-Y and F-AG50-Y had the lowest staphylococcal count (>10 cfu/g).  Sample CF50-Y had the lowest total plate count (5.1 x 10² cfu/g), fungal count (0.9 x 10² cfu/g) and staphylococcal count (>10 cfu/g) when compared with all the other treated samples. The most prominent microorganisms isolated from each dry-yam sample were Staphylococcus aureus, Bacillus subtilis and Aspergillus flavus. All the leave extracts suppressed growth of the isolated organisms. The combined form of the leave extracts (0.143 g/ml each) exhibited the strongest effect on the microorganisms.

Key words: Quantitative effect, abafe, agehu, microbial load, gbodo.