The microbial quality of pre-packed mixed vegetable salad in some retail outlets in Lagos, Nigeria

Abstract

Pre-packed mixed vegetable salad and salad ingredients- carrots, cucumber, cabbage, and lettuce were analyzed for
their microbial quality. The salads were obtained from fast food outlets (well packaged at 4 oC) and open markets
(exposed at 35oC) within Lagos metropolis. The analysis was both qualitative and quantitative. Microorganisms
isolated from salad samples from fast food outlets include Aspergillus fumigatus, Trichoderma spp, Staphylococcus
aureus and Proteus mirabilis, while those isolated from open market samples include Mucor spp, A. fumigatus,
Aspergillus niger, Trichoderma spp, Neurospora crassa, Proteus vulgaris, S. aureus, Citrobacter freundii, Proteus
mirabilis, and Corynebacterium spp. Those from salad ingredients include Mucor spp, A. fumigatus, Trichoderma
spp, N. crassa, Rhizopus spp, A. niger, P. vulgaris, P. mirabilis, S. aureus, Pseudomonas aeruginosa and C. fruendii.
The total viable count was highest in salad samples from open markets (5.9×106
cfu/g) and lowest in salad samples
from fast food outlets (2.6 × 104
cfu/g). The total viable counts obtained from the salad ingredients were generally
lower than those obtained from salads. Among the salad ingredients the highest count was however obtained from
carrot (3.0 × 102
cfu/g) and lowest count from cucumber (1.3 × 102
cfu/g). Gentamicin, chloramphenicol,
cotrimoxazoleoflaxacin were most effective against the bacterial isolates yielding greater zones of inhibition. The
storage temperature and the dirty nature of the open markets must have been responsible for the occurrence of
more microorganisms in salad samples from open markets than those from fast food outlets. The need for safe
salad can not be overemphasized.