SOME MICROBIOLOGICAL STUDIES ON CASSAVA FLOUR
SOME MICROBIOLOGICAL STUDIES ON CASSAVA FLOUR
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Date
1987-06
Authors
YOBE, VIVIAN NGOZI
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Abstract
ined from parts of Nigeria were analysed for
total aerobic bacteria, aerobic spore formers,
lactose ana non-lactose fermenting Enterobacteriaceae,
xerophillc and hydrophilic moulds and yeasts. The
flour samples were observed to be highly contaminated
by the various groups of microorganisms enumerated,
The range of counts obtained for the different
groups of microorganims were aerobic plate count
(1.1x104 -2.8x10 cfu/g), aerobic spore count
(<1.3x113 -2.9x106 cfu/g), lactose fermenters
(<1.0x103 -6.6x106 cfu/g), non-lactose fermenters
(<1.0x103-3.8x105 cfu/g), xerophilic moulds
(<1.0x102-1.6x105 cfu/g), hydrophilic moulds
(<1.0x102-6.4x105 cfu/g), yeasts (1.0x102-1.9x106
cfu/g).
The fungal isolates from the cassava flour
samples were identified. The predominant generation
of moulds were Aspergillus and Penicillium.
Sixty percent of the total number of samples were
contaminated by A. flavus which was the most
predominant species of Aspergillus. The second
most predominant fungus, A. niger, was isolated
from 43% of the total number of samples.
PeniciIlium spp. occurred in 48% of all the samples
examined. Other species of fungi isolated from
cassava flour were Sporcndonema sebi, Curvularia
lunata, Aureobasidium pullulans (a yeast-like
mould), Rhiiopus stolonifer, R. oryzae, pigmented
and non-pigmented yeasts.
Thirteen out of 60 A. flavus strains isolated
from cassava flour produced aflatoxins in yeast
extract broth medium containing 20% sucrose. Ten
of the aflatoxigenic strains produced aflatoxins
B1, B2, G1, G2 while three produced aflatoxins B1
and B2 only. The amount of aflatoxins produced
were relatively high and ranged from 3.0-14.2
ug/ml (B1,) 0.9-11.9 Ug/ml (B2), 0-12.5 ug/ml
(G1) and 0-9.2 ug/ml (G2). Aflatoxin producing
strains of A. flavus were isolated from cassava
flour samples obtained from different geographical
areas-of Nigeria. The results are discussed in
relation to possible sources of microbial cohtamination
of cassava flour and the need for improvement
in overall sanitation during production and
sale- of the product.
Description
A THESIS
Submitted to the Fostgraduate School
AHMADU BELLO UNIVERSITY, ZARIA
in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE
Dcpartmentof Microbiology
Faculty of Science,
Ahmadu Bello University,
Zaria, NIGERIA.
Keywords
MICROBIOLOGICAL,, CASSAVA FLOUR