Microbiology
of
Foods
Most
foods
are
excellent
media
for
rapid
growth
of
microorganisms.
There
is
abundant
organic
matter
in
foods,
their
water
content
usually
sufficient,
and
the
pH
is
either
neutral
or
slightly
acidic.
Foods
consumed
by
man
and
animals
are
ideal
ecosystems
in
which
bacteria
and
fungi
can
multiply.
The
mere
presence
of
microorganisms
in
foods
in
small
numbers
however,
need
not
be
harmful,
but
their
unrestricted
growth
may
render
the
food
unfit
for
consumption
and
can
result
in
spoilage
or
deterioration.
Some
organisms
grow
and
elaborate
secondary
metabolites
that
may
affect
the
food
quality,
which
may
be
either
desirable
or
undesirable..
For
example,
the
lactic
fermentation
of
milk
is
a
desired
change
and
is
not
considered
as
spoilage,
while
acetification
of
wine
is
an
undesirable
microbial
spoilage.
Some
organisms
may
not
only
cause
food
spoilage
but
also
produce
metabolites
which
may
be
extremely
toxic
to
man
and
animals.
Such
examples
are
the
production
of
toxins
by
clostridia
in
proteinaceous
foods,
the
elaboration
of
aflatoxin
by
aspergilli
in
feeds
etc.
Generally,
foods
carry
a
variety
of
organisms
of
which,
most
are
saprophytic.
Their
presence
cannot
be
avoided
since
these
are
mostly
from
the
environment
in
which
the
food
is
prepared
or
processed.
Also,
their
complete
elimination
is
difficult.
However,
it
is
possible
to
reduce
their
number
or
decrease
their
activities
by
altering
the
environmental
conditions.
A
knowledge
of
the
factors
that
either
favour
or
inhibit
their
growth
is
therefore,
essential
in
understanding
the
principles
of
food
spoilage
and
preservation.
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