...the
art
of
distell
‐
ing...
Freshness
Meter
User
Manual
Page
5
Introduction
Freshness
of
fish
and
its
measurement
Fish
is
a
highly
perishable
commodity.
When
newly
caught
it
has
pleasant,
sweet
flavours
that
are
highly
acceptable.
On
storage
these
flavours
are
progressively
lost
and
though
the
fish
is
acceptable,
it
is
not
of
such
high
quality.
Further
storage
produces
off
flavours,
and
ultimately
these
become
so
strong
that
the
fish
is
unfit
to
eat.
Fish
is
generally
stored
and
transported
in
ice,
and,
under
these
conditions
species
from
arctic
or
temperate
waters
will
reach
the
unfit
state
within
about
two
weeks.
Tropical
fish
can
be
held
somewhat
longer.
Spoilage
is
much
faster
if
the
fish
is
not
held
at
chill
temperatures.
It
is
therefore
important
for
anyone
concerned
with
quality
of
fish
to
be
able
to
measure
its
freshness
i.e.
the
amount
of
deterioration
that
has
occurred
since
it
was
caught.
Traditionally,
freshness
has
been
assessed
by
sensory
methods;
using
the
human
senses
of
sight,
smell
and
touch.
This
approach
gives
an
immediate
appraisal
of
quality
without
damage
to
the
fish.
However,
there
are
some
difficulties.
Trained
and
experienced
staff
is
required,
and
this
training
takes
a
long
time.
It
is
not
easy
to
make
sensory
assessment
quantitative.
The
changes
occurring
during
spoilage
can
be
described
and
codified,
but
individuals
may
interpret
these
descriptions
somewhat
differently.
Though
a
single
judge
may
be
consistent
within
himself,
different
judges
will
vary
among
themselves.
This
makes
it
difficult
to
establish
standards
that
can
be
applied
in
different
locations,
and
by
different
assessors.
There
is
therefore
a
need
for
objective
methods
for
measuring
freshness
that
do
not
depend
on
the
subjective
opinion
of
human
judges.
Several
chemical
procedures
are
in
use
for
this
purpose,
but
all
suffer
from
common
disadvantages
in
respect
to
quality
control
within
the
industrial
environment,
in
that
they
are
somewhat
slow
to
carry
out,
whereas
quality
controllers
and
inspectors
usually
require
an
immediate
answer.
The
analysis
requires
laboratory
facilities
and
appropriately
qualified
staff,
a
feature
which
renders
the
methods
unsuitable
for
field
work,
and
expensive
for
factory
use.
The
methods
are
destructive
and
the
damaged
fish
samples
are
no
longer
fit
for
processing.
Generally,
a
quality
controller
or
inspector
needs
to
evaluate
the
freshness
of
a
batch
of
fish
rather
than
one
individual
sample.
An
appropriate
number
of
fish
are
taken,
the
fish
evaluated
separately
and
the
average
of
the
batch
calculated.
The
recording
and
calculation
required,
though
simple,
are
inconvenient
to
carry
out
at
the
market
or
in
the
factory.
There
is
therefore,
a
requirement
for
a
rapid
and
objective
method
for
measuring
fish
freshness
in
a
wide
range
of
conditions.
The
method
should
be
accessible
to
untrained
staff
and
non
‐
destructive
in
use.
Preferably
it
should
also
allow
batch
grading
with
a
minimum
of
computation
and
record
keeping.
The
Fish
Freshness
Meter,
or
Torrymeter,
has
been
developed
to
meet
these
requirements.
Freshness
Meter
benefits
The
Fish
Freshness
Meter,
when
used
with
organoleptic
charts,
eliminates
the
uncertainty,
delay
and
cost
previously
incurred
by
sending
fish
samples
to
a
test
laboratory.
It
can
be
used
out
of
the
box
on
known,
calibrated
fish
species,
and
after
a
simple
calibration
procedure
for
new
species.
The
following
sections
of
the
manual
explain
fully
how
to
use
the
meter
and
organoleptic
charts.
Before
these,
it
will
be
useful
to
have
an
introduction
to
their
underlying
concepts.
