Rose, Robert E.

English

Research Papers in Economics

TIME-TEMPERATUREMONITORS
FOR FRESH AND FROZEN FOODS
by
Robert E. Rose
Kockums Chemical, Inc.
To preface my presentation today,
I would like to state the following
proposition, which is open to challenge
at any time:
Any system or tool designed to
provide evidence of loss of
quality in perishable foods
must, at least, integrate the
effects of both temperature
and time for the entire storage
life of that product.
At the present time there are
basically two systems which are used,
in various forms, to assure purchasers
of perishable foods - and these pur-
chasers include food distributors and
retailers, as well as consumers - that
quality has been adequately protected
in the products they buy. The first
of these is spot temperature checks
during selected phases of distribution.
These are essentially meaningless and
can be grossly unfair. Spot temperature
checks neglect the time factor, and can
in no way prwide a reasonable basis of
judgment as to the adequacy of handling
at the moment at which the check was
made. By their very nature, spot checks
can only measure a very minor proportion
of the goods flowing through distribu-
tion channels.
The second system, which has enjoyed
increasing popularity (or unpopularity,
depending upon the hat you wear) in
recent years as a result of increased
consumer awareness, is open dating - the
printing on the package of the date
beyond which the product should either
not be purchased or not sold. On the
surface, open dating appears to be in the
league with Mom and apple pie - who can
knock it? It is definitely one way of
keeping consumers better informed and
who will deny their right to more informa-
tion? For products not requiring con-
trolled temperature storage conditions~
whose shelf life is so brief or so long
that wide variations in temperature will
not appreciably affect its quality, open
dating is a valid form of guidance for
purchase and use. For perishable products,
however, it may not only be meaningless,
but can often be directly misleading.
The reason for this is that it completely
neglects the essential element of tempera-
ture. One leading spokesman for the
food industry, when confronted with the
problem of putting an open date on his
perishable products, stated that he would
probably have to go along with it, but
might just as well print his grandmother’s
birthdate on the packages for all the
good it would do. Open dating can only
be meaningful if perfect or near-perfect
temperature handling is afforded perish-
able products and this, while a goal of
the food industry, will take some time to
accomplish. The push for open dating for
perishable products is, therefore, a
definite case of putting the cart before
the horse.
For many years, various degrees of
attention have been given to the perfection
of some kind of device which could be
placed on packages or containers of perish-
able foods to give external evidence of
Journal of Food Distribution Research February 77/page 143what had happened to those products
during distribution. To date, some
sixty patents have been issued for
various kinds of indicating devices
which would, in different ways, attempt
to show when breakdowns in temperature
protection have occurred. Few of these
devices have enjoyed any measurable
degree of acceptance, however, for the
simple reason that they either do not
work or do work, but are economically
or practically unacceptable.
In the last 2 - 3 years, atten-
tion has been focused increasingly on
the benefits that could occur to both
buyers and ,s@llers of perishable foods
if the right kind of external indicating
device could be found. The topic of
temperature indicating devices has been
studied or taken up in these last years
by such diverse groups as the American
Frozen Food Institute, Consumer Union,
The Institute of Food Technologists,
the State legislatures of New York and
New Jersey, the United States Army and
some large supermarket chains. Judging
from the activities of groups such as
these, as well as from opinions ex-
pressed throughout the food industry,
it appears that there is currently
definite interest in a temperature
indicator for use in monitoring the
handling of perishable foods if it can
fulfill certain basic requiremmts. In
general, these requirements are as
follows:
1. The indicator must be economically
feasible. The cost of the indicator
itself, plus any added expenses which
result from the incorporation of a
monitoring system into distribution
practices, must be such that neither
the food industry nor the consuming
public is burdened with expenses which
are in excess of value received.
2. It must give a clear signal whose
implications are clearly understood by
all handlers of the products who will be
required to interpret and act upon this
signal.
3. It must protect buyer’s interests;
that is, it must show that a sufficient
amount of acceptable quality remains at
the time of purchase for his subsequent
normal use.
4. It must also protect sellers’ in-
terests by not in any way condemning
products which actually do have sufficient
quantities of acceptable quality remain-
ing in them. Failure to do this would
cause unnecessary and unacceptable waste
of food resources.
5. Its function must, directly or in-
directly, relate to the quality of the
products which it is monitoring. This
implies the necessity of functionally
combining both critical factors of tem-
perature and time.
6. It should ideally be self-policing;
that is it should enable buying or
acceptance decisions made on the basis of
its signal to constitute, by themselves,
an adequate control mechanism. It should
not require an extensive organizational
apparatus to implement or police its use.
7. It should permit corrective action to
be taken during the distribution process
so that product waste can be minimized.
In other words, the indicator message
should not be a suicidal one - “when the
spot turns color the package will self-
distruct” or, more realistically, the
indicator signal should not require im-
mediate removal of the product from
further distribution. Instead, it should
be such that distribution can be accel-
erated so that the product will still reach
February 77/page 144 Journal of Food Distribution Researcthe consumer in acceptable condition,
again preventing unnecessary food
waste from occuringo
8. Lastly, the indicator should be
reliable, and given the importance
of its function as outlined above, this
pre-requisite requires no comment.
Since 1970~, we at the i-point
Company in Malmo, Sweden have been
working to provide a temperature in-
dicator which would meet the require-
ments just outlined. This has been a
long and intricate development process
which has led us into completely new
areas of biochemical technology. We
now have a temperature monitoring in-
strument which can provide a valuable
service to all of us interested in
maximizing the retention of quality in
the perishable food products we sell or
consume. We have called our indicator
the i-point TTM, or Time/Temperature
Monitor.
It is a self-adhesive label
designed to monitor the temperature
handling of perishable products and
gives warning if unsatisfactory tem-
perature conditions occur.
Although the largest potential
area of use for this device is in the
distribution of frozen, fresh and refri-
gerated food products - it can also be
used for many other types df products
which must be handled at controlled
temperatures.
When we became engaged in this
project we realized there were several
standards this device must meet if it
were to be practically applicable.
It must be -
Reliable
Accurate
Small
Inexpensive
And it must have a message which
could be -
Clearly Understood
To be effective it should also -
Integrate both the length and
degree of all temperature exposures
It is well to point out that the idea
of a monitoring device to be used for
perishable products is not a new one.
In the United States alone, over 50
patents have been granted for various
types of temperature indicators.
None has met with commercial success,
however, because none has been able to
meet the qualifications just mentioned.
They simply have not been able to
do the job.
What exactly is the job to be done?
We discovered that this is not a
question to be easily answered and that
is one of the reasons why it has taken
us six years of intensive research and
development work to bring forth the first
generation of i-point TTM.
In our opinion the best way to show
the deterioration of biological products
is by using enzymatic reactions.
They are in this respect superior to
purely chemical or physical indicating
methods and devices.
The reaction of i-point TTM is based
on enzymatic degradation giving rise to
colored end products.
As an example, this type is based on
change in PH caused by enzymatic activity.
This device consists of two pouches,
one containing the enzyme and the other
the substrate.
Journal of Food Distribution Research February 77/page 145In the enzyme part we also have
liquid PH indicator.
The reaction is simply started by
applying pressure on the package where-
upon the seal between the two pouches
is broken and their contents mixed.
When stored at ideal temperatures,
the reaction proceeds very slowly.
As temperatures change, so does
the velocity of the reaction - slower
if the temperature is lowered and
faster if the temperature is increased.
Thus , a cumulative effect of time
and temperature is obtained.
When predetermined time/temperature
limits have been reached the device
reacts by changing color, clearly and
irreversibly - blue to yellow in this
case.
In looking at applications for our
time/temperature monitor, we found
several valid reasons for concentrating
our early efforts in the area of frozen
foods :
1. There is a great deal of information
publicly available concerning the
effects of temperature on the storage-
ability of frozen foods.
The pioneer contributions in this
area were the studies of Van Arsdel and
others at the USDA Western Regional
Research Laboratory in the 1950!s.
These studies resulted in the
time/temperature tolerance hypothesis
which have become basic guidelines in
questions of frozen food stability.
2. A second reason was that early
during our development work, the American
Frozen Food Institute, the major organ-
ization of frozen food rmocessors in
in the U.S. became interested in time/
temperature monitors.
We have cooperated closely with
this organization and individual member
companies in their efforts to evaluate
possibilities for application of monitor-
ing devices within the frozen food in-
dustry.
3. Thirdly, we found that i-point TTM
could function effectively in the entire
temperature range in which frozen foods
are handled, or mishandled, and it did,
indeed, respond in accordance with the
TTT conclusions.
The essential elements of these
time/temperature studies are:
1. Quality loss in a frozen product is
proportional to the integrated accumu-
lated effects of both time and temperature.
2. The rate of quality loss will increase
as storage temperature increases and
decrease as temperature decreases.
3, All quality losses are cumulative
and irreversible.
4. All temperature effects are com-
mutative - they have the same result on
product quality no matter when they occur
during the life of a product.
These qualities are true of most
food products, frozen as well as refri-
gerated and obviously also of many other
time/temperature sensitive products as
live viral vaccines and many pharmaceutical
products.
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February 77/page 146 Journal of Food Distribution Researcl

TIME-TEMPERATURE MONITORS FOR FRESH AND FROZEN FOODS

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