ASTM F1416-96

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 1416 – 96
Standard Guide for
Selection of Time-Temperature Indicators
This standard is issued under the fixed designation F 1416; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
ln~LIFE /LIFE !
1. Scope
1 2
E 5 3 R (1)
a
1 1
1.1 This guide covers information on the selection of
T T
1 2
commercially available time-temperature indicators (TTIs) for
noninvasive external package use on perishable products, such where LIFE and LIFE = shelf lives at temperatures T and T .
1 2 1 2
as food and pharmaceuticals. When attached to the package of
2.1.2 all-temperature time-temperature indicator—a TTI
a perishable product, TTIs are used to measure the combined
that continues to change at some rate at all temperatures.
time and temperature history of the product in order to predict
2.1.3 Arrhenius plot—a plot of the logarithm of the shelf
the remaining shelf life of the product or to signal the end of its
life of a product versus the reciprocal of temperature (1\T).
usable shelf life. It is the responsibility of the processor of the
2.1.3.1 Discussion—If the shelf life of a product exhibits
perishable product to determine the shelf life of a product at the
Arrhenius behavior, then an Arrhenius plot of the shelf life will
appropriate temperatures and to consult with the indicator
be a straight line. The activation energy of the shelf life is equal
manufacturer to select the available indicator which most
to the slope of the line times R (see 2.1.1.1). It is more accurate
closely matches the quality of the product as a function of time
to use a regression analysis to determine the slope based on the
and temperature.
data from at least three temperatures than to use only two
points as in the previous equation. A blank Arrhenius plot is
NOTE 1—Besides time-temperature indicator, TTI is also an abbrevia-
tion for time-temperature monitor and time-temperature integrator. shown in Fig. 1. The plot axes are the log of the shelf life and
the reciprocal of temperature. For ease of use, the Fahrenheit
1.2 Time-temperature indicators may be integrated into a
and Celsius temperatures are shown on the graph instead of the
Hazard Analysis and Critical Control Point (HACCP) plan.
inverse temperature.
Appropriate instructions should be established for handling
2.1.4 Arrhenius relationship—a relationship that describes
products for which either the indicator has signaled the end of
the dependence of the rate of a chemical reaction on tempera-
usable shelf life or the shelf life of the product at its normal
ture as follows:
storage temperature has been reached.
E
1.3 This standard does not purport to address all of the
a
k 5 A e 2 (2)
0 S D
RT
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
where:
priate safety and health practices and determine the applica-
k = rate constant,
bility of regulatory limitations prior to use.
A = constant with the same time units as k,
T = temperature, K (°C + 273), and
2. Terminology
R = universal gas constant.
2.1 Definitions:
When R = 0.001987 kcal/(mol · deg), the activation energy,
2.1.1 activation energy—the quantity commonly used to
E , is given in units of kcal/mol.
a
describe the dependence of the shelf life of a product (or the
When R = 0.00831 kJ/(mol · deg), the activation energy, E ,
a
rate of a reaction) on temperature, as given by the Arrhenius
is given in units of kJ/mol.
relationship.
2.1.4.1 Discussion—This relationship also describes the
2.1.1.1 Discussion—The higher the activation energy, the
dependence of the shelf life of many TTIs and perishable
more the shelf life of a product changes with temperature. If
products on the effective average temperature to which they are
the shelf life of a product is known at two temperatures, the
exposed. Since the shelf life is the time for the reaction to
activation energy is given by the following formula:
proceed to a specific extent, the Arrhenius relationship for shelf
life is given by the following formula:
E
a
This guide is under the jurisdiction of ASTM Committee F02 on Flexible
LIFE 5 Be (3)
S D
RT
Barrier Materials and is the direct responsibility of Subcommittee F02.30 on Test
Methods.
where B = constant with the same time units as LIFE.
Current edition approved Feb. 10, 1996. Published April 1996.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 1416
TTI that only changes at temperatures above a specific thresh-
old.
2.1.10 time-temperature indicator (TTI)—a device that can
be affixed to the package of a perishable product and that
exhibits a change in a physically measurable or visually
measurable property as a combined function of both time and
temperature. For example, properties that change include color,
light reflectance, or a moving boundary between two colors.
2.1.11 time-temperature integrator—see time-temperature
indicator.
2.1.11.1 Discussion—This term emphasizes the fact that the
indicator’s response is an integration of the effects of both time
and temperature.
2.1.12 time-temperature monitor—see time-temperature in-
dicator.
2.2 Definitions of Terms Specific to This Standard:
2.2.1 activation method—the method by which an inactive
TTI is changed to an active state.
2.2.1.1 Discussion—This may include a physical activation
method, such as removing or breaking a barrier, or may require
NOTE 1—This blank graph may be used to determine if the shelf life of
raising the temperature to the normal operating range of the
a product exhibits standard Arrhenius behavior. The plot axes are the log
TTI.
of the shelf life and the reciprocal of temperature. Note that the X-axis of
2.2.2 inactive state—the state in which a TTI does not
this plot is marked in Celsius degrees instead of inverse Kelvin degrees,
respond to changes in temperature over time.
so that the spacing between degrees is not uniform. For ease of use, the
Fahrenheit and Celsius temperatures are shown on the graph instead of the 2.2.2.1 Discussion—Some types of indicators are active
inverse temperature. To use, plot the shelf life of the product at
when manufactured and kept essentially inactive by storage at
temperatures for which it is known. If the shelf life follows the Arrhenius
low temperatures.
relationship, the points can be connected with a straight line. The
2.2.3 slackened-out product—a product that is stored frozen
activation energy may be calculated by the equation in 2.1.1.1.
for an indeterminate time and then thawed (slackened out) for
FIG. 1 Blank Arrhenius Plot
the final part of its distribution and use.
3. Significance and Use
2.1.5 dual function time-temperature indicator— a TTI that
combines both all-temperature and threshold-temperature re- 3.1 Expiration dates are often marked on the packages of
sponses, overlaid in a single indicator in order to modify the perishable products to indicate the presumed end of their shelf
total time-temperature response. lives. Since the shelf lives of most perishable products are
2.1.6 effective average temperature—the single constant temperature dependent, the expiration date is determined by
temperature that would have the same effect on the shelf life of assuming the product will be kept within a prescribed tempera-
a product as the actual temperature profile has for the same ture range for its entire life. A problem with this method is that
time period. there is no way to determine if the shelf life of a product has
2.1.7 hazard analysis and critical control points been shortened by exposure to a higher temperature. A time-
(HACCP)—a method to control food quality and safety by temperature indicator solves this problem when attached to the
identifying and controlling those processing and distribution package because it reaches its end point sooner when exposed
steps where a food safety hazard may be prevented, eliminated, to a higher temperature.
or reduced to acceptable levels. 3.2 In order to directly indicate the end of the shelf life, the
2.1.8 shelf life—the time required for various changes to a time-temperature indicator characteristics should be matched
product to accumulate to the point where the product no longer as closely as possible to the quality characteristics of the
meets predetermined criteria and is no longer considered product. When kept at the standard storage temperature for the
suitable for its original purpose.
product, the indicator should reach its end point at the same
2.1.8.1 Discussion—In some cases, such as where patho- time as the product’s shelf life. In addition, to determine the
genic microbial growth is involved, there may be a serious
accuracy of the match at other temperatures, the change of
health risk in using a product past its shelf life. In such cases, shelf life with temperature should be known for both the
the shelf life to be monitored should be conservative enough so product and the indicator. The Arrhenius relationship is a
that its expiration is signaled well before a health concern common and convenient method of describing the change of
develops. It may be desirable to indicate even short occur- shelf life with temperature. In cases where it is not applicable,
rences of undesirably high temperatures. Other changes may individual time-temperature points for the product may be
also occur, such as in color, texture, or rancidity, which render established and an approximate correlation with the TTI
a product unaccept
...