ASTM E2454-20

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2454 − 19a E2454 − 20
Standard Guide for
Sensory Evaluation Methods to Determine the Sensory
Shelf Life of Consumer Products
This standard is issued under the fixed designation E2454; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide provides recommended sensory testing approaches and decision criteria for establishing the sensory shelf life of
consumable products, including food, personal care, and household products, to manage business risk. It describes research
considerations that include: product selection and handling, appropriate application of specific sensory test methods, selection of
test intervals, and data analysis techniques for the determination of a product’s sensory shelf life end-point. This guide will focus
on the practical considerations and approaches, risks, and criteria that must be considered in designing, executing, and interpreting
sensory shelf life results.
1.2 This guide is not intended to provide a detailed description of how to conduct reliable sensory testing. It assumes knowledge
of basic sensory and statistical analysis techniques, focusing instead on special considerations for the specific application of
sensory testing methods to shelf life determination.
1.3 The shelf life measures in this guide refer to foods, household and personal care products stored as the manufacturer
intended and do not account for changes in sensory properties occurring after opening, partial consumption/use or in-home storage.
Once products have been manufactured, packaged and sent through the distribution channels, the condition of the products is not
typically under study. However, a company may wish to include such variables in their shelf life studies when there is a need to
evaluate the sensory quality of their products as they go through distribution channels and/or in-home storage or in-home storage,
or both, and use.
1.4 This guide is not intended to address non-sensory issues related to the shelf life of food, including microbial contamination
and chemical changes of products associated with aging, nor is it intended to address potential safety issues associated with aging
food and non-food consumer products.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E253 Terminology Relating to Sensory Evaluation of Materials and Products
E460 Practice for Determining Effect of Packaging on Food and Beverage Products During Storage
E1871 Guide for Serving Protocol for Sensory Evaluation of Foods and Beverages
E2139 Test Method for Same-Different Test
E2164 Test Method for Directional Difference Test
E2263 Test Method for Paired Preference Test
E2610 Test Method for Sensory Analysis—Duo-Trio Test
E3005 Terminology for Body Armor
E2943 Guide for Two-Sample Acceptance and Preference Testing with Consumers
This guide is under the jurisdiction of ASTM Committee E18 on Sensory Evaluation and is the direct responsibility of Subcommittee E18.05 on Sensory
Applications--General.
Current edition approved Nov. 15, 2019April 1, 2020. Published January 2020April 2020. Originally approved in 2005. Last previous edition approved in 2019 as
E2454 – 19.E2454 – 19a. DOI: 10.1520/E2454-19A.10.1520/E2454-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2454 − 20
2.2 ASTM Manuals:
MNL 13 Descriptive Analysis Testing
MNL 26 Sensory Testing Methods
MNL 30 Relating Consumer, Descriptive, and Laboratory Data to Better Understand Consumer Responses
STP 682 Manual on Consumer Sensory Evaluation
STP 758 Guidelines for the Selection and Training of Sensory Panel Members
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this guide see Terminology E253.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 accelerated storage/aging—storage/aging, n—subjecting a product to extreme or stressed conditions, such as elevated
temperatures or humidity, exposure to sunlight or other light, to speed up those changes in product characteristics that are assumed
to be related to aging the product.
3.2.2 control parameters for sensory shelf life determination (known as “control”)—“control”), n—specific product or data set
(based on previous sensory research) designated as the one to which the data from stored products are to be compared .compared.
3.2.3 controlled conditions—conditions, n—set of environmental parameters (including but not limited to temperature,
humidity, light, and oxygen) that are maintained and monitored so that changes in product attributes can be evaluated relative to
these parameters.
3.2.4 sensory end-point (end of shelf-life)—point at which a product no longer meets predetermined sensory attributes as defined
by the set end-point criterion or criteria (for example, discrimination, descriptive, or affective, or a combination thereof).
3.2.4 end-point criterion/criteria—criterion/criteria, n—the parameter(s) that will be used to determine the end of sensory shelf
life.
3.2.5 pull out date(s)—date(s), n—predetermined point(s) in time at which the product is removed from storage for evaluation.
3.2.6 sampling plan, n—the protocol that indicates which products are to be tested at which time intervals in a shelf life study.
3.2.7 sensory characteristics—characteristics, n—any attributes of the products that are assessed using the sensory methods that
measure the human response to that product.
3.2.8 sensory end-point (end of shelf-life), n—point at which a product no longer meets predetermined sensory attributes as
defined by the set end-point criterion or criteria (for example, discrimination, descriptive, or affective, or a combination thereof).
3.2.9 shelf life—life, n—time period that a product may be stored before reaching its end-point.
3.2.10 shelf life testing—testing, n—method(s) to determine the effects of aging or storage conditions, or both, on product(s)
characteristics for purposes of determining a product’sproduct’s shelf life.
3.2.11 uncontrolled ambient—ambient, n—also known as room temperature, uncontrolled conditions (that is, temperature of
storage location, humidity, or environmental factors, or both) which fluctuate with changes in weather, time of day, location, and
so forth (see 3.2.3).
3.2.11 zero time point—time when the shelf life testing begins.
3.2.12 use by date—date, n—Thethe date, usually stamped on the product by the manufacturer, indicating that the product
remains consumable or usable as it delivers sensory attributes as desired by the manufacturer. Inmanufacturer; in some countries,
this is referred to as the ‘best“best before date.’date.”
3.2.13 sampling plan—zero time point, n—The protocol that indicates which products are to be tested at which time intervals
in a shelf life study. time when the shelf life testing begins.
4. Summary of Guide
4.1 This guide is intended to cover the basic issues and practical requirements of conducting a shelf life study designed to
identify sensory end-points in a product’s shelf life.
4.2 Define Research Objective—The purpose/objective of a shelf life study should be clearly stated before the study is
implemented. The objectives are generally related to the criteria selected for defining the product’s end of shelf life, which are
determined prior to the study’s inception. Common objectives are as follows: “determine the amount of elapsed time a product
remains acceptable to consumers,” or “determine specific use-by dates,” or “understand the amount of time elapsed before a
sensory defect is detectable.”
4.3 Identify Decision Risk—Decision risk is defined as making an incorrect shelf life decision. There are two incorrect decisions
associated with shelf life testing: (1) stating the product has reached the end of shelf life when it has not, and (2) stating that the
product has not reached the end of shelf life when it has. A consequence of the former incorrect decision could be loss of potential
income from the product’s sale as it will be pulled from shelves and not sold when it still could be. The manufacturer will lose
E2454 − 20
sales. A consequence of the second error could be consumer rejection of a too-old product, as it will continue to be sold after the
sensory shelf life has been reached. Consumer repeat purchase of the same brand may be at stake. Before the researcher embarks
on a shelf life study, the risk to the consumer franchise must be balanced with the risk of costs associated with pulling sensory
acceptable products from the shelf, prior to the end of sensory shelf life.
4.4 Select Criteri/CriterionCriteria/Criterion to Determine the End-Point—End-point—All products change over time.
End-point criteria can refer either to the product’s sensory attributes or to consumer acceptance, or both.
4.4.1 The product’s overall sensory profile has changed.
4.4.2 Product attribute(s) that is (are) known or suspected to be key to consumers’ perception and acceptance of the product has
(have) changed, This includes decreases in the product’s characterizing or expected sensory attributes or sensory signals (for
example, “strawberry flavor” in a strawberry-flavored beverage or “meltability” of a processed cheese slice; for non-food products,
end-point criteria may include attributes that signal product performance such as lather attributes in cleansers, including lather
amount or stability, or surface feel after rinsing), increases in attributes that negatively impact the sensory perception of the product
(for example, increased “red pepper heat” in a mildly spiced product), loss of functionality (a cleaning pad that no longer removes
dirt), or the appearance of “off-notes”,“off-notes,” sensory properties that are not associated with the product (for example, “fish
flavor” in vegetable oil, “cardboard flavor” in a box of cookies, or an off-odor in a skin care cream.)
4.4.3 The product’s acceptability has decreased, either significantly or to a specific degree, compared to the fresh product.
4.5 Select Sensory Test Method—Discrimination, descriptive, or affective methods or a combination, combination of these
methods, can be used to determine the sensory shelf life of a product. Selection of the method depends on the chosen end-point
criteria. For example, affective testing is required if a given consumer acceptance is the chosen end-point criterion.criterion (see
6.2).
4.6 Define Appropriate Assessors—Appropriate assessors are essential for the determination of sensory shelf life, depending on
the chosen evaluation method. For discrimination and descriptive methods, best practice requires screened and trained assessors
(see STP 758). For acceptability measures, best practice requires screened and qualified assessors (see MNL 26, STP 682).
4.7 Select Representative Products—Products selected for shelf life testing must be from representative production batches and
production dates which are appropriately processed and packaged. In some situations, products should be subjected to typical
distribution conditions (including, but not limited to, vibration, temperature elevation/reduction, temperature cycling). If testing an
experimental product (for example, a product with changes in ingredients, formulation, processing, or packaging), samples should
be representative of production batches of the experimental product. The amount of product required from each production batch
is dependent on the estimated length of storage, number of storage conditions, methods of evaluation, and frequency of testing.
Collecting products of various ages from retail establishments is generally not recommended for determining a product’s shelf life,
as conditions that the product has experienced may not be known and may be atypical. This does not, however, preclude collecting
such samples for a product audit. Another consideration is product variation and the number of batches required to make a
reasonable determination of the shelf life. When testing products with more batch-to-batch variation, more than one batch might
be needed to assess shelf life. Testing more than one batch will be more resource intensive than testing only one batch of product.
When testing products with less batch-to-batch variation, one batch may be sufficient.
4.8 Determine the Sensory End-point—The end-point is selected based on the chosen end-point criteria, the type of product
tested, the test method selected, previous knowledge of product changes over time, and the company’s assessment of the
risk/opportunities.
5. Significance and Use
5.1 Sensory shelf life is the time period during which the product’s sensory characteristics and performance are as intended by
the manufacturer. The product is consumable or usable during this period, providing the end-user with the intended sensory
characteristics, performance, and benefits. After this period, however, the product has characteristics or attributes that are not as
intended, or it does not perform the same functions as fresh products or those consumed or used before the end of shelf life.
5.2 The goal of all shelf life determination is to estimate the time at which a consumer product is no longer usable, unfit for
consumption, or no longer has the intended sensory characteristics.
5.3 Prior to the commencement of sensory shelf life study, the criteria/criterion that are/is used to define shelf life end must be
defined. The criterion or criteria could be sensory attributes, consumer acceptance or product performance. Once the criteria are
defined, the test methodology for measuring the sensory shelf life can be selected. The criterion operationally defining the end of
shelf life is generally chosen based on one or more of the following changes in the product’s sensory and/or functional parameters:
1) or functional parameters, or both: (1) the aged product is perceptibly different from the fresh product overall, 2)(2) the aged
product has changed in specific sensory or functional attributes, either increasing some, decreasing others, or the appearance of
new attributes compared to the fresh product, or 3)(3) product acceptability of the aged product has decreased to a specific degree
from that of the fresh product. The determination of these sensory end-points is a function of the criteria selected, the test method
used, and sampling and statistical risks chosen by the researcher.
E2454 − 20
FIG. 1 Planning for Shelf-LifeShelf-life Evaluations—Process Flow Determination withWith Section References
5.4 The three following test methods are most commonly used for the three end-point criteria cited above: (1) discrimination,
(2) descriptive, and (3) affective. Researchers have to select criteria and methods that best suit the business risks associated with
the selection of a final shelf life end-point.
5.5 Once a product is made, underlying chemical and physical processes continue: Time, temperature, oxygen, humidity, or light
are some of the variables that can contribute to these chemical changes. The interaction of the product with the packaging may
also impact the sensory shelf life of the product. These are often the independent variables included in a shelf life study. However,
research techniques designed to identify the causes of sensory shelf life changes or to develop predictive models of shelf life are
beyond the scope of this document.
5.6 Previous sensory research with similar products, marketing research, product technology, manufacturing considerations,
marketing objectives, consumer comments, complaints, and other business criteria can all play a part in determining sensory
end-point criteria.
5.7 The decision risk, end-point criteria, and shelf life testing procedure should be reviewed and agreed to by stakeholders, such
as Marketing, Market Research, R&D, Quality Assurance, and Manufacturing.
6. Procedures
See Figs. 1-4 for flowcharts of the procedures needed to conduct a sensory shelf life evaluation.
6.1 See Figs. 1-4 for diagrams of the procedures needed to conduct a sensory shelf life evaluation.
6.2 Select Criteria to Determine the Sensory End-point—Determine the specific type of shelf life sensory end-point that will be
used. There are three common criteria used to define operationally end of shelf life –life: (1) a difference is detected between the
fresh and aged product (discrimination failure mode), (2) a descriptive attribute(s)is/are attribute(s) is/are changed so that sensory
experience/sensory signals of the product is/are no longer as intended (descriptive attribute failure mode)mode), or (3) the product
acceptance lowers to a pre-determined level (acceptability failure mode). Inputs from quality and manufacturing staff as well as
review of consumer complaint data for specific feedback on sensory attributes can be helpful in deciding the criteria for shelf life
end. (Seeend (see Fig. 1.)).
6.3 Identify the Test Method to beBe Used—The testing method is chosen based on the end-point criteria. Discrimination testing,
descriptive, or affective testing methods are the three major test method options. Combinations of these methods may also be used.
6.4 Determine the Sensory End-point—The sensory end-point is established as a significant overall difference from the control
based on a pre-stated degree of sensory difference, a significant or pre-determined level of change in the intensity of one or more
critical product attribute(s) or the appearance of specified ‘new’“new” attributes, or a predetermined level of decrease in
acceptability. The statistical criteria for measuring significance should also be included in the end-point definition (that is, α, β, and
the size of the difference desired to detect) along with the number of panelists needed at each testing interval.
6.5 Select Control—Choose the type of control product that will be used for the study. A common comparison product might
be a freshly made product, or one stored in refrigerated/frozen conditions, or held under controlled light or temperature conditions.
In the first case, the freshly made product represents the product at its best; in the case of the refrigerated/frozen product, the
product is expected to represent a product that has had aging stopped or slowed down significantly. While the presence of a control
product or control data is recommended, shelf life can still be determined without a physical control product, as long as specific
end of shelf life parameters are chosen prior to the beginning of the shelf life study. When comparing a fresh product with an aged
product, batch to batch product variations must be considered.
6.5.1 Option 1—Stable Control—1 (Stable Control)—This is a typical product that is held under conditions that minimize
changes over time, such as frozen or refrigerated storage or specified environmental conditions (e.g., (for example, temperature,
light, humidity, and oxygen exposure).exposure). If no storage condition is known to keep sensory changes to a minimum, this
type of control cannot be used.
6.5.2 Option 2—Statistical Control—2 (Statistical Control)—This is a set of numerical values obtained from sensory testing at
zero time. Sensory data can be a degree of difference (d-prime) for discrimination testing, descriptive analysis attribute ratings or
acceptance scores, depending on the chosen testing method.
E2454 − 20
FIG. 2 Multi-PointMulti-point Evaluations
FIG. 3 Single Point Evaluation: Staged Single-point Evaluation—Staged Entry Design
6.5.3 Option 3—Fresh Control—3 (Fresh Control)—If none of the above controls are feasible, a fresh control may be obtained
at each pull out date. However, this type of control can only be used if the difference between separate batches is demonstrated
to be minimal prior to the study, or if product variability is well understood and can be accounted for.
6.6 Select Test Product—Choose the test product(s) for the study. The product used for the study should be representative of
the intended product. If a control product is used, the test products should be obtained from the same batch of ingredients, where
possible, as the control product. Additionally, the test and control products should be as close in production as possible (that is,
same production date, same product location, etc.). If this is not feasible, this added variability may obscure the differences between
the control and test product. Furthermore, at the start of the storage period, an initial sensory test should be conducted to establish
the relative sensory comparability of the test and control products.
E2454 − 20
FIG. 4 Single Point Evaluation: Staged Single-point Evaluation—Staged Exit Design
6.7 Select Storage Conditions:
6.7.1 Typical Life Cycle—The typical life cycle of the product and the conditions to which it is exposed should be taken into
consideration when a shelf life test is designed. Shelf life test designers may be aware of those conditions or not, but must gather
as much information as possible before setting up a shelf life study. Shelf life storage conditions should reflect those real-world
exposure conditions as much as possible to ensure the test outputs are relevant. Estimates of environmental extremes and time spent
in the various stages of distribution can help determine appropriate conditions. Verification of test storage conditions through the
use of sensory or monitors us suggested, especially if ambient storage conditions are selected.
6.7.2 Controlled Storage Conditions—Products selected to be representative should be stored under defined environmental
conditions that may include variations in temperature, humidity, light, atmosphere, air pressure, and environmental cycling
(freeze/thaw, elevated temperature conditions, etc.). Environmental conditions typical of distribution can also be considered.
6.7.3 Accelerated Storage Conditions—Accelerated tests attempt to achieve changes in product characteristics in a shortened
period of time compared to non-accelerated storage conditions. Such tests can be valuable time savers if appropriately selected.
However, these tests are only approximations of how a product may behave under normal storage conditions.
6.7.3.1 Uses of accelerated conditions are often based on untested “rules of thumb” or beliefs rather than empirical data. During
accelerated storage, product changes may take place, or characteristics may develop that would not occur during non-accelerated
storage conditions. Elevated temperatures or exposure to humidity or light sources may cause different reactions than would
ordinarily occur under more typical storage conditions. Before determining shelf life end-points based on accelerated conditions,
one should establish the sensory, chemical, and mathematical relationships between accelerated conditions and typical storage
conditions to ensure the utility of using accelerated conditions to establish Sensory Shelfsensory shelf life (see ASTM MNL 30).
6.8 Determine Sampling Plan and Evaluation Points—Sampling plans are drawn up at the start of a shelf life study to indicate
how many products are needed, which lots, the storage conditions under which each sample will be held, and the time intervals
a specific quantity of product will be tested. A sampling plan is needed in a shelf life study to ensure sufficient quantities of each
product is available for testing at each interval. Lot to lot variability should be considered when establishing a sampling plan.
6.8.1 Determine Zero Time Point—The first step in developing a sampling plan is to establish a baseline or “zero time” point.
Choice of an appropriate zero time is determined by the nature of the product(s) and by the research objective. Examples of zero
time points include:
6.8.1.1 The date the product is manufactured,
6.8.1.2 The date the product reaches the retail shelf (the youngest product consumers would purchase),
6.8.1.3 The date the product is typically purchased, and
6.8.1.4 The date the product’s sensory profile reaches a steady state.
6.8.2 Determine Study End-point—The second step is to set the expected end-point of the product’s shelf life using one or more
of the following criteria:
6.8.2.1 Historical data from current or similar products,
E2454 − 20
6.8.2.2 The declared shelf life of the product or of competitive products,
6.8.2.3 Advertising or label declaration requirements,
6.8.2.4 Distribution requirements,
6.8.2.5 Expected shelf life based on predicted stability of the formulation considering the product’s ingredients, formulation,
processing and packaging, and
6.8.2.6 The age at which consumer complaint levels about sensory attributes of current or similar products reaches above normal
levels and are focused on sensory attributes or product functionality.
6.8.3 Minimum Evaluation Points—Considering the zero time and end-points as defined above, to be 100 % of the shelf life
period, choose appropriate time points for evaluations. A minimum of four evaluation points is recommended, for example, 0 %
(zero time), 50 %, 100 % (end-point), and one or more time points a percentage beyond the sensory endpoint,end-point, that is,
125 %. Evaluation points beyond the end-point are included in the event that the product achieves the expected shelf life and there
is the possibility that the shelf life could be extended. It is best to include a time point where product failure is likely to occur.
Even with these considerations, the shelf life of the product might be beyond all the planned evaluation points.
6.8.4 Additional Evaluation Points—Additional evaluation points over the shelf life period are recommended. These additional
evaluations should be timed at points where significant changes in the product are expected to occur. The following examples
demonstrate three sampling plans that could be used for specific product applications. These examples are designed to illustrate
that sampling plans should be developed and customized based on the objectives and requirements of the study, as well as the
resources available to conduct the evaluations. In all cases of shelf life studies where end-points for testing are planned, product
safety is also a consideration. In no case should a product sensory shelf life test be conducted when a product may be unsafe to
consume or use.
6.8.4.1 For a product predicted to change most early in the shelf life period, emphasis is placed on earlier evaluations: 0 %,
15 %, 30 %, 50 %,0, 15, 30, 50, 100 %, and some percentage beyond.
6.8.4.2 For a product predicted to change later in the shelf life period, emphasis is placed on later evaluations: 0 %, 50 %, 65 %,
80 %,0, 50, 65, 80, 100 %, and some percentage beyond.
6.8.4.3 For a new product with little, if any, prior shelf life history, more frequent evaluation points are recommended to assure
that the time of significant changes in the product are captured in evaluation. A minimum of 0 %, 25 %, 50 %, 75 %,0, 25, 50, 75,
100 %, and one or more points beyond the expected shelf life should be planned. Even with these considerations, the shelf life of
the product might be beyond all the planned evaluation points. Additionally, if results of shelf life are needed to inform an
important business decision, such as an equipment purchase, frequent evaluation points might be useful.
6.8.4.4 It is incumbent upon the researcher to determine whether evaluations at all planned time points should occur. The
researcher may choose not to continue planned shelf life evaluation points if:
(1) theThe product has reached the failure point prior to the anticipated end of shelf life, or
(2) theThe product has not reached the failure point but the decision to set the shelf-life shelf life at a point prior to failure has
been made.
E2454 − 20
6.9 Determine Product Quantities:
6.9.1 To determine the total amount of product needed to complete a shelf life study, one must take into consideration the
sampling plan test intervals, the storage temperature conditions desired, conditions desired (temperature, humidity, etc.), the
experimental design, and the sensory test methodologies best able to determine end-point criterion or criteria. Product quantities
must be calculated to allow for all possible combinations of testing needs.
6.9.2 It is often useful to include additional test product in each storage condition in case, for example, the product is more stable
than expected or unexpected changes occur that warrant more in-depth study. An overage of 20 %20 to 50 % is common practice.
6.10 Determine the Evaluation Plan: Multi-Point versus Single-Point Evaluation Plans—Evaluation Plan (Multi-point Versus
Single-point Evaluation Plans)—Multi-point and single-point evaluation plans are two different evaluation plans. Each has its own
advantages and disadvantages and may suit specific situations.
6.10.1 Multi-PointMulti-point Evaluations—Multi-point evaluation plans involve conducting the shelf life testing at multiple
times, according to the established pull out schedule. in accordance with the established pull-out schedule, either from a single
batch or from multiple batches. If the objective is to compare the shelf life of a control and a comparative product, both products
are tested at each evaluation period.
6.10.1.1 Advantages of Multi-PointMulti-point Evaluation Plans—Multi-point plans have the advantages of tracking the shelf
life over the shelf life period and providing an early indication of product change.change during the shelf life evaluation period.
6.10.1.2 Disadvantages of the Multi-Point Multi-point Evaluation Plans—One disadvantage of the multi-point evaluation plans
is the large quantities of control and test products necessary for multiple evaluations. Additionally, multiple evaluations are
resource intensive. These disadvantages can limit the time points that can be managed or the types of sensory methods that can
be used. Finally, when using multi-point evaluations, there are limitations on comparing the results of independent sensory tests,
especially when there are different assessors serving in each test, conducted at different time points. Even if the same assessors
performed all the evaluations, there is a higher chance of assessor variability over the evaluation time points than when using a
single-point evaluation plan.
6.10.2 Single-PointSingle-point Evaluations:
6.10.2.1 Single-point evaluations compare products of different ages in a single evaluation. evaluation, either from a single
batch or from multiple batches. Products representing the selected evaluation points are accumulated over time by one of several
methods. The method selected depends upon the nature of the product and the study objectives. The following are examples:
6.10.2.2 Staged Entry—A set of samples is placed into a control storage condition selected for its ability to preserve product
characteristics. Subsets of product are removed from the control storage condition, and placed in the Test storage condition(s) at
specified time points over the shelf life. Product held continuously under the control storage condition represents the fresh or
newly-made control product.
6.10.2.3 Staged Exit—A set of samples is placed into the test storage condition(s). At specified time points over the shelf life
period, subsets of product are removed from the test storage condition(s) and placed into the control storage condition, to prevent
a
...