ASTM E1909-13

Standard Guide for Time-Intensity Evaluation of Sensory Attributes

SIGNIFICANCE AND USE
5.1 The purpose of time-intensity measurements is to establish the pattern of development and decline of a particular sensory characteristic under study. T-I evaluations are applicable when measurements at a single time point (an averaging process) are not sufficient to distinguish products that have very different temporal characteristics. As pointed out by Lee and Pangborn (2)3, “This averaging process results in the masking or complete loss of important information such as rate of onset of stimulation, time and duration of maximum intensity, rate of decay of perceived intensity, time of extinction, and total duration of the entire process.”  
5.2 Products rated similarly using traditional single point techniques of product profiling may provide very different temporal sensory experiences to the consumer. Acceptability of the product may be affected, and traditional descriptive methodology does not reflect the changes in an attribute's intensity over time.  
5.3 T-I has applications for a variety of products. Examples include: food products, ranging from short-term sweetness in a beverage to long-term elasticity in chewing gum; personal care products, measuring the development and longevity of shampoo lather and the residual skin feel of a skin cream; household care products, monitoring the intensity of scents over time; pharmaceuticals, monitoring skin cooling after application of a topical analgesic. Auditory signals or visual changes in products can also be evaluated by the T-I technique.
SCOPE
1.1 This guide covers procedures for conducting and analyzing time-intensity (T-I) evaluations of products or other sensory stimuli. Time-intensity is the measurement of the intensity of a single sensory sensation over time in response to a single exposure to a product or other sensory stimulus. Simultaneous evaluations of multiple sensory attributes are possible, although are outside of the scope of this document. See Reference List for more information.  
1.2 This guide utilizes a specially trained panel to measure the intensity of a single continuous sensation during the time from initial exposure:  
1.2.1 To its extinction,  
1.2.2 To a specified intensity, or  
1.2.3 To a predetermined limit of time.  
1.3 Applications not covered in this guide include measuring:  
1.3.1 Multiple sensations,  
1.3.2 Multiple exposures within a single measurement, and  
1.3.3 Qualitative or hedonic changes in the perceived sensation.  
1.4 This guide includes protocols for the selection and training of judges, descriptions and use of physical data collection devices, and methods of data handling, summarization, and statistical analysis. Illustration of two different data handling and analysis approaches are included in the appendixes.  
1.5 This guide is not applicable to measure product shelf life or stability that require evaluations over extended time.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2013
• ICS: 67.240 - Sensory analysis
• Technical Committee: E18 - Sensory Evaluation
• Drafting Committee: E18.03 - Sensory Theory and Statistics

Relations

• Replaces: ASTM E1909-11 - Standard Guide for Time-Intensity Evaluation of Sensory Attributes
• Effective Date: 01-Oct-2013
• Replaced By: ASTM E1909-13(2017) - Standard Guide for Time-Intensity Evaluation of Sensory Attributes
• Effective Date: 01-Aug-2017

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1909 − 13
Standard Guide for
1
Time-Intensity Evaluation of Sensory Attributes
This standard is issued under the fixed designation E1909; 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 2. Referenced Documents
2
1.1 This guide covers procedures for conducting and ana- 2.1 ASTM Standards:
E253 Terminology Relating to Sensory Evaluation of Mate-
lyzing time-intensity (T-I) evaluations of products or other
rials and Products
sensory stimuli. Time-intensity is the measurement of the
intensity of a single sensory sensation over time in response to
3. Terminology
a single exposure to a product or other sensory stimulus.
Simultaneous evaluations of multiple sensory attributes are
3.1 Definitions of Terms Specific to This Standard: See Fig.
possible, although are outside of the scope of this document.
1.
See Reference List for more information.
3.1.1 area after I —post-peak area under the curve.
max
3.1.2 area before I —pre-peak area under the curve.
1.2 This guide utilizes a specially trained panel to measure
max
the intensity of a single continuous sensation during the time
3.1.3 AUC—area under the curve.
from initial exposure:
3.1.4 I or peak intensity—maximum observed intensity
max
1.2.1 To its extinction,
during the time of measurement.
1.2.2 To a specified intensity, or
3.1.5 perimeter—measured distance of perimeter of area
1.2.3 To a predetermined limit of time.
delineated by T-I curve.
1.3 Applications not covered in this guide include measur-
3.1.6 plateau—duration of peak intensity.
ing:
3.1.7 rate of increase—rateofintensityincreasebeforepeak
1.3.1 Multiple sensations,
intensity (slope).
1.3.2 Multiple exposures within a single measurement, and
3.1.8 rate of decrease—rate of intensity decrease after peak
1.3.3 Qualitative or hedonic changes in the perceived sen-
intensity (slope).
sation.
3.1.9 T or duration time—time from onset of sensation
dur
1.4 This guide includes protocols for the selection and
until it can no longer be perceived (T –T ).
ext onset
training of judges, descriptions and use of physical data
3.1.10 T or time to extinction—time from initial exposure
ext
collection devices, and methods of data handling,
to the stimulus (T ) until it can no longer be perceived.
init
summarization, and statistical analysis. Illustration of two
3.1.11 T —time of initial exposure to the stimulus, typi-
different data handling and analysis approaches are included in init
cally when the clock starts.
the appendixes.
3.1.12 T —time to reach maximum intensity of the sen-
max
1.5 Thisguideisnotapplicabletomeasureproductshelflife
sation after exposure to the stimulus.
or stability that require evaluations over extended time.
3.1.13 T —time point when the stimulus is first per-
onset
1.6 This standard does not purport to address all of the
ceived after initial exposure to the stimulus.
safety concerns, if any, associated with its use. It is the
3.1.14 T or truncated time—time until a specified mini-
responsibility of the user of this standard to establish appro-
trun
mum intensity or until a pre-determined time point has been
priate safety and health practices and determine the applica-
reached.
bility of regulatory limitations prior to use.
3.2 The graphical illustration of a typical time-intensity
curve is shown in Fig. 1. The time increment may be seconds,
1
This guide is under the jurisdiction of ASTM Committee E18 on Sensory
Evaluation and is the direct responsibility of Subcommittee E18.03 on Sensory
2
Theory and Statistics. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2013. Published October 2013. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1997. Last previous edition approved in 2011 as E1909 – 11. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1909-13. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E1909 − 13
care products, monitoring the intensity of scents over time;
pharmaceuticals, monitoring skin cooling after application of a
topical analgesic. Auditory signals or visual changes in prod-
ucts can also be evaluated by the T-I technique.
6. Time-Intensity Panel Selection and Training
6.1 Screening and Selection of Panelists
6.1.1 Time-Intensity evaluation is a specialized type of
descriptive analysis. Therefore, use of randomly selected,
naive panelists is neither appropria
...

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: E1909 − 11 E1909 − 13
Standard Guide for
1
Time-Intensity Evaluation of Sensory Attributes
This standard is issued under the fixed designation E1909; 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 covers procedures for conducting and analyzing time-intensity (T-I) evaluations of products or other sensory
stimuli. Time-intensity is the measurement of the intensity of a single sensory sensation over time in response to a single exposure
to a product or other sensory stimulus. Simultaneous evaluations of multiple sensory attributes are possible, although are outside
of the scope of this document. See bibliography Reference List for more information.
1.2 This guide utilizes a specially trained panel to measure the intensity of a single continuous sensation during the time from
initial exposure:
1.2.1 To its extinction,
1.2.2 To a specified intensity, or
1.2.3 To a predetermined limit of time.
1.3 Applications not covered in this guide include measuring:
1.3.1 Multiple sensations,
1.3.2 Multiple exposures within a single measurement, and
1.3.3 Qualitative or hedonic changes in the perceived sensation.
1.4 This guide includes protocols for the selection and training of judges, descriptions and use of physical data collection
devices, and methods of data handling, summarization, and statistical analysis. Illustration of two different data handling and
analysis approaches are included in the appendixes.
1.5 This guide is not applicable to measure product shelf life or stability that require evaluations at discrete time intervals.over
extended time.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
E253 Terminology Relating to Sensory Evaluation of Materials and Products
3. Terminology
3.1 Definitions of Terms Specific to This Standard: See Fig. 1.
3.1.1 area after I —post-peak area under the curve.
max
3.1.2 area before I —pre-peak area under the curve.
max
3.1.3 AUC—area under the curve.
3.1.4 I or peak intensity—maximum observed intensity during the time of measurement.
max
3.1.5 perimeter—measured distance of perimeter of area delineated by T-I curve.
3.1.6 plateau time—plateau—duration of peak intensity.
1
This guide is under the jurisdiction of ASTM Committee E18 on Sensory Evaluation and is the direct responsibility of Subcommittee E18.03 on Sensory Theory and
Statistics.
Current edition approved April 1, 2011Oct. 1, 2013. Published May 2011October 2013. Originally approved in 1997. Last previous edition approved in 20032011 as
E1909 – 97 (2003).E1909 – 11. DOI: 10.1520/E1909-11.10.1520/E1909-13.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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
1

---------------------- Page: 1 ----------------------
E1909 − 13
NOTE 1—Based on a figure from Ref (1).
FIG. 1 Representative Time-Intensity Curve with Selected Parameters Labeled
3.1.7 rate of increase—rate of intensity increase before peak intensity (slope).
3.1.8 rate of decrease—rate of intensity decrease after peak intensity (slope).
3.1.9 T or duration time—time from onset of sensation until it can no longer be perceived (T – T ).
dur ext onset
3.1.10 T or time to extinction—time from initial exposure to the stimulus (T ) until it can no longer be perceived.
ext init
3.1.11 T —time of initial exposure to the stimulus, typically when the clock starts.
init
3.1.12 T —time to reach maximum intensity of the sensation after exposure to the stimulus.
max
3.1.13 T —time point when the stimulus is first perceived after initial exposure to the stimulus.
onset
3.1.14 T or truncated time—time until a specified minimum intensity or until a pre-determined time point has been reached.
trun
3.2 The graphical illustration of a typical time-intensity curve is shown in Fig. 1.
...