ASTM_E_1909_-_13.pdf

Designation:E190913Standard Guide forTime-Intensity Evaluation of Sensory Attributes1This standard is issued under the fixed designation E1909;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide covers procedures for conducting and ana-lyzing time-intensity(T-I)evaluations of products or othersensory stimuli.Time-intensity is the measurement of theintensity of a single sensory sensation over time in response toa single exposure to a product or other sensory stimulus.Simultaneous evaluations of multiple sensory attributes arepossible,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 measurethe intensity of a single continuous sensation during the timefrom initial exposure:1.2.1 To its extinction,1.2.2 To a specified intensity,or1.2.3 To a predetermined limit of time.1.3 Applications not covered in this guide include measur-ing:1.3.1 Multiple sensations,1.3.2 Multiple exposures within a single measurement,and1.3.3 Qualitative or hedonic changes in the perceived sen-sation.1.4 This guide includes protocols for the selection andtraining of judges,descriptions and use of physical datacollectiondevices,andmethodsofdatahandling,summarization,and statistical analysis.Illustration of twodifferent data handling and analysis approaches are included inthe appendixes.1.5 This guide is not applicable to measure product shelf lifeor stability that require evaluations over extended time.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E253 Terminology Relating to Sensory Evaluation of Mate-rials and Products3.Terminology3.1 Definitions of Terms Specific to This Standard:See Fig.1.3.1.1 area after Imaxpost-peak area under the curve.3.1.2 area before Imaxpre-peak area under the curve.3.1.3 AUCarea under the curve.3.1.4 Imaxor peak intensitymaximum observed intensityduring the time of measurement.3.1.5 perimetermeasured distance of perimeter of areadelineated by T-I curve.3.1.6 plateauduration of peak intensity.3.1.7 rate of increaserate of intensity increase before peakintensity(slope).3.1.8 rate of decreaserate of intensity decrease after peakintensity(slope).3.1.9 Tduror duration timetime from onset of sensationuntil it can no longer be perceived(Text Tonset).3.1.10 Textor time to extinctiontime from initial exposureto the stimulus(Tinit)until it can no longer be perceived.3.1.11 Tinittime of initial exposure to the stimulus,typi-cally when the clock starts.3.1.12 Tmaxtime to reach maximum intensity of the sen-sation after exposure to the stimulus.3.1.13 Tonsettime point when the stimulus is first per-ceived after initial exposure to the stimulus.3.1.14 Ttrunor truncated timetime until a specified mini-mum intensity or until a pre-determined time point has beenreached.3.2 The graphical illustration of a typical time-intensitycurve is shown in Fig.1.The time increment may be seconds,1This guide is under the jurisdiction of ASTM Committee E18 on SensoryEvaluation and is the direct responsibility of Subcommittee E18.03 on SensoryTheory and Statistics.Current edition approved Oct.1,2013.Published October 2013.Originallyapproved in 1997.Last previous edition approved in 2011 as E1909 11.DOI:10.1520/E1909-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 minutes,hours,etc.,depending upon the characteristic of theparticular material under study.4.Summary of Guide4.1 This guide describes procedures utilizing speciallytrained panelists to measure the intensity of a single sensorysensation as it changes with time and the possible approachesto collect and analyze such data.Details on specific proceduresare given in Sections 6 9 of this guide.Examples oftime-related evaluations are included in the appendixes.5.Significance and Use5.1 The purpose of time-intensity measurements is to estab-lish the pattern of development and decline of a particularsensory characteristic under study.T-I evaluations are appli-cable when measurements at a single time point(an averagingprocess)are not sufficient to distinguish products that havevery different temporal characteristics.As pointed out by Leeand Pangborn(2)3,“This averaging process r