ASTM_E_1885_-_04_2011.pdf

Designation:E188504(Reapproved 2011)Standard Test Method forSensory AnalysisTriangle Test1This standard is issued under the fixed designation E1885;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 test method covers a procedure for determiningwhether a perceptible sensory difference exists betweensamples of two products.1.2 This test method applies whether a difference may existin a single sensory attribute or in several.1.3 This test method is applicable when the nature of thedifference between the samples is unknown.It does notdetermine the size or the direction of the difference.Theattribute(s)responsible for the difference are not identified.1.4 Compared to the duo-trio test,the triangle test canachieve an equivalent level of statistical significance withfewer assessors.For details on how the triangle test comparesto other three-sample tests,see Refs(1),(2),(3)and(4).21.5 This test method is applicable only if the products arehomogeneous.If two samples of the same product can often bedistinguished,then another method,for example,descriptiveanalysis,may be more appropriate.1.6 This test method is applicable only when the productsdo not cause excessive sensory fatigue,carryover or adapta-tion.1.7 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:3E253 Terminology Relating to Sensory Evaluation of Mate-rials and ProductsE456 Terminology Relating to Quality and StatisticsE1871 Guide for Serving Protocol for Sensory Evaluation ofFoods and Beverages2.2 ISO Standard:ISO 4120 Sensory Analysis Methodology TriangularTest43.Terminology3.1 DefinitionsFor definition of terms relating to sensoryanalysis,see Terminology E253,and for terms relating tostatistics,see Terminology E456.3.2 Definitions of Terms Specific to This Standard:3.2.1 (alpha)riskprobability of concluding that a per-ceptible difference exists when,in reality,one does not.(Alsoknown as Type I Error or significance level.)3.2.2 (beta)riskprobability of concluding that no per-ceptible difference exists when,in reality,one does.(Alsoknown as Type II Error.)3.2.3 pcprobability of a correct response.3.2.4 pd(proportion of discriminators)proportion of thepopulation represented by the assessors that can distinguishbetween the two products.3.2.5 productmaterial to be evaluated.3.2.6 sampleunit of product prepared,presented,andevaluated in the test.3.2.7 sensitivitygeneral term used to summarize the per-formance characteristics of the test.The sensitivity of the testis rigorously defined,in statistical terms,by the values selectedfor,and pd.3.3 triadthree uniquely coded samples given to an asses-sor in the triangle test;two samples are alike(that is,of oneproduct)and one is different(that is,of the other product).4.Summary of Test Method4.1 Clearly define the test objective in writing.4.2 Choose the number of assessors based on the level ofsensitivity desired for the test.The sensitivity of the test is,inpart,a function of two competing risks:the risk of declaring1This test method is under the jurisdiction of ASTM CommitteeE18 on SensoryEvaluation and is the direct responsibility of Subcommittee E18.04 on Fundamen-tals of Sensory.Current edition approved Aug.1,2011.Published August 2011.Originallyapproved in 1997.Last previous edition approved in 2004 as E1885 04.DOI:10.1520/E1885-04R11.2The boldface numbers given in parentheses refer to a list of references at theend of the text.3For 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.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 the samples different when they are not(that is,-risk)and therisk of not declaring the samples different when they are(thatis,-risk).Acceptable values of and vary depending on thetest objective and should be determined before the test(seeAppendix X3).4.3 Assessors receive a triad and are informed that two ofthe samples are alike and that one is different.The assessorsreport which they believe to be the different,or“odd,”sample,even if the selection is based only on a guess.4.4 Results are tallied and significance determined by ref-erence to a statistical table.5.Significance and Use5.1 This test method is effe