1、BRITISH STANDARD Sensory analysis Methodology Triangle test ICS 67.240 BS EN ISO 4120:2007 Incorporating May 2009 corrigendum This British Standard was published under the authority of the Standards Policy and Strategy Committee on 1 July 2004 BSI 2009 National foreword The UK participation in its p
2、reparation was entrusted to Technical Committee AW/12, Sensory analysis. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct a
3、pplication. BS EN ISO 4120:2007 This British Standard is the UK implementation of EN ISO 4120:2007. It is identical with ISO 4120:2004. It supersedes BS ISO 4120:2004, which is withdrawn. Compliance with a British Standard cannot confer immunity from legal obligations. ISBN 978 0 580 59377 2 Date Co
4、mments 31 May 2009 This corrigendum renumbers BS ISO 4120:2004 as BS EN ISO 4120:2007 Amendments/corrigenda issued since publication EUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM ENISO4120 July2007 ICS67.240 EnglishVersion SensoryanalysisMethodologyTriangletest(ISO4120:2004) AnalysesensorielleMthod
5、ologieEssaitriangulaire(ISO 4120:2004) SensorischeAnalysePrfverfahrenDreiecksprfung (ISO4120:2004) ThisEuropeanStandardwasapprovedbyCENon12July2007. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEuropean Standardthestatusofanationalstandardwit
6、houtanyalteration.Uptodatelistsandbibliographicalreferencesconcerningsuchnational standardsmaybeobtainedonapplicationtotheCENManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytranslation undertheresponsibilityof
7、aCENmemberintoitsownlanguageandnotifiedtotheCENManagementCentrehasthesamestatusasthe officialversions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Bulgaria,Cyprus,CzechRepublic,Denmark,Estonia,Finland, France,Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta
8、,Netherlands,Norway,Poland,Portugal, Romania,Slovakia,Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2007CEN Allrightsofexploitationinanyformandbyanymeansres
9、erved worldwideforCENnationalMembers. Ref.No.ENISO4120:2007:EIS:0214 O4002(E) I SO 4002 All irthgs ersedevr iii Contents Page Foreword iv 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle . 2 5 General test conditions and requirements. 3 6 Assessors 3 6.1 Qualification 3 6.
10、2 Number of assessors 3 7 Procedure. 4 8 Analysis and interpretation of results 4 8.1 When testing for a difference 4 8.2 When testing for similarity. 5 9 Test report 5 10 Precision and bias 5 Annex A (normative) Tables 6 Annex B (informative) Examples. 10 Bibliography . 15 BS EN ISO 4120:2007 EN IS
11、O 4120:2007 (E)Foreword The text of ISO 4120:2004 has been prepared by Technical Committee ISO/TC 34 “Agricultural food products” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 4120:2007 by Technical Committee CEN/SS C01 “Food Products“, the secretariat
12、 of which is held by CMC. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January 2008, and conflicting national standards shall be withdrawn at the latest by January 2008. According to the CEN/CE
13、NELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxe
14、mbourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of ISO 4120:2004 has been approved by CEN as EN ISO 4120:2007 without any modifications. iv BS EN ISO 4120:2007 EN ISO 4120:2007 (E)INTENRATIO
15、NAL TSANDADR IS:0214 O4002(E) I SO 4002 All irthgs ersedevr 1 Sensory analysis Methodology Triangle test 1 Scope This International Standard describes a procedure for determining whether a perceptible sensory difference or similarity exists between samples of two products. The method is a forced-cho
16、ice procedure. The method is applicable whether a difference exists in a single sensory attribute or in several attributes. The method is statistically more efficient than the duo-trio test (described in ISO 10399), but has limited use with products that exhibit strong carryover and/or lingering fla
17、vours. The method is applicable even when the nature of the difference is unknown i.e. it determines neither the size nor the direction of difference between samples, nor is there any indication of the attribute(s) responsible for the difference. The method is applicable only if the products are fai
18、rly homogeneous. The method is effective for a) determining that either a perceptible difference results (triangle testing for difference), or a perceptible difference does not result (triangle testing for similarity) when, for example, a change is made in ingredients, processing, packaging, handlin
19、g or storage; b) or for selecting, training and monitoring assessors. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced d
20、ocument (including any amendments) applies. ISO 5492:1992, Sensory analysis Vocabulary ISO 8589:1988, Sensory analysis General guidance for the design of test rooms 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 5492 and the following apply. 3.1 alp
21、ha-risk -risk probability of concluding that a perceptible difference exists when one does not NOTE This is also known as Type I error, significance level or false positive rate. BS EN ISO 4120:2007 EN ISO 4120:2007 (E)IS:0214 O4002(E) 2 I SO 4002 All irthgs ersedevr 3.2 beta-risk -risk probability
22、of concluding that no perceptible difference exists when one does NOTE This is also known as Type II error or false negative rate. 3.3 difference situation in which samples can be distinguished based on their sensory properties NOTE The proportion of assessments in which a perceptible difference is
23、detected between the two products is given the symbol p d . 3.4 product material to be evaluated 3.5 sample unit of product prepared, presented and evaluated in the test 3.6 sensitivity general term used to summarize the performance characteristics of the test NOTE In statistical terms, the sensitiv
24、ity of the test is defined by the values of , and p d . 3.7 similarity situation in which any perceptible differences between the samples are so small that the products can be used interchangeably 3.8 triad those three samples given to an assessor in the triangle test NOTE In the triangle test, each
25、 sample is marked with a different code. Two of the samples are alike (i.e. from one product) and one is different (i.e. from the other product). 4 Principle The number of assessors is chosen based on the sensitivity desired for the test. (See 6.2 and the discussion in A.3.) Assessors receive a set
26、of three samples (i.e. a triad) and are informed that two of the samples are alike and that one is different. The assessors report which sample they believe to be different, even if the selection is based only on a guess. The number of correct responses is counted and the significance is determined
27、by reference to a statistical table. BS EN ISO 4120:2007 EN ISO 4120:2007 (E)IS:0214 O4002(E) I SO 4002 All irthgs ersedevr 3 5 General test conditions and requirements 5.1 Clearly define the test objective in writing. 5.2 Carry out the test under conditions that prevent communication among assessor
28、s until all the evaluations have been completed, using facilities and booths that comply with ISO 8589. 5.3 Prepare the samples out of sight of the assessors and in an identical manner (i.e. same apparatus, same vessels, same quantities of product). 5.4 Assessors shall not be able to identify the sa
29、mples from the way in which they are presented. For example, in a taste test, avoid any differences in appearance. Mask any irrelevant colour differences using light filters and/or subdued illumination. 5.5 Code the vessels containing the samples in a uniform manner, preferably using three-digit num
30、bers, chosen at random for each test. Each triad is composed of three samples, each with a different code. Preferably, different codes should be used for each assessor during a session. However, the same three codes may be used for all assessors within a test, provided that each code is used only on
31、ce per assessor during a test session (e.g. if several triangle tests on different products are being conducted in the same session). 5.6 The quantity or volume served shall be identical for the three samples in each triad, just as that of all the other samples in a series of tests on a given type o
32、f product. The quantity or volume to be evaluated may be imposed. If it is not, the assessors should be told to take quantities or volumes that are always similar whatever the sample. 5.7 The temperature of the three samples in each triad shall be identical, just as that of all the other samples in
33、a series of tests on a given type of product. It is preferable to present the samples at the temperature at which the product is generally consumed. 5.8 The assessors shall be told whether or not they are to swallow the samples or whether they are free to do as they please. In this latter case, they
34、 shall be requested to proceed in the same manner for all the samples. 5.9 During the test sessions, avoid giving information about product identity, expected treatment effects, or individual performance until all testing is completed. 6 Assessors 6.1 Qualification All assessors should possess the s
35、ame level of qualification, this level being chosen on the basis of the test objective (see ISO 8586-1 and ISO 8586-2 for guidance). Experience and familiarity with the product may improve the performance of an assessor and, therefore, may increase the likelihood of finding a significant difference.
36、 Monitoring the performance of assessors over time may be useful for increased sensitivity. All assessors shall be familiar with the mechanics of the triangle test (i.e. format, task and evaluation procedure). 6.2 Number of assessors Choose the number of assessors so as to obtain the sensitivity req
37、uired for the test (see the discussion in A.3). Using large numbers of assessors increases the likelihood of detecting small differences between the products. However, in practice, the number of assessors is often determined by material conditions (e.g. duration of the experiment, number of availabl
38、e assessors, quantity of product). When testing for a difference, typical numbers of assessors are between 24 and 30. When testing for no meaningful difference (i.e. similarity), twice as many assessors (i.e. approximately 60) are needed for equivalent sensitivity. BS EN ISO 4120:2007 EN ISO 4120:20
39、07 (E)IS:0214 O4002(E) 4 I SO 4002 All irthgs ersedevr Avoid replicate evaluations by the same assessor whenever possible. However, if replicate evaluations are needed to produce a sufficient number of total evaluations, every effort should be made to have each assessor perform the same number of re
40、plicate evaluations. For example, if only ten assessors are available, have each assessor evaluate three triads to obtain a total of 30 evaluations. NOTE Treating three evaluations performed by ten assessors as 30 independent evaluations is not valid when testing for similarity using Table A.2. Howe
41、ver, the test for difference using Table A.1 is valid even when replicate evaluations are performed (see 9 and 10). Recent publications (see 6 and 7) on replicated discrimination tests suggest alternative approaches for analysing replicated evaluations in discrimination tests. 7 Procedure 7.1 Prepar
42、e worksheets and scoresheets (see B.1 and B.2) in advance of the test so as to utilize an equal number of the six possible sequences of two products, A and B: ABB AAB ABA BAA BBA BAB Distribute these at random in groups of six among the assessors (i.e. use each sequence once among the first group of
43、 six assessors; use each sequence once again among the next group of six assessors, etc.). This will minimize the imbalance that results if the total number of assessors is not a multiple of six. 7.2 Present the three samples of each triad simultaneously if possible, following the same spatial arran
44、gement for each assessor (e.g. on a line to be sampled always from left to right, in a triangle array). Within the triad, assessors are generally allowed to make repeated evaluations of each sample as desired (if, of course, the nature of the product allows for repeated evaluations). 7.3 Instruct th
45、e assessors to evaluate the samples in the order in which they were presented. Inform the assessors that two of the samples are the same and that one is different. Each assessor should then indicate which one of the three samples is different from the other two. 7.4 Each scoresheet should provide fo
46、r a single triad of samples. If an assessor is to carry out more than one test in a session, collect the completed scoresheet and unused samples prior to serving the subsequent triad. The assessor shall not go back to any of the previous samples or change the verdict on any previous test. 7.5 Do not
47、 ask questions about preference, acceptance or degree of difference after the initial selection of the odd sample. The selection the assessor has just made may bias the reply to any additional questions. Responses to such questions may be obtained through separate tests for preference, acceptance, d
48、egree of difference, etc. (See ISO 6658 for guidance.) A comment section asking why the choice was made may be included for the assessors remarks. 7.6 The triangle test is a forced-choice procedure; assessors are not allowed the option of reporting “no difference”. An assessor who detects no difference between the samples should be instructed to randomly select one of the samples and to indicate that the selection was only a guess in the comments section of the scoresheet. 8 Analysis and interpretation of results 8.1 When testi
