1、October 2007DEUTSCHE NORM English price group 13No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 67.240!$II$“1383801www
2、.din.deDDIN EN ISO 4120Sensory analysis Methodology Triangle test (ISO 4120:2004)English version of DIN EN ISO 4120:2007-10Sensorische Analyse Prfverfahren Dreiecksprfung (ISO 4120:2004)Englische Fassung DIN EN ISO 4120:2007-10SupersedesDIN ISO 4120:2005-04www.beuth.deDocument comprises 20 pages DIN
3、 EN ISO 4120:2007-10 2 National foreword This standard has been published in accordance with a decision taken by CEN/BT WG 162 to adopt, without alteration, International Standard ISO 4120:2004 as a European Standard. ISO 4120:2004 was prepared by Technical Committee ISO/TC 34 “Agricultural food pro
4、ducts” (Secretariat: AFNOR, France), Subcommittee SC 12 “Sensory analysis” (Secretariat: AFNOR, France). The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und land-wirtschaftliche Produkte (Foodstuffs and Agricultural Products Standards Committee), Technica
5、l Committee Sensorik. The DIN Standards corresponding to the International Standards referred to in the EN are as follows: ISO 5492 DIN 10950-1 ISO 8586-1 DIN 10961 ISO 8586-2 DIN 10961 ISO 8589 DIN 10962 ISO 10399 DIN 10971 Amendments This standard differs from DIN ISO 4120:2005-04 as follows: a) T
6、he number of the standard has been changed to DIN EN ISO 4120. b) The standard has not been revised in substance. c) The standard has been editorially revised and harmonized with current style rules. Previous editions DIN 10951: 1978-09, 1986-12 DIN ISO 4120: 1995-01, 2005-04 National Annex NA (info
7、rmative) Bibliography DIN 10950-1, Sensory analysis Part 1: Vocabulary DIN 10961, Training of assessors for sensory analysis DIN 10962, Areas for sensory analysis Specifications of testrooms DIN 10971, Sensory analysis Duo-trio test EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 4120 July
8、2007 ICS 67.240 English Version Sensory analysis - Methodology - Triangle test (ISO 4120:2004) Analyse sensorielle - Mthodologie - Essai triangulaire (ISO 4120:2004) Sensorische Analyse - Prfverfahren - Dreiecksprfung (ISO 4120:2004) This European Standard was approved by CEN on 12 July 2007. CEN me
9、mbers are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on applica
10、tion to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has
11、 the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Port
12、ugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any mea
13、ns reserved worldwide for CEN national Members. Ref. No. EN ISO 4120:2007: EContents Page 2 EN ISO 4120:2007 (E) Foreword . 3 1 Scope . 4 2 Normative references . 4 3 Terms and definitions 4 4 Principle . 5 5 General test conditions and requirements 6 6 Assessors 6 6.1 Qualification 6 6.2 Number of
14、assessors . 6 7 Procedure 7 8 Analysis and interpretation of results 7 8.1 When testing for a difference 7 8.2 When testing for similarity . 8 9 10 Annex A (normative) Tables 9 Annex B (informative) Examples 13 Bibliography . 18 Test report . 8 Precision and bias 8 Foreword The text of ISO 4120:2004
15、 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 of which is held by CMC. This European Standard
16、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/CENELEC Internal Regulations, the national standard
17、s 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, Luxembourg, Malta, Netherlands, Norway, Poland, Portu
18、gal, 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. 3 EN ISO 4120:2007 (E) 1 Scope This International Standard describes a procedure for determining wheth
19、er a perceptible sensory difference or similarity exists between samples of two products. The method is a forced-choice 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
20、 test (described in ISO 10399), but has limited use with products that exhibit strong carryover and/or lingering flavours. 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
21、indication of the attribute(s) responsible for the difference. The method is applicable only if the products are fairly 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
22、(triangle testing for similarity) when, for example, a change is made in ingredients, processing, packaging, handling 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.
23、For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (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 definit
24、ions For the purposes of this document, the terms and definitions given in ISO 5492 and the following apply. 3.1 alpha-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. 4 EN
25、ISO 4120:2007 (E) 3.2 beta-risk -risk probability 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
26、 assessments in which a perceptible difference is detected between the two products is given the symbol pd. 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
27、the test NOTE In statistical terms, the sensitivity of the test is defined by the values of , and pd. 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
28、 triangle test NOTE In the triangle test, each 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 th
29、e discussion in A.3.) Assessors receive a set 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
30、is counted and the significance is determined by reference to a statistical table. 5 EN ISO 4120:2007 (E) 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 assessors until all the eval
31、uations 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 samples from the way i
32、n 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 numbers, chosen at rand
33、om 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 once per assessor duri
34、ng 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 of product. The quant
35、ity 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 a series of tests on
36、 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 shall be requested
37、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 same level of qualifi
38、cation, 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. Monitoring the perf
39、ormance 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 required for the test (
40、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 available assessors, quantit
41、y 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. 6 EN ISO 4120:2007 (E) Avoid replicate evaluations by
42、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 replicate evaluations. For example, if only ten assessors are available, have each asses
43、sor 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. However, the test for difference using Table A.1 is valid even when replicate evaluations
44、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 Prepare worksheets and scoresheets (see B.1 and B.2) in advance of the test so as to utilize
45、 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 six assessors; use each sequence once again among the next group of six assessors, et
46、c.). 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 arrangement for each assessor (e.g. on a line to be sampled always from left to right, in a
47、 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 the assessors to evaluate the samples in the order in which they were presented. Inform
48、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 for a single triad of samples. If an assessor is to carry out more than one test in a se
49、ssion, 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 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, degree of difference, etc. (See ISO 6
