1、August 2010 Translation by DIN-Sprachendienst.English price group 13No part of this translation 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
2、 67.240!$iR“1709847www.din.deDDIN ISO 8587Sensory analysis Methodology Ranking (ISO 8587:2006)English translation of DIN ISO 8587:2010-08Sensorische Analyse Prfverfahren Rangordnungsprfung (ISO 8587:2006)Englische bersetzung von DIN ISO 8587:2010-08Analyse sensorielle Mthodologie Classement par rang
3、s (ISO 8587:2006)Traduction anglaise de DIN ISO 8587:2010-08SupersedesDIN 10963:1997-11www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprises 25 pages07.10 Contents Page National foreword .3 National Annex NA (informative) Bibliography.4 1 Sco
4、pe 5 2 Normative references 5 3 Terms and definitions6 4 Principle6 5 General test conditions.6 6 Assessors .7 6.1 Qualification .7 6.2 Number of assessors 7 6.3 Preliminary discussion7 7 Procedure .8 7.1 Presentation of the samples.8 7.2 Reference samples 8 7.3 Test technique8 7.4 Answer form .9 8
5、Expression and interpretation of results.9 8.1 Summary of the results and calculation of the rank sums9 8.2 Statistical analysis and interpretation .9 9 Test report 13 Annex A (normative) Determination of the test conditions.19 Annex B (informative) Practical example of application Complete block de
6、sign 20 Annex C (informative) Practical example of application Balanced incomplete block design.22 Annex D (informative) Example of an answer form24 Bibliography 25 2 DIN ISO 8587:2010-08 National foreword This standard has been prepared by Technical Committee ISO/TC 34 “Food products” (Secretariat:
7、 AFNOR, France), Subcommittee SC 12 “Sensory analysis” (Secretariat: IRAM, Argentina). The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Food and Agricultural Products Standards Committee), Working Committee NA 057-01-01 AA
8、 Sensorik. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 3534-1 E DIN ISO 3534-1 ISO 5492 DIN EN ISO 5492 ISO 5495 DIN EN ISO 5495 ISO 8586-1 DIN 10961 ISO 8586-2 DIN EN ISO 8586-2 ISO 8589 DIN EN ISO 8589 Amendments This standard dif
9、fers from DIN 10963:1997-11 as follows: a) The text of ISO 8587:2006 has been adopted in its entirety. b) In clause 4 “Principle”, the number of samples to be presented to the assessors has been increased to three or more samples. c) Clause 5 “General test conditions” has been extended. d) Subclause
10、s 6.1 “Qualification” and 6.2 “Number of assessors” have been rendered more precise. e) Requirements in subclause 7.1 “Presentation of the samples” have been extended taking into account the designs chosen, e.g. balanced incomplete block designs may also be used. f) The methods of statistical analys
11、is (8) have been extended and brought in line with the state of the art. g) Annex A (normative) with Table A.1 “Choice of the parameters of the test based on its aim” has been included. h) In Annex B (informative) “Practical example of application Complete block design”, the number of assessors has
12、been increased from 8 to 14. i) Annex C (informative) “Practical example of application Balanced incomplete block design” has been added. j) The standard has been brought in line with the current rules of presentation. Previous editions DIN 10963: 1997-11, 1982-11 3 DIN ISO 8587:2010-08 National Ann
13、ex NA (informative) Bibliography DIN EN ISO 5495, Sensory analysis Methodology Paired comparison test DIN EN ISO 8586-2, Sensory analysis General guidance for the selection, training and monitoring of assessors Part 2: Expert sensory assessors DIN EN ISO 8589, Sensory analysis General guidance for t
14、he design of test rooms DIN ISO 3534-1, Statistics Vocabulary and symbols Part 1: General statistical terms and terms used in probability DIN 10961, Training of assessors for sensory analysis 4 DIN ISO 8587:2010-08 DIN EN ISO 5492, Sensory analysis Vocabulary Sensory analysis Methodology Ranking 1 S
15、cope This International Standard describes a method for sensory evaluation with the aim of placing a series of test samples in rank order. This method allows for assessing differences among several samples based on the intensity of a single attribute, of several attributes1)or of an overall impressi
16、on. It is used to find if differences exist, but cannot determine the degree of difference that exists between samples. The method is suited for the following cases: a) evaluation of assessors performance 1) training assessors, 2) determining perception thresholds of individuals or groups; b) produc
17、t assessment 1) pre-sorting of samples i) on a descriptive criterion, ii) on hedonic preference; 2) determination of the influence on intensity levels of one or more parameters (e.g. order of dilution, influence of raw materials, of production, packaging or storage methods) i) on a descriptive crite
18、rion, ii) on hedonic preference; 3) determination of the order of preference in a global hedonic test. 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 l
19、atest edition of the referenced document (including any amendments) applies. ISO 5492, Sensory analysis Vocabulary ISO 6658, Sensory analysis Methodology General guidance 1) In this case, each attribute is tested through a different test in which the same products have different codes and are served
20、 in different orders to the same assessor. 5 DIN ISO 8587:2010-08 ISO 8586-1, Sensory analysis General guidance for the selection, training and monitoring of assessors Part 1: Selected assessors ISO 8586-2, Sensory analysis General guidance for the selection, training and monitoring of assessors Par
21、t 2: Experts ISO 8589, Sensory analysis General guidance for the design of test rooms ISO 3534-1, Statistics Vocabulary and symbols Part 1: General statistical terms and terms used in probability ISO 11035, Sensory analysis Identification and selection of descriptors for establishing a sensory profi
22、le by a multidimensional approach ISO 11036, Sensory analysis Methodology Texture profile 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 3534-1 and ISO 5492 apply. 4 Principle The assessors receive simultaneously three or more samples in random orde
23、r. NOTE Although it is possible to rank two samples, the paired comparison method, as described in ISO 54951, usually is preferred. The assessors are asked to rank the samples according to a specified criterion: either a unidimensional criterion (i.e. particular attribute or specific characteristic
24、of an attribute) or a global intensity (e.g. overall impression). The rank sums are determined and statistical comparisons are made. 5 General test conditions Refer, where available, to the standards (see ISO 6658) describing the sampling methods, the room in which tests are conducted (see ISO 8589)
25、 and the apparatus. When preparing the test samples, the important points to be taken into consideration are as follows: a) preparation, coding and presentation of the test samples; b) number of samples to be compared that can be compared reliably (to be determined based on the nature of the test pr
26、oduct (saturation sensitivity effects) and the design chosen; the number of samples shall be adapted based on 1) the type of product e.g. up to 15 samples can be assessed by selected assessors (ISO 8586-1) or experts (ISO 8586-2) on mild samples, while three can be a real maximum for harsh, spicy or
27、 high fat products assessed by consumers, and 2) the criterion to be assessed (e.g. sweet is less saturating than bitter); c) possible illumination of the samples. 6 DIN ISO 8587:2010-08 6 Assessors 6.1 Qualification The qualification of assessors depends on the aim of the test (see Annex A). All as
28、sessors should preferably have the same level of qualification, this level being chosen according to the purpose of the test: a) selected assessors or experts, for 1) training assessors, 2) assessment on a descriptive criterion, for instance determining the influence of intensity levels of one or mo
29、re parameters (e.g. order of dilution, influence of raw materials, of production, packaging or storage methods), 3) determination of perception thresholds of individuals or groups; b) untrained assessors or consumers, already trained on the method 1) for hedonic preference, 2) when pre-sorting sampl
30、es (to select a few products from a large number, as a preliminary test). For the conditions with which assessors shall comply, see ISO 6658, ISO 8586-1 and ISO 8586-2. They shall all be specially trained on the ranking procedure and on the selected descriptors being used. 6.2 Number of assessors Th
31、e number of assessors depends on the aim of the test (see Annex A). When testing assessors performance, training assessors or determining perception thresholds of individuals or groups, no minimum or maximum number is required. For descriptive product assessment, the minimum number of assessors is d
32、etermined by the levels of statistical risks accepted and shall comply with ISO 11035 or ISO 11036, i.e. preferably around 12 to 15 selected assessors. For determining the order of preference in a hedonic test, the minimum number of assessors is determined by the levels of statistical risks accepted
33、, e.g. a minimum of 60 assessors per group of consumer type. For statistical analysis of the results, other things being equal (for example, test conditions, qualification of assessors), the larger the number of assessors, the greater the probability of revealing any systematic difference in rank am
34、ong products. 6.3 Preliminary discussion The assessors shall be informed of the purpose of the test, i.e. ranking of test samples. If necessary, a demonstration of a ranking procedure can be given. It is essential in this test to ensure common understanding by all assessors of the criterion under te
35、st. The preliminary discussion shall not influence assessors expectations. 7 DIN ISO 8587:2010-08 7 Procedure 7.1 Presentation of the samples The assessors shall not be able to draw conclusions about the samples from the way in which they are presented. Prepare samples out of sight of the assessors
36、and in an identical manner: same apparatus, vessels, same quantity of products, same temperature, same presentation. All irrelevant differences in samples shall be masked to avoid influencing the ranking. It is preferable to present the samples at the temperature at which the product is generally co
37、nsumed. The vessels are identified by 3-digit numbers, chosen at random, and different from one sample to another within one session (and preferably from one assessor to another). The presentation takes into account the design chosen. In a “complete block” design, each assessor ranks all the samples
38、. It is the preferred procedure. But, if the number of samples or their nature makes it impracticable to rank all the samples, a “balanced incomplete block” design may be used. In either case, it is necessary to ensure that all assessors complete their part of the design and do not omit any assessme
39、nt. For balanced incomplete block designs, each assessor is presented a specific subset of the samples in a randomized order (see Annex C for an example). NOTE The use of a certain Balanced Incomplete Block is only possible when such a block variation exists in reality. So it is necessary to look fo
40、r a predefined block from literature, e.g. Reference 5 in the Bibliography. Each assessor is presented with k of the p samples (k F, from Table 4 considering the number of assessors, the number of products and the chosen risk, H0is rejected. It is concluded that there are consistent differences amon
41、g the rank orders of the products. For balanced incomplete block designs: Ftest= ()()().222131121prn kRRrgpk g + +where Riis the rank sum of product i; r is the number of repeats of the basic balanced incomplete block design; k is the number of samples each assessor ranks; n is the number of times e
42、ach sample is evaluated in the basic balanced incomplete block design; and g is the number of times each pair of samples is evaluated together in the basic balanced incomplete block design. If Ftest F, from Table 4 considering the number of assessors, the number of products and the chosen risk, H0is
43、 rejected. It is concluded that there are consistent differences among the rank orders of the products. If the number of samples or the number of assessors is not in Table 4, the critical values are found by an approximation that treats Ftestas 2with p 1 degrees of freedom, where p is the number of
44、products. Critical values of 2are given in Table 5. 11 DIN ISO 8587:2010-08 8.2.3.2 Test which products are significantly different from others If it was concluded by the Friedman test that there are consistent differences among the rank orders of the products, then to determine which products are s
45、ignificantly different calculate a Least Significant Difference (LSD) at the chosen risk ( = 0,05 or = 0,01). In considering the level of (the significance level, or risk of concluding that there is a difference when there is none), one of the two following approaches shall be chosen: a) If the leve
46、l of risk applies to each pair individually, then the risk to be associated is . For instance, with a risk = 0,05 (i.e. 5 % risk), then, in the calculation of the LSD, the value of z (corresponding to a two-tailed normal probability of ) is 1,96. This is known as comparison-wise or individual risk.
47、If the risk is for each pair, there is a risk that is much greater than of wrongly attributing a significant difference to one or more pairs in the whole experiment. b) If the risk applies to the whole experiment, then the risk to be associated with each pair of products is , where = 2/p(p 1). For e
48、xample, when p = 8, at risk = 0,05, then = 0,001 8 and then z (corresponding to a two-tailed normal probability of ) is 2,91. This is known as experiment-wise or global risk. In most cases, it is the second of these, experiment-wise risk, that is most relevant to practical decisions about products.
49、For complete block designs: ()1LSD6jppz+= For balanced incomplete block designs: ()( )1LSD6rk nk n gz+= If the observed difference between the rank sums of two products is equal to or greater than the LSD, then it is concluded that the two products have been given significantly different ranks. If the observed difference is less than the LSD, then the two products have not been given significantly different ranks. 8.2.4 Tied ranks If two or more ranks are tied, F
