1、Ref. No. DIN 10970 : 2002-09English price group 09 Sales No. 010911.04DEUTSCHE NORM September 200210970Continued on pages 2 to 9. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e.V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has
2、the exclusive right of sale for German Standards (DIN-Normen).Sensory analysisTime-intensity testTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.ICS 67.240Sensorische Prfverfahren ZeitintensittsprfungIn keeping with curre
3、nt practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.ContentsPageForeword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Scope . . . .
4、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5、. . . . . . . . . . . . . . . 24 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Assessors . . . . . . . . . .
6、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.1 Qualification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.2 Number of assessors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7、. . . . . 47 Test room and test equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47.1 Test room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47.2 Test equipment . . . . . . . . . . . . . . . . . . . . . . . . . . .
8、 . . . . . . . . . . . . . . . . . . . . 47.3 Data recording . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Preparation of test portions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48.1 Particular test details to be spec
9、ified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48.2 General information on procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48.3 Test portion coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Procedure . . . . . .
10、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49.1 Calibration of test panel performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49.2 Specification of time intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
11、.3 Plotting time-intensity curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12、 . . . . . . . . . . . . . . . . . . . 510.2 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.3 Comparison of parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.4 Curve averaging . . . . . . . . . .
13、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511 Test report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Annex A Presentation of results (examples) . . . . . . . . . . . . . . . . . . . . . . . . . . 7Page 2DIN 10970 :
14、 2002-09ForewordThis standard has been prepared by Technical Committee Sensorik of the Normenausschuss Lebensmittel undlandwirtschaftliche Produkte (Foodstuffs and Agricultural Products Standards Committee).1 ScopeThis standard specifies a method of describing a sample on the basis of a single senso
15、ry attribute and ofmeasuring its intensity as it changes with time. It may be used to characterize product standards, compareproducts and develop or optimize products.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. These norma-tive
16、 references are cited at the appropriate places in the text, and the titles of the publications are listed below.For dated references, subsequent amendments to or revisions of any of these publications apply to thisstandard only when incorporated in it by amendment or revision. For undated reference
17、s, the latest edition ofthe publication referred to applies.DIN 10950-1 Sensory analysis ConceptsDIN 10956 Universal test glasses and lids for use in sensory analysis Requirements and instructionsfor useDIN 10960 Wine-tasting glasses for use in sensory analysisDIN 10961 Training of assessors for sen
18、sory analysisDIN 10962 Specifications of test rooms for use in sensory analysisISO 11035 : 1994 Sensory analysis Identification and selection of descriptors for establishing a sensoryprofile by a multidimensional approach1 Overbosch, P., van den Enden, J. C. and Keur, B. M., An improved method for m
19、easuring perceived inten-sity/time relationships in human taste and smell. Chemical Senses, 1986: 11, 331338.2 Liu, Y.-H. and MacFie, H. J. H., Methods for averaging time-intensity curves. Chemical Senses, 1990: 15,471484.3 van Buuren, S., Analyzing time-intensity responses in sensory evaluation. Fo
20、od Technology, 1992: 46,101104.3 ConceptsSee DIN 10950-1.4 PrincipleThis method is used to determine how the perception of the intensity of a sensory attribute varies with time,using an intensity scale. As a rule, the perceived intensity of the attribute concerned is translated into amovement of the
21、 hand, which is registered by a linked recording system. Time-intensity curves are preparedfrom the results obtained by individual assessors, and various other characteristic parameters are tabulated.The curves so obtained can be combined to form an overall curve as shown in figure 1. Such a curve u
22、suallycovers the basic parameters listed below this figure.Page 3DIN 10970 : 2002-09KeyIextIntensity not perceptibleImaxPeak intensity during testTinitTime at which stimulus is offeredTonsetTime when stimulus is first perceivedTmax ATime to reach maximum intensity of sensationTmax ETime at which pea
23、k intensity finishesTtrunTime at which a specified minimum intensity has been reachedTextTime at which stimulus can no longer be perceivedTdurTime from onset of sensation until it can no longer be perceived1 Lag time (time before stimulus is perceived)2 Increase in intensity3 Pre-peak area under the
24、 curve4 Plateau time (duration of peak intensity)5 Post-peak area under the curve6 Area under the curve between Tmax Eand Ttrun7 Decrease in intensityFigure 1: Overall time-intensity curve5 SamplingThe method used to collect the test sample (sample, for short) will depend on the nature of the produc
25、t andon the objective of the test. The test portions shall be collected so as to be representative of the sample material.6 Assessors6.1 QualificationPersons with experience of descriptive sensory analyses shall be used as assessors. They shall be capable ofidentifying from memory a given attribute
26、of the test portion independently of other attributes and of assessingits intensity on a specified scale over a given time interval, optionally translating it into a movement of the handrepresenting the intensity rating.The assessors shall be trained and coached in respect of specific products, as s
27、pecified in DIN 10961, and shallundergo regular training sessions as specified in ISO 11035 to ensure reproducible results are obtained.Because of the complexity of procedures and the associated technology, the final selection of assessors shallbe made after training, the reproducibility of the resu
28、lts produced by an individual assessor being more impor-tant than agreement between the assessors.IntensityTimePage 4DIN 10970 : 2002-096.2 Number of assessorsAt least six assessors will be necessary to obtain interpretable results.7 Test room and test equipment7.1 Test roomA test room as specified
29、in DIN 10962 should be used.7.2 Test equipmentAll items of equipment shall be made of the same material and be identical in size, shape and colour. They shallhave no influence on the results. The nominal capacity and shape of the containers shall be matched to the sizeof the test portions and the na
30、ture of the sample material. If available and suitable, glasses as in DIN 10956 orDIN 10960 shall be used.7.3 Data recordingThe data shall be acquired by recording the intensity of sensation against time, the following equipment beingspecifically suitable for this purpose:a) computers, with a mouse
31、or joystick;b) a ball for pressing;c) a resistor with recorder.It shall be ensured that the evaluation be made on the basis of an adequate number of measurements.8 Preparation of test portions8.1 Particular test details to be specifiedAs far as applicable and depending on the test objective and the
32、nature of the sample material, the followingshall be specified:a) preparation and presentation of test portions;b) size of test portions;c) number of test portions;d) temperature of test portions;e) masking of individual attributes;f) test schedule and number of replicate evaluations.The test portio
33、ns shall be served in the state in which they are normally consumed. The assessor shall not beable to identify the samples from the manner in which they are presented. All test portions shall be served inthe same way.8.2 General information on procedureIf several test portions are to be dealt with i
34、n one session, their number will depend on the sample materialavailable, the complexity of testing and the exposure times.The size of test portions shall be identical and such as to allow a complete assessment of the attributeconcerned.Each test portion shall be assessed at least twice by each asses
35、sor on the basis of a suitable test schedule.8.3 Test portion codingTest portions shall preferably be coded using three-digit random numbers and shall be re-coded before everytest.9 Procedure9.1 Calibration of test panel performanceThe panel of assessors shall be capable of identifying and quantifyi
36、ng the attribute to be assessed. In addition,they shall be trained in a suitable data recording procedure, preferably using special reference portions.The form of time-intensity curves and the Imaxvalues shall be highly similar between individual assessors9.2 Specification of time intervalsBoth the
37、total time over which the intensity is to be recorded and the time intervals at which measurements areto be made shall be specified, a choice being made between the following options:Page 5DIN 10970 : 2002-09a) continuous intensity recording, i.e. the intensity of the selected attribute is determine
38、d continuously;b) discrete intensity recording, i.e. the intensity is determined at given times, which is preferable for totalexposure times of more than one minute.Prior to the actual test, the assessors shall be familiarized with the test schedule, the test procedure and theintensities to be asses
39、sed.As part of the calibration of test panel performance, it will be necessary to ensure that they provide reproducibleresults for selected parameters (see clause 4).9.3 Plotting time-intensity curves9.3.1 Presenting the test portionsThe test portions should be identical in appearance in terms of si
40、ze and equipment used, and shall be servedto the assessors in the same way.9.3.2 Seating planThe seating plan will depend on the test objective and shall provide identical test conditions for all the asses-sors.9.3.3 TestingThe test shall be performed as an individual test. Depending on the nature o
41、f the sample material and theattribute, a test instruction shall be provided that comprises:a) sample size;b) type of sample ingestion;c) details of chewing and swallowing;d) start of data recording;e) duration of data recording;f) details of neutralization;g) any further ingestion;h) translation of
42、 perceived intensity into a movement of the hand.10 Evaluation10.1 GeneralThe following are the main points to be taken into account in assessing time-intensity test results.a) The intensity is to be assessed continuously over a fairly long time (it is not a one-off measurement asin profile testing)
43、.b) There is far greater variation in assessors compared with other sensory analyses, both the level of theintensity assessment and the duration of the sensation varying from assessor to assessor, i.e. every asses-sor produces a curve having a unique shape (the curve signature).The analysis of resul
44、ts should take account of these subjective factors.10.2 Data analysisPrior to any in-depth statistical evaluation, the curves produced by each assessor for each individual testportion shall first be compared visually. Only then can a decision be made as to the nature of the subsequentanalysis, a com
45、parison of a few parameters, such as Tmax, Imaxand AUC, often being sufficient. If there is insuf-ficient agreement between the curves, it may be necessary to subject the raw data to more in-depth analyses.10.3 Comparison of parametersFor specific objectives, it is sufficient to compare individual c
46、urve parameters for the sample being assessed.This procedure is the same as that for profile testing (see DIN 10967).Depending on the design of the test, a variance analysis shall be used to check whether the individual param-eters differ significantly for different samples, it being essential to be
47、ar in mind that the assessors are to beincluded in the analysis as a factor that causes variance. Frequently, there are highly significant differencesbetween the assessors in the case of individual curve parameters. These differences in the curves cannot beeliminated by training.Furthermore, as in p
48、rofile testing, a principal components analysis of the curve parameters may also be per-formed.10.4 Curve averagingThe curves for different samples may be compared using the following methods.Page 6DIN 10970 : 2002-0910.4.1 Simple averaging of intensity assessments for each collection timeBecause of
49、 the subjective differences between curves, simple averaging is not particularly advisable sinceaveraging creates a curve not produced by any assessor. Intensive training of the assessors or measurementsrepeated many times may, however, counteract this.10.4.2 Overbosch, van den Enden and Keur method 1This method divides the curve into rising and falling sections, both parts of Tmaxbeing separated. It involvesthe following five steps:1. Calculation of geometric mean of Imaxvalues.2. Normalization of individual curve values to this mean value.3. Subdivision of each i
