1、ICS 67.100.01Butyrometrische Bestimmung des Fettgehaltes von Milch undMilchprodukten Teil 2: Produktspezifische AnforderungenIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.Fore
2、wordThis standard has been prepared by Technical Committee Chemische und physikalische Milchuntersuchungof the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Foodstuffs and Agricultural Prod-ucts Standards Committee).AmendmentsThis standard combines and updates the March 1970 edition
3、 of DIN 10310 and the August 1975 edition ofDIN 10315. The scope has been extended to cover various dairy products and validation data have beenincluded.Previous editionsDIN 10310: 1970-03; DIN 10315: 1975-08.1 ScopeThis standard specifies methods of determining the fat content of specific dairy pro
4、ducts by butyrometry. Itcovers milk having a fat content of 0 % to 10 % by mass, milk containing preservatives, homogenized milk,sour milk (if the fat can be uniformly dispersed), unsweetened condensed milk, buttermilk, whey, powderedmilk, cream, ice cream, mixes for milk-based ice cream, butter and
5、 cheese, although the results may beinaccurate for some types of cheese (see note in subclause 9.6). The method described has hitherto beenvalidated only for homogenized milk and raw milk.NOTE: The butyrometric determination of the fat content of milk has been largely replaced by other routineanalys
6、es (e.g. by infrared spectroscopy). However, dairy products such as cheese can either not beanalysed by these methods or require extensive sample preparation. For such products, butyrometricmethods therefore remain an adequate alternative.CAUTION. Milk samples whose fat content is to be determined a
7、s in this standard shall not contain sodiumazide, NaN3, as a preservative.Ref. No. DIN 10479-2 : 2001-11English price group 08 Sales No. 010809.02DEUTSCHE NORM November 200110479-2Continued on pages 2 to 7. No part of this translation may be reproduced without the prior permission ofDIN Deutsches In
8、stitut fr Normung e.V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Butyrometric determination of fat content ofmilk and milk productsPart 2: Testing of specific dairy productsTranslation by DIN-Sprachendienst.In case of doubt, t
9、he German-language original should be consulted as the authoritative text.Supersedes DIN 10310,March 1970 edition, andDIN 10315, August 1975edition.Page 2DIN 10479-2 : 2001-112 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. These no
10、rmativereferences are cited at the appropriate places in the text, and the titles of the publications are listed below. Fordated references, subsequent amendments to or revisions of any of these publications apply to this standardonly when incorporated in it by amendment or revision. For undated ref
11、erences, the latest edition of the pub-lication referred to applies (including any amendments).DIN 10284 Roeder butyrometer for cream, verifiableDIN 10285 Schulz butyrometer for cream, verifiableDIN 10286 Van Gulik butyrometer for cheese , verifiable, having a measurement range from 0 to 40 %DIN 103
12、13 Determination of fat content of cheese and cheese spread by Schmid-Bondzynski-Ratzlaffreference methodDIN 10329 Determination of fat content of cream by Roeder gravimetric methodDIN 10332 Determination of fat content of cream by Schulz and Kley methodDIN 10342 Determination of fat content of milk
13、 and milk products by Weibull-Berntrop gravimetricmethodDIN 10479-1 Butyrometric determination of fat content of milk and milk products General guidance onthe use of butyrometric methods and requirements for amyl alcoholDIN 12836-1 Milk butyrometer, verifiable, with a measuring range of 0 to 5 % and
14、 aboveDIN 12836-2 Milk butyrometer, verifiable, with a measuring range of 0 to 4 %DIN 12836-3 Milk butyrometer, verifiable, with a measuring range of 0 to 10 %DIN 12837 Pipettes for milk butyrometersDIN EN ISO 707 Milk and milk products Guidance on sampling (ISO 707 : 1997)DIN EN ISO 1211 Milk Deter
15、mination of fat content Gravimetric method (Reference method)(ISO 1211 : 1999)DIN EN ISO 1736 Dried milk and dried milk products Determination of fat content Gravimetric method(Reference method) (ISO 1736 : 2000)DIN EN ISO 1737 Evaporated milk and sweetened condensed milk Determination of fat conten
16、t Gravimet-ric method (Reference method) (ISO 1737 : 1999)DIN EN ISO 1854 Whey cheese Determination of fat content Gravimetric method (Reference method)(ISO 1854 : 1999)DIN EN ISO 2450 Cream Determination of fat content Gravimetric method (Reference method)(ISO 2450 : 1999)DIN EN ISO 3727 Butter Det
17、ermination of water, solids-not-fat and fat contents on the same test portion(Reference method) (ISO 3727 : 1977)DIN EN ISO 7208 Skimmed milk, whey and buttermilk Determination of fat content Gravimetric method(Reference method) (ISO 7208 : 1999)DIN EN ISO 7328 Milk-based edible ices and ice mixes D
18、etermination of fat content Gravimetric method(Reference method) (ISO 7328 : 1999)ISO 5725-2 : 1994 Accuracy (trueness and precision) of measurement methods and results Part 2: Basicmethod for the determination of repeatability and reproducibility of a standard measure-ment method3 Concepts3.1 Gerbe
19、r fat contentThe content of fat and fatty substances in a milk sample, determined as specified in this standard and reportedas a percentage by mass or in g/100 g of sample material.3.2 Van Gulik fat contentThe content of fat and fatty substances in a cheese sample, determined as specified in this st
20、andard andreported as a percentage by mass or in g/100 g of sample.4 PrincipleSee DIN 10479-1.5 Reagents5.1 GeneralUnless otherwise specified, the sulfuric acid and amyl alcohol (isoamyl alcohol) used shall meet the requirementsof DIN 10479-1.CAUTION. The safety regulations relating to the handling
21、of sulfuric acid shall be observed.Page 3DIN 10479-2 : 2001-115.2 VolumesUnless otherwise stated, the volumes of sulfuric acid, amyl alcohol and milk or liquid milk products shall be10 ml, 1 ml and 10,75 ml, respectively, all measured at (20 t 2) C.6 Apparatus6.1 GeneralAll the equipment used shall
22、meet the requirements of DIN 10479-1.In addition to standard laboratory equipment, the following shall be used.6.2 Butyrometers and stoppers, as listed below for the product being analysed and the method used.6.2.1 Milk butyrometer (e.g. DIN 12836-A4, DIN 12836-A5, DIN 12836-A6, DIN 12836-A7 or DIN
23、12836-A10butyrometer).6.2.2 Sichler skimmed milk butyrometer, with constricted scale.6.2.3 Teichert dried-milk butyrometer.6.2.4 Roeder cream butyrometer (e.g. DIN 10284-A40, DIN 10284-A55, DIN 10284-A75, DIN 10284-A90cream butyrometer with DIN 10284-B or DIN 10284-D rubber stopper and DIN 10284-C c
24、ream beaker).6.2.5 Schulz cream butyrometer (e.g. DIN 10285-A40 cream butyrometer).6.2.6 Khler cream butyrometer.6.2.7 Van Gulik cheese butyrometer (e.g. DIN 10286-40 butyrometer with DIN 10284-B or DIN 10284-Drubber stopper and DIN 10286-B or DIN 10286-C sample weighing device).6.2.8 Khler ice crea
25、m butyrometer.6.2.9 Roeder ice cream butyrometer.6.2.10 Roeder butter butyrometer.6.3 Sulfuric acid dispenser (e.g. DIN 12837-B pipette or automatic device for dispensing (10 t 0,15) ml).6.4 Amyl alcohol dispenser (e.g. DIN 12837-C pipette or automatic device for dispensing (1 t 0,05) ml).6.5 Milk d
26、ispenser (e.g. DIN 12837-A milk pipette or automatic device for dispensing (10,75 t 0,075) ml oranalytical balance).6.6 Centrifuge.6.7 Water bath.7 SamplingAs in DIN EN ISO 707.8 Sample preparationSamples shall be prepared as specified in the reference methods listed in table 1.Page 4DIN 10479-2 : 2
27、001-119 Procedure9.1 GeneralAnalyses shall be carried out in accordance with the general guidance given in DIN 10479-1, while observing therequirements for the products specified in subclauses 9.2 to 9.8.9.2 Milk (Gerber method)9.2.1 Whole milk, partly skimmed milk and sour milk9.2.1.1 To determine
28、the Gerber fat content, pour 10 ml of sulfuric acid, 10,75 ml of milk and 1 ml of amylalcohol into a butyrometer as in subclause 6.2.1 in that order so that the milk forms a layer on the sulfuric acidand the amyl alcohol forms one on the milk. Take care that no mixing occurs before shaking, and the
29、neck ofthe butyrometer is not wetted.9.2.1.2 Seal the butyrometer with its stopper without mixing the liquids.9.2.1.3 Shake the butyrometer vigorously until the proteins are completely dissolved and then invert it until theliquid is thoroughly mixed. Adjust the butyrometer stopper so that the gradua
30、ted tube is filled with liquid, butnot the butyrometer bulb.9.2.1.4 Centrifuge the butyrometer. After reaching a relative centrifugal acceleration of (350 t 50) g1) asdescribed in DIN 10479-1, maintain the speed for four minutes.9.2.1.5 Heat the butyrometer for at least five minutes at (65 t 2) C in
31、 the water bath, taking care that the waterlevel reaches the bulb when the butyrometer is immersed with the stopper at the bottom.9.2.1.6 Holding the butyrometer vertically with the meniscus at eyelevel, adjust the butyrometer stopper so thatthe column of fat is within the tube with the graduated sc
32、ale. Use the stopper to align the sulfuric acid/fatinterface with a graduation of the scale and read off the level of the fat column at the lowest point in the meniscus,if necessary also estimating the value at a point centred between two graduations.9.2.2 Formaldehyde-preserved milkDissolving the p
33、roteins as described in subclause 9.2.1.3 can be difficult if formaldehyde has been used aspreservative. In such cases, proceed as described in subclauses 9.2.1.1 to 9.2.1.6, but first heat the butyrometerin the water bath at (65 t 2) C, removing and shaking it from time to time until the protein is
34、 completely dissolved.9.2.3 Homogenized milk9.2.3.1 Proceed as described in subclauses 9.2.1.1 to 9.2.1.6, but centrifuge the butyrometer for five minutes,three times in succession. Place the butyrometer in the water bath at (65 t 2) C for five minutes to maintain itstemperature after both the first
35、 and second centrifugation and take a reading each time as described insubclause 9.2.1.6.Table 1: Reference methods for determining fat contentProducts Reference method as inRaw milk, processed liquid milk, partly skimmed milk DIN EN ISO 1211Skimmed milk, whey, buttermilk DIN EN ISO 7208Powdered mil
36、k and dried milk products DIN EN ISO 1736Condensed milk and sweetened condensed milk DIN EN ISO 1737Whey cheese DIN EN ISO 1854Cream DIN EN ISO 2450Ice cream and milk-based ice cream mixes DIN EN ISO 7328Cheese, cheese spread DIN 10313Butter DIN EN ISO 37271) g = 9,81 ms2.Page 5DIN 10479-2 : 2001-11
37、9.2.3.2 If the value obtained after the second centrifugation is more than 0,05 % higher than after the first,repeat the heating and centrifuging not more than twice.9.2.3.3 If the difference in the results of two consecutive analyses is a maximum of 0,05 % in the proceduredescribed in 9.2.3.1, repo
38、rt the higher value as the fat content of the milk.9.2.3.4 If a difference exceeding 0,05 % is also obtained between the last two repeats, discard the result ofthis analysis.9.2.4 Skimmed milkProceed as described in subclauses 9.2.1.1 to 9.2.1.6 using a butyrometer (as in subclause 6.2.2), but repea
39、tthe centrifuging once after placing the butyrometer in the water bath at (65 t 2) C for five minutes.9.2.5 Unsweetened condensed milkPrior to analysis, heat the condensed milk to 50 C and then cool it. Dilute the cooled condensed milk with waterin a volumetric ratio of 1:1. Then perform the analysi
40、s as described in subclauses 9.2.1.1 to 9.2.1.6.9.2.6 Buttermilk (Gerber method as modified by Mohr and Baur)For the fat determination, add 10 ml of buttermilk and 2 ml of amyl alcohol to 10 ml of sulfuric acid in abutyrometer as in subclause 6.2.1, seal and shake the butyrometer and then centrifuge
41、 it immediately for tenminutes as described in subclause 9.2.1.4 to prevent formation of a plug. Then proceed as described insubclauses 9.2.1.5 and 9.2.1.6.9.3 WheyProceed as described in subclause 9.2.4.9.4 Powdered milkIn a butyrometer (as in subclause 6.2.3), cover 10 ml of sulfuric acid with 7,5
42、 ml of water and 1 ml of amyl alcohol.Weigh 2,5 g of powdered milk into a weighing pan and transfer it to the butyrometer via a funnel using a finebrush. Seal the butyrometer and carefully shake it several times, placing it in the water bath at (65 t 2) C forfive minutes after each shaking. Then cen
43、trifuge the butyrometer twice for five minutes in the heated centrifugeand read off the fat content after placing it in the water bath for a further five minutes.9.5 Cream9.5.1 Roeder gravimetric methodProceed as specified in DIN 10329 using a butyrometer as in subclause 6.2.4.9.5.2 Schulz-Kley grav
44、imetric methodProceed as specified in DIN 10332 using a butyrometer as in subclause 6.2.5.9.5.3 Khler volumetric methodIntroduce 10 ml of sulfuric acid, 5 ml of cream, 5 ml of water and 1 ml of amyl alcohol in that order into abutyrometer as in subclause in 6.2.6. If a cream syringe is used, rinse i
45、t thoroughly by sucking up water severaltimes before sucking up the 5 ml of water for the analysis. Seal the butyrometer, shake it and centrifuge it forfive minutes. Take a reading from the zero point after keeping it in the water bath at (65 t 2) C for five minutes.9.6 Cheese (Van Gulik method)NOTE
46、: Although this method can be applied to all types of cheese, it has been found that it is not completelysatisfactory for the following:a) extra mature cheese, because lipolysis alters the composition of the triglycerides, falsifying the result;b) cheese made from homogenized milk, which always give
47、s results that are too low;c) cheese with a low or high fat content, which does not always give results that agree with those obtainedby the reference method (see DIN 10313);d) cheese containing additives that may interfere with the reaction and agglutinate at the base of the fatcolumn since this gi
48、ves results that are too high or too low compared with the Weibull-Berntrop method (seeDIN 10342);e) cheese made from milk other than cows milk since the composition of the milk fat varies and everybutyrometric determination yields varyingly erroneous results.9.6.1 Weigh 3 g of the sample prepared a
49、s in clause 8 to an accuracy of 0,005 g into the weighing device ofa butyrometer as in subclause 6.2.7, onto a piece of cellophane or, in the case of a pasty sample, into a perforatedPage 6DIN 10479-2 : 2001-11glass beaker fitting the butyrometer, and transfer it to the butyrometer. If a piece of cellophane or a glass beakeris used for weighing, introduce them into the butyrometer together with the cheese.9.6.2 Add about 15 ml of sulfuric acid to the sample in the butyrometer. If a rubber-stoppered butyrometer witha weighing device (as in s
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