BS PD CEN TS 15634-5-2016 Foodstuffs Detection of food allergens by molecular biological methods Mustard (Sinapis alba) and soya (Glycine max) Qualitative detection of a s.pdf

1、Foodstuffs Detection of food allergens by molecular biological methods Part 5: Mustard (Sinapis alba) and soya (Glycine max) Qualitative detection of a specific DNA sequence in cooked sausages by real-time PCR PD CEN/TS 15634-5:2016 BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 1

2、5/05/2013 15:06National foreword This Published Document is the UK implementation of CEN/TS 15634-5:2016. The UK participation in its preparation was entrusted to Technical Committee AW/275, Food analysis - Horizontal methods. A list of organizations represented on this committee can be obtained on

3、request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 90303 8 ICS 07.100.30; 67.120.10 Compli

4、ance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards Policy and Strategy Committee on 31 July 2016. Amendments/corrigenda issued since publication Date Text affected PUBLISHED DOCUMENT PD CEN/TS 15634-5

5、:2016 TECHNICAL SPECIFICATION SPCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATION CEN/TS 15634-5 June 2016 ICS 07.100.30; 67.120.10 English Version Foodstuffs - Detection of food allergens by molecular biological methods - Part 5: Mustard (Sinapis alba) and soya (Glycine max) - Qualitative detection of

6、a specific DNA sequence in cooked sausages by real-time PCR Lebensmittel - Nachweis von Lebensmittelallergenen mit molekularbiologischen Verfahren - Teil 5: Senf (Sinapis alba) sowie Soja (Glycine max) - Qualitativer Nachweis einer spezifischen DNA-Sequenz in Brhwrsten mittels Real-time PCR This Tec

7、hnical Specification (CEN/TS) was approved by CEN on 18 April 2016 for provisional application. The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the CEN/TS ca

8、n be converted into a European Standard. CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel t

9、o the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, G

10、reece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMU

11、NG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TS 15634-5:2016 E PD CEN/TS 15634-5:2016CEN/TS 15634-5:2016 (E) 2 Contents Page European foreword . 3 1 Scope

12、 4 2 Principle . 4 3 Reagents . 4 4 Apparatus and equipment . 6 5 Procedure. 6 5.1 General 6 5.2 Sample preparation 6 5.3 DNA extraction with CTAB . 7 5.4 DNA purification by means of solid phase extraction 7 5.5 Measuring the mass concentration of the extracted DNA and setting to target concentrati

13、on . 8 5.6 Real-time PCR . 8 5.7 Temperature/Time program 9 6 Validation status and performance criteria 9 6.1 General information on the interpretation of the real-time PCR 9 6.2 Reliability of the method . 10 6.2.1 Setup of the interlaboratory study 10 6.2.2 Results of the interlaboratory study sa

14、mples 10 6.2.3 Qualitative interpretation. 10 7 Test report 12 Bibliography . 13 PD CEN/TS 15634-5:2016CEN/TS 15634-5:2016 (E) 3 European foreword This document (CEN/TS 15634-5:2016) has been prepared by Technical Committee CEN/TC 275 “Food analysis - Horizontal methods”, the secretariat of which is

15、 held by DIN. EN 15634, Foodstuffs Detection of food allergens by molecular biological methods, is currently composed with the following parts: Part 1: General considerations; Part 2: Celery (Apium graveolens) Qualitative determination of a specific DNA sequence in cooked sausages by real-time PCR T

16、echnical Specification; Part 3: Hazelnut (Corylus avellana) Qualitative detection of a specific DNA sequence in chocolate by real-time PCR Technical Specification; Part 4: Peanut (Arachis hypogaea) Qualitative detection of a specific DNA sequence in chocolate by real-time PCR Technical Specification

17、; Part 5: Mustard (Sinapis alba) and soya (Glycine max) Qualitative detection of a specific DNA sequence in cooked sausages by real-time PCR Technical Specification. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be

18、 held responsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark

19、, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. PD CEN/TS 15634-5

20、:2016CEN/TS 15634-5:2016 (E) 4 1 Scope This Technical Specification specifies a procedure for the qualitative detection of species specific DNA from white mustard (Sinapis alba) and soya (Glycine max) in cooked sausages using singleplex real-time PCR based on the genes MADS-D (mustard) and lectin (s

21、oya) 1. A mustard content of 10 mg/kg or greater and a soya content of 10 mg/kg or greater can be detected with a probability of 95 %. 2 Principle The DNA of the sample is extracted and is set to a definite concentration after photometric measurement. A 74 base pair (bp) long sequence of the DNA for

22、 the MADS-D protein of Sinapis alba (NCBI accession no. Y08626) or a 81 bp long sequence from the soya lectin gene is multiplicated from the sample DNA by real-time PCR. The amplicons formed are detected and verified by annealing a sequence-specific probe and generating a fluorescence signal 2. 3 Re

23、agents As a rule, analytical grade chemical reagents suitable for molecular biology shall be used. The water used shall be double distilled or equivalent quality. Solutions should be prepared by dissolving the appropriate reagents in water and autoclaving, unless indicated differently. 3.1 DNA extra

24、ction with CTAB: 3.1.1 Chloroform. 3.1.2 Ethanol, volume fraction = 96 %. 3.1.3 Ethylenediaminetetraacetic acid disodium salt (Na 2 EDTA). 3.1.4 Cetyltrimethylammoniumbromide (CTAB). 3.1.5 Hydrochloric acid, mass fraction w = 37 %. 3.1.6 Isoamyl alcohol. 3.1.7 Isopropanol. 3.1.8 Proteinase K. 3.1.9

25、Sodium chloride. 3.1.10 Sodium hydroxide. 3.1.11 Tris(hydroxymethyl)aminomethane (TRIS). 3.1.12 Chloroform isoamyl alcohol mixture. Mix 24 parts by volume of chloroform (3.1.1) with one part by volume of isoamyl alcohol (3.1.6). Commercially available and comparable mixtures can be used. 3.1.13 CTAB

26、 extraction buffer solution, containing CTAB (mass concentration = 20 g/l), sodium chloride (substance concentration c = 1,4 mol/l), TRIS (c = 0,1 mol/l), Na 2 -EDTA (c = 0,02 mol/l). Adjust the pH value with hydrochloric acid to 8,0. PD CEN/TS 15634-5:2016CEN/TS 15634-5:2016 (E) 5 3.1.14 Ethanol so

27、lution, = 70 %. 3.1.15 Proteinase K solution, = 20 mg/ml. Store aliquots of the solution at 20 C. 3.1.16 TE buffer solution, containing TRIS (c = 0,01 mol/l) and Na 2 -EDTA (c = 0,001 mol/l). Adjust the pH value with hydrochloric acid or sodium hydroxide solution to pH = 8,0. 3.2 DNA purification by

28、 means of solid phase extraction: Various systems are commercially available, among them spin filter columns or plates or also using vacuum operated systems. Suitable, commercially available kits can be used. Observe the manufacturers data for this. 3.3 Real-time PCR reagents: 3.3.1 Universal master

29、 mix (2 ) for the real-time PCR, containing thermostable DNA polymerase (for hot-start PCR) and PCR buffer solution 1)(containing reaction buffers, dNTPs, MgCl 2and Hotstart Taq polymerase), double concentrated. 3.3.2 Oligonucleotides 2: Primers and probes for the real-time PCR are shown in Table 1.

30、 Table 1 Primers and probes for the real-time PCR Name DNA sequence of the oligonucleotide Soya lectin gene Lectin-F 5 TCC ACC CCC ATC CAC ATT T 3 Lectin-R 5 ggC ATA gAA ggT gAA gTT gAA ggA 3 Lectin probe 5 FAM AAC Cgg TAg CgT TgC CAg CTT Cg TAMRA-3 aMustard (Sinapis alba) MADS D protein 2 MADS D-F

31、5 TGA AAA CTC TCT TCC CCT CTT AGG 3 MADS D-R 5 ACA AAT GCA CAC AAG ACA GAG ATA TAG A 3; MADS D probe 5 FAM TAC ATG ATG CTT ACC TCG C TAMRA 3 aaFAM: 6-carboxyfluorescein, TAMRA: 6-carboxytetramethylrhodamine; equivalent reporter and/or quencher dyes may be used if they are shown to give comparable or

32、 better results. 3.4 Controls: 3.4.1 Negative PCR control, conducted with DNA-free water instead of the DNA extract from the sample and without PCR inhibitors. 1) Ready-to-use reagents or single components may be used as a PCR master mix. Quantitect Multiplex Mastermix (2), available from QIA- GEN,

33、Hilden; was used within the interlaboratory study. PD CEN/TS 15634-5:2016CEN/TS 15634-5:2016 (E) 6 3.4.2 Extraction blank control, performing all steps of the DNA extraction procedure, except addition of the test portion, e.g. by substitution of a corresponding amount of water for the test portion.

34、3.4.3 Positive PCR control, sample containing the target sequence, which shall be treated in the same way as the samples to be examined. 4 Apparatus and equipment General aspects are described in EN ISO 24276 3. In addition to the usual laboratory facilities, the following equipment is required. Due

35、 to the high sensitivity of the PCR analytics and the risk of DNA contamination resulting from it, the use of aerosol protected filter tips is obligatory. 4.1 DNA extraction: 4.1.1 Suitable reaction vials, 1,5 ml and 2 ml, Nucleic acid-free. 4.1.2 50 ml centrifuge tubes, Nucleic acid-free. 4.1.3 The

36、rmostat or water bath, preferably with shaker function. 4.1.4 Centrifuge, suitable for centrifuging 50 ml centrifuge tubes at 8 000 g 2) . 4.1.5 Centrifuge, suitable for centrifuging 1,5 ml and 2 ml reaction vials at 16 000 g. 4.1.6 Apparatus and/or material for grinding the sample, e.g. a blender.

37、4.1.7 UV spectrometer, suitable for estimating the amount of DNA. 4.2 PCR: 4.2.1 Suitable PCR tubes. 4.2.2 Microcentrifuge for PCR tubes. 4.2.3 Real-time PCR equipment, suitable for excitation and for emission measurement of fluorescence-marked oligonucleotides. 5 Procedure 5.1 General General aspec

38、ts are described in EN ISO 24276 3. 5.2 Sample preparation Ensure that a representative sample is made available to the laboratory for investigation. The sample shall be transported and stored so that damage and/or changes are prevented. Ensure that the test sample is representative of the laborator

39、y sample, e.g. by milling or homogenizing. 2) g = 9,81 m s -2 . PD CEN/TS 15634-5:2016CEN/TS 15634-5:2016 (E) 7 5.3 DNA extraction with CTAB Measures and work steps to be considered for the DNA extraction are described in EN ISO 21571 4. An extraction blank control (3.4.2) shall be performed in para

40、llel. Weigh 2 g of the homogenized test sample into 50 ml centrifuge tubes; Add 10 ml of CTAB buffer (3.1.13); Add 30 l of Proteinase K (3.1.15) and mix; Incubate and shake for 90 min at 65 C; Centrifuge for 5 min at 6 000 g to 8 000 g; Place 500 l of chloroform isoamyl alcohol mixture (3.1.12) in 2

41、 ml reaction vials; Add 700 l of supernatant and mix thoroughly for 30 s; Centrifuge for 15 min at approximately 16 000 g; Place 500 l of cold isopropanol (3.1.7) in 1,5 ml reaction vials; Add 500 l of supernatant (aqueous phase) and mix carefully; Incubate for 30 min at room temperature; Centrifuge

42、 for 15 min at approximately 16 000 g; Carefully remove and discard the supernatant; Fill the reaction vial with 500 l ethanol solution, = 70 % (3.1.14) and swirl the reaction vial several times; Centrifuge for 5 min at about 16 000 g; Remove supernatant carefully and discard; Dry the extracted DNA

43、at 50 C (alternatively in vacuum); Dissolve the dried DNA extract in 100 l of TE buffer solution (3.1.16). 5.4 DNA purification by means of solid phase extraction Purification shall be performed by means of solid phase extraction. In the interlaboratory study, the QIAQuick PCR Purification Kit 3)(Qi

44、agen, Hilden) was used corresponding to the manufacturers information. Other suitable methods for the DNA purification by means of solid phase extraction can be applied. 3) QIAQuick PCR Purification Kit is an example of a suitable product available commercially. This information is given for the con

45、venience of users of this European Standard and does not constitute an endorsement by CEN of this product. PD CEN/TS 15634-5:2016CEN/TS 15634-5:2016 (E) 8 5.5 Measuring the mass concentration of the extracted DNA and setting to target concentration The mass concentration of a DNA aliquot can be dete

46、rmined by means of a UV spectrometer at a wavelength of 260 nm. Calculate the DNA mass concentration as follows: (DNA) in g/ml = 50 optical density dilution factor of the measured aliquot NOTE Other suitable methods for the DNA mass concentration determination can be applied. In order to check its p

47、urity, the sample can in addition be measured at 280 nm. The ratio of the values for optical density at 260 nm and 280 nm should be approximately 1,8. The DNA extracts are brought to a mass concentration of approximately 250 ng/l by dilution, e g. with sterile water. If one or more of the DNA sample

48、s exhibit a DNA mass concentration below 250 ng/l, repeat the extraction for these sample(s). If the majority of the DNA solutions exhibit a mass concentration below 250 ng/l and/or the mass concentration 250 ng/l still cannot be attained even after repeated extraction, use the DNA solutions for the

49、 real-time PCR analysis as they are. 5.6 Real-time PCR Prior to use, the gently thawed reagents should be carefully mixed and centrifuged briefly. Store the reagents cooled in the ice bath or cooling block while preparing the PCR batch. To prevent false-negative results due to co-extracted PCR inhibitors or highly degraded DNA, the amplifiability of the extracted DNA should be assessed prior to the analysis via real-time