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GB 5009.168-2016 (GB5009.168-2016)

GB 5009.168-2016_English: PDF (GB5009.168-2016)
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BASIC DATA
Standard ID GB 5009.168-2016 (GB5009.168-2016)
Description (Translated English) National food safety standard -- Determination of eicosapentaenoic acid and docosahexaenoic acid in foods
Sector / Industry National Standard
Classification of Chinese Standard X09
Word Count Estimation 22,242
Date of Issue 2016-12-23
Date of Implementation 2017-06-23
Older Standard (superseded by this standard) GB 5413.27-2010; GB/T 17376-2008; GB/T 17377-2008; GB/T 22223-2008; GB/T 5009.168-2003; GB/T 9695.2-2008; NY/T 91-1988; SN/T 2922-2011
Regulation (derived from) National Health and Family Planning Commission Notice No.17 of 2016

Standards related to: GB 5009.168-2016

GB 5009.168-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard
Determination of fatty acids in foods
ISSUED ON. DECEMBER 23, 2016
IMPLEMENTED ON. JUNE 23, 2017
Issued by. National Health and Family Planning Commission of the
People’s Republic of China;
China Food and Drug Administration.
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Table of Contents
Foreword ... 4
1 Scope ... 5
2 Principle ... 5
3 Reagents and materials ... 6
4 Apparatus and equipment ... 7
5 Analysis procedure ... 8
6 Expression of analysis results ... 11
7 Principle ... 14
8 Reagents and materials ... 15
9 Apparatus and equipment ... 17
10 Analysis procedure ... 17
11 Expression of analysis results ... 19
12 Principle ... 20
13 Reagents and materials ... 20
14 Apparatus and equipment ... 20
15 Analysis procedure ... 21
16 Expression of analysis results ... 21
17 Precision ... 22
18 Quantitation limits ... 22
Annex A Molecular formula and CAS number of single fatty acid methyl ester
standards ... 23
Annex B Typical reference chromatogram of 37 kinds of fatty acid methyl ester
standard solutions ... 25
Annex C Retention time and relative retention time reference for fatty acid
methyl esters ... 26
Annex D Coefficients for conversion between fatty acid methyl esters, fatty
acids and fatty acid triglycerides ... 28
Annex E Quantitation limits for fatty acids ... 30
Foreword
This Standard replaces GB/T 5009.168-2003 “Determination of eicosapentaenoic acid
and docosahexaenoic acid in foods”, GB/T 22223-2008 “Determination of total fat,
saturated fat, and unsaturated fat in foods - Hydrolytic Extraction - Gas
Chromatography”, GB 5413.27-2010 “National food safety standard - Determination of
fatty acids in foods for infants and young children milk and milk products”, GB/T
9695.2-2008 “Meat and meat products - Determination of fatty acids”, GB/T 17376-
2008 “Animal and vegetable fats and oils - Preparation of methyl esters of fatty acids”,
GB/T 17377-2008 “Animal and vegetable fats and oils - Analysis by gas
chromatography of methyl esters of fatty acids”, SN/T 2922-2011 “Determination of
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in foods for export -
Gas chromatography”, NY/T 91-1988 “Determination of erucic acid in the oil of
rapeseed - Gas chromatographic method”.
Compared with GB/T 5009.168-2003, the main changes of this Standard are as follows.
- the standard name is changed to “National food safety standard - Determination
of fatty acids in foods”;
- ADD the internal standard method and the normalization method;
- MODIFY the chromatographic column in the original standard, changing the glass
column to capillary chromatographic column.
National food safety standard
Determination of fatty acids in foods
1 Scope
This Standard specifies the determination method for the content of fatty acids in foods.
This Standard applies to the determination of total fats, saturated fats (fatty acids) and
unsaturated fats (fatty acids) in foods.
In this Standard, the hydrolysis-extraction method applies to the determination of the
content of fatty acids in foods; the transesterification method applies to the
determination of the content of fatty acids in fat samples with free fatty acid content of
not more than 2 %; the acetyl chloride-methanol method applies to the determination
of the content of fatty acids in milk powder and anhydrous cream samples with water
content less than 5 %.
Method I Internal standard method
2 Principle
2.1 Hydrolysis-extraction method. after the fats in the sample that has added with
internal standard are extracted with hydrolysis-ether solution, saponify and methyl-
esterify the sample under alkaline conditions to produce fatty acid methyl esters. After
analyzed by capillary column gas chromatography, use internal standard method to
quantitatively determine the content of fatty acid methyl esters. According to the
content and conversion coefficients of various fatty acid methyl esters, calculate the
content of total fats, saturated fats (fatty acids), monounsaturated fats (fatty acids) and
polyunsaturated fats (fatty acids).
Animal and vegetable fat samples are directly saponified and fatty-acid-methyl
esterified after adding with internal standard, without fat extraction.
2.2 Transesterification method (applies to fats with free fatty acid content of not more
than 2 %). DISSOLVE fats in isooctane; after adding internal standard, ADD potassium
hydroxide methanol solution to make the sample methyl-esterified through
transesterification. After the reaction is complete, USE sodium sulfate to neutralize the
residual potassium hydroxide to avoid saponification of methyl esters.
3 Reagents and materials
Unless otherwise stated, the reagents used in this method are analytical regents and
the water is the Grade 1 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Hydrochloric acid (HCl).
3.1.2 Ammonia (NH3 · H2O).
3.1.3 Pyrogallic acid (C6H6O3).
3.1.4 Ether (C4H10O).
3.1.5 Petroleum ether. with a boiling range of 30 °C ~ 60 °C.
3.1.6 Ethanol (C2H6O) (95 %).
3.1.7 Methanol (CH3OH). chromatographically pure.
3.1.8 Sodium hydroxide (NaOH).
3.1.9 N-heptane [CH3(CH2)5CH3]. chromatographically pure.
3.1.10 Boron trifluoride methanol solution, with a concentration of 15 %.
3.1.11 Anhydrous sodium sulfate (Na2SO4).
3.1.12 Sodium chloride (NaCl).
3.1.13 Isooctane [(CH3)2CHCH2C(CH3)3]. chromatographically pure.
3.1.14 Sodium bisulfate (NaHSO4).
3.1.15 Potassium hydroxide (KOH).
3.2 Preparation of reagents
3.2.1 Hydrochloric acid solution (8.3 mol/L). WEIGH 250 mL of hydrochloric acid;
DILUTE with 110 mL of water; MIX well. It can be placed for 2 months at room
temperature.
3.2.2 Ether-petroleum ether mixture (1 + 1). TAKE the same volume of ether and
petroleum ether; MIX well for further use.
3.2.3 Sodium hydroxide methanol solution (2 %). TAKE 2 g of sodium hydroxide and
to the walls of the flask are mixed into the solution. After the hydrolysis is complete,
REMOVE the flask and COOL to room temperature.
Acid and alkali hydrolysis method. cheeses. ADD 5 mL of ammonia, MIX well. PLACE
the flask in a water bath at 70 °C to 80 °C to hydrolyze for 20 min. SHAKE the flask
once every 5 min so that the particles adhering to the walls of the flask are mixed into
the solution. Then ADD 10 mL of hydrochloric acid, CONTINUE to hydrolyze for 20
min. SHAKE the flask once every 10 min so that the particles adhering to the walls of
the flask are mixed into the solution. After the hydrolysis is complete, REMOVE the
flask and COOL to room temperature.
5.2.1.3 Fat extraction
ADD 10 mL of 95 % ethanol to the hydrolyzed sample, MIX well. TRANSFER the
hydrolyzate in the flask to a separatory funnel; USE 50 mL of ether petroleum ether
mixture to rinse the flask and stopper; ADD the rinsing solution to the separatory funnel;
COVER the cap. SHAKE for 5 min, STAND for 10 min. COLLECT the ether layer
extract to a 250-mL flask. EXTRACT the hydrolyzate three times according to the
above procedure. Finally, USE ether petroleum ether mixture to rinse the separatory
funnel and COLLECT the rinsing solution in a 250-mL flask. USE rotary evaporator to
concentrate to dryness and the residue is the fat extract.
5.2.1.4 Saponification of fats and methyl esterification of fatty acids
ADD 8 mL of 2 % sodium hydroxide methanol solution in the fat extract; CONNECT to
the reflux condenser; REFLUX in 80 °C ± 1 °C water bath until the oil droplets
disappear. ADD 7 mL of 15 % boron trifluoride methanol solution from the top of t...
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