GB 5009.168-2016 PDF English
US$125.00 · In stock · Download in 9 secondsGB 5009.168-2016: National food safety standard - Determination of fatty acids in foods Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedureStatus: Valid GB 5009.168: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB 5009.168-2016 | English | 125 |
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National food safety standard - Determination of fatty acids in foods
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| GB/T 5009.168-2003 | English | 239 |
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Determination of eicosapentaenoic acid and docosahexaenoic acid in foods
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GB 5009.168-2016: National food safety standard - Determination of fatty acids in foods---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GB5009.168-2016
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.
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
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.
3.2 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.
3.3 Standards
3.4 Preparation of standard solutions
3.4.1 Triundecanoin internal standard solution (5.00 mg/mL). accurately WEIGH 2.5 g
(accurate to 0.1 mg) of triundecanoin to a flask; ADD methanol to dissolve; TRANSFER
into a 500-mL volumetric flask; DILUTE with methanol to constant volume. It can be
stored for 1 month when refrigerated in the refrigerator.
3.4.2 Mixed fatty acid methyl ester standard solution. TAKE the appropriate amount of
fatty acid methyl ester to mix with standard; TRANSFER to a 10-mL volumetric flask;
DILUTE with n-heptane to constant volume; STORE in the refrigerator of -10 °C below;
VALID for 3 months.
4 Apparatus and equipment
4.1 Homogenizer or laboratory tissue pulverizer or grinder.
4.2 Gas chromatograph. with a hydrogen flame ion detector (FID).
4.3 Capillary chromatographic column. with polydipyldiphenyl siloxane strong polar
stationary phase, a column length of 100 m, an inner diameter of 0.25 mm and a film
thickness of 0.2 μm.
4.4 Constant temperature water bath. with a temperature range of 40 °C ~ 100 °C,
temperature control ± 1 °C.
4.5 Analytical balance. with a division of 0.1 mg.
4.6 Rotary evaporator.
5 Analysis procedure
5.1 Preparation of samples
During sampling and preparation, it shall avoid sample contamination. Solid or semi-
solid samples are pulverized using a tissue pulverizer or grinder. Liquid samples are
homogenized using a homogenizer, stored at -18 °C or below, and used for analysis
after thawed.
5.2 Pretreatment of samples
5.2.1 Hydrolysis-extraction method
5.2.1.1 Weighing of samples
WEIGH 0.1 g ~ 10 g (accurate to 0.1 mg, containing about 100 mg ~ 200 mg of fats)
of uniform sample into a 250-mL flat-bottom flask; accurately ADD 2.0 mL of
triundecanoin internal standard solution. ADD about 100 mg of pyrogallic acid; ADD
several zeolites;
5.2.1.2 Hydrolysis of samples
Acid hydrolysis method. foods (except dairy products and cheeses). ADD 10 mL of
hydrochloric acid solution, MIX well. PLACE the flask in a water bath at 70 °C to 80 °C
to hydrolyze for 40 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.
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.
5.2.2 Transesterification method
Applies to fat samples with free fatty acid content of not more than 2 %.
5.3 Determination
5.3.1 Chromatographic reference conditions
INJECT the single fatty acid methyl ester standard solution and the fatty acid methyl
ester mixed standard solution INTO the gas chromatograph respectively, and
QUALIFY the chromatographic peaks. The gas chromatogram of the fatty acid methyl
ester mixed standard solution is shown in Annex B.
5.3.2 Determination of samples
6 Expression of analysis results
6.1 Content of single fatty acid methyl ester in the sample
The content of single fatty acid methyl ester in the sample is calculated according to
equation (1).
6.2 Content of saturated fats (fatty acids) in the sample
The content of saturated fats (fatty acids) in the sample is calculated according to
equation (3), and the content of single saturated fatty acids in the sample is calculated
according to equation (4).
6.4 Content of polyunsaturated fats (fatty acids) in the sample
The content of polyunsaturated fats (fatty acids) in the sample (XPoly-Unsaturated Fat) is
calculated according to equation (8), and the content of single polyunsaturated fatty
acid is calculated according to equation (9).
7 Principle
7.1 Hydrolysis-extraction method. after the fats in the sample 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 external standard method to quantitatively determine the content
of fatty acids.
7.2 Acetyl chloride-methanol method (applies to milk powder and anhydrous cream
samples with water content of less than 5 %). acetyl chloride reacts with methanol to
produce hydrochloric acid-methanol and make the fats and free fatty acids methyl
esterified. After extracted with toluene, separately tested with gas chromatography,
and quantify with external standard method.
7.3 Transesterification method (applies to fats with free fatty acid content of not more
than 2 %). DISSOLVE the fat sample in isooctane; ADD potassium hydroxide methanol
solution to make the sample methyl-esterified through transesterification. After the
reaction is complete, NEUTRALIZE the residual potassium hydroxide with sodium
sulfate, and USE external standard method to quantitatively determine the content of
fatty acids.
8 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.
8.1 Reagents
8.1.1 Hydrochloric acid (HCl).
8.1.2 Ammonia (NH3 · H2O).
8.1.3 Pyrogallic acid (C6H6O3).
8.1.4 Ethyl ether (C4H10O).
8.1.5 Petroleum ether. with a boiling range of 30 °C ~ 60 °C.
8.1.6 Ethanol (C2H6O) (95 %).
8.1.7 Methanol (CH3OH). chromatographically pure.
8.1.8 Sodium hydroxide (NaOH).
8.1.14 Toluene (C7H8). chromatographically pure.
8.1.15 Acetyl chloride (C2H3ClO).
8.1.16 Isooctane [(CH3)2CHCH2C(CH3)3]. chromatographically pure.
8.1.17 Sodium bisulfate (NaHSO4).
8.1.18 Potassium hydroxide (KOH).
8.2 Preparation of reagents
8.2.1 Hydrochloric acid solution (8.3 mol/L). the same as 3.2.1.
8.2.2 Ether-petroleum ether mixture (1 + 1). the same as 3.2.2.
8.2.6 Sodium carbonate solution (6 %). WEIGH 6 g of anhydrous sodium carbonate in
a 100-mL flask; ADD water to dissolve; TRANSFER to a 100-mL volumetric flask and
DILUTE with water to constant weight.
8.2.7 Potassium hydroxide methanol solution (2 mol/L). the same as 3.2.5.
8.3 Standards
8.4 Preparation of standard solutions
8.4.1 Single fatty acid methyl ester standard solution. the same as 3.4.3.
9 Apparatus and equipment
9.1 Homogenizer or laboratory tissue pulverizer or grinder.
9.2 Gas chromatograph. with a hydrogen flame ion detector (FID).
9.4 Constant temperature water bath. with a temperature range of 40 °C ~ 100 °C,
temperature control ± 1 °C.
9.5 Analytical balance. with a division of 0.1 mg.
9.6 Centrifuge. with a speed ≥ 5000r/min.
9.7 Rotary evaporator.
9.8 Screw glass tube (with a screw cap with inner lining made of PTFE). 15 mL.
9.9 Centrifuge tube. 50 mL.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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