GB 5009.211-2022 PDF English
US$170.00 · In stock · Download in 9 secondsGB 5009.211-2022: National food safety standard - Determination of folates in food Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedureStatus: Valid GB 5009.211: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB 5009.211-2022 | English | 170 |
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National food safety standard - Determination of folates in food
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| GB 5009.211-2014 | English | 85 |
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National Food Safety Standard -- Determination of folates in food
| Obsolete |
| GB/T 5009.211-2008 | English | 479 |
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Determination of folates in foods
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GB 5009.211-2022: National food safety standard - Determination of folates in food---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/GB5009.211-2022
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Determination of Folates in
Food
Issued on. JUNE 30, 2022
Implemented on. DECEMBER 30, 2022
Issued by. National Health Commission of the People’s Republic of China;
State Administration for Market Regulation.
Table of Contents
Foreword... 3
1 Scope... 4
2 Principle... 4
3 Reagents and Materials... 4
4 Instruments and Equipment... 6
5 Preparation and Stock of Strains... 7
6 Analytical Procedures (all operations must be performed in the dark)... 7
7 Expression of Analytical Results... 10
8 Precision... 12
9 Others... 12
Appendix A Preparation of Culture Medium... 13
Foreword
This Standard serves as a replacement of GB 5009.211-2014 National Food Safety Standard –
Determination of Folates in Food.
In comparison with GB 5009.211-2014, the main changes are as follows.
---the determination method with microplate is added;
---the requirements for precision are modified;
---Appendix A is modified.
National Food Safety Standard - Determination of Folates in
Food
1 Scope
This Standard specifies the methods of determining folates in food.
This Standard is applicable to the determination of folates in food.
2 Principle
Folates is an essential nutrient for the growth of Lactobacillus rhamnosus. Under certain
controlled conditions, inoculate the Lactobacillus rhamnosus bacterial solution into the medium
containing the specimen solution; after culturing for a period of time, determine the light
transmittance (or absorbance value). Within a certain determination range, in accordance with
the standard curve of folates content and light transmittance (or absorbance value), the folates
content in the specimen can be calculated.
3 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are analytically pure; the water
is Grade-2 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Hydrochloric acid (HCl).
3.1.2 Sodium hydroxide (NaOH).
3.1.3 Sodium chloride (NaCl).
3.1.4 Sodium phosphate dodecahydrate (Na3PO4 12H2O).
3.1.5 Disodium hydrogen phosphate heptahydrate (Na2HPO4 7H2O).
3.1.6 L-ascorbic acid (C6H8O6).
3.1.7 Toluene (C7H8).
3.1.8 Anhydrous ethanol (C2H6O).
3.1.9 Lyophilized chicken pancreas powder. containing -glutamyl hydrolase.
3.2.3 Sodium hydroxide ethanol solution (0.01 mol/L). weigh-take 0.4 g of sodium hydroxide;
use 20% ethanol solution to dissolve and reach a constant volume of 1 L; mix it up.
3.2.4 Sodium hydroxide solution (1 mol/L). weigh-take 40 g of sodium hydroxide; add water
to dissolve and reach a constant volume of 1 L; mix it up.
3.2.5 Hydrochloric acid soaking solution. measure-take 100 mL of hydrochloric acid
(concentration. 36% ~ 38%); mix it up with 50 times of water.
3.3 Culture Medium
3.3.1 Agar medium for strain stock. in accordance with A.1, prepare it.
3.4 Reference Substance
Folates reference substance (C19H19N7O6, CAS. 59-30-3). purity 97%, or reference substances
certified by the state and awarded with a reference substance certificate.
3.5 Preparation of Standard Solutions
4 Instruments and Equipment
4.1 Balance. with a division value of 0.1 mg and 1 mg.
4.3 Autoclave.
4.4 Vortex oscillator.
4.5 Centrifuge. 3,000 r/min.
4.6 Inoculating loops and needles.
4.8 Tissue shredder and grinder.
4.9 UV-visible spectrophotometer.
4.10 Ultra-clean workbench.
4.11 Ultrasonic oscillator.
4.12 Microplate reader.
4.13 Centrifuge tube.
4.14 Microplate (sterile).
4.15 Filter membrane (0.22 m).
4.16 Volumetric flask.
5 Preparation and Stock of Strains
5.1 Strains
Lactobacillus rhamnosus (ATCC 7469) or equivalent strains.
5.3 Preparation of Inoculum
One day before the experiment, take 2 mL of the folates standard working solution and mix it
with 4 mL of the medium for folates determination, then, divide it into two test tubes.
6 Analytical Procedures (all operations must be performed in the dark)
6.2 Specimen Extraction
6.2.1 Direct extraction method
When determining the content of folates added in the sample, the direct extraction method can
be adopted.
Accurately weigh-take 0.1 g ~ 2 g of solid specimen or 0.5 mL ~ 2 mL of liquid specimen,
accurate to 0.001 g; transfer it into a conical flask. Add 80 mL of sodium hydroxide ethanol
solution, with a stopper. Perform ultrasonic oscillation for 0.5 h ~ 4 h, until the specimen is
completely dissolved or dispersed, then, transfer it into a 100 mL volumetric flask; use water
to dilute to the scale.
6.2.2 Enzymatic extraction method
The enzymatic extraction method should be adopted for the naturally occurring folates in food
specimens, such as. cereals, potatoes, meat, eggs, dairy, fruits, vegetables, bacteria, algae, beans
and nuts, etc.
6.3 Dilution
In accordance with the folates content in the specimen, use water to appropriately dilute the
specimen extract, so that the folates content in the specimen diluent is within the range of 0.2 ng/mL ~ 0.3 ng/mL.
6.4 Specimen Determination
6.4.1 Test tube method
6.4.1.1 Specimen and enzyme blank series tubes
Take three test tubes; respectively add 1.0 mL, 2.0 mL and 3.0 mL of specimen diluent (Vx);
add water to 5.0 mL; mix it up. Take another three test tubes; adopt the same method to add
enzyme blank solution. For each gradient, perform 2 parallels.
6.4.1.4 Inoculation and culture
After the series tubes used for determination are cooled down to room temperature, under the
conditions of aseptic operation, add 40 L of inoculum to each 10 mL of the medium for folates
determination; mix it up. Add 5 mL of the inoculated medium for folates determination to each
determination tube; mix it up. Place it in a constant-temperature incubator at 36 C 1 C to
culture for 20 h ~ 40 h. When the maximum turbidity is obtained, terminate the culture. Prepare
another standard 0 tube (containing 0.00 ng of folates) that is not inoculated and regard it as the
0 control tube.
6.4.1.5 Determination
Use a vortex oscillator to mix the cultured standard series tubes, specimens and enzyme blank
series tubes. Use a 1 cm cuvette, at 540 nm, adjust the light transmittance to 100% (or the
absorbance value is 0) with the 0 control tube that is not inoculated; successively determine the
light transmittance (or the absorbance value) of the standard series tubes, specimens and
enzyme blank series tubes. If the 0 control tube is turbid, it suggests that it may be contaminated
with bacteria, and the experiment needs to be re-performed.
6.4.2 Microplate method
6.4.2.1 Specimen series tubes
Firstly, under aseptic conditions, use a sterile aqueous filter (0.22 m) to filter and sterilize the
specimen diluent in 6.3.Take three 1.5 mL sterile centrifuge tubes; respectively add 100 L,
200 L and 300 L of the specimen diluent; add sterile water to 500 L. For each gradient,
perform 2 parallels.
6.4.2.2 Standard series tubes
7 Expression of Analytical Results
7.1 Standard Curve
Take the folates content of the standard series tubes as the x-coordinate; take the average value
of light transmittance (or absorbance value) of each standard point as the y-coordinate; draw a
standard curve.
7.2 Result Calculation
From the standard curve, calculate the corresponding content of folates (cx) in the specimens or
the enzyme blank series tubes. If the folates content of two of the three specimen series tubes
is within the range of 0.10 ng ~ 0.80 ng, and the deviation of folates content per milliliter of
specimen extract between the tubes is less than 10%, then, continue the result calculation in
accordance with Formula (1), Formula (2) and Formula (3), otherwise, re-sample and determine it.
8 Precision
For general foods, the absolute difference between two independent determination results
obtained under repeatability conditions must not exceed 15% of the arithmetic mean value. For
nutritional supplements and fortified foods, the absolute difference between two independent
determination results obtained under repeatability conditions must not exceed 10% of the
arithmetic mean value.
9 Others
Test tube method. when the sampling size of fruits and vegetables specimens is 5 g, the
detection limit is 0.2 g/100 g and the quantification limit is 0.4 g/100 g; when the sampling
size of specimens with high protein and starch is 5 g, the detection limit is 1.0 g/100 g and the
quantification limit is 2.0 g/100 g; when the sampling size of nutritional supplements and
fortified foods is 1 g, the detection limit is 0.5 g/100 g and the quantification limit is 1.0 g/100 g.
Microplate method. for samples with folates added, when the sampling size is 1.0 g and the
dilution factor is 1, the detection limit is 0.5 g/100 g and the quantification limit is 1.0 g/100 g.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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