GB 5009.227-2023 PDF in English
GB 5009.227-2023 (GB5009.227-2023) PDF English
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| GB 5009.227-2023 | English | 155 |
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National food safety standard - Determination of peroxide value in foods
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| GB 5009.227-2016 | English | 75 |
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Method for analysis of hygienic standard of edible oils
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Standards related to (historical): GB 5009.227-2023
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GB 5009.227-2023: PDF in English GB 5009.227-2023
GB
NATIONAL STANDARD OF THE
PEOPLE'S REPUBLIC OF CHINA
National food safety standard - Determination of peroxide
value in food
ISSUED ON: SEPTEMBER 6, 2023
IMPLEMENTED ON: MARCH 6, 2024
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
Method A - Indicator titration method ... 4
2 Principle ... 4
3 Reagents and materials ... 4
4 Instruments and equipment ... 6
5 Analysis steps ... 6
6 Presentation of analysis results ... 8
7 Precision ... 10
Method B - Potentiometric titration ... 10
8 Principle ... 10
9 Reagents and materials ... 10
10 Instruments and equipment ... 11
11 Analysis steps ... 11
12 Presentation of analysis results ... 12
13 Precision ... 12
National food safety standard - Determination of peroxide
value in food
1 Scope
This standard specifies the method for the determination of peroxide value in food.
Method A is suitable for the determination of peroxide value in food.
Method B is suitable for the determination of peroxide value in edible animal and
vegetable oils, fats, and margarine.
Method A - Indicator titration method
2 Principle
The prepared oil and fat sample is dissolved in chloroform-glacial acetic acid solution,
the peroxide reacts with potassium iodide to generate iodine, and the precipitated iodine
is titrated with sodium thiosulfate standard titration solution. The amount of peroxide
value is expressed as the mass fraction of peroxide equivalent to iodine or the number
of millimoles of active oxygen in 1 kg of the sample.
3 Reagents and materials
Unless otherwise stated, the reagents used in this method are of analytical grade, and
the water is the third-grade water specified in GB/T 6682.
3.1 Reagents
3.1.1 Glacial acetic acid (CH3COOH).
3.1.2 Trichloromethane (CHCl3).
3.1.3 Potassium iodide (KI).
3.1.4 Petroleum ether: The boiling range is 30 ℃~60 ℃.
Confirmation of petroleum ether: Take 100 mL of petroleum ether in a rotary
evaporation bottle, and evaporate to dryness under reduced pressure by using a rotary
evaporator in a water bath not higher than 40 °C. Wash the rotary evaporation bottle
several times with 30 mL of chloroform-glacial acetic acid solution, and combine the
washing liquid into a 250 mL iodine flask. Accurately add 1.00 mL of saturated
potassium iodide solution, plug the bottle cap tightly, and shake gently for 0.5 min.
Leave it in a dark place for 3 min, add 1.0 mL of starch indicator, and mix well. If no
blue color appears, this petroleum ether can be used for the sample preparation; If a
blue color appears after adding 1.0 mL of starch indicator and mixing, the reagent needs
to be replaced.
3.1.5 Anhydrous sodium sulfate (Na2SO4).
3.1.6 Soluble starch.
3.1.7 Acetone (CH3COCH3).
3.1.8 Amylase (CAS number: 9000-92-4): The enzyme activity is ≥2000 U/g.
3.1.9 Papain (CAS number: 9001-73-4): The enzyme activity is ≥6000 U/mg.
3.1.10 Sodium thiosulfate (Na2S2O3 • 5H2O).
3.2 Reagent preparation
3.2.1 Chloroform-glacial acetic acid solution (2+3): Mix trichloromethane and glacial
acetic acid in a volume ratio of 2:3.
3.2.2 Starch indicator (10 g/L): Weigh 1 g of soluble starch, add about 5 mL of water to
make it into a paste, add 95 mL of boiling water to the paste while stirring, boil for 1 to
2 minutes, and cool. Prepare the indicator fresh just before use.
3.2.3 Saturated solution of potassium iodide: Weigh about 16 g of potassium iodide,
add 10 mL of newly boiled and cooled water, shake well, store in a brown bottle, cap
the bottle, and store in a dark place for later use. Ensure that there are saturated
potassium iodide crystals in the solution. If the blank volume requirement in 5.2 is
exceeded, it shall be prepared again.
3.3 Preparation of standard solution
3.3.1 Sodium thiosulfate standard titration solution (0.1 mo1/L): It shall be prepared
and calibrated in accordance with the requirements of GB/T 5009.1; or a standard
titration solution with national certification and a Reference Material Certificate.
3.3.2 Sodium thiosulfate standard titration solution (0.01 mo1/L): It is prepared from
diluting 0.1 mo1/L sodium thiosulfate standard titration solution with newly boiled and
cooled water. Prepare the solution fresh just before use.
3.3.3 Sodium thiosulfate standard titration solution (0.002 mo1/L): It is prepared from
diluting 0.01 mo1/L sodium thiosulfate standard titration solution with newly boiled
5.1.2.2 Margarine
Place the sample in a closed container, heat it in an electric constant-temperature drying
oven at 60 °C to 70 °C until it melts, shake and mix, continue heating until the
emulsification breaks down into layers, and filter the oil layer through the rapid
qualitative filter paper into a beaker. The filtrate in the beaker is the sample to be tested,
and the sample to be tested shall be clarified. Take a sample and measure it immediately
while the sample to be tested is in a liquid state.
5.1.2.3 Non-dairy cream
Take a representative sample in a beaker, add about 5 times the sample volume of
petroleum ether, and stir for 2 minutes by using an overhead stirrer to mix evenly. While
stirring, add anhydrous sodium sulfate of about 1.6 times the mass of the sample,
continue stirring and mixing for 5 minutes, remove the beaker, and let the solution stand
for 5 minutes to allow the petroleum ether to layer (if emulsification occurs, cover the
top of the beaker with a layer of plastic wrap, and place the beaker in a water bath of
not higher than 40 °C for 10 minutes to stratify the petroleum ether). Pour out the
supernatant, add about 2 times the sample volume of petroleum ether to the beaker, and
repeat the above stirring and standing operations; combine the petroleum ethers, filter,
and transfer the filtrate into a brown rotary evaporation bottle; in a water bath of not
higher than 40 ℃, use a rotary evaporator to evaporate the petroleum ether to dryness
under reduced pressure. The residue is the sample to be tested, and the extraction
amount is not less than 5 g.
5.1.2.4 Powder oil products
Weigh a representative sample into a brown iodine flask, and add 0.02 g of papain and
0.02 g of amylase for every 1 g of the sample. Add 2 times the sample volume of water,
mix well, and cap the bottle. Place the iodine flask in a 50 °C constant-temperature
water bath oscillator, oscillate 60 times/min to 100 times/min for 30 minutes, take it out,
and cool it. Add acetone of the same volume as water and mix. Add 3 times the sample
volume of petroleum ether and shake to extract for 1 minute; transfer it to a separatory
funnel, let it stand for 30 minutes to separate layers, and discard the lower layer. If
emulsification occurs, the layers can be separated by a high-speed refrigerated
centrifuge (5000 r/min, 15 °C, 3 min), and then the organic phase can be transferred to
a separatory funnel. Add water of the same volume as petroleum ether to wash the
organic phase, discard the lower layer, and transfer the upper organic phase to a funnel
containing anhydrous sodium sulfate for filtration. Transfer the filtrate into a brown
rotary evaporation bottle, and use a rotary evaporator to evaporate the petroleum ether
to dryness under reduced pressure in a water bath of not higher than 40 °C. The residue
is the sample to be tested, and the extraction amount is not less than 5 g.
NOTE: For wall material samples containing only protein, only papain can be added; for wall material
samples containing only carbohydrates, only amylase can be added.
5.1.3 Plant foods and their products (made by frying, puffing, baking, preparing,
stir-frying, steaming, and other processing techniques) and animal food products
(made by quick freezing, drying, pickling, frying, and other processing techniques)
Take out the edible part of the representative sample from all the samples taken, and
remove the oil-free part. Quick-frozen prepared meat samples containing more moisture
can be prepared after draining the water with gauze. Crush and mix the sample
thoroughly, place it in a wide-mouth bottle, add 2 to 3 times the sample volume of
petroleum ether, shake well, mix thoroughly, seal, and let it stand and extract for more
than 12 hours; ultrasonic treatment for 5 to 10 minutes if necessary. Filter through a
funnel containing anhydrous sodium sulfate, take the filtrate, and use a rotary
evaporator to evaporate the petroleum ether to dryness under reduced pressure in a
water bath of not higher than 40 °C. The residue is the sample to be tested, and the
extraction amount is not less than 5 g.
5.2 Sample determination
Sample determination shall be avoided under direct sunlight. Weigh 2 g~3 g of the
prepared sample (accurate to 0.001 g), place it in a 250 mL iodine flask, add 30 mL of
chloroform-glacial acetic acid solution, and shake the sample gently until it is
completely dissolved. Accurately add 1.00 mL of saturated potassium iodide solution,
plug the bottle cap tightly, shake gently for 0.5 min, and place in a dark place for 3 min.
Take out and add 100 mL of water, shake well and immediately use sodium thiosulfate
standard titration solution (when the estimated peroxide value is 0.15 g/100 g and below,
use 0.002 mol/L standard titration solution; when the estimated peroxide value is greater
than 0.15 g/100 g, use 0.01 mol/L standard titration solution) to titrate the precipitated
iodine. When the solution turns to light yellow, add 1 mL of starch indicator, continue
titrating, and shake vigorously until the blue color of the solution disappears, that is the
end point. A blank test is carried out at the same time. The volume V0 of sodium
thiosulfate standard titration solution consumed in the blank test shall not exceed 0.1
mL.
6 Presentation of analysis results
6.1 When the peroxide value is expressed as the mass fraction of peroxide equivalent
to iodine, it is calculated according to formula (1).
where:
X1 -- peroxide value, the unit is grams per hundred grams (g/100 g);
The preparation is the same as 3.3.
10 Instruments and equipment
10.1 Balance: The sensitivities are 0.01 g, 0.001 g, and 0.0001 g, respectively.
10.2 Electric constant-temperature drying oven.
10.3 Potentiometric titrator: The accuracy is ±2 mV.
10.4 Magnetic stirrer.
NOTE: All vessels used in this method must not contain reducing or oxidizing substances. The ground
glass surface must not be coated with oil.
11 Analysis steps
11.1 Sample preparation
The preparation is the same as 5.1.1 and 5.1.2.2.
11.2 Sample determination
Weigh 5 g of the prepared sample (accurate to 0.001 g) and place it into the titration
cup of the potentiometric titrator, add 50 mL of isooctane-glacial acetic acid solution,
and shake gently to completely dissolve the sample. If the solubility of the sample is
poor (such as stearin or animal fat), first add 20 mL of isooctane to the titration cup,
shake gently to dissolve the sample, then add 30 mL of glacial acetic acid, and mix well.
Accurately add 1.00 mL of saturated potassium iodide solution to the titration cup, start
the magnetic stirrer, and react at a suitable stirring speed for 60 s±1 s. Immediately add
30 mL~100 mL water to the titration cup, insert the electrode and titration head, set the
titration parameters, run the titration program, perform the titration, and observe the
titration curve and potential changes. The added amount of sodium thiosulfate standard
titration solution is generally controlled at 0.05 mL/drop~0.2 mL/drop. After reaching
the titration end point, record the volume of standard solution consumed at the titration
end point. After the titration of a sample is completed, the stirrer or stirring magnet,
titration head, and electrode need to be immersed in isooctane to clean the oils and fats
on the surface.
A blank test is performed at the same time. Carry out titration and observe the titration
curve and potential changes. The added amount of sodium thiosulfate standard titration
solution is generally controlled at 0.005 mL/drop. After reaching the titration end point,
record the volume V0 of the standard solution consumed at the titration end point. The
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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