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GB/T 37493-2019

Chinese Standard: 'GB/T 37493-2019'
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GB/T 37493-2019English99 Add to Cart Days<=3 Inspection of grain and oils -- Determination of soluble sugar in cereals and pules seeds -- Shaffer-Somogyi Valid GB/T 37493-2019
GB/T 37493-2019Chinese15 Add to Cart <=1-day [PDF from Chinese Authority, or Standard Committee, or Publishing House]  

   

BASIC DATA
Standard ID GB/T 37493-2019 (GB/T37493-2019)
Description (Translated English) Inspection of grain and oils--Determination of soluble sugar in cereals and pules seeds--Shaffer-Somogyi
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard C53
Classification of International Standard 67.060
Word Count Estimation 6,611
Date of Issue 2019-05-10
Date of Implementation 2019-12-01
Drafting Organization Agriculture and Rural Department Grain and Product Quality Supervision, Inspection and Testing Center (Harbin)
Administrative Organization National Grain and Oil Standardization Technical Committee (SAC/TC 270)
Proposing organization National Food and Material Reserve Board
Issuing agency(ies) State Administration of Markets and China National Standardization Administration

GB/T 37493-2019
Inspection of grain and oils--Determination of soluble sugar in cereals and pules seeds--Shaffer-Somogyi
ICS 67.060
C53
National Standards of People's Republic of China
Grain and oil inspection. Determination of soluble sugar in grains and beans
Copper reduction-iodometric method
Published on May 10,.2019
2019-12-01 Implementation
State Administration of Market Supervision
Published by China National Standardization Administration
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by the State Food and Material Reserve Bureau.
This standard is under the jurisdiction of the National Grain and Oil Standardization Technical Committee (SAC/TC270).
This standard was drafted. The Grain and Products Quality Supervision, Inspection and Testing Center of the Ministry of Agriculture and Rural Affairs (Harbin).
The main drafters of this standard. Su Ping, Du Yingqiu, Shan Hong, Wang Lekai, Yang Huanchun, Cheng Aihua.
Grain and oil inspection. Determination of soluble sugar in grains and beans
Copper reduction-iodometric method
1 Scope
This standard specifies the principle of copper reduction-iodine content determination method for soluble sugar in grains and beans, reagents, instruments and equipment, sample preparation,
Sample measurement, result calculation and precision.
This standard applies to the determination of soluble sugar in grains and legumes.
The quantitative range of this standard method is 0mg ~ 2.5mg reducing sugar.
2 Normative references
The following documents are essential for the application of this document. For dated references, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
Preparation of GB/T 601 chemical reagent standard titration solution
GB/T 5490 General Rules for Inspection of Grain and Oil
GB/T 6682 Analytical laboratory water specifications and test methods
3 Principle
Soluble sugars in grains and beans are hydrolyzed to reducing sugars and interact with Cu2 in alkaline copper reagents to form cuprous oxide (Cu2O) precipitates.
Lake. Under the acidic conditions of sulfuric acid, cuprous oxide can quantitatively consume the iodine produced by potassium iodate and potassium iodide.The remaining iodine in the solution is thiosulfur
Titrate the sodium standard solution, and use water instead of the sample solution to do the blank titration. Substitute the titration difference between the blank and the sample solution.
The linear equation of the liquid calculates the soluble sugar content in the sample.
4 Reagent
Unless otherwise specified, the reagents used in this method are of analytical grade, and the water is Grade III water specified in GB/T 6682.
4.1 Anhydrous sodium carbonate (Na2CO3).
4.2 Sodium potassium tartrate (KNaC4H4O6 · 4H2O).
4.3 Copper sulfate (CuSO4 · 5H2O).
4.4 Sodium bicarbonate (NaHCO3).
4.5 Potassium iodide (KI).
4.6 Potassium iodate (KIO3).
4.7 absolute ethanol (C2H5OH).
4.8 Potassium oxalate (K2C2O4 · H2O).
4.9 Sulfuric acid (H2SO4).
4.10 Zinc sulfate (ZnSO4 · 7H2O).
4.11 Potassium ferrocyanide ([K4Fe (CN) 6] · 3H2O).
4.12 Hydrochloric acid (HCl).
4.13 Sodium hydroxide (NaOH).
4.14 Sodium thiosulfate (Na2S2O3 · 5H2O).
4.15 Glucose (C6H12O6).
4.16 Soluble starch.
4.17 Methyl red (C15H15O2N3).
4.18 Copper sulfate solution (100g/L). Weigh 10g of copper sulfate (4.3) in water and make up to 100mL.
4.19 Alkaline copper reagent. Weigh 25.0g of anhydrous sodium carbonate (4.1) and 25.0g of sodium potassium tartrate (4.2) in a 1000mL beaker,
It was dissolved in 500 mL of water. 75 mL of copper sulfate solution (4.18) was added below the liquid level through the funnel. Then add 20.0g of sodium bicarbonate
(4.4), after it is completely dissolved, 5.0 g of potassium iodide (4.5) is added, and finally transferred into a 1000 mL volumetric flask. Accurately weigh 0.8917g of iodine
Potassium acid (4.6) (dried at 105 ° C for 2h), dissolved in water, and transferred to the above volumetric flask, made up to volume with water, filtered and used overnight.
4.20 Ethanol solution (41). Measure 800mL of absolute ethanol (4.7) and dilute to 1000mL with water.
4.21 Potassium iodide-potassium oxalate solution. Weigh 2.5g of potassium iodide (4.5) and 2.5g of potassium oxalate (4.8) in water and dilute to 100mL.
Validity period is 7d.
4.22 Sulfuric acid solution (1mol/L). Measure 56mL of sulfuric acid (4.9) and slowly add it to 800mL of water and dilute to 1000mL.
4.23 Zinc sulfate solution (300g/L). Weigh 30g zinc sulfate (4.10) to dissolve in water, and make up to 100mL.
4.24 Potassium ferrocyanide solution (150g/L). Weigh 15g potassium ferrocyanide (4.11) in water and make up to 100mL.
4.25 Hydrochloric acid solution (1 1). Measure 500mL of hydrochloric acid (4.12) and dilute to 1000mL with water.
4.26 Sodium hydroxide solution (1mol/L). Weigh 40.00g of sodium hydroxide (4.13) in a 250mL beaker.
1000mL.
4.27 Sodium thiosulfate standard solution (0.1mol/L). Weigh 26.00g of sodium thiosulfate (4.14) and 0.2g of anhydrous sodium carbonate (4.1) to dissolve
In 1000mL of water, boil slowly for 10min. After cooling, make up to 1000mL with boiling and cooling water. Store in brown bottle, store in low
In warm and dark places, use after calibration according to GB/T 601.
4.28 Sodium thiosulfate standard working solution (0.005mol/L). It is accurately diluted from sodium thiosulfate standard solution (4.27). Active use
Match, valid for 24h.
4.29 Glucose standard solution. Accurately weigh 0.1250g of glucose (4.15) dried at 96 ℃ ± 2 ℃ for 2h.
250mL. This solution is equivalent to 0.5 mg glucose per milliliter.
4.30 Starch indicator. Weigh 1.0g of soluble starch (4.16) in a beaker, add a small amount of cold water to make a paste, add 100mL to boil
Water, then continue to boil, cool it, store in a drip bottle, and store in the refrigerator.
4.31 Methyl red indicator (1g/L). Weigh 0.1g of methyl red (4.17) and dissolve it in absolute ethanol (4.7), and make it to 100mL.
5 Instruments and equipment
5.1 Analytical balance. Sensitivity 0.1mg.
5.2 Experimental grinding.
5.3 Electric hot water bath.
5.4 Basic burette. 25mL.
5.5 Volumetric flask. 100mL.
5.6 Test tube with stopper scale. 50mL.
6 Analysis steps
6.1 Sample preparation
Divide not less than 20g of the test sample that is mixed uniformly, and crush it with an experimental mill (5.2) so that 90% of the sample passes through the hole diameter of 0.425mm
(40 mesh) test sieve, combine the upper and lower sieve, mix thoroughly, save at room temperature for future use.
6.2 Sample processing
Weigh sample (6.1) 1g ~ 5g (accurate to 0.0001g, preferably with soluble sugar at 40mg ~ 80mg) to 100mL volumetric flask
(5.5), add about 80mL of ethanol solution (4.20) and extract in 80 ℃ water bath for 30min, shaking several times during the period. After cooling with ethanol solution
(4.20) Fix volume and filter. Take 50mL of the filtrate in a 100mL evaporating dish and evaporate the ethanol on a 60 ℃ ~ 70 ℃ water bath to 2mL ~
When 3mL, add 1mL each of zinc sulfate solution (4.23) and potassium ferrocyanide solution (4.24), shake well, and then wash into a 50mL volumetric flask
Medium, constant volume, filtration. Take 25mL of the filtrate in a 50mL volumetric flask, add 2.5mL of hydrochloric acid solution (4.25), and hydrolyze in a water bath at 80 ℃
After 10 minutes, add two drops of methyl red indicator (4.31) after cooling, neutralize to neutral with sodium hydroxide solution (4.26), and make up to volume with water.
6.3 Standard curve drawing
Accurately draw 1.00mL, 2.00mL, 3.00mL, 4.00mL, 5.00mL glucose standard solution (4.29) (equivalent to 0.5mg,
1.0mg, 1.5mg, 2.0mg, 2.5mg glucose) in 50mL stoppered test tube (5.6), add water to make up to 5.00mL. Join
5.0mL of basic copper reagent (4.19) was placed in a boiling water bath and heated for 15min. Immediately after taking out, cool it in cold water for 5min, add it along the tube wall
2mL potassium iodide-potassium oxalate solution (4.21), then add 3mL sulfuric acid solution (4.22), immediately shake to completely dissolve the copper oxide (no acid added
Do not shake before). When titrating to a light yellow-green color with sodium thiosulfate standard working solution (4.28), add 6 drops of starch indicator (4.30),
Continue the titration until the blue color disappears as the end point. At the same time, water was used as a blank instead of the glucose standard solution.
Take the mass of standard glucose (mg) as the abscissa, and take the difference between the titration of the blank test and the standard glucose solution as the ordinate.
Quasi-curve.
6.4 Determination of sample
According to the content of soluble sugar in different samples, draw 6.2mL ~ 5.00mL of 6.2 sample treatment solution, add water to make up to 5.00mL.
The operation is as follows from 6.3 "Adding 5.0mL alkaline copper reagent (4.19)", and water is used instead of the sample solution to make a blank. Blank and try
The difference between the sample titration and the standard curve can be used to obtain the sugar content in the sample solution, so as to calculate the soluble sugar content in the sample.
7 Results calculation
The content of soluble sugar in the sample is calculated according to formula (1).
X =
m/100 × 25/50 × V × 100 × (1-H) ×
100 (1)
Where.
X --- the content of soluble sugar in the sample (expressed on a dry basis), the unit is grams per hundred grams (g/100g);
A --- Substitute the difference between the blank and the sample titration into the standard curve to obtain the mass of glucose in the sample solution, the unit is milligram (mg);
m --- sample mass, unit is gram (g);
V --- the volume of sample liquid absorbed during the measurement, the unit is milliliter (mL);
H --- moisture content of the sample, the unit is grams per hundred grams (g/100g).
Take the average of the two measurement results, the calculation results are retained to two decimal places.
When the measurement results do not meet the repeatability requirements, the measurement shall be re-measured according to the provisions of GB/T 5490, and the results shall be calculated.
8 Precision
The absolute difference between two independent determination results obtained under repeatable conditions should not exceed 10% of the arithmetic mean.
Related standard:   GB 12695-2016  GB 14883.10-2016
Related PDF sample:   GB 31604.8-2016  GB 14883.1-2016
   
 
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