GB 5009.9-2023 National food safety standard - Determination of starch in foods
1 Scope
This standard specifies the method for determination of starch in foods.
Methods I and II of this standard is applicable to the determination of starch in foods (excluding meat products). Method III is applicable to the determination of starch in meat products. This standard is not applicable to the determination of starch in foods containing substances that produce reducing sugars (except for maltodextrin and soluble sugars) upon hydrolysis.
Method I - Enzymatic hydrolysis method
2 Principle
After the removal of fat and soluble sugars from the specimen, starch is sequentially enzymolyzed by amylase and further hydrolyzed by hydrochloric acid into glucose. The glucose content is then measured and converted to determine the starch content in the sample.
3 Reagents and materials
Unless otherwise specified, only analytically pure reagents and Grade 3 water specified in GB/T 6682 are used for the purpose of this method.
3.1 Reagents
3.1.1 Iodine (I2).
3.1.2 Potassium iodide (KI).
3.1.3 α-amylase: EC 3.2.1.1, with an enzyme activity ≥1.6 U/mg.
3.1.4 Anhydrous ethanol (C2H5OH) or 95% ethanol.
3.1.5 Petroleum ether: with a boiling range of 60–90°C.
3.1.6 Diethyl ether (C4H10O).
3.1.7 Toluene (C7H8).
3.1.8 Chloroform (CHCl3).
3.1.9 Hydrochloric acid (HCl).
3.1.10 Sodium hydroxide (NaOH).
3.1.11 Copper sulfate (CUSO4·5H2O).
Foreword i
1 Scope
2 Principle
3 Reagents and materials
4 Instruments and apparatus
5 Analytical procedures
6 Expression of analysis results
7 Precision
8 Principle
9 Reagents and materials
10 Instruments and apparatus
11 Analysis procedures
12 Expression of analysis results
13 Precision
14 Principle
15 Reagents and materials
16 Instruments and apparatus
17 Analytical procedures
18 Expression of analysis results
19 Precision
Annex A Conversion relationship between millimoles of sodium thiosulfate and glucose content (m3)
