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)
