ISO/TC 93 - Starch (including derivatives and by-products)

ISO 5379:2013 specifies two methods (an acidimetric method and a nephelometric method) for the determination of the sulfur dioxide content of starches and derived products.

ISO 10504:2013 describes a high-performance liquid chromatographic (HPLC) method for measuring the composition of dextrose solutions, glucose syrups, fructose-containing syrups, hydrogenated glucose syrups, sorbitol, mannitol and maltitol. The constituents are mainly glucose, maltose, maltotriose, fructose, sorbitol, mannitol, maltitol and malto-oligosaccharides. The use of a column packed with cation-exchange resin is essential.

Gives a method for the determination of the moisture content of native or modified starch using oven-drying at 130 °C under atmospheric pressure.

Applies to modified starch, both granular and soluble in cold water. The methods specified enable to measure total and free acetyl contents; bound acetyl content is calculated as the difference of the two values. Total content is determined by heating the sample with dilute hydrochloric acid and converting the acetate with adenosine-5-triphosphate (ATP) and coenzyme A (CoA) to acetyl-CoA. The methods are suitable for determining acetyl contents up to 2 % (m/m).

Reaction of a solution of iodine, sulphur dioxide, pyridine and 2-methoxyethanol with the water contained in the product dispersed previously in a mixture of methanol and formamide. The method described in ISO 760 is improved by determing the content directly using the special solvent.

Destruction of the organic substances by digestion with a sulpho-nitric mixture and conversion of phosphates to orthophosphates. Formation of a phosphomolybdate. Measurement of the intensity of the blue colour at a wavelength of 825 nm. The method applies to contents up to 5 % (m/m).

A solution or suspension of the sample is titrated with a standard volumetric silver nitrate solution. The method is not applied to cationic starches and amyloids soluble when cold.

Incineration of a test portion, in the presence of sulphuric acid, at a temperature of 525 25 °C. The result is expressed as a percentage by mass either of the product as received or on dry basis.

Determination on an undiluted product, at a specified temperature; calculation of the wanted content by means of tables showing the index as a function of composition, concentration and temperature. The method is also applicable to syrup containing fructose.

Titration of a prescribed volume of mixed Fehling's solution with a solution of a test portion under specified conditions, using methylene blue as internal indicator. An informative annex provides a metod for testing standard reference anhydrous D-glucose, necessary for the procedure.

Incineration of a test portion at a temperature of 900 °C, until complete disappearance of the carbon in the residue. The method specifies a procedure for the evaluation of natural and added mineral substances together. It applies to contents up to 2 %. It does not apply to hydrolysis products nor to oxidized starches, nor to other products containing more than 0,2 % of chloride. In other cases, see ISO 5809.

The method consists in drying of a test portion, diluted with water and mixed with kieselguhr at 70 °C and at a pressure not exceeding 34 mbar. It is applicable to syrups irrespective of their method of production, also to dried syrup, starch sugar and syrup containing fructose.

The method is applicable to the anhydrous product and to the monohydrat. It consists in drying of a test portion at 100 °C and a pressure not exceeding 135 mbar.

The found value only includes free amino acids, compounds producing amino acids on hydrolysis and ammonium compounds. The principle consists in destruction of organic matter by sulphuric acid in the presence of a compound catalyst (see ISO 1871), alkalization of the reaction products, distillation of the liberated ammonia and collection in a boric acid solution, followed by titration with a standard volumetric sulphuric acid solution. The method applies to contents greater than 0,01 % (m/m). For products with contents less than 0,025 % (m/m), see ISO 5378.

Destruction of organic matter by sulphuric acid in the presence of a compound catalyst (see ISO 1871), alkalization of the reaction products, destillation of the liberated ammonia and collection in a sulphuric acid solution, followed by measuring of the ammonium salt formed after the addition of Nessler reagent. The method is provided for contents less than 0,025 % (m/m). For greater contents, see ISO 3188.

Hydrolysis of the product by boiling hydrochloric acid, and coagulation of the insoluble products by cooling. Separation by filtration, drying and isolation the wanted matter by solvent extraction. The method applies to contents less than 1,5 % (m/m).

Entrainment in a current of nitrogen of the gas extracted from the acidified and heated product, and fixing and oxidation of the gas by bubbling through a dilute solution of neutral hydrogen peroxid. Titration of the sulphuric acid formed with standard volumetric sodium hydroxide solution of nephelometric determination in the case of low contents.