Dextrose equivalent
The dextrose equivalent (DE, for English dextrose equivalent ) of a polysaccharide mixture describes the percentage mass fraction of reducing sugars (calculated as glucose) in the dry substance . It therefore corresponds to the mass of glucose (= dextrose), which would have the same reducing power per 100 g of dry matter . The DE value is a measure of the extent to which the polymer has broken down , which is why products with a low DE value contain a high proportion of polysaccharides and a low content of low molecular weight sugars, while products with a high DE value mainly consist of low molecular weight sugars.
The dextrose equivalent of starch is 0, that of glucose 100. That of maltodextrin is between 3 and 20, depending on the degree of hydrolysis . Products with DE values above 20 are classified as glucose syrups .
With a higher DE value, the following properties increase:
- Sweetness
- solubility
- Hygroscopicity
- Osmolality
- Lowering the freezing point
determination
The determination of the dextrose equivalent according to the European Pharmacopoeia uses the reactions of the Fehling's sample and the method of a titration . The sample solution to be tested is added dropwise with a burette to a Fehling reagent, i.e. to an alkaline solution containing Cu 2+ ions. The reducing sugars contained in the added sample solution convert the Cu 2+ ions to brick-red, solid copper (I) oxide , which is deposited. The first drop of excess sample solution, for which there is no longer an equivalent amount of Cu 2+ ions in the Fehling's reagent, reduces blue methylene blue to a colorless product (leuco form of methylene blue). The redox indicator methylene blue is added to the Fehling's reagent before the start of the titration. At the transition point, there is a color change from blue to colorless. An inversely proportional relationship applies to the evaluation: the higher the consumption of sample solution up to the point of transition, the lower the content of reducing sugars.
literature
- Gerhard Eisenbrand, Peter Schreier (Ed.): Römpp-Lexikon Lebensmittelchemie. 2nd Edition. Thieme, Stuttgart / New York 2006, ISBN 3-13-736602-X .