The degree of hydrolysis of the starch, whether by acid or enzyme or a combination of the two, governs the composition of the final product. Complete or 100% hydrolysis of starch gives dextrose, and starch and dextrose are thus the two extremes of the range. The DE scale is therefore related to these two products. Starch has undergone 0% hydrolysis and is thus given a nominal value of 0 DE whilst dextrose, the ultimate hydrolysis product, is given a value of 100 DE. Intermediate values represent the gradual degradation or breakdown of the starch first into large glucose polymers of 20-30 units in size then into much smaller products of 20 units and below. Depending on its DE, a glucose syrup will therefore contain a greater or lesser percentage of high and low molecular weight glucose polymers and it is the percentage of the individual saccharides in a syrup which gives that syrup its unique properties and which differentiates one syrup from another.
Unfortunately it is not simply a matter of determining the DE of a glucose syrup to deduce its properties, as it is possible using different hydrolysis techniques to produce two (or even three) syrups of the same DE with different carbohydrate composition and thus different properties.
Whilst the scale of DE covers the range from 0 to 100 not all these products are considered as glucose syrups industrially. From 3-20 DE, the products are described as maltodextrins, from 20 to about 75 DE as glucose syrups and above about 75 DE as hydrolysates.
Traditional hydrolysis products from 3-45 DE are generally available as spray dried powders and from 30-95 DE as syrups. Products from 30-45 DE are available in both forms.
It is interesting to note, however, the appearance on the market of spray dried hydrolysates of about 95 DE which traditionally were only available in syrup form. Although industrially glucose syrups are manufactured and sold at a specific DE it is not usually possible for a manufacturer to produce a syrup of the same DE on every occasion. Where for example a 42 DE syrup is specified, the actual manufacturing tolerances are typically 41-44 DE. This is of no great consequence to the user of the syrup since there is very little practical difference in properties over this narrow range.