Food | Dry Matter In Syrup
The dry matter in corn syrups, that have different contents of glucose (dextrose), fructose and maltose, can easily be determined by refractive index measurement, which is described in the reference standards ISO1743:1982 and ISI 06.
Corn syrup can be produced by hydrolysis of corn starch and is often an ingredient of bakery products, confectioneries, ice creams and table syrups.
For syrup production, big corn starch molecules (polysaccharides) are degraded into smaller sugars (oligosaccharides, disaccharides) and reducing sugars (monosaccharides, e.g. glucose and/or fructose) by hydrolyzation. This can be done either enzymatically or by hydrolysis with acid.
Acid conversion (AC)
During the process of acid conversion, e.g. hydrochloric acid (HCl) is added to the starch slurry before it is heated to speed up the hydrolysis. This process is limited to the production of smaller sugars and reducing sugars. In case of using HCl, its content in an aqueous solution can be also checked by using Anton Paar Abbemat refractometers.
Dual conversion (DC)
Corn syrup uses both enzymes (e.g. glucoamylase) and acid for liquefaction to break down more starch than acid conversion (hydrolysis). The dual conversion can be used to produce syrups with only 3 % of remaining starch.
There are many different kinds of syrups available and each of these can be characterized by their sugar composition, as well as their production process. For solutions made from corn starch, dextrose equivalents (DE) is an estimate of the percentage of reducing sugars (glucose and intermediates) in the syrup. Starch and sucrose have a DE of zero, whereas the final end product of hydrolysis has a DE of 100. This means a standard corn syrup with 42 DE contains 42 % reducing sugars in the total dry mass (g/100 g). Sweeter syrups containing more reducing sugars in the range of 70 DE and up to 97 DE.
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