Raw starch determination by use of Hydrochloric acid principle accroding to Ewers
Starch is an essential ingredient in human nutrition for the provision of energy. The human digestive process breaks down starch into glucose units with the aid of enzymes. Those glucose molecules circulate in the blood stream as an energy source. Starch products, for example glucose and fructose syrups, are often used to add sweetness to food products like soft drinks, fruit drinks, brewing and alcoholic beverages. Beyond the food industry, further applications exist. Some examples are: Pet food: The high protein content of starch co-products makes them a very good meat substitute for pet food, while native and modified starches are used as binders and thickeners. Paper industry: Starch products are used in paper bags, tissues and packaging paper, corrugating board, and stationery – for, for example, wet end addition, size-press, and surface coating. Pharmaceuticals: Starches are used in pharmaceuticals and make a variety of contributions – from binder to sugarless sweetener – to products as varied as toothpaste, tablets, emulsions, lotions, liquid medicines, and creams. Quality control in those products often requires determination of the starch content. The most accurate method is the determination of the optical rotation.
Measure ISO 10520: 1997 – Starch according to Ewers
The ISO (international organization for standardization) 10520: 1997 regulates the determination of the native starch content by using polarimetry. This standard was introduced by E. Ewers in 1997. It specifies a polarimetric method for the determination of the starch content of native starch, except for starch with high amylose content. The Schmidt + Haensch UniPol as well as the Polartronic V are suitable and reliable instruments for the measurement of the starch content according to the ISO standard. The iPR FR process refractometer by Schmidt + Haensch can also be used to determine the starch content inline.
Polarimeters rely on polarized light. Starch solutions rotate the plane-polarized light and are therefore optically active. Starch is a white, granular, organic chemical that is produced by all green plants. Most commercial starch is made from corn, but wheat, tapioca, rice, and potato are also used.