When starch granules are viewed under the microscope by polarized light they exhibit a phenomenon known as birefringence - the refraction of polarized light by the intact crystalline regions to give a characteristic "Maltese cross" pattern on each granule. The disappearance of these crosses on heating a starch suspension is used to determine gelatinization temperature.
Starch that has been treated with low levels of oxidant to improve whiteness without materially affecting other key properties such as viscosity.
I device to determine the viscosity of a product by determining the amount of flow a product shows during a given amount of time. The product is placed in a try behind a trap door. The door is released and the product is allowed to flow freely for a defined amount of time. The distance traveled is defined as the Bostwick viscosity.
Brabender is the name of the manufacturer [Duisburg, Germany] of the Brabender Amylograph or Viscograph, which was the starch industry's established method for determining the viscosity characteristics of starch as it gelatinizes in water. The instrument is a rotational viscometer that allowed the continuous determination of viscosity as the initial suspension of granular starch is heated, gelatinized to a paste, then cooled under closely controlled conditions. Starch concentration, heating/cooling rates and holding periods at defined temperatures can be varied. The Brabender viscosity of a starch is not an absolute quantity; different instruments can give different results even under the "same" test conditions.
The Broofield Synchro-lectric Viscometer is a portable rotatory instrument where a rotating cylinder or disc known as the "spindle" is immersed in a test liquid and rotated by a synchronous motor. Apparent viscosity is calculated from the scale reading by use of factors that depend on spindle number (size) and roatation speed.
The apparent density of a powder or particulate product. It is the weight of a unit volume of the powder including the pores and inter-particle voids. The bulk density maybe determined on the loose unpacked powder and on the powder after tamping ('packaging') under defined conditions.