Starch enzyme-susceptible

Radiation radiation, depending on wavelength and dose, has been shown to have a variety of effects, including increased gelatinization temperature, improved stability and reduced viscosity, swelling power and enzyme susceptibility. Radiation has also been used to promote chemical modification. Marquette et al.118 have a patent for microwaving starch to improve rheological stability and hot water dispersibility. They... 

The complexation of starch and thin-boiled starches with alkyl and aryl sulfonates gives a product that is readily soluble in warm water. This complexation also decreases the temperature of maximum swelling. Enzymic susceptibility is decreased and retrogradation is impeded.780... 

Sullivan JW, Johnson JA (1964) Measurement of starch gelatirrization by enzyme susceptibility. Cereal Chem 41 73-77... 

Srichuwong, S., Isono, N., Mishima, T., Hisamatsu, M. (2005). Structure of linterized starch is related to X-ray diffraction pattern and susceptibility to acid and enzyme hydrolysis of starch granules. Int. J. Biol Macromol, 57,115-121. 

Starch Liquefaction. Starch in its natural state is only degraded slowly by CC-amylases. To make the starch susceptible to enzymatic breakdown, it is necessary to gelatinize and liquefy a slurry with a 30—40% dry matter content. Gelatinization temperature depends on the type of starch (67) com is the most common source of industrial starches followed by wheat, tapioca, and potatoes. Liquefaction is achieved by adding a heat-stable a-amylase to the starch slurry. The equipment used for liquefaction may be stirred tank reactors, continuous stirred tank reactors (CSTR), or a jet cooker. Most starch processing plants liquefy the starch with a single enzyme dose in a process using a jet cooker (Fig. 9). 

Immobilized cellulase and amylase are able to hydrolyze cellulose and starch. However, the immobilized enzymes possess only about 1-6% of the activity of the soluble forms. In addition, immobilization clearly enhanced the thermal stability of amylase. Immobilized amylase retained more than half of its activity, even after incubation at 125°C. By comparison, soluble amylase was almost completely inactivated under these conditions. Furthermore, kinetics modeling indicates that the susceptibility to product inhibition is dependent on the amylase source. Finally, immobilization can reduce the susceptibility to product inhibition fQ was less for each of the immobilized forms, compared with their soluble counterparts. 

The porous internal structures of A-type starch granules agree with known features for example, A-type starches exhibit faster chemical penetration and derivatization reactions,325 have weak points, are more susceptible to enzyme-catalyzed hydrolysis,38... 

This review has shown that most studies on barley starches have been focused on understanding the fine structures, particle size distribution, chemical composition, gelatinization properties and susceptibility towards enzyme hydrolysis. However, there is a dearth of information on the rheological and retrogradation characteristics of barley starches from different cultivars. Furthermore, the response of small and large barley starch granules towards physical and chemical modification needs investigation. Research in the above areas is underway in our laboratories. It is hoped that this study may improve the utilization of different types of barley starches for specific products within the food and paper industry. 

---