Define starch retrogradation, Biology

Assignment Help:

Starch Retrogradation

The starch paste or solution obtained after the gelatinisation is not stable and generally produces a viscoelastic, firm  and rigid gel. Structural transformation occurs during storage. As starch pastes are cooled and stored, the starch becomes progressively less soluble. In dilute solution, starch molecules will precipitate, with the insoluble material being  difficult to redissolve by heating.  The collective processes of dissolved starch becoming less soluble  are called retrogradation.

Retrogradation of cooked starch involves constituent polymers, amylose and amylopectin, with amylose undergoing retrogradation at a much more rapid rate than does amylopectin. Upon cooling, the dispersed starch polysaccharides re-associate. Concentrated amylose solutions rapidly  gel on cooling to room temperature. Subsequently, some of the amylose molecules slowly crystallize. The gel can only be melted at 160°C. The amylopectin with gelatinized granules can also crystallize but this association can be reversed by heating to 70°C. Thus after retrogradation of a starch-water mixture, a partially crystalline polymer system is again obtained.   

 


Related Discussions:- Define starch retrogradation

Briefly explain about the sit-ups test, Briefly explain about the Sit-ups T...

Briefly explain about the Sit-ups Test? To measure muscular endurance, bent knee sit-ups can be done. Sit-ups begin with the subject lying flat on their backs with their knees

What is absorption, What is absorption?   Absorption involves  the  tr...

What is absorption?   Absorption involves  the  transfer of materials  through  the mucosa of the  alimentary tract  into blood and lymph vessels.

#title a&p, list all of the parts of a generalized cell that might be invol...

list all of the parts of a generalized cell that might be involved support movement coordination respiration digestion transportation excr production making proteins and reproducti

What are the capillaries of the vascular system, What are the capillaries o...

What are the capillaries of the vascular system? Capillaries are small blood vessels that perform exchange of substances among the blood and the body tissues. Capillaries are n

Explain antioxidants, Antioxidants  Antioxidants are the substances tha...

Antioxidants  Antioxidants are the substances that can delay onset, or  slow the rate of oxidation of autoxidizable materials. By virtue of this property,  they provide protect

Explain the energy - releasing metabolic process, The energy - releasing me...

The energy - releasing metabolic process in which substrate is oxidised without an external electron acceptor is known as: 1. Glycolysis 2. Fermentation 3. Aerobic respira

How cad patients response in hypertenstion, Q. How CAD Patients Response in...

Q. How CAD Patients Response in Hypertenstion? An exercise rise in systolic blood pressure (over 200 mm Hg) has been used as a reason to terminate exercise in some centers. She

Safety measures in drug administration, introduction of safety measures of ...

introduction of safety measures of drug administration

Explains the definition of semi-conservative, Meselson and Stahl demonstrat...

Meselson and Stahl demonstrated that DNA replication is a semi-conservative process. Which of the following best explains the definition of "semi-conservative"? A. The two stra

Glycogen degradation and glycogen synthesis , If glycogen degradation  and...

If glycogen degradation  and glycogen synthesis were allowed to occur concurrently,  the  net  effect  would  be  hydrolysis  of  UTP,  a  so-called  futile  cycle. To stop this, b

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd