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

Explain the dimensions of practice of nutrition care process, The nutrition...

The nutrition care process acknowledges the common dimensions of practice by  the following: Defining a common language that allows nutrition practice to be more measurable,

Explain disease jet lag, Jet Lag   Disturbance of body and environmental...

Jet Lag   Disturbance of body and environmental rhythms resulting from a rapid change in time zones gives rise to jet lag, which is characterized by insomnia, decreased quality

How is the human karyotype usually represented, Can two normal individuals ...

Can two normal individuals of the same species with sexual reproduction have identical genomes and identical karyotypes? How is the human karyotype usually represented? Except

Regeneration and its examples, R E GENER A TIO N - Natural ability...

R E GENER A TIO N - Natural ability of living being to replace worn out parts, to repair damaged parts, to regrow cost off organs & to reform entire body from a small piec

Valvular heart diseases, Valvular heart diseases :  Congenital and acquire...

Valvular heart diseases :  Congenital and acquired valvular heart diseases often require surgical intervention. 1 is well known that conservative surgery by valve repair gives bet

Explain control of oedema in nutritional care, Explain Control of Oedema in...

Explain Control of Oedema in Nutritional Care? Low levels of circulating proteins lead to oedema due to loss of colloidal osmotic pressure to maintain the normal fluid shift me

Explain about the reproduction in fungi, Explain about the Reproduction in ...

Explain about the Reproduction in Fungi? Fungi, we have seen above, reproduce both sexually and asexually. Asexual mode of reproduction include budding, binary fission and more

Most appropiate hypothesis about the origin of life on earth, What is the m...

What is the most accepted hypothesis about the origin of life on earth? How does it compare to the other main hypotheses? The heterotrophic hypothesis is the strongest and most

Nitrogen fixation in soil, what is the process of nitrogen fixation in soil...

what is the process of nitrogen fixation in soil by bacteria

Synthetic conduits, Synthetic Conduits Dacron, Polytetra fluro ethylen...

Synthetic Conduits Dacron, Polytetra fluro ethylene (PTFE) and polyglycolic acid grafts have extremely poor results and are not used any more.

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