Submitted to: Starch/Starke
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 8, 2003
Publication Date: January 1, 2004
Citation: Kim, S., Willett, J.L. 2004. Isolation of amylose from starch solutions by phase separation*. Starch/Starke. 56:29-36. Interpretive Summary: Starch is a low-cost agricultural product that finds wide use in foods and industrial applications. Most starches are comprised of two components, a linear fraction (amylose) and a branched fraction (amylopectin). When starch is dispersed into certain solvents, such as water, the two fractions separate into two phases rather than forming a homogeneous solution. Although starch is widely used, fundamental aspects of this process, called phase separation, are not well understood. We have demonstrated that phase separation can be used to isolate and purify the amylose fraction of the starch in a controllable manner with high yield. This purification method is easier and quicker than other methods used to purify amylose. Purified amylose has properties that for some applications make it preferred to whole starch, and there is much interest in methods of producing it. These results will benefit scientists and technologists who conduct research on fundamental properties of starch or develop new foods or other products using starch.
Technical Abstract: Conventionally, fractionation of the two components of starches, amylopectin and amylose had been achieved by aqueous dispersion or aqueous leaching of granules, and selective retrogradation or alcohol precipitation of one component from starch dispersion. Recently, we found that starch solutions show vertical phase separation when their solutions are stored at a given temperature provided that the concentration of starch and kind of solvent medium are properly chosen. By constructing the phase diagram of starch solution, it is realized that starch solutions behave in the same way as a pseudo-binary system like a synthetic polymer solution, polystrene/poly(butadiene)dioctylphthalate and show UCST (upper critical solution temperature) behavior. In this article, we show that the phase behavior of starch solutions provides us a new method of isolating amylose from starch solutions.