Starch melting

Lai and Kokini, (1991) also measured the effect of high pressure on starch melting. The characteristic temperatures were increased—as would be expected for a process involving a net increase in polymer volume. Two separate enthalpy peaks were observed, possibly due to A- and B-type starches. 

It is well known that every starch processing method is facilitated by the presence of water. Water depresses the melting point of amylopectin crystallites and lowers starch melt viscosity. Native potato starch contains about 18% water when stored at ambient atmosphere (room humidity about 55%). If one does not add more than about 10% water the melt-processed starch will solidify when cooling down. If more water is added to the starch, its glass transition falls below room temperature (Zeleznak Moseney, 1987). The moulding then exhibits a rubbery state and solidifies later when the excess water evaporates. 

RS. Buehler, J. Casanova, H. Ernst, and H.-J. Schultze, Process and apparatus for producing starch melt and products obtainable by this process, US Patent 5316578, assigned to Ems-Inventa AG (CH), May 31,1994. 

WUlett J.L., MUlard M.M., Jasberg B.K., Extrusion of waxy maize starch Melt rheology and molecular weight degradation of amylopectin. Polymer, 38,1997, 5983-5989. 

In general form, it is considered that plasticized starch melt has a shear-fliinning behavior, which can be expressed in the power-law equation ... 

Starch has been illustrated by the fact that Nodax improves a range of PLA properties (ductibility, high temperature hydrolytic stability, and heat sealability) and of starch processing characteristics (Nodax can lower starch melt temperature, improve starch UV and light stability, clarity) and in both cases improves barriers properties (49,50]. 

Igura, N., Katoh, T., Hayakawa, I. and Fujio, Y. (2001) Degradation profiles of potato starch melts through a capillary tube viscometer. Starch/Starice, 53, 623-8. 

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