Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 14, 2007
Publication Date: January 5, 2008
Citation: Peterson, S.C., Eller, F.J., Fanta, G.F., Felker, F.C., Shogren, R.L. 2008. Comparison of the effects of critical fluid and reflux-extracted techniques on cornstarch pasting properties. Carbohydrate Polymers. 71(1):74-79. Interpretive Summary: In this work a relatively novel method for extracting 0-99 percent of the natural fat from cornstarch was carried out and compared to an older, more conventional fat extraction technique. The newer method, called critical fluid extraction, uses less toxic chemicals than the older method, and has easily controllable variables that affect the efficiency of the fat extraction. Depending on the amount of natural fat extracted from the cornstarch, the starch is altered so that its thickening properties can be changed quite significantly. Thus, critical fluid extraction is shown to be a very flexible, controlled means of making starch with a variety of thickening properties by manipulating the natural fat content of the starch. This work would impact the food industry, and could bring about the production of starches with a range of thickening properties and use less toxic chemicals in the process.
Technical Abstract: Critical fluid extraction of native lipids from cornstarch using 75/25 (v/v) ethanol/water was carried out, successfully extracting over 99 percent of the native lipid. The percentage of native lipid extracted could be altered by changing the solvent:starch ratio. The pasting profile of a critical fluid-extracted sample differed from one defatted by refluxing with 75/25 (v/v) n-propanol/water although in terms of native lipid content they were nearly identical. Starch samples from which the native lipid had been extracted appeared visually smaller than the control starch, although swelling power was roughly equal for each sample. The percent of soluble starch in the lipid-extracted starches was roughly twice that of the control starch, which was expected since extraction of native lipids reduces the number of helical inclusion complexes within the starch granule and enables more intragranular amylose to be leached out. The lipid-extracted starch granules were denser than the control starch because they had less amylose than the control granules yet the same swelling power. Starch that had been defatted using the reflux method had a high degree of granular adhesion compared to the control and critical fluid-extracted samples, and may explain why retrogradation was inhibited for that sample. This work demonstrates the potential to control the pasting properties of cornstarch via the manipulation of the native lipid content by critical fluid extraction, which is a convenient, scalable, non-toxic process.