Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2000
Publication Date: N/A
Interpretive Summary: Treatment of a mixture of oil, water, and starch with high pressure steam, using a commercial technique known as steam jet cooking, yields a uniform dispersion of microscopic oil droplets suspended in a water solution of starch. Products of this type have been given the trademark Fantesk**TM by the USDA. The oil component of these mixtures does not coalesce because of a thin layer of starch that surrounds each oil droplet. When paraffin wax was used as the oil component we were able to isolate solidified droplets of starch-coated paraffin wax, determine the amount of surface starch, and examine the starch coatings in detail to discover what factors are responsible for their formation. These basic studies will enable us to tailor Fantesk products for end-use applications in foods, cosmetics, lubricants, and drug delivery.
Technical Abstract: Starch-paraffin wax compositions were prepared by passing aqueous mixtures of cornstarch and paraffin wax through a steam jet cooker. Solidified droplets of starch-coated paraffin wax were isolated from the surface by dilution of jet cooked dispersions with excess water followed by centrifugation. Weight percent interfacial starch in isolated wax droplets varied from about 3-8%, depending upon whether waxy, normal, or high amylose starch was used and whether jet-cooked dispersions were diluted with hot or cold water prior to centrifugation. The effects of small amounts of lipid (normally present in cereal starches) on weight percent interfacial starch was determined by examining products prepared from starch that was solvent extracted to remove the lipid component. Extraction of lipid from normal cornstarch produced a product having a lower percentage of interfacial starch than a comparable product prepared from unextracted starch. The morphology of the starch layer as observed by SEM was also affected by the presence or absence of lipid in the starting starch. The amylose component of cornstarch was preferentially adsorbed at the paraffin/water interface when lipid was present, suggesting that lipid enhances the surface activity of amylose through the formation of helical inclusion complexes. X-ray diffraction patterns of interfacial starch were consistent with this interpretation. Nitrogen analyses suggested that proteins present in commercial cornstarch may also adsorb along with starch at the paraffin/water interface.