Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 9/17/1998
Publication Date: N/A
Technical Abstract: Investigation of the basis for the unusual stability of starch-oil composites produced by co-jet cooking led to the discovery of the formation of thin, stable starch coatings surrounding the oil droplets. Starting with the basic example of cornstarch co-jet cooked with soybean oil, a protocol for isolating and viewing the starch coatings by dilution, centrifugation, washing, ethanol precipitation, and critical point drying was developed. Intact and broken spheres of starch could be seen in the preparations by scanning electron microscopy, the oil having been extracted with ethanol. Analysis of the oil-rich water-miscible supernatant and the precipitated starch confirmed the origin and composition of the precipitate. Differences in shell thickness and texture were observed among various dilution techniques, types of starch or other polymers used, and types of lipid phase. Starch sphere formation was observed over a wide range of conditions and concentrations. Scanning EM images confirmed preliminary observations of starch coatings on lipid droplets by light microscopy. Ratios of lipid droplet volume to mass of adhering starch are proposed to contribute largely to the observed behavior of jet-cooked starch-oil composites.