Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2004
Publication Date: 5/15/2005
Citation: Peterson, S.C. 2005. FREE FATTY ACID AND MONOGLYCERIDE CONTENT OF CORN STARCH SPHEROCRYSTALS. American Chemical Society Abstracts. xx.
Technical Abstract: The formation of spherocrystalline particles in slowly cooled, jet-cooked starch solutions has been well-documented. When corn or rice starch is used, two distinct morphologies of spherocrystal have been observed; one roughly spherical in shape with rough surface texture, and the other disc or torus-shaped, frequently with spiral surface striations. Current literature indicates that spherocrystals are formed when amylose forms a helical inclusion complex (HIC) around a core molecule (in this case, the native lipid contained in the starch). X-ray powder diffraction patterns for the two different spherocrystal morphologies have indicated that the larger, spherical form has seven amylose molecules per turn of the HIC while the smaller, torus-shaped form has only six. It is not clear what factors cause the formation of one morphology over the other, but one hypothesis is that the native starch lipids may play a role. Since the native lipids make up the core of the HIC it is logical to assume that differences in the lipid core molecule may affect the HIC size discrepancy reported for these two morphologies. The lipids forming the core of the HIC are most likely either free fatty acids or monoglycerides since both are linear molecules which would easily facilitate HIC formation. The aim of this paper is to analyze the lipid content of the two different spherocrystal morphologies as well as the native lipid of two different corn starch starting materials (normal food-grade starch and high-amylose corn starch) and compare the differences. Extraction of the lipid from the native starch or spherocrystal was followed by a selective esterification method so that free fatty acids could be discerned from monoglycerides. Once esterified, the lipid samples were analyzed by gas chromatography.