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Effects of Heat Treatment and Moisture Contents on Interactions Between Lauric Acid and Starch Granules
F. CHANG (1), Q. Huang (1), X. He (1), J. l. Jane (2). (1) South China University of Technology, Guangzhou, China; (2) Iowa State University, Ames, IA, U.S.A.

Lipids are commonly added to starchy food products to improve the texture and reduce the glycemic response. Effects of amylose chain length and lipid structures on the physicochemical properties of amylose-lipid complex have been extensively studied. Most lipids, however, are not evenly dispersed in the aqueous phase and when mixed with granular starches they cannot penetrate into starch granules to complex with amylose in the granules. The objective of this study was to develop methods to enhance the complex formation between the lauric acid (LA) and the normal cornstarch (NC) granules. We hypothesized that modulating the moisture contents (10, 20, 30, 40, and 50%) of the NC and adding the LA before or after a hydrothermal treatment of the NC at 80 °C could produce different contents of slowly digestible- and resistant-starch. After the hydrothermal/LA treatments, the starch pasting temperature increased, the peak viscosity decreased, and starch gelatinization was suppressed, resulting from the amylose-LA complex formation. The hydrothermal/LA treatments increased the V-type crystallinity. Among the different procedures studied, adding LA to the NC with different moisture contents before heating was favorable for the amylose-LA complex formation. The largest contents of slowly digestible- and resistant-starch were obtained at 40% moisture content of the NC. This study provided a better understanding of the formation mechanism and physicochemical properties of granular starch-lipid complexes.

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