Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/16/2011
Publication Date: 10/19/2011
Citation: Felker, F.C., Kenar, J.A., Fanta, G.F., Byars, J.A. 2011. Comparison of microwave processing and excess steam jet cooking for spherulite production of from starch:palmitic acid inclusion complexes. AACC Annual Meeting.
Technical Abstract: It was previously shown that toroid and spherical/lobed spherulites were formed upon slow cooling of aqueous dispersions of corn starch and palmitic acid after passing through an excess steam jet cooker. Spherulite yield was 86% based on amylose. In order to determine whether excess steam jet cooking is essential for spherulite formation, or if larger spherulites with different morphology could be formed, microwave processing for spherulite production was examined. This alternative method can provide rapid heating to 140°C (as is typical for jet cooking) with minimal shear. High-amylose starch was combined with palmitic acid (5% based on apparent amylose content) at a solids content of 3.5%, analogous to the conditions used for spherulite production with jet cooking. After treatment at 140°C for 5 min with magnetic stirring in a closed Teflon microwave processing cell, the dispersion was stirred while allowing to cool to 95°C, then cooled for 22 h from 95°C to 40°C without stirring. Spherulites were formed with morphologies similar to those obtained by steam jet cooking, suggesting that the shear-induced reduction in amylose molecular weight associated with jet cooking is not essential for spherulite formation. However, the presence of swollen starch granule fragments and palmitic acid crystals in the dispersions suggests that less amylose was dissolved, and uncomplexed palmitic acid remained. It was concluded that even though spherulites in small quantities might be obtainable with microwave processing, excess steam jet cooking is still the most efficient approach for large-scale spherulite production because of its ability to provide sufficient heat and shear in a single step.