Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 21, 2003
Publication Date: December 1, 2003
Citation: Byars, J.A., Fanta, G.F., Felker, F.C. 2003. The effect of cooling conditions on jet-cooked normal corn starch dispersions. Carbohydrate Polymers. 54:321-326. Interpretive Summary: Excess steam jet cooking is an essential part of the FanteskTM process that has been used at NCAUR to develop a number of important products. This work shows that the way in which a jet-cooked starch dispersion is cooled can have a significant effect on its final properties. Both the cooling rate and stirring conditions during cooling can change the characteristics of the final product. An understanding of the effects of the cooling conditions allows for better control of the FanteskTM properties, and opens new areas of application.
Technical Abstract: When aqueous dispersions of normal corn starch are jet-cooked under excess steam conditions, the properties of the final product depend on the manner in which the cooked dispersion is cooled. Phase separation of amylose and amylopectin dramatically alters the final properties, and the extent of phase separation depends on the processing history of the sample. The aim of this study was to determine the effects of cooling rate, stirring rate and starch concentration on the rheology and microstructure of the cooled dispersion. A Rapid Visco Analyser was used to obtain a range of cooling profiles and stirring rates. Rheological measurements showed that samples that were stirred during cooling had formed stronger gels than unstirred samples. Light microscopy revealed that after cooling, both irregular, amorphous particles and spherical or toroidal crystalline particles were observed in various proportions depending on starch concentration, cooling rate and stirring during cooling.