36D-9 |
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G. CHEN1, O. H. Campanella1, C. M. Corvalan2, S. Purkayastha3, and M. Peleg4. (1) Dept. of Agricultural and Biological Engineering, Purdue Univ., 1146 Agricultural and Biological Engineering Bldg., West Lafayette, IN 47907-1146, (2) Dept. of Food Science, Purdue Univ., 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009, (3) A.E. Staley Manufacturing Co., 2200 E. Eldorado St., Decatur, IL 62525, (4) Dept. of Food Science, Univ. of Massachusetts, Amherst, 228 Chenoweth Lab., Box 31410, Amherst, MA 01003-1410 Models that accurately predict the viscosity of suspensions containing deformable particles, like gelatinized starch, are hard to find in the literature. This is because of the complexity of the interactions between the particles and suspending liquid in addition to the shear effects. Yet, since viscosity plays a significant role in heat transfer, the ability to predict the viscosity of starch based pastes will help to optimize thermal processes so that while safety will not be compromised, adverse effects on quality will be minimized. The objective of this study was to quantify the major factors that affect the viscosity of swollen cross-linked cornstarch suspensions and develop a mathematical model for its estimation. The viscosity of such suspensions is primarily affected by: (a) the suspending medium,s viscosity, (b) the granules, volume fraction, (c) the granules, deformability and (d) the imposed shear rate. Suspensions containing granules with different degrees of swelling using water as the suspending media were prepared and their rheological properties determined. The measured flow curves could all be described by the power law model whose consistency value (k) and the flow index (n) were used to quantify the roles of these factors. Experimental rheological data was used to obtain empirical equations relating these parameters and a rheological model able to predict the viscosity of these suspensions. The developed viscosity model provided a good estimation of the viscosity of aqueous suspensions of swollen starch granules. Rheological models of the kind developed in this work can serve as tool in the design and improvement of heat processes that involve starch based food products.
Session 36D, Food Engineering: Rheology
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |