Heat Transfer to Three Canned Fluids of Different Thermo-Rheological Behaviour Under Intermittent Agitation
2002
Tattiyakul, J. | Rao, M.A. | Datta, A.K.
Heat transfer to canned 5% cross-linked waxy maize (CWM) and 3.5% corn (CN) starch dispersions (STDs), and a 5.6 °Brix tomato juice (TJ) which exhibited different thermo-rheological (TR) behaviours was studied. The three fluids had approximately the same maximum viscosity (∼2.6 Pa s) at some point during thermal processing. The ηa–T profiles of the 5% CWM STD were determined using a pressurized viscometer system, while those of the 3.5% CN STD and 5.6 °Brix TJ were obtained from Yang and Rao1 and Sornsrivichai2, respectively. A simulation program (FIDAP) was used to solve the governing mass, momentum, and energy transport equations for heating each fluid in a 81mm×111mm horizontal can at 121.6 °C under going intermittent rotation as in a SteritortTM. The 3.5% CN STD which exhibited sol-gel-sol transition over a narrow range of temperature, had the highest heating rate and the most uniform temperature distribution. In contrast, the 5% CWM STD, which gelatinized at a lower temperature and formed a heat- and shear-stable gel, had the slowest heating rate. In the 5.6 °Brix TJ, which had high initial viscosity, the heating rate increased as the viscosity decreased according to the Arrhenius model and attained heating rates higher than in the 5% CWM STD.
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