Mathematical characterization of residence time distribution curves of carrot cubes in a pilot scale aseptic processing system

Abstract

Residence time distribution (RTD) of food particles and carrier fluid was evaluated in a commercial pilot scale aseptic processing system using o full factorial design of experiments employing flow rate (15 and 20 kg/min), temperature (80 and 100°C), holding tube length (1.5, 17.5 and 26.7m) particle (carrot cubes) size (6 and 13 mm) and starch concentration (30 and 50 g/kg) of the carrier fluid as factors. RTD curves of carrot cubes were characterized in this study using a special case of the logistic model (autocatalytic or inverse exponential model). Three model parameters (an accumulation rate factor, B; a concentration limit factor, U and a half-time factor, M) fully described the RTD curve: F = C/[1 + e-B(n-M)]. The model was used to describe the influence of various process parameters and to obtain E-type RTD curves. All test factors were significant (P < 0.05) in influencing the parameters associated with the logistic model. Using multiple regression, the logistic parameters were related to the experimental factors (R2 > 0. 78). © 1993 Academic Press, Inc.